摘要:

AUGUST, 1913. Vol. XXXVIII., No. 449. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. AN ELECTROCHEMICAL INDICATOR FOR OXIDISING AGENTS. BY ERIC K. RIDEAL, PH.D., B.A., AND ULICK R. EVANS, B.A. (Read; at the Meeting, June 4, 1913.) IT is well known that small traces of oxidising agents exert a considerable depolarising action at an electrode, where, in their absence, hydrogen or a reducing agent would be formed.At high concentrations this depolarising action depends only to a small degree on the actual value of the concentration of the oxidiser, and often causes a decrease of as much as a volt in the amount of the electrode potential difference. A depolarising action of this kind is utilised in the bichromate battery. A zinc and copper couple immersed in a simple acid solution will give an E.M.F.of less than a, volt, but if a soluble bichromate be added this can be increased to two volts. The increase is not greatly affected by small changes in the concentration of the bichrornate. On the other hand, if the oxidising agent is present in minute quantity, then the depolarising effect varies considerably with the amount actually present, and can be used as a means of estimating as well as detecting the oxidiser.The depolarising action does not cease to be measurable until the amount is very small. I t must, however, be remembered that the depolarising action of the oxidiser in a, cell furnishing any appreciable current will involve a destruction of part of the oxidiser as such.Thus the E.M.F. of any such system will depend on the rate at which it is made to produce a current. This principle may be made clear by a description of one of its applications- namely, the detection of minute traces of free or available chlorine. The addition of chlorine, hypochlorites, and ozone is becoming general for sterilising waters intended for drinking, domestic, and trade purposes, and for the treatment of sewage effluents.A difficulty is found in judging the right quantity to add, for the liquor to be treated always varies in its power of consuming chlorine or other oxidising agent, while the sterilising solution, whatever its source, also fluc- tuates in its oxidising power. Hence it is often found that on some days the water flows out of the treatment-tank without any excess of oxidiser, and is therefore354 RIDEAL AND EVANS: incompletely sterilised; on other occasions the water may contain an excess of chlorine and chlorine products, which are highly injurious to whatever use the water may be put.To insure the addition of the correct quantity of steriliser it would be necessary to keep a continuous check upon the amount of free oxidising agent in the water leaving the waterworks.What is essential, therefore, is an analytical method of estimating small concentrations of unabsorbed steriliser. Such a method must be accurate for the dilutions met with in practice; and, further, it is advisable that the whole procedure should be as automatic as possible. It was found by us that the potassium iodide and starch reaction, usually employed in this connection, did not offer a practical basis for the solution of the + To - R E.FIG. 1. Insulator = mmmm Metar problem ; this is also true of the other chemical analytical methods, and we turned our attention to the physical and electrochemical changes produced by the presence of oxidising substances in water. We had to look for some property which water containing a powerful oxidising agent would possess, and which water containing no such agent would not possess.It was clear that any change which would be pro- duced, for instance, in the density, colour, or refractive index of the water by the addition of a trace of an oxidising agent would be negligible compared to the fluctua- tion due to other causes.Nor would a measurement of the electrical conductivity be of use ; for, although this value varies enormously with the salinity of the water, the addition of oxidising agents as such will have no appreciable effect. On the other hand, the depolarising action of an oxidising substance, which does not depend substantially on the value of the conductivity or on the presence of neutral, non- oxidising salts, may very well be used as a means of detecting and determining oxidising agents.AN ELECTROCHEMICAL INDICATOR FOR OXIDISING AGENTS 35 5 Various forms of apparatus were considered, some being experimentally tested.In the end, the form (Figs. 1 and 2) which will now be described was adopted. It consists of a copper tube, (Fig. 1) C, 3.5 cm.long and 4 mm. internal diameter. Within this, running axially through it, is a platinum rod, P (diameter 1 mm.), which is insulated at the two ends from the copper tube by the ebonite caps E, El. Liquid is allowed to enter the tube at the lower end and flow out at the top. The copper and platinum are joined to the two poles of a sensitive current-detector of high resistance; in the particular case of the instrument used in most of our experiments this had a resistance of 200 ohms, and registered *000004 ampere per degree.If tap-water is FIG. 2. run through the cell approximately at a constant rate, there is practically no deflec- tion so long as oxidising agents are absent. When, however, a trace of hypochlorite or chlorine is present, a movement of the pointer over the dial occurs, and the per- manent deflection produced serves as a measure of the free chlorine-content of the water.Fig. 3 shows the relation between the concentration of free chlorine added as hypochlorite and the galvanometer-reading produced by it. It will be observed that the divisions of the ammeter used in obtaining Curve A roughly represents parts per 10,000,000 of chlorine with the conditions observed-namely, rate of flow 230 C.C.per minute, at a, temperature of 13' C. Curve B shows the readings obtained at higher concentrations by the use of another less sensitive ammeter of 10 ohms resistance.356 RIDEAL AND EVANS: It is always observed that the pointer takes a short time to reach its maximum position; and after this, if tap-water containing chlorine is being used, a slow retrogressive movemant takes place, showing that the chlorine is being absorbed by the free organic matter in the water, and that it is, therefore, diminishing in amount.This has been confirmed by titration. When tap-water free from chlorine is again allowed to pass the pointer sinks at once, although it takes some minutes to reach its exact zero position.The effect of adding to the tap-water all substances likely to occur therein, in the largest quantities likely to be found in practice, has been tried, and in no case has there been any appreciable deflection produced. The additions I 5: cr? FIG. 3.-FREE CHLORINE CONCENTRATION IN PARTS PER TEN MILLION. tested include sodium chloride, sulphate, carbonate, nitrite, and nitrate, as well as ammonium salts.The effects of temperature and rate of flow have been investigated. Both these influences, as will be seen from Fig. 4, exert a considerable effect on the reading. It is, therefore, necessary to take the precaution of keeping the rate of flow sufficiently constant, In practice this is not difficult, since there will usually be the same head of water forcing the stream through the instrument.The temperature- coefficient is such that a rise of about 4 per cent. per 1' C. occurs in the reading, the head of water and other conditions being constant. There is no necessity to correct for this effect of temperature, for in warm weather the right quantity of chlorine (or other oxidising agent) which ought to be present in the water leaving a treatment station is smaller than in winter.For not only is a larger proportion of theAN ELECTROCHEMICAL INDICATOR FOR OXIDISING AGENTS 357 sterilisation done in the waterworks itself, but the oxidising agent is actually more active at the higher temperature. Chlorine, ozone, and potassium permanganate, if present in tap-water, all cause a deflection in the apparatus.To the latter, as in the case of chlorine, the instrument is very sensitive. To ozone it is also extremely sensitive, and actually affords the best means of detecting and estimating that oxidiser, which has only a slow action on potassium iodide at the concentrations at which it gives a deflection of some degrees on the instrument. The weaker oxidising agents-e.g., ferric chloride- cause no deflection.The appearance of a deflection on the latter may therefore be regarded as a sure proof that a powerful oxidising agent is present. On running a solution of hydrogen peroxide through the apparakus, a temporary deflection in the opposite direction is seen; this dies away gradually, and a low positive deflection appears. The phenomenon will serve to distinguish hydrogen peroxide and ozone at dilutions at which no other method will serve.The presence of mineral acids in the water causes a temporary positive jump. This initial deflection, appearing when an I 2 3 Rate of flow. C.C. per second. FIG. 4. acidified liquor is first run through, soon diminishes; but in the case of a, liquid containing a mineral acid never quite disappears.The deflection remaining is, in the case of hydrochloric acid, only about i+-v of that obtained with an equivalent amount of free chlorine. Of course: free mineral acids do not occur in the class of liquors to be tested. Although most reducing agents are without effect (unless they happen to be acids), phenylhydrazine hydrochloride gives a distinct negative reading, which is apparent 1 y permanent.Finally, we may mention the fact that the current given out by the instrument is much less affected by large changes in the external resistancs than would be expected from Ohm’s law, assuming the E.M.F. to be constant. Although the external resistance is in both cases greater than the internal, the reading of the instrument under certain constant conditions was only changed from 7.2 to 6.7 divisions on altering the external resistance from 200 to 1,200 ohms (by the insertion of a 1,000-ohm coil).358 RIDEAL AND EVANS: Some of these statements may seem rather irregular, but the explanation will in most cases appear from the following discussion of the theory : First, consider the action of the water containing a certain small amount of dissolved salts (as all waters do), but no free oxidising agent (e.g., chlorine). When it flows through the tube between the copper walls and the central platinum rod a certain current will pass at first.Copper passes into solution at the one pole and turns out hydrogen at the other; thus the copper tube will be left negatively charged, for the copper assumes a positive charge on entering the ionic condition, while the platinum rod will receive a positive charge from the discharging hydrogen ions.But this current can only continue as long as the hydrogen concentration in and around the platinum does not exceed a certain very low value. All ordinary hydrogen concentrations in the platinum-if caused by extraneous agency-would actually involve an E.M.F.in the opposite direction. It is well known that hydrogen at normal pressures can remove copper from its solutions. If, however, the hydrogen concentration at the platinum be below a certain value, there is an E.M.F. tending to produce a current through the liquid from the copper to the platinum, and this E.M.F. only vanishes when the hydrogen pressure at the platinum reaches that very low critical amount depending on the electrolytic solution pressure of the copper.Now, if there were no flow through the tube and no diffusion, this concentration would soon be arrived at, and current would cease to flow. But since the water flowing over the platinum surface is continually carrying off small quantities of hydrogen in solution, the concentration is kept slightly below this value, and there is thus a small E.M.F.produced; a current therefore passes which, when a state of constancy has been set up, is exactly sufficient to replace the hydrogen carried off by the flowing liquid. With the apparatus used, which has the platinum surface small compared to that of the copper, the amount of current produced in the absence of chlorine is so small as to be barely detectable on the ammeter.It rarely exceeds 0.1 div., and can be allowed for in the zero adjustment of the instrument. If, however, chlorine or some similar body which readily combines with hydrogen is present in the water, the case is different. The rapid attack of the chlorine keeps the concentration of hydrogen at the platinum pole permanently below the critical value, and thus there is always an E.M.F. acting from the copper to the platinum through the liquid.Therefore if these two electrodes are joined through a current measurer, a permanent current will be registered of a strength suacient to replace the hydrogen carried off by the chlorine. It is immaterial whether the chlorine is regarded as a body which is continuously abstracting from the platinum electrode hydrogen which has already been discharged there, or whether we consider it as the active component of the electrode which attracts hydrogen ions which would not otherwise be discharged.The presence of chlorine implies that the hydrogen concentration in the platinum is kept low, although it may not reduce it, under the conditions in question, to the value demanded by the equilibrium : C1, + H,T-- 2HC1. Passage of the liquid through the tube is required only for the renewal of the chlorine which is used up in the production of the current.The current thusAN ELECTROCHEMICAL INDICATOR FOR OXIDISING AGENTS 359 becomes a measure of the amount of chlorine passing within striking distanoe of the platinum, and thus is not greatly dependent upon the resistance of the circuit.In other words, if the apparatus is required to furnish a current over a low resistance the E.M.F. automatically drops, whereas over a high resistance it yields nearly as great a current, but at a higher pressure.* The reactions occurring at the two electrodes may be expressed by the following equations : I. IN ABSENCE OF CHLORINE.(a) At the copper pole the copper assumes the ionic condition : cu- cu++ + 20. In solutions originally neutral this will clearly leave an excess of OH ions, and so confer alkalinity upon the solution : 2H-t --+H,+ 20. As a whole, these equations can be summed up as : (b) At the platinum pole hydrogen leaves the ionic condition. Cu+2H++ Cu++ +H, +2@ + 20 ; CU + 2H-t + 20H- -+ CU+ + 20H- + H, + 20 + 20, - Water.or, an equation which involves the absorption of heat. 11. WHEN CHLORINE IS PBESENT AT THE PLATINUM SURFACE. (a) At the copper pole the copper enters the ionic state as before, leaving the electrode negatively charged : C U - + C U + + + ~ ~ . . . . . A. (b) At the platinum pole an equivalent amount of hydrogen ions are discharged 2H+ --+ H2+20 .. . , . . ( b ) 1, which hydrogen is to a large extent taken up, as it is formed, by the chlorine : H2+C12-2H++2C1- c .,/ . . , , (b) 2. Hydrochloric Acid. When the chlorine is present in comparatively large amount this latter equation becomes practically complete, and we can now regard the platinum-pole equation as the sum of (b) 1 and ( b ) 2, thus : 2H+ + C12---+2H+ + 2C1- +2@ .. . B, Hydrochioric Acid. which result is identical with that obtained by regarding the platinum pole as a * Tllc comparative independence of the current upon the total resistance is of no practical value. In any case, the external resistance would be kept constant, and would be made great enough to render negligible any changes in the internal resistance due to fluctuations in the conductivity of the water used.However, the case of a chemical cell which approxiniates more closely to a constam! current generator than to a constant E.M.F. generator may be of interest. The case is an exaggeration of the “polarisation” of inefficient batteries, which drop their true E.M.F. when made to discharge too quickly.360 RIDEAL AND EVANS: chlorine electrode.case. I t will be noticed that no excess of OH- is left behind in this By adding A and B together we get the equation for the total reaction : Cu+2H+ + CI,---~Cu++ + 2E+ + 2Cl- +2@+20; or omitting 2H+ : c u + CI, *cu++ + 2c1- + 2 0 + 20. Since the equation, Cu + C1, --- Cu++ + 2Cl-, represents an exothermic reac- tion, the source of the electrical energy needed to produce the current is largely furnished without any cooling to the liquid.Disturbances undoubtedly may occur, due to the fact that chlorine is present at the copper pole also, and may dissolve copper chemically ; it is possible, therefore, that a copper chloride concentration cell is thus set up. This effect, however, will undoubtedly be small compared to that of the main electro-chemical reaction.Neglecting disturbances of this kind, one would imagine that the E.M.F. obtained by the cell discharging over a very high external resistance would be proport ionat e to a+log Cc1, where a is a constant, and C C ~ is the chlorine concentration, Thus it will be almost independent of the free chlorine concentration at high concentrations of the latter. This is confirmed by experiment.The current-concentration curve becomes asymptotic at high concentrations of chlorine, While elemental chlorine does not cause alkalinity during its depolarising action, oxidisers like sodium hypochlorite, ozone, and permanganate, presumably leave the liquid slightly alkaline, What determines the sensitiveness of the indicator to different reagents is, however, the speed and completeness with which they reduce the concentration of hydrogen in the platinum.When neutral liquors have been running through the instrument for a short time, a state of constancy is arrived at in which the hydrogen contained in the platinum is practically in equilibrium with the hydrion of the liquid (it differs from the equilibrium amount only on account of the very small rate of removal due to the flow of the liquid, and replacement by the current produced).If, however, an acidified liquid with a vastly increased hydrion concentration be caused to run in, then the equilibrium relation will no longer hold ; a temporary current will pass, which will tend to raise the hydrogen-concentration in the platinum. As the concentration of liquid hydrogen in the platinumfapproaches a value which could balance the hydrion concentration of the liquid, the current will sink ; but it will never reach the minute value obtained for neutral solutions, since at its higher absolute concentrations in the platinum, the amount of hydrogen carried off by the flowing liquid will be increased.Thus acids give a high temporary, followed by a low permanent, deflection.Again, after water free from oxidising agents or acids has been passing through the tube for some time, and has brought the hydrogen concentration in the platinum The action of acids can now be readily understood.AN ELECTROCHEMICAL INDICATOR FOR OXIDISING AGENTS 36 I to the constant value, and then water containing an oxidiser is run through the tube, it is always possible that the oxidiser may set up a cell of the type : (Cu), oxjdiser I H,, (Pt).The oxidiser will be reduced at the copper surface, while the hydrogen will be oxidised from the platinum and re-enter the ionic condition. This will cause a current in the opposite direction to that usually experienced, but this current can only continue until the hydrogen in the platinum has been reduced to a certain very small value, after which any E.M.F.due to this cause must cease. Then the ordinary type of change must continue, and the oxidiser will act as a depolariser on the platinum (not the copper) surface, by attacking the hydrogen forced out by ihe solution of the copper; this will involve a passage of a current in the normal II n v 0 10 2 0 30 40 I Time in hours.PIG. 5. 60 direction. This phenomenon of a temporary current in the wrong direction is to be expected from oxidisers, which exert a greater power of absorbing hydrion at the copper surface than of attacking hydrogen occluded in the platinum. Undoubtedly the electrode material exerts a considerable catalytic action upon electrodic and chemical changes, and it is really impossible to say, on apriori grounds, as to which oxidisers, if any, will show this phenomenon.As a matter of fact, it has been observed in the case of hydrogen peroxide and sodium peroxide, and perhaps the comparative slowness with which the full positive deflection is shown in the case of hypochlorites may be due to a similar cause. There remains to be mentioned the effect of passing reducing agents through the apparatus.Reducers sufficiently powerful to evolve hydrogen might conceivably act as a depolariser at one pole, absorbing (OH)’ ions at that pole, and causing the discharge of H+ ions at the other. As to which electrode would be the one at which362 RIDEAL AND EVANS: hydrogen was evolved-i.e., as to which would become the positive pole-prophecy is difficult.One can only say that this will depend upon the relative catalytic action of the two metals. It ie possible that the reducer, instead of forcing out hydrogen at the pole a t which it is not oxidised, may cause the discharge of copper ions, which are the result of some chemical attack of the copper further up the tube. At all events, the only case of a reducing aged being responsible for a current, when run through the apparatus, is that of phenylhydrazine hydrochloride ; this substance sends a current in the “negative” direction ( i e ., from platinum to copper, through the liquid). It is possible that the explanation given in this case is incorrect, but the experiment has been repeated and the result confirmed. chlorometer ” as a laboratory instrument, we append curves obtained by its use showing the gradual ‘( absorption ” of free chlorine by typical potable waters (Fig.5 ) . A certain small amount of hypochlorite of sodium was added to the water at the commencement of the experiment, and the residual amount determined from time to time by means of the apparatus. It will be seen that a great deal of the chlorine initially added is quickly taken up by the quickly oxidisable matter; after this, a slow reduction of the chlorine occurs, due to the slow oxidation of the more stable organic compounds.As an oxample of the use of the DISCUSSION. Mr. A. CHASTON CHAPMAN asked whether, when the flow-rate was increased, the readings were increased in the same proportion; in other words, with the same water, would the readings be doubled if the flow-rate were doubled? He also asked what was the nature of the influence of temperature on the readings.Dr. LESSING asked whether the results would be affected by differences in the dimensions of the apparatus. Would it be possible that discrepant results are obtained in different sets of apparatus in which the distance between the poles is varied ? I t seems conceivable that a polarising current might be set up which would counteract the main reaction to a greater or lesser extent, and so influence the reading.Dr. STEVENS asked whether the authors’ investigations as to chlorine absorption had gone far enough to enable them to say what connection there was between the chlorine absorption curve and any particular characteristic of the water-the propor- tion of nitrites, for example. Dr.E, RIDEAL said that an increase in the flow-rate increased the readings in considerably less proportion. Changes in temperature affected the readings to the extent of about 4 per cent. for each degree Centigrade; so it was important to keep the temperature as constant as possible.At present they had only worked with two such instruments, and had found the results to be practically the same in both cases, though for extreme accuracy exact standardisation would certainly be necessary. If the distance between the poles were unduly large, small eddy currents would be formed, and something depended upon where the water was allowed to enter and leave the instrument. They had not done much work on the subject of chlorine absorption; but different kinds of organic matter would probably be attacked byAN ELECTROCHEMICAL INDICATOR FOR OXIDISING AGENTS 363 chlorine at different rates, which could be ascertained by experiment. One advantage of determining the chlorine absorption in this way appeared to be that the observa- tions could be made at very short intervals, and an infinite gradation obtained for the different substances attacked. They had investigated the effect of some of the salts usually present in water-sodium chloride, magnesium carbonate, potassium nitrate, potassium nitrite, etc.-in larger quantities than would be present even in badly polluted water, and had found no disturbance to be caused by these. Dr. S. RIDEAL remarked that chlorine was now being used for the purification of public water-supplies in all parts of the world, the latest instance he had met with being that of British Guiana, where the water in the reservoirs was being treated by adding a little bleaching-powder once a month. That seemed ti crude method; but even in that case an instrument of this sort would be useful for ascertaining exactly how much available chlorine wa8 being added, and whether the quantity was sufficient or not.

ISSN:0003-2654    

DOI:10.1039/AN9133800353

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

AN ELECTROCHEMICAL INDICATOR FOR OXIDISING AGENTS 363 Per Cent. (2) 70.15 (3) 10.0 (2) 7'5 (2) 13'95 ( 2 ) 1-3 THE ANALYSIS OF VARIOUS EAST-INDIAN TANNED HIDES. Per Cent. Per Cent. Per Cent. Per Cent. (ti) 77'6 (1) 73'9 (4) 69'95 (3) 74'8 (S) 4.97 (3) 6.83 (4) 7-9 (4) 4.85 (7) 5 55 ( 2 ) 5'9 (4) 7'55 (3) 4.86 (6) 13'5 ( 1 ) 17'0 (4) 14'6 (3) 15'06 (6) 2-51 (1) 0'5 (4) 0'87 (3) 0'53 BY M. C.LAMB. (Read at the Neeting, June 4, 1913.) DURING the past few years the writer has often been asked by interested leather dressers whether East-Indian tanned hides were being weighted by the Indian tanner by the addition of mineral matter, or oil, more than was formerly the case. The flesh side of many East-Indian tanned hides, plastered over as they are with a mixture of a natural chalk, would certainly lead one to believe that these goods were being artificially weighted, and heavily so.With a view to ascertaining which particular tannages were the most heavily adulterated, a considerable number of analyses of samples obtained from a variety of different sources have been made. The average results of these are in the following table : Tannage : Leather Fibre ... ...Oil and Fattv Matter ... H{:y- Bombay Coconada. Coast. Colombo. 1 1 1 1 Miscel- laneou~. Per Ceut. (6) 70'2 (7) 7 4 ( 8 ) 7:9 (lj) 13.73 (b) 4% Tlie above figures are the mean of a number of determinations of different samples. Tlie figures in brackets indicate the number of the samples analysed. In the case of the Bangalore tannages, which are generally considered to be one of the best of the East-Indian imported leathers, the amount of added oil and fatty matter varies from as low as 6.3 per cent.to as high as 17.9 per cent., though this latter amount is somewhat exceptional. The water soluble matter ranges from364 THE ANALYSIS OF VARIOUS .EAST-INDIAN TANNED HIDES 6.7 per cent. to 1 0 4 per cent., though again this latter figure is higher than the average. The water soluble in every case consisted of excess tanning matter, and no sophistication with sugary matters was found to have taken place.The Madras tannages were found to vary considerably more than others from different sources. One sample contained upwards of 7.1 per cent. mineral matte]., and another no less than 13.1 per cent. of fatty matter.The amounts of oil and fatty matter found in the Bombay samples range from as low as 2.3 per cent. to 7.2 per cent. The mineral matter, which in three cases was as low as that found in the Bangalore tannages, was in two cases very much higher, these being cuttings from goods somewhat heavily plastered, and in some cases the water soluble matter was particularly low, showing the almost entire absence of loading by over-tanning. The leather fibre figure is the highest average of any of the various tannages analysed.Owing to the limited amount of the Coconada samples available for the purpose it was only possible, except in one instance, to determine the oil and fatty matter present; this varied in the three samples from 3.8 per cent. to 10-9 per cent. The Coast tannages are additional to the Madras tannages, and the results obtained are practically confirmatory of those obtained on the Madras samples.The Colombo and Bombay tannages give the largest percentage of leather fibre; the amount of mineral matter is particularly low, and in two cases the amount of fatty matter is not more than would be found in a leather that had been simply oiled over for the purpose of protecting the grain surface whilst drying, and not with the idea of materially increasing its weight. Three samples of up-country tannages were analysed for oil and fatty matter, and gave results as follows : A.B. C, Average. 5.5 per cent. 9.6 per cent. 4.7 per cent. 6.6 per cent. Two samples of tanned buffalo gave an average leather fibre 71.3 per cent., oil and fatty matter 796 per cent., moisture 13.7 per cent., water soluble matter 6.9 per cent.It would appear from the above analyses that adulteration of Indian tannages by the use of a large excess of oil and fatty matter, by use of mineral weighting matters, or an excess of tanning matter, is not nearly so common as one has been led to believe. Whilst in many instances the amount of oil and fatty matter found is more than necessary to assist in obtaining a good coloured leather on drying by providing a film of oil to the grain side, except in a few cases the gain of weight obtained by the addition of oil is not so great as one would have expected by a visual examination. The analyses compare very favourably indeed with the home-tanned calf and dressing hides, and prove that adulteration is not general amongst this class of leather.I n conclusion, I would like to record my indebtedness to Mr. Charles Furneaux for carrying out the detailed analyses, and to Messrs. Flack, Chandler and Co., Culverwell, Brooks and Co., Dyster, Nalder and Co., Samuel Baprow and Bros., Scriven Bros., Malcolm Inglis, and others who have supplied authentic samples. The ash and mineral matter found was 0.9 per cent.

ISSN:0003-2654    

DOI:10.1039/AN9133800363

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

FOOD AND DRUGS ANALYSIS 365 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Analysis of Amyl Aeetates and Collodions. N. Chereheffsky. (Les Matidres Grasses, 1913, 6, 3103-3110.)-The so-called pure,amyl acetate of commerce consists of a mixture of amyl acetate and amyl alcohol. Its purity may be ascer- tained by a determination of its principal physical constants, and the proportion of amyl acetate may be calculated from the sauonification value : A.Amyl alcohol (iso-) . . . ... Amyl acetate (iso-) ... ... Ethyl acetate ... ... Propyl acetate (normal) .. . Acetone ... ... ... Benzene ... ... ... White spirit ... ... ... Sp. Gr. at 15" C. 0.820 0.875 0.794 0.807 0.792 0.887 0.777 Boiling-Point. "C. [ N ~ D 15" C. Oleorefrac- tometer Reading a t 15" C.Saponifica- tion Value. 129-1 3 1 139 78.4 98 56.3 80.5 150-1 70 1.4100 1-4035 1.3640 1.3890 1-3640 1.5050 1.4365 + 29 0 - 170 - 60 - 170 -I- 420 + 135 In commercial amyl acetate derived from fuse1 oils the impurities may include ethyl acetate, normal propyl acetate, iso-butyl acetate, and their corresponding alcohols. Their presence is indicated by the laevo-oleorefractometer readings obtained with the products of the fractional distillation of the sample into ten parts.The boiling-points of these fractions will also differ materially from those of the corre- sponding fractions of pure amyl acetate. The fraudulent addition of larger quantities of ethyl acetate may be detected by boiling 5 C.C. of the sampIe for thirty minutes beneath a reflux condenser with 25 C.C.of a 15 per cent. solution of potassium hydroxide in amyl alcohol, distilling the saponified product, and collecting the first 1 to 1.5 C.C. of the distillate. This fraction is shaken with water, and the aqueous layer tested with potassium carbonate and iodine, A distinct iodoform reaction is obtained if the sample contained 1 per cent. of ethyl acetate.For a quantitative estimation, 50 grms. of the sample are saponified with a, solution of 25 to 30 grms. of potassium hydroxide in about 50 grms. of amyl alcohol, the product distilled, and about 50 grms. of the distillate shaken in a separating funnel with 100 C.C. of calcium chloride solution of sp. gr. 1.250 and 30 C.C. of pure cymene. The lower layer is drawn off, the shaking twice repeated, each time with 50 C.C.of fresh calcium chloride solution, and the united saline layers distilled. The first 50 C.C. of the dis- tillate are filtered, the sp. gr. determined, and the corresponding percentage volume of ethyl alcohol thus obtained. The result multiplied by 1.508 gives the percentage of ethyl acetate (by weight) in the sample of amyl acetate. The method gives good results provided large amoiints of propyl and butyl acetates are not present.Acetone366 ABSTRACTS OF CHEMICAL PAPERS may be detected and approximately estimated by the following thermometric method : Ten C.C. of the sample axe exactly neutralised with sodium hydroxide, and treated in a Dewar's vacuum-tube with 5 C.C. of sodium bisulphite solution (sp. gr. 1*320), and the rise in temperature noted.The number of degrees C. corresponds approximately to the percentage of acetone (by volume), and satisfactory results are thus obtained for amounts ranging from 5 to 20 per cent. Cyclic and acyclic hydrocarbons are detected by the physical properties, and especially the oleorefractometer reading. As a further test, from 2 to 3 C.C. of the sample are shaken with an equal volume of sulphuric acid (sp. gr.1.84) in a stoppered graduated cylinder. In the presence of benzene (10 per cent.) a characteristic turbidity appears after the cylinder has stood for five to ten minutes, whilst with toluene and xylene, solution takes place without subsequent turbidity. When acyclic hydrocarbons are present, however, a supernatant layer is formed, and the amount may be measured after the separation is complete (five to ten minutes).In examining collodion, the nitrocellulose is pre- cipitated by means of petroleum spirit boiling below 70" C., and the precipitate dried at 90" C. on a tared filter. Another portion is evaporated to dryness, and the residue weighed, the results thus obtained being usually somewhat higher than in the nitro- cellulose estimation.The solvent is quantitatively distilled in a current of steam from 50 grms. of the sample, sodium chloride being placed in the receiver to prevent solution of ethyl acetate in the water. Any ethyl acetate dissolving in the saline liquid may be detected by the iodoform reaction. The separated solvent is then examined by the methods described.C. A. M. Chloral Hydrate Test for Charlock. A. L, Winton. (Eighth Inter. Colzg. App. Chem., 1912, vol. 26, 409.)-Wagge (Ber. d. Pharm. Ges., 1893, 153) first described the detection of charlock in mustard flour by means of chloral hydrate. Freshly made chloral solutions, which are not at all acid, fail to give the test, but do so at once if acidified, or if kept till free hydrochloric acid is liberated.The test is best performed as follows : Sixteen grms. of the chloral hydrate crystals are dissolved in 10 C.C. of water, and 1 C.C. of strong hydrochloric acid are added. About 10 mgrms. of the mustard flour are placed on a slide in the reagent, the whole carefully heated (never to boiling) for a moment, and then examined under a lens. The proportion of fragments of hulls that acquire a carmine red colour (charlock) to those that do not is then noted.H. F. E. H. Comparative Study of the Composition of Hops grown in Different Parts of the World. H. V. Tartar and B. Pilkington. (J. Ind. and Eng. Chem., 1913, 5, 478-480.)-Representative samples of hops from different parts of Europe and America were analysed in the endeavour to correlate prices and quality, considerable variations in brewing value being set upon the crops from different localities.It is considered that the major part of the actual brewing value of hops lies in the content of soft bitter resins, and the authors consider that their results indicate that hops which hold a high position in the market are in reality inferior in composition to others which are rated lower commercially.Especially is this the case with certain European samples. Siller's method (ANALYST, 1909, 34, 485) forFOOD AND DRUGS ANALYSIS 367 rannin 2.02 1.30 3.06 2.52 1.40 2.40 1.16 1-58 2.22 1-66 1.67 1-99 - the separation of the soft a and /3 resins was employed, and Chapman’s cinchonine method for the estimation of tannin (ibid., 1908, 33, 95, and 1909, 34, 372).Wax is the matter soluble in ether and insoluble in alcohol, The hard, total, and soft (bitter) resins were determined by the methods of Tartar and Bradley (ibid., 1912, 37, 191). In all cases the samples were of the 1911 crop : The following are some of the results recorded in the paper. Seeds. 4.86 2.50 0.06 18.35 7-55 0.22 9.55 7.90 6.15 12.50 11-50 1.42 Nil Nil Locality.Washington (State) New York, No. 1 .. ,, ,, No. 3 .. California, No. 2 .., ,, No. 4 ..< Wisconsin . . . ... England : Worcester ,, East Kent ,, Sussex ... ,, Farnham Oregon, No. 1 ... ,, No. 4 ... Saae, No. l . . . ... ,, No. 3... ... Mois- ture. 3.90 2.40 4-10 3-70 5-70 4.00 2.50 2.50 4-10 4.80 6.30 6.80 6.50 8.20 Total Resin. 17.55 14.20 18.51 17.10 15.76 15.82 12.21 11.70 12.70 12.34 18.35 19-80 16.25 13.75 Total Soft Resin.15.64 12-81 16.61 15-72 14-10 8.68 9-97 10-51 10.35 L1-06 16.76 17.62 14.19 12.60 Hard Gam- ma Resin 1.91 1.39 1.90 1.38 1-66 7.14 2-24 1-19 2.35 1-28 1-60 2.18 2.06 1.15 sort Beta Resin 14.85 8.92 13.81 11-65 9.14 7.93 6.60 7.30 6.05 6-65 10.56 9.48 7-20 7.62 Soft Alpha Resin 0.79 3-89 2.80 4.07 4.96 0.75 3.37 3-21 4.27 4-41 6.19 8.14 6.99 4.98 WSX, -~ 0.37 0.60 0.71 0.52 0.33 0.50 0.47 0.44 0-39 0.33 0.41 0.54 0.45 - Leaves and Stems. 5-00 15.40 9.00 8.80 13.50 1-08 1.20 0.90 0.60 0.00 7.60 4.00 Nil Ni 1 H. F.E. H. Estimation of Glycyrrhizin in Sweets and in Liquorice. E. Dwrier. (Ann. Fulsif., 1913, 6, 252-255.)-The following method is recommended for the estimation of glycyrrhizin in sweets, the quantity of this liquorice constituent found being a measure of the amount of liquorice present.‘( Liquorice juice ” contains from 8 to 25 per cent. of glycyrrhiein, and, taking the minimum quantity as a standard, sweets should yield at least 0.32 per cent. of glycyrrhizin to indicate that they contain not less than 4 per cent. of “liquorice juice,” this being the minimum quantity allowed by French law in liquorice preparations. Twenty grms.of the finely divided sample are extracted for fifteen hours a t the ordinary temperature with 10 per cent. ammonia; 150 C.C. of 95 per cent. alcohol are then added slowly, and, after five hours, the liquid is poured through a filter, and the precipitate is washed with about 100 C.C. of 70 per cent.alcohol. The filtrate and washings are evaporated to a syrup ; this is dissolved in 50 C.C. of water, 1 C.C. of ammonia (sp. gr. 0-92) is added, and, after the lapse of thirty minutes, the glycyrrhieic acid is precipitated by the addition of 2 C.C. of hydrochloric acid. At the end of twenty-four hours the precipitate is collected on a filter, washed with small quantities of water (25 C.C.altogether), dried for thirty minutes a t 100” C., then dissolved in ammonia, the solution is filtered, the filtrate evaporated to dryness, and the residue weighed after368 ABSTRACTS OF CHEMICAL PAPERS being dried for six hours at 100' C. To the weight found is added 0.023 grm. to correct for the solubility of the glycyrrhizic acid in the quantity of water used. A similar method is used in the case of liquorice extract, but the preliminary extraction with ammonia and precipitation with alcohol must be repeated several times. w.P. s. Freezing-Point of Milk. J. B. Henderson and L. A. Meston. (Proc. Boy. Soc., Queensland, 1913, 24, 165-181.)-The authors find that the freezing-point of pure fresh milk from herds of cows in Southern Queensland never shows a greater variation than from - 0.55' C.to - 0.56" C., the mean being - 0.555" C. They are of opinion, as the result of their experience, that the freezing-point determines with accuracy the proportion of water added to any milk from a herd, and distinguishes watered rich milk from naturally poor milk. w. P. s. Method of Distinguishing Jamaica Rum from Artificial Rum.H. Fineke. (Xeitsch. Untersuch. Nahr. Genussm., 1913, 25, 589-596.)-Estimations of the free and combined formic acid in rums afford data which are of some use in determining the character of the spirit, especially when compared in conjunction with the other analytical results. The author finds that Jamaica rum contains from 3.28 to 5.03 mgrms. of free formic acid per 100 c.c., and from 3.34 to 4.45 mgrms.of formic acid in the form of esters. Artificial rum contains from 2.68 to 26.01 rngrms. of free formic acid, and from a trace to 4.84 mgrms. of combined formic acid per 100 C.C. Whilst in the case of Jamaica rum the free and combined formic acid is present in approximately equal quantities, the relation between the amounts varies widely in the artificial spirit.w. P. s. Composition of Port Wine. A. Kickton and' R. Murdfield. (Zeitsch. Untersuch. Nahr. Genussrn., 1913, 25, 625-675.)-Analyses of some hundreds of samples of port wine are recorded, the samples for the most part representing the wine produced by recognised Portuguese firms and imported into Germany. The results obtained were as follows : Alcohol, 14.5 to 17.5 per cent.by weight, or 18 to 22 per cent. by volume; total solids (including sugars), 8.0 to 11.5 per cent. ; total acid, 0.3 to 0.5 per cent. ; sugar-free extract, 1.5 to 2.5 per cent, ; ash, 0.15 to 0.3 per cant. ; glycerol, 0.5 to 0-7 per cent. ; phosphoric acid, 0.015 to 0.030 per cent. As a rule, the wines contained considerably more lamdose than dextrose. The white port wines examined did not differ in their composition from that of the red wines.w. P. s. Estimation of Glycerol in Wines. E. Bertainchand. (Ann. Falsv., 1913, 6, 278-281.)--Fifty C.C. of the wine are neutralised with barium hydroxide solution and evaporated at a temperature of 70° C. to a volume of 10 c.c.; in the case of red wines, a small quantity of animal charcoal is added at this point.The evaporation is then continued at 60' C. until a syrup is obtained; to this are added 5 grms. of sand and, when the mixture is cold it is extracted four times with absolute alcohol, using 5 C.C. of the latter each time. The alcoholic extracts are decanted, withoutFOOD AND DRUGS ANALYSIS 369 filtration, into a 100 C.C. flask. The residue is then extracted four times with pure ethyl acetate, 20 C.C.being used each time, and the extracts are added to the alcohol solution. The contents of the 100 C.C. flask are made up to the mark with ethyl acetate, a further 1 C.C. of the latter is added to correct for thevolume of the insoluble matter, and, after shaking, the turbid solution is filtered. Eighty C.C. of the filtrate (40 C.C. of wine) are evaporated at 60" C., and the residue of glycerol is dried at this temperature to constant weight.w. P. s. Estimation of Sulphate in Wines. C. von der Heide. (Zeitsch. anal. Chem., 1913, 52, 440-451.)-More sulphate is found in the ash of wines than is found by addition of barium chloride to the wine itself. In the author's experiments the difference could not be attributed to sulphur derived from gas used for evaporation and ignition, and was found to be due to the oxidation of sulphur dioxide and organic sulphur compounds during evaporation and ignition. The ratio of organic to sulphate sulphur may be as high as 1 : 5, and no wine is quite free from sulphite. Even when sulphate is determined without previous incineration, some of the sulphur dioxide present is oxidised to sulphate, and the author recommends previous distillation of the acidified wine in a current of carbon dioxide. This distillation may be made to serve simultaneously for the estimation of sulphite, but phosphoric acid should not be used for acidifying the wine, if the residue in the still is to serve for a sulphate determination. Some 10 C.C. of 10 per cent. hydrochloric acid is used to decompose sulphites, and no oxidation need be feared if this acid be diluted with 100 C.C. of water, heated to boiling, and the flask filled with carbon dioxide before introducing the wine. G. C . J.

ISSN:0003-2654    

DOI:10.1039/AN9133800365

出版商:RSC    

年代:1913

数据来源: RSC

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FOOD AND DRUGS ANALYSIS 369 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Application of Dialysis and Estimation of Oxidising Power as Aids in Judging Soils. J. Konig, J. Hasenbaumer, and K. Glenk. (Landw. Yersuchs- Stat., 1913, 79-80, 491-534 ; through Chem. Zentralbl., 1913, I . 2001.)-The authors have followed up the work of Petermann (Landw. Yersuchs-Stat., 14, 465), who first suggested the use of dialysis in the estimation of the available plant food in soil.They record the fact, established by them, that, when soils are heated, the percentage of dialysable material is increased, but their resFarches lead them to the conclusion that dialysis is not likely to prove of much service in the judgment of soils, as the results are too irregular and the time occupied by the experiments too long.As the acids formed in the soil dissolve and render available as plant food the various constituents of the soil, the authors suggest that the estimation of the oxidising power of a soil, that is to say, the rate at which carbon dioxide and nitric acid are produced in it, should aid in the formation of a correct judgment as to its probable fertility. They have studied the effect of additions of dextrose to soils.Such additions increase the rate of formation of carbon dioxide and decrease the electrical conductivity of the soil. Soil which has been heated gives better yields in pot cultures than soil which has not been so treated. G. C. J.370 ABSTRACTS OF CHEMICAL PAPERS Method for Detecting the Vitality of Seeds. S. Tashiro. (Eighth Inter.Cong. App. Chem., 1912, vol. 26, 163.)-With an apparatus capable of detecting and measuring as little as one ten millionth of a grm. of carbon dioxide, the author has been enabled to show that a dry living seed liberates this gas as long as it is alive. By stimulating a living seed by bruising or crushing, a large increase in the liberation of carbonic acid was observed.H. F. E. H. Estimation of Lactic Acid in Urine. Me Dapper. (Biochem. Zeitsch., 1913, 51, 398-407.)-Five hundred C.C. urine are concentrated at 50’ to 60’ C. in vacuo to 100 to 120 c.c., 60 per cent. phosphoric or sulphuric acid added, and extracted in a Lindt apparatus for twenty-four hours with pure ether. The ether extract, after addition of ammonia, is concentrated on the water-bath, the residue introduced into a flask, 300 C.C.dilute sulphuric acid added, and distilled. After 200 C.C. have distilled, the residue is oxidised with. permanganate, distilled, and the aldehyde in distillate estimated by titration with bisulphite and iodine according to the method of V. Fiirth-Charnasz (ANALYST, 1910, 35, 445). In order to guard against possibility of urine containing substances other than lactic acid which on oxidation yield products that react with bisulphite or iodine, the author recommends the analysis of the zinc salt prepared from inolated lactic acid.E. W. Search for Pathogenie Microbes in ‘‘ Raw ” River Water and in Crude Sewage. A. C. Houston. (Ninth Research Report, Metropolitan Water Board.)- The author suggests as an alt,ernative title for the present report, “Where is the Typhoid Bacillus?” and answers the question as follows : ‘‘ The home of the typhoid bacillus is not so much in impure water, or even in the crude sewage from a large community, as in the ‘factories’ of disease, as exemplified by the ‘carrier’ case.” Owing to the discovery of typhoid ‘‘ carriers,” the question of accident has assumed a new and even a deadly significance.We know now that a relatively gross pollution derived from the sewage of a large community may be less dangerous than traces of contamination coming from a single individual of unknown health-history. If the danger unit is a carrier (and some authorities estimate that three to four out of every 1,000 persons are in this condition), his or her discharges may be 10,000 times more infectious than crude sewage volume for volume.The danger of pollution (volume for volume) would seem to rank as follows : (1) The carrier unit, the con- centrator and factory of disease--the genesis of epidemics; (2) the unit person of unknown health-history, who may be in the position of (l), and is therefore, in a potential sense, placed second, but who in the great majority of cases, one would hope, is an almost negligible factor ; (3) the collection of individuals on a large scale, exemplified in a contaminating sense by the sewage of a large town. Here, the dangerous $‘ carrier ’’ element being reduced by dilution to normal proportions, less than one typhoid bacillus per 0.001 C.C.of sewage might be anticipated to be present on the basis of the foregoing observations.Attention is drawn to the fact that in American cities the typhoid fever death- rate compares very unfavourably with European cities, as the following selected figures show :BACTERIOLOGICAL. PHYSIOLOGICAL. ETC . 37 1 Edinburgh Dresden ... Berlin ... London ... Vienna ... Hamburg ... Paris ... Boston ... New York ...Philadelphia Washington Minneapolis ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... Population . 320. 000 550. 000 2.000. 000 7.280. 000 2.000. 000 950. 000 2.750. 000 670. 000 4.766. 883 1.549. 008 331. 069 301. 408 Death-rate per 100.000 . 1.3 2.2 2.9 3.3 3-8 4-1 5.6 11-3 11.6 17.5 23.2 58.7 American sanitarians especially attribute a considerable proportion of their total typhoid fever cases to the consumption of impure water ; but in the author’s view the part played by water-supply in causing endemic typhoid fever is apt to be exaggerated.especially as it can be shown by calculation that the customary draught of water (half a pint) of a satisfactory. or perhaps even of an unsatisfactory. water-supply does noti contain 1. 000 excremental bacteria. and therefore cannot be expected to contain even a single typhoid bacillus . I n cases. however. where the pollution is from the urine of a typhoid carrier. there may be no faxal bacteria. yet an abundance of typhoid bacilli . H . F . E . H .

ISSN:0003-2654    

DOI:10.1039/AN9133800369

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 37 1 ORGANIC ANALYSIS. Detection of Benzoic Acid in the Presence of Phenol and Salicylic Acid. L. Robin. (Ann. Falsif., 1913, 6, 277-278.)-The test consists in nitrating the benzoic acid and reducing the m-dinitrobeneoic acid by means of ammonium sulphide, an amino compound having a red colour being thus obtained. Phenol and salicylic acid also yield a red coloration; but these two substances may be destroyed by the action of permanganate in sulphuric acid solution, whilst the benzoic acid is unaffected. The ethereal solution of the benzoic acid, and possibly of phenol or salicylic acid, obtained in the usual manner from a food or other substance, is shaken with a mixture of 20 C.C.of water, 5 C.C. of alcohol, and 0.2 grm. of sodium hydrogen carbonate.The aqueous solution is separated, evaporated, the residue is taken up in a small quantity of water, and, after acidifying with sulphuric acid, the solution is heated to 80° C., and potassium permanganate solution is added drop by drop until a pink coloration is obtained. After cooling, the mixture is again extracted with ether and the salicylic acid obtained from the ethereal solution is identified by means of the test described above.w. P. s. characteristics and Differentiation of Native Bitumens and their Residuals. C. Richardson. (J. Ind. and Eng. Chem., 1913, 5, 262-266.)-Native bitumens differ so much in character from one another that means of differentiating between them are much to be desired, especially by those who wish to utilise them or their residuals for highway construction.The most important considerations in characterising native bitumens are the ratio of saturated to unsaturated hydro-372 ABSTRACTS OF CHEMICAL PAPERS carbons, the percentage of sulphur, and, in the case of petroleums, the proportion of this sulphur which is removed on distillation in a current of steam, and the percentage of coke (ash-free) which they yield under defined conditions.The viscous oils remaining in the still when various petroleums are distilled to 325" F. are used for fluxing solid asphalts for road making, and are referred to as fluxes. Paraffin fluxes, the residuals from paraffin petroleums, are characterised by their notable content of paraffin scale (4 to 14 per cent.), by the predominance of saturated hydro- carbons (74 to 86 per cent.), comparatively low density (0.92 to 0.94 per cent.), low sulphur content (0.4 to 0.6 per cent,), and low residual coke (2 to 4 per cent.).These paraffin fluxes will flux true asphalts, but not gilsonite or grahamite. Mexican petroleum stands in a class by itself, and the residual flux obtained from it contains only 2 per cent.paraffin scale and 40 to 50 per cent. saturated hydro- carbons, has a density exceeding 1, contains 4 per cent. of sulphur, and gives 10 per cent. residual coke. Between the typical paraffin fluxes and those derived from the true asphaltic petroleums of Trinidad and California stand a class of fluxes derived from the semi-asphaltic petroleums of Texas, which are valuable road- making material, since they flux satisfactorily such solid bitumens as gilsonite and grahamite.They are characterised by a low content of paraffin scale (0.3 to 4.0 per cent.), a somewhat lower percentage of saturated hydrocarbons (68 to 80 per cent.) than the paraffin fluxes, a higher density (0.95 t o 0*97), and low sulphur and low residual coke. Fluxes derived from true asphaltic petroleums contain no paraffin scale, under 50 per cent.saturated hydrocarbons, 6 to 7 per cent. residual coke, usually much sulphur (2 to 3 per cent.), and have a density above 1. Bitumens derived from residual fluxes by treatment with sulphur or air at high temperatures have appeared on the market. They are short, or lacking in ductility and cheesy, or non-adhesive.The result of the treatment is to increase the percentage of residual coke (to 9 to 20 per cent.), reduce that of saturated hydrocarbons (to 35 to 65 per cent.), and introduce more or less sulphur, according to the process adopted. The sulphur may approximate 5 per cent., but is usually less than 2 per cent. The solid residual pitches, used for highway construction, fall into four main classes, corresponding to their origin in Texas, California, Trinidad, and Mexico.Texas residual pitches are characterised by a small percentage of parafh scale (0.5 to 1.2 per cent.), less than 1.25 per cent. of sulphur, and a very high percentage of residual coke (17 to 24 per cent.). Californian residual pitches are distinguished from those derived from Texas oil by the lower percentage of saturated hydrocarbons (26 to 32 per cent.against 48 to 66 per cent.), and the lower yield of residual coke (9 to 13 per cent.). They carry but a trace of paraffin scale (nil to 0-6 per cent.), and less than 1.4 per cent. of sulphur. Trinidad residual pitches are differentiated from those above described by their sulphur content (2 per cent.), and further from Californian products by their low content of saturated hydrocarbons (24 to 31 per cent.).blexican residual pitches contain 5 to 7 per cent. of sulphur, which sharply differentiates them from the products above described. They contain 1.0 to 2.4 per cent. paraffin scale, and yield 12 to 30 per cent. of coke. Native asphalts contain 4 to 8 per cent. of sulphur, less than 25 per cent, of saturated hydrocarbone, and no paraffin scale.The glance pitches (Egyptian andORGANIC ANALYSIS 373 Sp. Gr. a t 15" C. 0.9271 0.9200 Manjak), very hard and brittle materials, contain only 6 to 7 per cent. of saturated hydrocarbons, whilst, of the solid native bitumens other than asphalt, gilsonite contains 6 per cent. and grahamite a mere trace (0.3 per cent.).G. C. J. Melting- Solidifying 4oo c. Acid Value. Saponification Iodine Value Point. Point . Value. (Wijs). "C . "C. 47.2 34.9 .la452 9 1.94 189.3 23.24 38-5 31-6 1.4575 1.00 188.8 58.34 &a1 Oil. Hardened fish and marine animal oils give characteristic colour reactions, the intensity of the coloration depending upon the extent to which they have been hydrogenised. For example, the following colorations were obtained : Whale Oil.Liver Oils. Fish Oils. I HARDENED OILS. ~ Red brown. Red-yellow, then brown-red. Red, then brown. Brown. - tion of liquids. Pale yellow mass. Blue ring a t junc- Brown ; afterwards Blood-red, then Brown, then black- Violet to violet- brown. black. Yellow, then red- Yellowish-red, brown. onion red, and black-brown. bluish-red to brown finally red-brown.Red-brown, Red. Red-brown. Red. - - - - Fuming nitric acid ... Sulphuric acid (sp. gr. Nitric and sulphuric acids Syrupy phosphoric acid.. , Aqua regia ... Sodium hydroxidk'' Phosphomolybdic acid yi per cent.) added to chloroform solution of fat 1*65-ls70) (1: 1) Brown. Green, then brown to black. Yellow, green t o brown. Red- brow n . Red-brown. - - The colorations given by the hardened oils did not correspond to those described Nickel may best be as characteristic of the original fish and marine animal oils.detected in these fats by means of Fortini's dimethylglyoxime reagent. C. A. M. Estimation of Carbon Tetriodide in the Presence of Iodoform. M. Lantenois. (Comptes rend., 1913, 156, 1629-1631.)-Silver nitrate (in 20 per cent.solution) reacts with iodoform giving a quantitative yield of carbon monoxide and silver iodide, Carbon tetriodide under the same conditions yields on the one hand carbon monoxide and carbon dioxide and, on the other hand, silver iodide and iodate, the two reactions apparently occurring simultaneously : GI, + 4AgN0, + 2H20 = GO, + 4HN0, + 4AgI. 3C1, + lSAgNO,+ 6H20 = 3C0 + AgIO, -I- l l A $ + 12HN03.374 AESTRACTS OF CHEMICAL PAPERS For a gravimetric estimation of the carbon tetriodide it would therefore be necessary to reduce the iodate, but a gas-volumetric method may be based upon the fact that whatever the relative proportions of carbon monoxide and dioxide, their total volume is directly proportional to the weight of carbon tetriodide. This reaction may be used in the estimation of carbon tetriodide in the presence of iodoform, the measure- ment of the gas affording an exact estimation or' the amount of carbon in the com- pound.One grm. of carbon tetriodide yields 42.9 C.C. of gas, whilst 1 grm. of iodoform yields 56.6 C.C. C . A. M. Estimation of Organic Matter in Clays. P. Ehrenberg, C. Diebel, and H. Veckenstedt. (Zeitsch.anal. Ckern., 1913, 52, 408-418.)-The authors confirm the statement of earlier workers (e.g., Warington and Peake, J. Chem. Soc., 1880, 37, 617) that the organic carbon of clays cannot be determined with certainty by methods depending on moist combustion. Some clays yield the whole of their carbon as carbon dioxide when treated with chromic acid, others less than half. In no case was more than 80 per cent.of the carbon obtained as carbon dioxide when permanganate was employed as oxidising agent, The following method is recom- mended : From 10 to 20 grms. of the air-dried clay is treated with at least enough phosphoric acid to decompose any carbonates present. The mixture is dried, then ground up and mixed with finely divided copper oxide, and a combustion made in the usual manner.A number of clays examined by this method showed from 0-1 to 0.7 per cent. humus when the organic carbon was calculated to humus by the factor 1.7. As they are unable to find any record of clays with more than a small fraction of the 15 per cent. of humus said by Rohland (Zeitsch. Chern. Ind. Kolloide, 1906, 1, 78) to be occasionally present, the authors conclude that Rohlands state- ment was based on some one rare specimen.They do not disagree with Rohland's view that the organic matter of clays may be one of the factors which determines their plasticity and other physical properties, and agree that even such small amounts as they found may conceivably exercise a profound influence. But since their samples included the whole range of clays used in a large works, they conclude that the maximum effect of the organic matter must be reached when the percentage is still very small, of a different order of magnitude even from Rohland's 15 per cent.G. C . J. Preliminary Report of the Committee on Coal Analysis of the American Society for Testing Materials and the American Chemical Society. W. A. Noyes and Others.(J. Ind. and Eng. Chem., 1913, 5, 517-528.)-The Comniittee appointed a number of sub-committees, each of which now presents an interim report drawn up by its chairman. These interim reports are not endorsed by the committee as a whole, and in some cases do not represent the unanimous opinion of the sub- committee, but only the view of its chairman. They are published mainly to elicit criticism or confirmation of the views now expressed, before bringing the experimental work to a close, and endeavouring to agree on a final report.No novel suggestion is made as regards sampling, but it is proposed to lay down rules as to the size to which coal is to be reduced before each reduction of bulk by quartering. These rules findORGANIC ANALYSIS 375 sanction in the results obtained by Bailey (ANALYST, 1909,34,237) in his mathematical treatment of the subject.Alternative methods are given for determining moisture. The first consists in drying for one hour at 104-110' C. in a current of air dried by means of sulphuric acid. For lignites and coals approaching lignite in character, air must not be used, and the use of dry carbon dioxide is suggested, though the report goes on to say that a current of dry nitrogen is to be preferred in all cases where the highest accuracy is desired.Recognising that these recommendations imply the presence of special apparatus not available everywhere, the committee propose to make permissive drying to constant weight in vacuo at room temperature, but point out that the vacuum must be high-not above 3 mm.of mercury. For volatile matter the seven-minute heating is retained, with a preliminary five-minute '( smoking off" period for lignites (cf. Cox, ANALYST, 1907, 32, 298). The manner of heating is changed however, the alternatives offered being-(a) heating in a 10 C.C. crucible sup- ported on a tripod in a mufle at 950" C., and ( b ) heating in a 20 C.C.crucible set 1 cni. above the top of a No. 4 MQker burner, having an outside diameter at the top of approxi- mately 25 mm., and giving a flame not less than 15 cm. high, the temperature (900- 950" C.) being controlled by a thermocouple or by the m.p. of potassium chromate (940' C.). Ash is to be determined by ignition in a muffle at 700-750" C., or over a small Bunsen flame, but coals containing more than 0.5 per cent.of calcium carbonate are to be treated differently. The ash of such coals is to be sulphated, the amount of carbonate in the coal is to be determined in terms of carbon, and three times this weight of carbon is to be deducted from the weight of sulphated ash. Sulphur may be determined by the Eschka method, by Atkinson's method (J.SOC. Chem. Ind., 1886, 5,154), or by the peroxide fusion method, which is most conveniently carried out in the bomb of a Parr calorimeter. I t is reported that sulphur is always underestimated (by 3 per cent. or more) when determined in the washings of an oxygen bomb calorimeter. For the determination of calorific power two specifications are given, one of which suf- fices when an error of 1 per cent.is allowable, the other being applicable to exact work where triplicate determinations may be required to fall within a range of 0.3 per cent. For exact work, the (' oxygen " used must contain not less than 95 per cent. of that gas, and the bomb must contain at least 5 grms. oxygen per grm. of coal. A simplified method of computation is recommended. It reduces the calculations to negligible proportions, but the possible error which may result from the substitution of this simplified method of computation for the more closely approximate formulz of Pfaundler and others is not stated.It must be small, as the committee consider that the r,esults of two analysts should never differ by more than 0.4 per cent. G. C. J. Quantitative Separation and Determination of Subsidiary Dyes in the Permitted Food Colours.W. E. Matthewson. (CircuZar No. 113, Bureau of Chem. U.S. Dept. of Agric., through Chem. News, 1913, 107, 218-219.)-For the determination of fast red E in amaranth a solution containing about 0.2 grm. of the dye is treated with 5N hydrochloric acid and diluted to 50 C.C. The solution is shaken out with three separate portions of 50 C.C.of amyl alcohol in three different funnels, and the amyl alcohol portions are washed in the funnels with three portions of376 ABSTRACTS OF CHEMICAL PAPERS 50 cc. of $ hydrochloric acid, these being passed through the series in the same order as was the original solution. The alcohol is next diluted with light petroleum and the fast red removed with very dilute caustic soda solution, and determined by the method of Knecht and Hibbert, using titanium trichloride (ANALYST, 1911,36,80).Approximate figures may be obtained by diluting 2.5 C.C. of the 1 per cent. solution of the dye with 30 C.C. of & hydrochloric acid, and shaking with 15 C.C. of amyl alcohol, which is then compared colorimetrically with pure standards. For the approximate determination of new coccin and similar dyes in amaranth 50 C.C.of the 0.02 per cent. solution of the colour is treated with 10 C.C. of TT benzidene solution (9.2 grms. per litre in $ hydrochloric acid), well mixed, and allowed to stand exactly two minutes, filtered, and 50 C.C. of the filtrate titrated against titanium trichloride. Blank determinations with known amounts of pure amaranth and new coccin are carried out'at the same time.As fast red E and similar colours interfere if this method has been used for their separation, the extracted solution and washings containing the amaranth are combined and taken to dryness in the water-bath to remove the acid and dissolved amyl alcohol. This evaporation does not affect the amaranth. The determination of monosulphonated dyes in ponceau 3R if carried out by means of amyl alcohol and dilute hydrochloric acid gives high results for crocein orange if this dye be present.An accurate separation can be made by first removing the bulk of the ponceau with dilute acid (about TT), and completing the washing with 5 per cent. sodium chloride solution. The procedure is similar to that adopted for fast red E.The monosulphonated dye present in commercial ponceau 3R is probably mainly sodium trimethylbenzene-azo-naphthol-sulphonate derived from diazotised pseudo-cumidin and S-salt. Instead of this crocein orange was used, and figures are given showing that the separation is very accurate. I n the determination of orange I1 in orange I advantage is taken of the greater solubility of the latter in dilute sodium carbonate solution, amyl alcohol and a 5 per cent.solution of this alkali being employed as described for fast red E. The equilibrium between the concentrations of the orange I in the two layers is not very quickly established, and the mixtures must be well shaken and given some time to separate, or they may be very quickly separated with a centrifuge.Determined by these methods in the dyes intended for sale as food colours, amaranth contains from 1 to 5 per cent. lower sulphonated colours, and somewhat more new coccin and similar dyes. Ponceau 3R contains from 1 to 5 per cent. lower sulphonated dyes, and orange I the same amount as orange 11. H. F. E. H. Identification of Small Amounts of Dyestuffs by Oxidation with Bromine.W. E. Matthewson. (Chem. News, 1913,107, 265.)-A small quantity of the dye solution is treated with bromine water drop by drop, until about twice as much has been added as is required to destroy the colour. Hydrazine sulphate is then added to take up the excess of bromine, and finally an excess of sodium carbonate. A second test portion is treated similarly, except that a few drops of a 10 per cent.solution of a-naphthol in 50 per cent. alcohol are added before the sodium carbonate. I n general, it may be said that if, in testing unknown solutions,ORGANIC ANALYSIS 377 the dye is bleached by bromine and restored by hydrazine, or if the coloration with a-naphthol and sodium carbonate is different from that with sodium carbonate alone, a coal-tar dye is present.A concentration of the dye of 1 in 10,000 is suitable for the test, except with some basic dyes which give precipitates which tend to obscure colour reactions. The solution to be tested should be neutral or faintly acid, preferably with hydrochloric acid, which may be present in considerable concentration without interfering. The reactions of fifteen coal-tar colours and three naturally occurring colouring matters are given in tabular form in the paper.In such cases a greater dilution is preferable. G. C. J. Method of Distinguishing Natural from Artificial Colouring Matters by means of their Electrical Conductivity. G. W. Chlopin and P. J. Wassiljewa. (Zeitsch. Unter. Nahr. Genussm., 1913, 25, 596-598.)-The authors outline a method which depends on the fact that vegetable and animal colouring matters exhibit a much larger electrical resistance than do artificial colouring matters.The difference in resistance is generally greater in alcoholic than in aqueous solution. For instance, in alcoholic solution, taking the resistance of picric acid as unity, saffron has a resis- tance of 6, quercitin of 27, etc.; in aqueous solution, cochineal exhibits a resistance 18 times greater than picric acid, and 4 times greater than auramine or chrysoidine. The method will possibly be of use in the analysis of mixtures of colours. w. P. s. International Commission for Unification of the Testing Methods of the Stability of Explosives, Final Report (July 25, 1912). (Eighth Inter. Coitg. App.Chem., 1912, vol. 25, 305.)-The diverse requirements and natures of explosives in different countries have made it impossible to lay down any fixed rules, but the Commission recommends that for the transport of industrial explosives the packing should be made uniform, and that the following three tests, the first of which would eliminate at once explosives unfit for transport, should be applied : (1) Preliminary test : Two samples, not dried, of 10 grms.each are warmed in loosely covered glass capsules 35 mm. in diameter and 50 mm. high, at 75" C . for forty-eight hours. There must be no decomposition, or alteration in appearance or smell, or evolution of red fumes from nitro-explosives. (2) Shock test : The explosive, powdered and dried, is compared with an equal weight of similarly prepared picric acid ; 5 to 10 cgrms.are placed in a +inch layer on a steel anvil, and covered with a steel cylinder half an inch in diameter and the same in height. The average fall-height for explosion is deter- mined from ten consecutive tests, and must not exceed that for picric acid, ( 2 b ) Friction test : The sample must be at least as insensitive as picric acid when rubbed in an unglazed china mortar warmed to 20-30" C.(3) Fire-resistance test : (a) Explosives which when powdered take fire in a glass tube from a fuse burning at 1 cm. per second are regarded as easily inflammable; ( b ) explosives passing (a) are powdered and poured in quantities increasing from 0.5 to 5 grms. into a red-hot hemi- spherical iron capsule 12 cms.in diameter and 1 mm. thick ; (c) after preliminary trials 100 grms. of explosive are tested on an asbestos sheet with an iron bar heated to about 900" C. ; it must burn slowly, without explosion, and should go out on378 ABSTRACTS OF CHEMICAL PAPERS removing the bar. behaviour under these tests. Explosives will fall into various classes according to their 0. E. M.Methods for the Determination of the Effective Strength of High Explosives. A. M. Comey and F. B. Holmes. (Eighth Inter. Coizg. App. Chem., 1912, vol. 25, 217.)-The lead block compression test gives results which depend upon the rate of detonation and not on the power. More accurate determinations of the rate of detonation are effected by means of the Dautriche and Bichel tests. For determining the power, the ballistic mortar gave the best results.The Druckmesser measures the pressure directly, giving valuable results, while the Trauzl block gives figures only comparable for the same nature of explosive, and affected by the velocity of detonation. The ballistic mortar has been standardised at the Eastern Laboratories, and is there used almost exclusively for power-determinations. 0.E. M. Detection and Estimation of Formic Acid. H. Fincke. (Biochenz. Zeitsch., 1913,50,253-288.)-The material to be examined is treated with sufficient tartaric acid to liberate all volatile acids completely, the mixture heated on water batb, and steam passed through, and the issuing vapour passed through a flask containing a suspension of calcium carbonate in boiling water and then condensed.The calcium carbonate suspension is filtered and washed, and the formic acid in the filtrate estimated by the mercuric chloride met hod. Sulphurous, sorbic, glyoxylic, and hvulinic acids are disturbing factors, as also are several acids of the aromatic series. If sulphurous acid is present, the calcium carbonate filtrate is treated with 1 C.C.sodium hydroxide and 5 C.C. hydrogen peroxide, allowed to stand four hours, and the excess of peroxide decomposed by adding an excess of freshly precipitated mercuric oxide. After standing for half an hour, the liquid is filtered, and the filtrate neutralised with hydrochloric acid. Glyoxylic acid, if present, colours the suspended calcium carbonate yellowish-brown ; it is rendered harmless by gentle boiling with zinc and sulphuric acid for some hours.Lmulinic acid forms a mercury salt readily soluble in hydrochloric acid; it can, therefore, be removed by treating the calomel precipitate with hydrochloric acid. Cinnamic acid does not interfere if the liquid be filtered hot. Salicylic acid gives no precipitate if sodium chloride is added ; fumaric acid requires addition of sodium chloride and subsequent treatment with hydrochloric acid, as in the case of lzvulinic acid.The formate solution thus prepared is made faintly acid with hydro- chloric acid, sodium acetate, sodium chloride, and mercuric chloride added, and the mixture heated for two hours on a water-bath in a flask to which a reflux tube is attached. The mercurous chloride is dried at 100" C.and weighed. If formic acid is present both as free acid and as esters, as in brandies, the slightly acid liquid is treated with 1 to 2 grms. sodium acetate and distilled. The residue is then acidified with tartaric acid, 2 grms. for each grm., sodium acetate being added, and the free acid determined as above. The distillate which contains the volatile esters is saponified with alkali, and the formic acid produced is estimated.The detection and estimation of minute amounts of formic acid is rendered difficult owing to the pro- duction of formic acid by the decomposition of sugars on boiling. I n order to Sorbic acid occurs only in unripe service berries.ORGANIC ANALYSIS 379 distinguish between ready-formed formic acid and that produced by decomposition of carbohydrates, successive fractions of the steam distillate are examined separately ; if the formic acid is ready formed, the concentration of successive fractions will diminish. If it is being formed during the distillation, the successive fractions will contain the same or increasing amounts of formic acid, provided that the proportion of sugar to decomposition product is large.The paper contains a useful critical review of known methods. E. W. Estimation of Lactic Acid. A. Bellet. (UzdZ. SOC. Chi???,., 1913, 13, 565-572.) -The process consists essentially in extracting the lactic acid with ether and then converting it into acetaldehyde by the action of potassium permanganate, the acetal- dehyde being collected in alkaline silver nitrate solution.The solution or extract containing lactic acid is treated with acid mercuric nitrate solution and heated to precipitate proteins. After filtration, the filtrate is neutralised with sodium hydroxide, evaporated to a syrup, and mixed with anhydrous sodium sulphate and sand, so as to form a dry powder ; 2 C.C. of dilute sulphuric acid are added to liberate the lactic acid.The powder is then extracted with ether for three hours in a Soxhlet apparatus, which has a tap on its stem in order to allow the ether to flow back continuously into the extraction flask. The ethereal solution is evaporated, the residue is dissolved in water, transferred to a flask, diluted to 200 c.c., and acidified with sulphuric acid. The flask is connected with a condenser, and a set of receiving vessels are provided containing a known quantity of alkaling silver nitrate solution (silver nitrate, 15 grms.; ainmonia, 150 grms. ; sodium hydroxide solution, 100 C.C. ; and water to 500 c.c.). The solution in the flask is boiled, aud a 1.5 per cent. potassium permanganate solution is added drop by drop from a tapped funnel at such a rate that each drop is decolourised before the next is admitted.When the permanganate added is no longer reduced, the contents of the receivers are mixed, filtered through asbestos and glass-wool, and the excess of silver is titrated in the filtrate. One moleculs of silver is equivalent to one molecule of lactic acid or one molecule of acetaldehyde according to the equation- Succinic, oxalic, and P-hydroxybutyric acids, if present in the material under exam- ination, are extracted together with the lactic acid, but they do not interfere with the estimation of the latter, as succinic acid is not attacked by the permanganate, oxalic acid yields carbon dioxide, and P-hydroxybutyric acid gives acetone.Ag,O + CH,.CHO = Ag, + CH,.COOH. w. P. s. New Method for the Identification of Methyl Alcohol.€'. N. Raikow. (Eighth Inter. Gong. App. C?2enz., 1912, vol. 25, 417.)-The methyl alcohol is con- verted into nitromethane, which yields with nitroprusside a blue, and on standing a green, and finally a yellow, coloration. The sample (200 c.c.) is acidified with phosphoric acid, and 10 C.C. distilled. The distillate is treated with 4 grnis. of red phosphorus and 25 grms.of iodine under a reflux condenser. After twenty minutes the mixture is fractionated, and the first 5 C.C. of distillate slowly distilled with 2 to 3 grms. silver nitrite. The distillate is collected in portions of 3 to 4 drops, and380 ABSTRACTS OF CHEMICAL PAPERS to each of these strong ammonia and a small quantity of concentrated sodium nitro- prusside solution added.The presence of acetone, which gives a colour similar to Hofmann's violet, does not vitiate the test. 0. E. M. Colour Reaction of Proteins. L. Lewin. (Ber., 1913, 46, 1796-1798.)- Many proteins, even in very dilute solution, give a violet coloration when treated with a 0.1 per cent. solution of triformoxime (Kahlbaum's trioximinomethylene) in unpurified sulphuric acid, or in any concentrated sulphuric acid to which a trace of selenious acid has been added.The reaction is given distinctly by egg albumin and Witte's peptone in a dilution of 0.05 per cent., and a solution of half this strength gives a coloration which is easily seen against a white background. Serum albumin, casein, pepsin, and nucleoproteins also give the reaction, but gelatin does not, in any concentration.Indol gives a similar colour (A= 536 pp), and some alkaloids- for example, codein-give a blue colour with the reagent. Paraformaldehyde may be substituted for the reagent, but is less satisfactory, the intensity of coloration produced being somewhat less, and the use of a large excess of paraformaldehyde completely inhibits the production of the violet coloration.G. C. J. Polarimetric Method fop the Determination of Starch in Paper. C. E. G. Porst and H. A. Crown. (Eighth Inter. Cong. App. Chenz., 1912, vol. 26, 13-16.)- The specific rotatory power of maize starch when determined in 0.5 per cent. solution was found to be [uID2O= 187.9". A modification of Lintner's polarimetric method was employed (ANALYST, 1909, 34, 832; ibid, 1912, 37, 498), using 5 grms.of paper moistened with 20 C.C. of water in an ice-cold mortar. Forty C.C. of ice-cold concentrated hydrochloric acid are added, and the whole well macerated. After standing a t 20" C. for thirty minutes the mixture is washed into a 200 C.C. flask with acid of 1,125 sp. gr., and 10 C.C. of 4 per cent. phosphotungstic acid are added. After making up to 200 C.C.the contents of the flask are kept at 20" C. for half an hour, filtered, and the reading taken in a 400 mm. tube fifteen minutes after the filtration has begun; lo V. is equivalent to 1.845 per cent. starch. H. F. E. H. The Determination of Tartaric Acid. P. B. Dunbar. (Eighth Inter. Cong. App. Chem., 1912, vol. 26, 361-373.)-When a solution of tartaric acid or tartrates containing between 0-2 and 3.0 grms.of total tartaric acid per 100 C.C. is treated under definite conditions with uranyl acetate, its optical rotation is much increased (ANALYST, 1911, 36, 498), and is proportional to the amount of tartaric acid present in the solution. A measured volume of the tartaric acid solution is made slightly alkaline to litmus with soda, 5 grrns.of sodium acetate are dissolved in it, and the solution reacidified in slight excess with strong citric acid, and the whole diluted to 100 C.C. Powdered uranyl acetate is added to this solution, the mixture being mechanically agitated for three hours, enough of the salt being used to leave some undissolved at the end of this period. Under these conditions each grm. of tartaric acid per 100 C.C.produces a rotation of + 19.6' V. in a 200 mm. tube. A standard Lippich type triple field saccharimeter is employed with white light. The reading so obtained, if multiplied by 0.051, gives the percentage of tartaric acid, unless malicORGANIC ANALYSIS 381 acid or other optically active substance is present, in which case a portion of the solution must be freed from tartaric acid by precipitation with dry powdered normal lead acetate and polarised separately. The algebraic difference between this reading and that obtained in the uranium-treated solution is the reading due to the uranyl tartaric complex.Very dark-coloured solutions may often be cleared by vigorous shaking with a few drops of bromine, followed by filtration just before reading.H. F. E. H. Determination of Malic and Tartaric Acids in the Same Solution. P. B. Dunbar. (Eighth Inter. Gong. App. Chem., 1912, vol. 26, 375-386.)-The author and R. F. Bacon have described a method (ANALYST, 1912, 37, 29) for the estimation of malic acid based on the increase in rotation produced by the addition of uranyl acetate, and as an extension of this work (see preceding abstract) suggested a method for the estimation of malic and tartaric acids when present together depending on the facts that the optical rotation of both acids is increased independently of the other when treated with uranyl acetate under definite conditions, and that both acids may be oxidised quantitatively to oxalic acid by heating with alkaline permanganate. The presence of any other substances which form oxalic acid on oxidation incapable of being removed before treatment with permanganate interferes with the method. Under the conditions described in the previous abstract, it was shown that 1 grm. of tartaric acid per 100 C.C. produced a rotation of + 19-61' V. ; and as described by the author and Bacon (Zoc. cit.), 1 grm. of malic acid per 100 C.C. will rotate - 27.77" V. One grm. of potassium permanganate is equivalent to 0.475 grm. of tartaric acid, or 0.353 grm. of malic acid, while 1 grm. of oxalic acid is equivalent to 0.526 grm. of rnalic acid, or 0-595 grm. of tartaric acid. One grm. of malic acid equals 1.90 grm. of oxalic acid, or 2.8297 grms. of potassium permanganate, while 1 grm. of tartaric acid equals 2,1062 grms. of permanganate, or 1-68 grms. of oxalic acid. If x = grms. of malic acid in 100 c.c., y = grms. of tartaric acid in 100 c.c., a = polarisation in degree V. after treatment with uranyl acetate and b= grms. of permanganate required to oxidise the acids in 100 C.C. ; then- 2 == - 0.0185~~ + 0*1720b, ?/ = 0.0248~~ 4 0.24363 ; while if the amount of oxalic actually found is used instead of the permanganate required to oxidise this acid, the equations become- x = 0.020~~ + 0*233~, y = 0.023a + 0*331c, when cis equal to the grms. of oxalic acid formed by oxidation of the acids in 100 c.c. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9133800371

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

ORGANIC ANALYSIS 381 INORGANIC ANALYSIS, Application of Folin’s Method for the Determination of Ammonia to Fertilisers. 0. Folin and A. W. Bosworth. ( J . Ind. and Eng. Chem., 1913, 5, 485.)-Two grms. of fertiliser are placed in a 100 C.C. graduated flask, about 50 C.C. of water added, and then 25 C.C. of approximately hydrochloric acid. The volume382 ABSTRACTS OF CHEMICAL PAPERS is made up to 100 C.C.with water, the contents of the flask are shaken, and after a few minutes' standing are shaken again. The flask is next allowed to stand till the heavier undissolved particles have settled ; then 5 C.C. of the supernatant liquid are withdrawn and transferred to the tube of the Folin apparatus (J. Biol. Cliern., 11, 493). Two C.C. of a saturated solution of potassium oxalate, a few drops of kerosene, and then 2 C.C.of a saturated solution of potassium carbonate are then added. The apparatus is at once closed, and air is passed through for ten to twenty minutes. The ammonia is collected in 20 C.C. of Go- hydrochloric acid. If the air current is produced by a blast, the ammonia is collected in a flask, and 25 C.C. of water are added to the 20 C.C.of acid to prevent loss of ammonia. The aminonis is titrated against Tc soda,, using alizarin red as indicator. The results agree well with the values obtained when the sample is distilled with magnesium oxide in the ordinary way. H. I?. E. H. Estimation of Sulphate in Ammonium Sulphate Solution, with Special Reference to the Testing of Illuminating Gas. R. S. McBride and E.R. Weaver. ( J . Ind. awl Eng. Chem., 1913, 5, 469-474.)-For the determination of sulphate, in cases where an approximate estimation is all that is required, the following turbidimetric method is recommended. The solution is neutralised with hydrochloric acid, of which an excess of about 1 C.C. is then added. Paranitrophenol is the most convenient indicator to use, as the acid solution is then colourless. The solution is made up to 270 c.c., 360 c.c., or other multiple of 90 c.c., and 90 C.C.is then mixed at 25 to 30" C. with 10 C.C. of 10 per cent. barium chloride solution. After stirring a, minute, the mixture is poured slowly into a graduated glass cylinder, with polished bottom, and contained within an outer copper cylinder, until the filament of a 16 c.p.carbon filament lamp, fixed below the apparatus, can no longer be seen. The height of the liquid in the cyIinder is then measured, and its content of sulphate sulphur determined by reference to a curve, constructed from the results of experiments with known quantities of sulphuric acid under the same conditions, among which that of temperature is the most important. Between the concentrations of 2 and 11 mgrms. sulphato sulphur per 100 c.c., corresponding to a measured height of liquid of from 110 to 25 mm., the extreme error of a single determination is 7 per cent.The use of oxalic acid and other additions to the barium chloride, as hag been recommended by some authors, is not advisable. Such additions give a more opaque mixture, but duplicate determinations are more discordant.A volumetric method, capable of giving results never so much as 1 per cent. in error, is the following : The solution is diluted or concentrated to 300 c.c., neutralised, and then acidified with 10 C.C. of dilute (1 : 1) hydrochloric acid, and heated to boiling. Exactly 15 C.C. of barium chloride solution (50 grrns. crystals per litre) is added, the mixture boiled for five minutes, and then exactly 15 C.C.of a chromate solution, rather more than equivalent to the barium solution (e.g., 30-5 grms. potassium bichromate per litre), is added, together with a few drops of ferric chloride solution. Ammonia is added until a permanent precipitate appears, when a further 5 C.C. of 10 per cent. ammonia is added, the mixture is boiled, filtered and washed with hot water, the ferric hydroxide facilitating these processes.To theINORGANIC ANALYSIS 383 cooled filtrate, acidified with hydrochloric acid, 2 grms. potassium iodide are added, and the liberated iodine is titrated with thiosulphate. A similar blank experiment is made, starting with 309 C.C. distilled water. The consumption of thiosulphate in the blank test is subtracted from that in the determination proper, and the remainder calculated to sulphate sulphur.S = 3Na,S,O,. The method does not differ in principle from methods previously described, but its greater accuracy is due to the use of the blank test. I n methods depending on the use of a hydrochloric acid solution of barium chromate, the reducing action of the acid on the chromate has introduced errors.I n others depending on the use of exactly equivalent solutions of barium chloride and potassium chromate, any inexactness in strength has introduced error, whilst methods depending on the use of solid barium chromate require a salt absolutely free from alkali chromate, and this is not readily obtainable in comnierce. All methods of this type are affected by the solubility of barium chromate.The use of a chromate solution slightly stronger than the barium solution, together with a blank test, eliminate all these sources of error, and the small error that remains (1 per cent.) is mainly due to the smallness of the quantity (6 to 30 mgrms.) to be estimated. G. C. J. Separation of Cadmium from Zinc. W. D. Treadwell and K.S. Guiter- man. (Zeitsclz. and. Chem., 19 13, 52, 459-470.)-The separation of cadmium from zinc, by means of hydrogen sulphide, is best effected in sulphuric acid solution. In hydrochloric acid solution much more zinc is co-precipitated with the cadmium. Cadmium sulphide is quite insoluble in 6 N sulphuric acid at 18" C., whereas at 70" C. it is soluble in 2 N acid. The best results are obtained by making the solution 4 to 5 normal wihh sulphuric acid, heating to 80' or 90" C., and then allowing the solution to attain the temperature of the room whilst passing a current of hydrogen sulphide through it.Precipitation of cadmium is then quantitative, and the quantity of zinc co-precipitated is negligible if zinc is present in amount only equal to the cadmium.In presence of relatively large quantities of zinc, separation cannot be effected by a single precipitation. For example, 0.1 grm. of cadmium, when precipitated as sulphide in presence of 2 grms. of zinc, will take down with it 6 mgrms. of zinc. When, therefore, cadmium has to be estimated in presence of more than its own weight of zinc, the precipitated sulphides are re-dissolved in hot dilute hydrochloric acid, the solution is evaporated to dryness, the chlorides are decomposed by heating with sulphuric acid, and the cadmium is finally re-precipitated as sulphide.Small quantities of cadmium can be separated from quantities of zinc not exceeding 1 grm. by electrolysis in oxalate solution. To the neutral solution of the chlorides or sulphates, 8 grms.potassium onalate, 2 grms. ammonium oxalate, and 0-4 grm. oxalic acid are added, and the solution is diluted to about 120 C.C. It is then heated to 70" to 80' C., and electrolysed by a, current of 0.03 ampAre, correspond- ing to a P.D. between the terminals of about 1.5 volts. Some four or five hours are required to deposit 0.1 grm. cadmium, and the electrolysis is most conveniently carried out in a beaker nearly filled with the electrolyte, a, round-bottomed flask, through which water is passed, can be set on such a beaker so as to touch the liquid,384 ABSTRACTS OF CHEMICAL PAPERS and serves the double purpose of preventing evaporation and inducing circulation of the liquid.Quantities of cadmium between 0.04 and 0.2 grm. can be separated from fifty times their weight of zinc by electrolysis in cold sulphuric acid solution.The neutral solution of the sulphates is most conveniently acidified by addition of 5 grms. of sodium bisulphate. A rotating cathode is used, and a constant cathode potential of 2.5 volts corresponding to a current of from 0.3 to 0.05 ampAre. More than 0.2 grm. can be deposited in fifty minutes. The method is !ess troublesome than the oxalate method, but for very small quantities of cadmium it is less accurate.G. C. J. Rapid Method for Estimating Carbon in Iron and Steel. E. Szasz. (Zeitsch. nngew. Chem., 1913, 26, 281-286.)--The method and apparatus described have been designed with a view to making an accurate determination of carbon in any iron, steel, or steel-making alloy in the shortest possible time; and, since they accomplish this purpose, the author does not hesitate to recommend an apparatus which is both costly and complicated.Once set up, the apparatus is extremely easy to manipulate, and, apart from the fact that platinum apparatus has a high scrap value, it is suggested that the capital locked up in this apparatus will be highly remunerative in many cases-for example, in controlling an electric furnace utilising mixed scrap.A carbon determination can be completed in less than ten minutes. The principle of the method is direct, dry combustion, with measurement of the carbon dioxide produced. A necessary condition of such a method is the use of as small an excess of oxygen as possible, since otherwise a gas burette of incon- veniently large dimensions would be required, and another essential is to have the dimensions of the combustion apparatus as small as possible. The combustion chamber is constructed of platinum, with water-jacketed platinum tubes for the introduction of oxygen and egress of gases, and a water-jacketed stopper.It is only just sufficiently large to accommodate the boat and the surrounding platinum cylinder which safeguards the combustion chamber walls from damage by spirting.The use of au unnecessary excess of oxygen is avoided by taking advantage of the well-known fact that, when a certain temperature is reached in the combustion of iron in oxygen, there is a very rapid absorption of oxygen, so rapid as to require prompt manipulation of the oxygen supply, or special appliances (cf.Blount and Levy, ANALYST, 1909, 34, 93) designed to adjust the supply automatically. The author charges his apparatus with oxygen after inserting the boat, disconnects the train of apparatus leading to the measuring burette by turning a cock, but leaves the combustion apparatus connected to a supply of oxygen through an apparatus which guards against any backward movement of gas during the first stage of heating.The combustion apparatus is then heated by means of a Mkker burner supplied with producer gas and air under pressure. I n one and a half minutes or less the period of rapid absorption of oxygen is reached (over 1,000' C.), and at the end of this one and a half minutes the cock connecting with the measuring burette is opened, and its evelling cylinder is lowered at such a rate that the burette (200 c.c., with 150 C.C.bulb and 50 C.C. divided stem) is nearly filled with gas at the end of a further two orINORGANIC ANALYSIS 385 three minutes. The gas in the water-jacketed burette is then measured, transferred to a potash pipette, returned and remeasured. The temperature of the combustion apparatus continues to rise after the expiration of the preliminary period of one and a half minutes, and reaches 1,15O0-1,2OO0 C.after two minutes or a little longer. The supply of oxygen is freed from carbon monoxide, said to be often present in com- mercial oxygen, by passing it through a heated quartz tube containing thin platinum wires, before conducting it to the usual potash vessel.The gases resulting from the combustion of the iron are also passed through a heated quartz tube containing copper oxide to oxidise any carbon monoxide, platinum failing in this position in absence of excess of oxygen. The gases are deprived of sulphur dioxide by passing over glass beads moistened with a few drops of chromic acid solution, and contained in a water-jacketed U-tube which serves to cool the gases on their way to the burette.Some sixty test numbers given do not differ from the results obtained on the same material by proved gravimetric methods by more than the difference between duplicate gravimetrio results. Some special steels and steel-making alloys require slightly special treatment, but, of the fifteen types of material experimented with, none has failed to yield the whole of its carbon as ‘carbon dioxide.On the use of diluents to keep the material open, oxidising agents, and materials to hold back volatile metallic oxides in the boat, there are some notes which apply to the direct dry combustion of special steels and steel-making alloys generally, and not merely to the present modification of that process.G. C. J. Estimation of Carbon Dioxide. L. W. Winkler. (Zeitsch. anal. Chem., 1913, 52, 421-440.)-Apart from a modification of Pettenkofer’s apparatus for the deter- mination of carbon dioxide in air, there is nothing new in this paper, but within its comparatively narrow limits will be found descriptions of methods and illustrations of apparatus by means of which carbon dioxide can be determined in almost any material with satisfactory accuracy.Half the paper is devoted to a detailed de- scription of the author’s method and apparatus for the estimation of total carbon dioxide in natural waters (cf. Zeitsch. anal. Ckem., 1908,42, 735), and to showing that the criticism to which that method has been subjected is not well founded. His well known method (Zeitsch.anal. Chem., 1901, 40, 523) for the estimation of carbon dioxide in mineral waters i s redescribed in sufficient detail to enable anyone to use it, with notes on a simple method of taking and preserving samples of such waters. An apparatus for the determination of carbon dioxide in solid carbonates (cf. Ekkert, Chem. Zeit., 1905, 29, 1316) is also described and illustrated, and shown to afford a means of making this determination with great accuracy and at the same time wit4 the minimum expenditure of time and attention. Finally the following modification of Pettenkofer’s apparatus is described. It consists of a hollow stopper for the large bottle employed by Pettenkofer. The stopper has approximately the form of an 8-inch x I-inch test-tube, constricted about 3 inches from its mouth, which is ground to serve as the stopper. The capacity of the stopper above a mark on the constricted portion is 50 c.c., and before the analysis it is inverted and filled to the mark with lime-water, after which it is pressed into the neck of the inverted bottle.After agitation and long standing, the liquid is allowed to collect again in the hollow stopper386 ABSTRACTS OF CHEMICAL PAPERS as far as possible, the stopper is removed, plugged at the constriction by a rubber stopper mounted on a glass rod, and when the precipitate has settled, leaving the liquid clear, 25 C.C.of the latter is pipetted off and titrated in the usual manner. G. C. J. Gravimetric Estimation of Carbon Dioxide. A. Dej eanne. (BzdZ.80c. China., 1913, 13, 556-560.)-The carbon dioxide liberated in the usual way from a carbonate, etc., is absorbed in a definite quantity (an excess) of barium hydroxide solution; magnesium chloride solution is then added, the mixture is diluted to a definite volume, filtered, and the excess of barium in the filtrate is estimated by sulphating an aliquot portion of the latter.The addition of the magnesium chloride is for the purpose of converting the excess of barium hydroxide into barium chloride, a corre- sponding quantity of magnesium hydroxide being precipitated and filtered off with the barium carbonate ; precautions to exclude atmospheric carbon dioxide during the filtration are unnecessary, w. P. s. Iodimetric Estimation of Free and Combined Chromic Oxide.M. Groger. (Zeitsch. anorg. Chenz., 1913, 81, 233-242.)-Chromic oxide and most of its compounds, except chrome ironstone, are decomposed by nitric acid and potassium chlorate, with complete solution of the ohromium as chromate. This method of decomposition is therefore preferred to nitre fusions, which involve the somewhat rapid destruction of platinum crucibles. I t is shown that the accuracy of the results often obtained by precipitating the chromic acid as barium chromate is due to compensation of errors, which in many cases do not exactly balance each other, but result in a net error of as much as k 2 per cent.An iodimetric deter- mination of the chromate, on the other hand, need not be in error by as much as corresponds to 0.05 C.C. of Fc thiosulphate.The substance (0.3 grm.) is heated on the water-bath with 10 C.C. of concentrated nitric acid contained in a 300 C.C. flask closed with a smdl funnel, and about 1 grm. of potassium chlorate is added in small portions a t a time, the additions being spread over about one hour. The funnel is removed, heating continued for an hour to expel chlorine, the solution cooled and diluted to 250 c.c., and 50 C.C.treated with excess of potassium iodide and titrated with thiosulphate. Heating for an hour suffices to expel chlorine, as portions of the solution evaporated to dryness before treatment with iodide yield substantially identical results. A warning is given that 10 C.C. of nitric acid sold as (( chemically pure ” may contain as much ferric salt as corresponds to 0-05 C.C.& thiosulphate. The method gives results of the accuracy stated in presence of large quantities of calcium, barium, strontium, magnesium, zinc, cadmium, aluminium, nickel, and cobalt, and artificial chromites containing magnesium, zinc, cadmium, and nickel, gave quantitative results, but required about 1.5 grms. of chlorate and about two hours for complete decomposition.Chrome ironstone is not completely decomposed by the acid mixture. Iron existing in any form other than chromite can be eliminated, like copper, by precipitation with hot caustic alkali and filtration, the whole of the chromic acid passing into the filtrate, in which its estimation iodi-INORGANIC ANALYSIS 387 metrically presents no difficulty. I n presence of manganese, the method fails owing to the formation of an insoluble compound of manganese dioxide and chromic oxide.G. C. J. Quantitative Separation of Iron and Chromium. F. Bourion and A. Deshayes. (Comptes rend., 1913, 156, 1769-1771.)-The method described by Bourion for the separation of iron and titanium, depending on the volatilisation of the former in a current of hydrogen chloride and sulphur monochloride (ANALYST, 1912, 37, 323), is not applicable to the separation of iron and chromium.In presence of chromium some iron always remains unvolatilised. Since anhydrous chromic chloride is insoluble in water, it was thought that a separation might be effected by converting the mixed oxides into chlorides by the action of chlorine and sulphur dichloride, and subsequent treatment with water.Unfortunately, chromic chloride is not quite insoluble in solutions of ferric chloride ; but in mixtures con- taining not more than 30 per cent. of chromium the latter element can be determined with an error not exceeding -0.4 per cent. by proceeding as follows: The mixed oxides, contained in a boat in a combustion-tube, are heated gradually from 200" to 650" C., whilst a slow stream- ( 5 to 15 bubble% per minute) of chlorine, saturated at 30" to 40" C.with the vapour of sulphur dichloride, is led through the tube. NO ferric chloride remains in the boat, but some of the chromic chloride is volatilised and condenses on the cooler portions of the tube. The boat is withdrawn and weighed, and the contents of the tube are rinsed out and filtered through a Gooch crucible to recover the volatilised chromic chloride.When the proportion of chromic oxide in the mixture to be analysed exceeds 40 per cent., the error of the above method increases, and 95 per cent. of chromic oxide might be under-estimated by as much as 5 per cent. Any mixture can be analysed with an error not exceeding -0.4 per cent.by proceeding as follows : The mixed oxides are mixed in the boat with an equal volume of ammonium sulphate before commencing the experiment. The mixture is then heated gradually (three to four hours) to 650" C. in a current of chlorine and sulphur dichloride, and the volatilised portion of the chromic chloride is separated from ferric chloride as already described. The ammonium sulphate fuses before decomposing, and the resultant mass is of such a character that the amount of chromic chloride volatilising is small, and that which does volatilise condenses as a compact mass close to the boat, this compact mass being less easily brought into solution by ferric chloride than the minute crystals which spread over a considerable length of the tube when ammonium sulphate is not used.G. C. J. Volumetric Estimation of Chromium in Presence of Iron. A. Kurte- nacker. (Zeitsch. anal. Chem., 1913, 52, 401-407.)-The solution, contained in a measuring flask, is treated with excess of bromine-water, then with excess of caustic alkali, heated on the water-bath for half an hour with frequent shaking, cooled,made up to the mark, and filtered.The chromate in an aliquot portion of the filtrate is determined in the manner described later, whilst the precipitate of ferric hydroxide is washed, dissolved in hydrochloric acid, reduced and titrated with permanganate, using Reinhardt's manganese phosphate solution. Before the chromate in the388 ABSTRACTS OF CHEMICAL PAPERS filtrate can be determined iodimetrically, the hypobromite and bromate must be destroyed.The former is readily destroyed by acidifying and heating the solution, when bromine is expelled and more bromate results. In presence of the bromide simultaneously present, the bromate is also decomposed in acid solution, but for the reaction to be quantitative and reasonably quick, the hydrion concentration must not be too low. On the other hand, if it be too high, hydrogen bromide may reduce chromic acid. It is possible to destroy hypobromite and bromate whilst not reducing chromic acid, but the permissible limits of acid concentration are very narrow in the case of hydrochloric acid, and restricted in the case of sulphuric acid.The point of the present communication is the discovery that potassium bisulphate in com- paratively low concentration serves to make the destruction of broinate quantitative, whilst even in concentrations ten times as high it does not support the reduction of chromic acid.The chromate solution (100 C.C. or less) is acidified cautiously with sulphuric acid until it acquires a permanent brown colour. About 20 C.C. of 30 per cent. potassium bisulphate is added and the mixture boiled for five minutes.As a rule this suffices to destroy all bromate and expel all bromine, but if any smell of bromine is apparent, a further 10 C.C. of bisulphate solution is added and the boiling repeated. The solution is then cooled, potassium iodide, sulphuric acid, and a considerable amount of water, are added, and the liberated iodine is titrated with thiosulphate.The maximum error recorded corresponds to 0.05 C.C. of & thio- sulphate, and in some experiments the concentration of the potassium bisulphate in the mixture boiled to destroy bromate was as high as 13 per cent., in others as low as 5 per cent. G. C. J. Analysis of Copper-Tin Alloys. W. Gemmell. (J. Xoc. Chem. Ind., 1913, 32, 581-584.)-1t is not necessary to remove tin before proceeding to the estimation of copper by electrolysis, provided the tin is kept in solution. Copper-tin alloys are completely soluble in nitrosulphuric acid, and from solutions of suitable concentration the copper can be deposited electrolytically in a pure condition.The alloy (2 grms.) is dissolved in a, mixture of 10 C.C. nitric acid (sp. gr. 14), 10 C.C. sulphuric acid, and 30 C.C.water ; the solution is diluted to about 100 C.C. and electrolysed, using rotating platinum electrodes and a current of about 8 amp8res. Deposition of the copper is complete in thirty minutes. The beaker containing the exhausted solution is removed, and immediately replaced by one containing water, without breaking the electrical circuit, and the electrodes are rinsed down with distilled water, immersed in alcohol, dried at 100' C., and weighed.The copper on the cathode contains no trace of tin. If lead be present, some of it is deposited on the anode ELB peroxide, and some separates as sulphate at the bottom of the vessel. For the determination of tin, the solution which has been electrolysed for copper, together with the water used to wash the electrodes, is poured into a cold 2 per cent.solution of sulphuric acid saturated with hydrogen sulphide. After boiling for a few minutes, the precipitated sulphides are filtered off and washed with 1 per cent. acid saturated with hydrogen sulphide. The tin sulphide is dissolved on the filter by means of freshly-prepared ammonium sulphide, the solution is electrolysed to recover the tin, and any leadINORGANIC ANALYSIS 389 sulphide left on the filter-paper can be converted into lead sulphate, and the lead found added to that recovered as peroxide.The test numbers show that 1 or 2 per cent. of lead in a copper-tin alloy can be determined in this manner with an error not exceeding 4 per cent. of the lead present, but the following more exact method is recommended for the determination of small proportions of lead: The alloy (5 to 10 grms.) is dissolved in nitrosulphuric acid, and the solution evaporated until the sulphuric acid fumes.Water is next added until the concentration of acid is about 25 per cent. by volume. Such a solution can be boiled if necessary to insure solution of copper and tin as sulphates, since at this concentration of acid there is no risk of tin being precipitated as oxide.When cool, the solution is diluted until the acid is at a concentration of about 7 per cent. by volume, and after standing, preferably over- night, the lead sulphate is filtered off, dried, ignited, and weighed. Most commercial copper alloys contain nickel, the proportion of which may exceed 0.4 per cent.with- out any intentional addition of the metal. After precipitation of the tin from the solution which has been electrolysed for copper, nickel and iron are determined as follows : The filtrate from the tin sulphide is boiied to expel hydrogen sulphide, aqua regia is added to oxidise iron, and iron and nickel are precipitated together by addition of caustic soda. The precipitated hydroxides are filtered off, washed, dissolved in hydrochloric acid, excess of ammonium chloride is added, and the iron reprecipitated by addition of ammonia.In the filtrate from the ferric hydroxide, nickel is determined by precipitation by means of dimethylglyoxime. Zinc is determined in the filtrate from the hydroxides of nickel and iron. This filtrate is acidified with sulphuric acid and evaporated until fumes arise, cooled, diluted, made alkaline with caustic soda, and then acidified with acetic acid.The zinc is deposited electrolytically on a platinum electrode which has been previously plated with copper. A current of 3 amperes suffices to remove 0.7 grm. zinc in less than forty minutee. The test numbers are good, the highest error recorded being one of +0.08 per cent, on the alloy, representing an error of 2 per cent.on the constituent estimated (zinc), Maximum error for copper -0.03 per cent. with 80 per cent. present, for tin +Om04 per cent. with 20 per cent. present, for iron f0.02 per cent. with 1 per cent. present. The methods are also said to be more rapid than other less accurate ones. G. C. J. Rapid Estimation of Copper in Burnt Pyrites.H. Koelsch. (Chew. Zeit., 1913, 37, 753.)-An addition of sodium hypophosphite to the hydrochloric acid causes rapid reduction and solution of the ferric oxide in burnt pyrites. Ten grms. of the finely powdered material are heated with 6 to 7 grms. of solid sodium hypo- phosphite and 40 C.C. of hydrochloric acid (sp. gr. 1-16), and the solution diluted with 100 C.C.of hot water and treated with 50 C.C. of sodium sulphide solution (40 grms. per litrc). The precipitate rapidly agglomerates on shaking, and is filtered after five minutes and washed with hot water, It is then ignited, decomposed with nitric acid, heated with sulphuric acid, washed with 100 C.C. of water into a beaker, and the copper estimated electrolytically. Or a volumetric method may be used, the small proportion of iron not affecting the results of either method.C. A. M.390 ABSTRACTS OF CHEMICAL PAPERS Use of “Cupferron” in the Separation of Titanium from Aluminium. J. Bellucci and L. Grassi. (Gazz. Chim. Ital., 1913,43,570-576.)--The ammonium salt of nitroso-phenyl-hydroxylamine, C,H,(NO)N.ONH,, which Baudisch termed ‘‘ cupferron,” and used as a reagent for the precipitation of copper and iron (ANALYST, 1911, 36, 520), also precipitates titanium as a bright yellow salt, [C,H,(NO)NO],Ti, which on ignition readily yields a residue of titanium oxide, TiO,.It is essential that the solution of the titanium salt should be decidedly, but not excessively, acid before the addition of the reagent. The precipitate is collected, washed repeatedly with cold water, and ignited in a tared porcelain crucible.I n using the method for the separation of titanium from aluminium, the precipitate must be washed, first by decantation and then on the filter, with very dilute hydrochloric acid in order to remove all traces of aluminium. The method is shown to give good results with mixtures containing 1 part of titanium to 50 of aluminium.In another portion of the solution the titanium and aluminium are precipitated simultaneously as hydroxides, and weighed together as A1,0, + TiO,. The reagent may also be used for the separa- tion of titanium from chromium, nickel, cobalt, manganese, etc. C. A. M. Reduction of Ferric Salts, and their Titration with Potassium Per- manganate. A.Leclere. (J. Pharm. Chim., 1913, 7, 587-589.)-The method is based upon the formation of the stable ferrous ammonium sulphate in the solution of the ferric salts. The liquid is treated with a fragment of granulated zinc and of platinum wire, and acidified with 1 to 2 per cent. of sulphuric acid, From 2 to 3 grms. of ammonium sulphate are then added, and the flask gently heated for at least an hour upon the water-bath or over a small flame, until the reduction of the iron is complete.The solution of ferrous salt is filtered through glass-wool, and the filtrate and washings titrated with standard permanganate solution in the usual way. C. A. M. Volumetric Determination of Gold. V. Lenher. (J. Amer. Chem. SOC., 1913, 35, 733-736.)-Auric chloride when treated with potassium iodide is quantita- tively reduced to aurous chloride, with liberation of iodine, which can be titrated with standard sulphurous acid. The results are exact, as are those obtained by substituting potassium bromide for potassium iodide, with subsequent titration of the liberated bromine.If the auric solution to be titrated be first mixed with an equal bulk of a saturated solution of sodium chloride or with magnesium chloride, the colour of the auric solution is intensified, and the titration with sulphurous acid can be conducted without the use of potassium iodide or bromide.The results are exact, but auric solutions cannot be directly titrated in hydrochloric acid solution free from alkali salts. I n such circumstances, the colour of the solution is paler to start with, sulphurous acid has no distinct bleaching effect, and metallic gold is readily separated.I n applying the above methods to metal, the latter is dissolved by means of chlorine- water or hydrochloric acid and potassium chlorate, and free chlorine is removed by addition of ammonia until a permanent precipitate forms. The solution is then acidulated with hydrochloric acid, warmed until the precipitate dissolves, and the gold is determined by any of the above methods.No attempt must be made to expelINORGANIC ANALYSIS 391 chlorine from the gold solution by evaporation, as some aurous chloride always results when this is done. The sulphurous acid solution is standardised either against stardard iodine solution, or against an acidified solution of potassium iodide to which a measured volume of standard permanganate has been added.By direct titration of sulphurous acid against permanganate, the author was unable to establish the strength of the former within 1 per cent. G. C . J. Volumetric Estimation of Manganese by the Volhard- Wolff Method. Chemikerkommission des Vereins deutscher Eisenhuttenleute.(Stahl u. Eisen, 1913, 33, 633-642 ; through Chem. Zentralbl., 1913, I., 2003).-1n blank tests the permanganate consumption is the same whether a small or a large excess of zinc oxide is used. Nitric acid solutions give the highest consumption of permanganate, hydrochloric acid less, and sulphuric acid the least consumption. In presence of sulphates the consumption of permanganate is less than in presence of an equivalent quantity of chloride or nitrate.In sulphuric acid solution the consumption of permanganate is greatest when the excess of zinc oxide is very small. In solutions of chlorides or nitrates the amount of zinc oxide present has no measurable influence on the results. The influence of varying concentration of the manganese solution is also negligible.The consumption of permanganate is highest when the titration is made in boiling or almost boiling solution. If the permanganate is added in several portions, halting between each addition, or if the solution be continuously shaken throughout the titration, the consumption of permanganate is too low. In exact work, the removal of the iron precipitate by filtration is essential.Even when iron is removed, manganese may be over-estimated if cobalt is present in quantity. No other metals, in the proportions in which they are likely to be present, interfere. The permanganate solution must be standardised on a solution of known manganese content under conditions closely approximating those obtaining in actual anrtlytical work. G. C. J. Gasometric Estimation of Nitric Oxide and Oxygen, depending on the Formation of Nitrous Anhydride.G. Klinger. (Bey., 1913, 46, 1744-1748.)- In an earlier paper (ANALYST, 1913, 45) it was stated that nitric oxide could be oxidised quantitatively to nitrous anhydride, provided it was confined together with some stick potash over mercury before admitting air. Under these conditions no nitrogen tetroxide is formed, since the nitrous anhydride is removed by the potash as fast as it is formed.It was also stated that inaccurate results were obtained when the process was reversed and the nitric oxide led into excess of air or oxygen confined with potash over mercury. It is now shown that these inaccurate results were due, not to excess of oxygen) but to presence of moisture. To obtain accurate results, the gases should be dry, and the potash should not be unnecessarily exposed to the air.A piece of stick, from one of the sealed bottles in which potash is sold for analytical purposes, serves well, but it should come from a bottle which has been kept sealed, and be quickly transferred to the gas pipette. With these precautions, the method is available, not only for the determination of nitric oxide, but for the392 ABSTRACTS OF CHEMICAL PAPERS determination of oxygen by use of an excess of nitric oxide. The criticism of Koehler and Marqueyrol (ANALYST, 1913, 171), that the method is not available in presence of carbon dioxide, is met by the statement that the gas in which nitric oxide is to be estimated can be freed from carbon dioxide and its content of that gas determined by the use of the same potash pipette that is used in the nitric oxide estimation.The use of this apparatus containing solid potash for absorbing carbon dioxide has the advantage that it does not, like a potash solution, absorb nitrous oxide, should that gas be present in the mixture under analysis. G. C. J. Estimation of Water-Soluble Phosphates in Ammonium Superphosphates.E. Biittner. (Chew. Zeit., 1913, 37, 662.)-The official method of the Verein Deutscher Diingerfabrikanten for the analysis of ammonium superphosphates does not prescribe any definite temperature for the aqueous extraction. The effect of temperature, however, is shown in the results-obtained by the author. Analyses of two samples containing 5 and 3 per cent. of nitrogen and 10 and 15 per cent.of phosphoric acid (P,O,) respectively gave from 0.3 to 0.6 per cent. less phosphoric acid than was anticipated. Dining the thirty minutes' shaking the temperature had fallen to about 16" C.; by using water at about 35" C., so that the temperature after thirty minutes' shaking did not fall below 18" to 20" C., about 0-5 per cent.more phosphoric acid was obtained. Somewhat higher results were also obtained by pass- ing the sample through a sieve of 1 mm. mesh. Note by Abstractor.-It is not stated whether the temperature has the same influence in the analysis of other superphosphates. C. A. M. Estimation of. Polythionate in Presence of Thiosulphate and Free Sulphurous Acid. W. Feld. (Zeitsch. angezu.Chew., 1913, 26, 286-288.)-The method previously described by the author (Zeitsch. angezu. Chem., 1911,24,290) gives accurate results when the amount of sulphur dioxide in the solution is very small. But when solutions containing notable amounts of sulphur dioxide are boiled with mercuric chloride, a large part of the sulphur dioxide escapes before the oxidation is complete. The following modification of the method gives accurate results even in presence of large proportions of sulphur dioxide. It depends on the fixation of sulphur dioxide as manganous thiosulphate by treatment with excess of manganous sulphide.On subsequent treatment with mercuric chloride, the manganous thio- sulphate liberates hydrochloric acid : 3S0, = 2MnS,0, = 4HC1. When treated with mercuric chloride, a molecule of ammonium thiosulphate, like manganous thiosulphate, liberates two molecules of hydrochloric acid, whereas ammonium tetrathionate liberates twice as much acid.On these reactions and the known behaviour of sulphur dioxide and thiosulphates towards iodine, the new method is based. A measured portion of the solution is first titrated with iodine, and then, after addition of ammonium chloride, with caustic alkali of the same normality as the iodine solution, using methyl orange as indicator.Half the consumption of alkali is the measure of the sulphur dioxide originally present, and if half the volume of alkali used be subtracted from the volume of iodine consumed in the first titration, the remainder is the measure of the thiosulphate.A separate portion of the original393 INORGANIC ANALYSIS solution is treated in the cold with excess in suspension of iiianganous sulphide, and the mixture is left for half an hour, with occasional agitation. It is then made up to known volume, filtered, and an aliquot portion of the filtrate is boiled with excess of mercuric chloride, and after addition of ammonium chloride is titrated with caustic alkali.From the amount of acid found, that due to the sulphur dioxide and thiosulphate originally present is deducted, and the remainder is calculated to tetra- thionate. solution of manganous sulphate is warmed to 60° C., and treated with hydrogen sulphide to reduce any higher oxides of manganese. When the solution appears to undergo no further change, a few drops of caustic potash solution are added, the current of hydrogen sulphide continued for a few minutes, and the solution'is filtered. The filtrate is warmed to 60" C., and hydrogen sulphide is again passed through it, when it should remain clear.The stream of hydrogen sulphide is now made a, vigorous one, and a solution of some 56 grms. of caustic potash (not soda) in a, little water is added drop by drop.The mixture is next kept at about 80" C. on the water-bath until it no longer smells of hydrogen sulphide, and until the supernatant liquid no longer reacts with iodine. The process may be hastened by leading hydrogen over the surface of the liquid. The mixture is finally diluted to 1,000 c.c., and is then an approximately suspension of manganous sulphide in approximately Fc manganous sulphate solution.The suspension of manganous sulphide is prepared as follows : 600 C.C. of a I t keeps unchanged for many months. G. C . J. Estimation of Alkali Sulphides. D. McCandlish and J. A. Wilson. (Collegzzm, 1912, 80-84 ; through Chem. Zentralbl., 1913, I., 1892.)-With regard to the method proposed by Blockey and Mehd (ANALYST, 1912, 37, 325), the authors point out that the ammonium chloride solution employed is not sufficiently alkaline GO prevent loss of hydrogen sulphide due to hydrolysis of sodium sulphide in aqueous solution, and that it does not contain enough ammonia to prevent the zinc from being precipitated as hydroxide by the lime liquor.This difficulty may be overcome by using a solution containing a suficient but not undue quantity of alkali, and an ammoniacal zinc sulphate solution is recommended containing such an amount of ammonia as will inhibit the precipitation of zinc hydroxide without interfering with the precipitation of the zinc as sulphide by converting the zinc into a complex amino-salt. Concordant results may be obtained in the analysis of sulphide solutions containing varying quantities of calcium hydroxide when ammoniacal zinc sulphate solution is used, whilst ammonium chloride solution gives erratic figures. I n the case of sulyhide solutions which are stronger than :G, it is recornmended that 25 C.C. of the solution be titrated with TG zinc solution; another portion of 25 C.C. of the sulphide solution is then treated with three-fourths of the quantity of zinc solution required for the first titration, the mixture is diluted to 100 c.c., filtered, and 25 C.C. of the filtrate are titrated ; the amount of zinc sulphate solution required for this last titration is multiplied by 4, and the result added to the number of C.C. (three- fourths) introduced previously. w. P. s.394 ABSTRACTS OF CHJMICAL PAPERS " Salt Error " in Colorimetric Estimation of Hydrogen Ion Concen- tration of Sea-Water. S. P. L. Sorenesen and S. Palitzsch, (Biochem. Zeitsch., 1913, 51,307-314.)-The relation between salt-content of the water and the correction that must be applied to hydrogen ion concentration found colorirnetrically is expressed graphically in the form of curves. The correction varies with the indicator used and liquid with which it is compared. Experiments were made with the following combinations : (1) Borate mixture and phenolphthalein, (2) borate mixture and naphtholphthalein, (3) phosphate mixture and naphtholphthalein, (4) phosphate mixture and neutral red. Correction curves are given for the first three ; in the case of phosphate mixture and neutral red no correction is necessary if the salt-content is less than 10 per 1,000. E. W.

ISSN:0003-2654    

DOI:10.1039/AN9133800381

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

394 ABSTRACTS OF CHJMICAL PAPERS APPARATUS, ETC. Dialysing Apparatus. W. Kopac- zewski. (Comptes rend., 1913, 156, 1853- 1855.)-The apparatus here shown may be used for the rapid dialysis of, e.g., enzymes into pure running water, the distillation of the water, and the concentration of the \ dialysable part. The dialyser A communi- cates by means of a two-way tap with the flask B, and with an exterior tube for taking samples of the water.The cork of the flask receives three tubes, one of which, T , com- municates with a vacuum pump, the second with the dialyser, and the third (of tin) with the Soxhlet coolers C, which are connected together by means of a tin tube with two arms. In using the apparatus, the flask is charged with a quantity of water equal to that to which it is desired to bring the dialysable part of the liquid, The tap R is closed while a vacuum is created within the flask, after which the tap r is closed, the liquid then heated to boiling-point, and the dialysis carried out at a temperature of about 40" C.The apparatus may also be used for distillations in vacuo without previous - dialysis. C. A. M. International Standards for Coloured Fluids, and a Suggested Plan for such Standardisation.H. V. Amy. (Eighth Inter. Cong. App. Chem., 1912, Vol. 26, 319-327.)-The author describes a method of colour-matching in which heAPPARATUS, ETC. 395 uses slightly acidulated (hydrochloric acid) solutions of (red) cobalt chloride (yellow) ferric chloride, and (blue) cupric sulphate, and blends these in any desired proportion. Starting with the possible combinations of the three colours that would make 1 2 C.C.when fractional portions of the C.C. are not employed, he has prepared a, set of eighty-eight blends, the tints of which, tabulated in the paper, range from the pink of cobalt to the blue of copper. H e suggests a system of colour nomencla- ture based on the proportion of the solutions employed to make the tint, and reports at length on such '' Go-Fe-Cu " factors for solutions of caramel and cudbear.H. F. E. H. Apparatus for Gas Analysis. J. S. Agraz. (Zeitsch. anal. Chem., 1913, 52, 418- 419.)-The apparatus, which is made by the Vereinigte Fabriken fur Laboratoriumsbedarf in Berlin, was designed with a view to producing a single piece of apparatus which would serve for a variety of purposes.The illustration is self- explanatory, except that the graduated tube is of 100 C.C. capacity, divided to 0.1 C.C. The dimensions given are fractions of a meter. G. C. J. Standardisation of Hydrometers. (rWemorandunz issued by the Director of the National Physical Laboratory, through Nature, 1913, 91, 412-413.)-The Director has issued these notes with a view of eliciting opinions from makers and users, and of obtaining informa- tion from other countries, as there is at present much ambiguity as to tbe bases of standardisa- tion of hydrometers graduated to read direct in degrees of sp.gr. The instruments are in all cases graduated for use in a liquid at a definite temperature, called the standard temperature of the instrument, and give the sp.gr. of this liquid a t some definite temperature, which may or may not be the standard tempera- ture of the instrument, referred to water at the same or some other temperature. The following three cases have arisen in practice, and it is desirable to fix upon one of them as the standard method : I. The water to which the sp. gr. is referred must be at the standard tempera- ture of the instrument.11. The water to which the sp. gr. is referred must be at some other definite temperature-e.g., 60" F., or possibly 4" C. Thus, if 85" F. is the standard tempera- ture of the instrument, and 60" F. that of the water, the sp. gr. of the liquid at 85" F. is referred to water at 60" F. 111. The graduations are such as to give the value which would be found for the396 ABSTRACTS OF CHEMICAL PAPERS sp.gr. of the liquid if it were cooled or heated to some other temperature and referred to water at that [or IV. some other] temperature. Thus, if the standard temperature of the instrument is 8 5 O F., the instrument would be used at this temperature, but its graduations would be such as to give the sp. gr., which would be found for the liquid if cooled to 60" F., and referred to water at 60" F.Thus, using a sugar solution at 85" F. of sp. gr. 1.1484 (Method I.), Method 11. would show 1.1447, and Method 111. 1.1500. Method I. has been the usual practice at Kew, 60" F. being the standard temperature ; No. 11. has the advantage that the reference temperature of the water is fixed, and gives results in agreement with the usual definition of sp.gr., which assumes a, fixed temperature for the water. H. F. E. H. Apparatus and Method for Determining Hydrogen Sulghide in Illumin- ating Gas. E. P. Harding and E. Johnson. (Eighth Inter. Cony. App. Chem., 1912, vol. 25, 673.)-The hydrogen sulphide is absorbed by a solution of cadmium chloride, liberated in a partial vacuum by hydrochloric acid, and titrated with standard iodine.This gives much more accurate results than Tutwiler's method, and agrees well with the gravimetric cadmium chloride method, which is the most accurate at present in use, but is not sufficientlyrapid for control work. The method described requires only from seven to ten minutes for a determination. 0. E. M. Apparatus fok the Determination of Dissolved Oxygen in Water.G. A. Soper. (Eighth Inter. Cony. App. Chem., 1912, vol. 26, 265.)--The method depends upon the measurement by permanganate of the oxidation caused in ferrous sulphate by the oxygen dissolved in water. A special form of apparatus is described which allows of the addition of the reagents (ferrous sulphate solution, sodium carbonate, and sulphuric acid) without exposing the water to the air.The bottle employed has a capacity of about 500 c.c., and has a long funnel-shaped top rising above the stopper, which is convex at the bottom, and when in place allows about 15 C.C. of liquid to stand in the funnel without overflowing. The capacity of the bottle is accurately gauged with the stopper in position. After filling the bottle with the water to be examined: and emptyiug the excess which rises in the funnel, 6 C.C.of the standard ferrous sulphate (144 grms. of sulphate and 15 C.C. concentrated sulphuric acid diluted to 3 litres) are delivered by a pipette to the bottom of the bottle. The stopper is replaced, and the water which rises in the funnel is gently poured off. Five C.C. of sodium carbonate solution (20 grms.crystals per 100 c.c.) are then poured into the funnel, and the stopper gently raised sufficiently to allow the heavy alkali to sink through the water to the bottom of the bottle. The stopper is lowered, the excess of water in the funnel is poured off, and the bottle shaken until the free oxygen is entirely absorbed. Ten C.C. of a 50 per cent. solution of sulphuric acid are then added in the same way, and the contents of the bottle are then turned out into an Erlenmeyer flask and titrated with permanganate.A blank determina- tion is made whenever the water contains much organic matter or chlorine, the same process being followed, omitting, however, the addition of sodium carbonate. H. F. E. H.APPARATUS, ETC. 397 Practical Field Method for the Determination of Dissolved Oxygen in Water.G. A. Soper and P. B. Parsons. (Eighth Inter. Cong. App. Chem., 1912, vd. 26,267-269.)-The method employed is similar to that in the preceding abstract, the sample being collected in a special form of apparatus, consisting of a separating funnel connected with an empty bottle of much larger capacity. The two are lowered together by a rope to any desired depth, the method of their connection being such that before the bottle can be filled the separating funnel has first to fill and empty itself several times.The separating funnel is then filled with the sample of water in the bottle, and the determination of the dissolved oxygen proceeded with as already de- scribed. A control sample which has been collected in a similar manner is also tested, but in this case the sulphuric acid is added first and the whole well shaken before introducing the ferrous sulphate, the acid reaction thus preventing the dissolved oxygen from acting on any of the ferrous salt.The difference between these results is the amount of ferrous salt acted on by the dissolved oxygen of the water. The form of separating funnel is substantially the same as that described by G.A. Letts (Appendix VII., Fifth Report of the Royal Commission on Sewage Disposal). The method is claimed to be especially suitable for field work and for tidal waters, or those containing nitrites. H. F. E. H. Methods and Apparatus used in Petroleum Testing. Part 11.: Viscosi- metry. W. F. Higgins. ( J . SOC.Chem. Ind., 1913,32,568-572.)-An abstract of a paper which described experiments made at the National Physical Laboratory, the chief object of which appears to have been to determine whether some simple expression could be found connecting true viscosities with the observed times of efflux from a Redwood viscosimeter, and to determine the order of accuracy which would attach to viscosities calculated by the use of such an expression.A comparison is also instituted between the results obtained by Redwood’s and Engler’s viscosinieters respectively. For a particular instrument of the Redwood type, and with times of efflux ranging from 40 to 2,000 seconds, it was found that the expression qt= (0*0026T---,)S gave numbers which differed from the true viscosities by less than + 5 per cent., T being the time of efflux in seconds and 6 the density of the liquid at to C., the temperature at which the experiment is made and at which it is desired to know the true viscosity, qt.Ubbelohde (Tabellen xum Englerschen Viskosimeter, 1907) has arrived at the formula qt= (0.001435 T - ’$) 6 for calcula- ting viscosities from the observed times of efhx from Engler’s viscosimeter, T in this case being the time of efflux, not of 50 c.c., as used with Redwood’s instrument, but of the normal Engler quantity of 200 C.C. From these two equations the author has calculated the ratio TE/T, (time of efflux with Engler’s viscosimeter / time of efflux with Redwood’s viscosimeter) for nine values of T,.For values of T, from 5,000 down to 150, this ratio is almost a constant, 1.81.As T, is further diminished, it increases slightly, becoming 1.83 when T, =; 40. Experimental comparison of an Engler and a Redwood instrument pointed to a ratio RE/R, = 1.8 k0.06. The same series of experiments showed that Ubbelohde’s formula or tables, when used to 1.715398 ABSTRACTS OF CHEMICAL PAPERS calculate viscosities from the results of experiments with the particular Engler viscosimeter possessed by the author, gave numbers mostly above the truth, the errors ranging from - 2 per cent.to + 8 per cent. Note by Abstractor.-The paper as printed contains two errors clearly attributable to its having been curtailed for purposes of publication, and the printed text would justify the assumption that the author was putting forward his formula, as applicable to all Redwood viscosirneters.This would conflict with the universal experience that the indications of these instruments may vary, and the printed discussion shows that the author is aware of such variations. The full text of the paper may be expected to appear in the next volume of “Collected Researches of the National Physical Laboratory,” or in some publication of the International Petroleum Commission, on whose behalf the experiments were made.G. C . J. Apparatus for Recovery of Evaporated Organic Solvents. W. Friese. (Pharm. Zentralhalle, 1913, 54, 419 ; through Chem. Zentralbl., 1913, I., 2015.)-The apparatus consists of an inverted double-walled, water-cooled funnel standing on three feet in a glass or metal circular trough, which fits over the evaporating basin, and has a side tube through which the recovered solvent runs off.I t is made by Hugmshofl, Leipzig. 0, E. M. New Thermo-Regulator. E. Esclangon. (Conzptes rend,, 1913, 156, 1667- 1670.) - This consists of a circular tube, A C B, closed at A and open at B. It revolves round its centre, 0, and at P carries a pulley, from which is suspended a weight, Q.The closed part of the tube, A, contains a saturating vapour, the nature of which ..A depends upon the temperature which the apparatus is required to maintain. Thus for temperatures between 35’ and 40” C. ether is a suitable substance, for temperatures about 55” C. acetone may be used, and for tempera- tures about 100’ C. water is suitable.The centre of gravity of the apparatus is on the axis 0. Any alteration in the temperature will destroy the equilibrium and cause move- ments of the apparatus, the extent of which is controlled by the stops x and y. All that is required is to connect the movements with a heating or cooling apparatus. C. A. M. Comparison of Redwood’s and Engler’s Viscosimeters. W. Meissner. (Chem.Rev. Fett Ind., 1913, 20, 123-126.)-Practical tests with standard instru- ments have been made, and the results compared with those calculated by means of the author’s formulae (ANALYST, 1912, 37, 223). The relationship between the twoAPPARATUS, ETC. 399 viscosimeters was found to vary with the temperature. The ratio between the Redwood values and the Engler degrees, which at 20" C.deviated from unity by amounts up to 11 per cent., was found to be about 6 per cent. greater at 50" C. than at 20" C. The explanation is that at 50" C. there are differences in temperature between the different parts of the apparatus, but it has not yet been ascertained in which type of viscosimeter the influence of these differences is the greater. C. A. M. Precision Viscosimeter for Measurement of Relative Viscosity and the Relative Viscosities of Water at O", 18", 25" and 50" C.E. W. Wash- burn and G. y. Williams. (J. Amer. Chem. SOC., 1913, 35, 737-750.)-An improved viscosimeter of the Ostwald type is described. Its water-constant at a given temperature is not changed by cleaning with hot mixtures or by subjecting the viscosimeter to large variations of temperature.The water-constant (about 580 seconds at 25" C.) can be repeatedly reproduced to about 0.03 second under a given set of conditions. For effective pressures within the limits 130 and 300 mm. of water the deviations of the viscosimeter from Pouseuille's law is less than 0.03 per cent. The relatively large size and flattened shape of the lower bulb of the viscosimeter have the effect of reducing to negligible proportions any error due to small inequalities in the volume of liquid taken for the test.The normal charge with this instrument is 65 c.c., and an error of 1 C.C. in the measurement has so little effect on the mean head of liquid during the experimental interval that the time of flow varies no more than 0.05 per cent. A single instrument of this type can be used for a large temperature range, because its dimensions do not vary with varying temperature. The quartz viscosimeter is made by the Silica Syndicate, London. The relative viscosities of water at 0", 18O, 25", and 50' C. are given as qls/qo = 0.58978, q25/qo = 0.49741, and qso/q0 = 0030640, with a probable error of k 0.03 per cent. In obtaining these results the authors made use of chronometric apparatus permitting periods of time up to one hour to be recorded within 0.01 second, and of thermostatic appliances permitting temperature regulation to within a few thousandths of 1" C. These appliances are described in the paper, which also includes a statement of the reasons which determined the choice of the exact form and dimensions of the viscosimeter. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9133800394

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

APPARATUS, ETC. 399 REVIEWS. Pp. xx+ 726. INDUSTRIAL AND MANUFACTURING CHEMISTRY : ORGANIC. By GEOFFREY MARTIN, Loodon : Crosby Lockwood and To review a book of this cyclopaedic character fairly is always difficult, especially so when, as in the present case, the reviewer comes from his perusal of it with a more lively sense of its shortcomings than of its merits. The first question which will be aeked concerning such a book is, For whom does it cater or set out to cater, and what is its scope? Let the preface speak for itself : Ph.D., M.Sc. (and Others).Son. 1912. Price 21s. net.400 REVIEWS “ This book is a treatise on the applications of organic chemistry to the arts and manufactures. It embraces both British and American practice, and affords, so far as is ascertainable in view of the many secret processes employed, thoroughly up-to- date information regarding the various branches of chemical industry.. . . The editor’s aim has been to cover the whole range of subjects with which the industrial chemist and manfacturer are usually concerned, and the book will serve either as a textbook or as a work of reference ; it is intended to meet the requirements of all business and practioel men interested in chemical processes, of manufacturers, con- sulting chemists, chemical engineers, patent workers, inventors, technical lawyere, lecturers on technology, fire-insurance inspectors, and others.” Any chemist reading the above will appreciate the reviewer’s difficulty, especially if one or more subsections of the work are useful contributions to chemical litera- ture, for the book as a whole must fail to achieve the editor’s aims.Thorpe’s “Dictionary of Applied Chemistry” even achieves less, and the editor of that work did not attempt the almost impossible task of providing matter which should be at once intelligible to insurance inspectors and technical lawyers, and yet instructive to chemical engineers and manufacturers. The book is divided into twenty-three sections, and the labour of producing it has been very unequally shared by fifteen contributors.As the sections are still further subdivided (Section I., for example, into thirteen subsections, the work of five writers), no reviewer can be expected to indicate the relative value of each fragment of the text, nor could a reviewer be found competent to deal with 6‘ the whole range of subjects with which the industrial chemist is concerned.” All that can be attempted is to examine the book as to its possible usefulness to any of the varied types of person to whom it is addressed. Readers of this journal will wish to know if the book is likely to afford any help to the analyst faced with a proposition unfamiliar to him.Now, in fairness to the contributors, it must be pointed out that the book makes no pretence to be a text- book of analytical methods. But a description of analytical methods is a prominent feature of the book, and one has a right to expect such information and references as are given to be accurate. On pp. 263-264 we are told that (‘ the percentage of extract in malt is usually determined in the laboratory by first grinding it into the finest possible powder, and then extracting with a definite quantity of water at 60 to 65” C., and taking the rotation of the filtered solution with the polarimeter.” For details of this method we are referred to Bailey’s (‘ Brewers’ Analyst.” Now Bailey’s Brewers’ Snalyst ” will not bear the most casual scrutiny of a chemist, and no one with any knowledge of the work of a brewing laboratory could have been guilty of the paragraph quoted.The section on brewing which is by the editor and Mr. C. H. Grifiths, a brewing engineer, contains far too many mistakes to be a safe work of reference: the real technologist will learn nothing, and other readers may be misled. The name of Dr.A. Slator, who is an authority on brewing chemistry, appears on the title-page, but his sole contribution is a two-page article on the rate of alcoholic ferment ation. As this book claims to embrace both British and American practice, we put ourselves in the position of a British manufacturer seeking information on anREVIEWS 40 1 industry which has attained to an exceptional state of development in America-the maize starch industry. We found eight lines on p.178. The preface says that particular pains have been taken to incorporate minor industries, as such minor industries, through absence of competition, frequently afford profits far greater than those of fully developed trades. It is within the reviewer’s knowledge that the apparent gross profit to be made out of caramel has tempted many persons to inquire into this industry.I n the index to this book such a person will find “ Caramel, 142, 176, 265,” and on turning to these pages will learn that sucrose on heating loses water, yielding caramel ; that Germany produces from starch about 5,000 tons of caramel or burnt sugar; and that, in order to obtain dark beer and produce a pronounced malt flavour, caramel and black malt are added in small amount, mixed with the other brewing materials.Rather a poor reward for turning up three references ! The above experience directed your reviewer’s attention to the index, which occupies no less than sixty pages-surely a good point in a work of reference, if quality matches quantity. acetone ” was selected at random.Apart from sub-indexing, under “recovery ” and other words, no less than ten page references follow the word (‘ acetone.” Of these, three are in heavy type, and a note informs us that “When several references are given, the ones with heavier type denote the more important.” Will it be believed that one of the three refer- ences is to a page dealing with the synthesis of the eucaines? Further experi- ment with the index confirmed the impression that it was the work of someone unfamiliar with the subject-matter.Such a, person might be excused for the heavy-type reference to the page relating to the synthesis of the eucaines, for that page not only contains the word acetone ” several times, but is embellished with the graphic formula of that substance duly labelled. Relegating the indexing of a technical book to an incompetent person, however, is inexcusable.I t may waste incalculable hours if the book gets a circulation. Anyone looking up ‘‘ tartar emetic,” for instance, would turn to p. 583, glance at it, suspect a misprint, try p. 383, or consult the twenty-page table of contents, and then give it up. There is no misprint.The only reference in the book to tartar emetic is the statement that it is used as a mordant in dyeing leather, and this appears on p. 583. The omission of any further reference to tartar enietic is unimportant, but the naome of the substance h;zs no right to appear in the index at all. Many of the articles in the book are carefully written, the names of the contributors being almost sufficient guarantee of this.For example, the section on leather, by D. J. Law, appears to be an excellent cyclopEdia article. Mr. Law does not attempt to cater for the varied clientele to which the editor appeals in his preface. He has neither tried to impress expert critics with his erudition, nor written down to the level of the fire-insurance inspector. Consequently, a chemist or engineer xith little or no knowledge of the leather industry, suddenly compelled to acquire a broad acquaintance with some branch of it, will probably find the section helpful, and will certainly not be misled.Mr. C. A. Mitchell’s name is a guarantee of the care with which some other sections have been written, but it is difficult to understand why he was asked to write a three-page To test its quality,402 REVIEWS article on essential oils.No one will doubt Mr. Mitchell’s capacity to write a bcok on the subject, but in three pages what can he tell which is not to be found in one or more books on the shelves of every chemist, even those whose work seldom or never brings them up against essential oils? As the section is scarcely intelligible to the non-chemist, it is difficult to see what useful purpose it can serve.AS has been said already, your reviewer cannot take a book of this kind section by section and say which are trustworthy. In the sections dealing with the industries with which he is most familiar he finds so many inaccurate statements that he would fear to trust to other sections by the same writers for information on subjects less familiar to him.His duty would therefore seem to be to warn others against relying on the book. It is often necessary for a chemist or engineer unfamiliar with a particular industry to make himself acquainted with the general features and lay-out of the plant employed in that industry. Often he can find few illustrations, and those antiquated.The illustrations in this book are numeroas, and almost all of them reproduced from current makers’ catalogues. G. CECIL JONES. The illustrations deserve a word. BEURRES ET GRAISSES ANIMALES. Par ALBERT BRUNO. (MANUELS PRATIQUES This manual, one of the series of practical treatises on chemical analysis, pub- lished under the direction of Mons. Bordas and Roux for use in official laboratories and elsewhere, is chiefly concerned with French official methods for the examination of butter, animal fats, and margarine.The methods set forth are almost entirely of an official character and conse- quently somewhat ponderous, as such methods usually are. They are, however, well and carefully described, but being intended principally for French official prac- tice, they are not likely to be of great use to the English chemist, who will find more practical and more modern methods in the literature of his own country.Still they have the advantage of showing him how results are obtained in French official prac- tice, and their value is enhanced by a most useful chapter on (‘ International Nota- tion,” and the methods by which results as usually obtained may be converted into this form of expression, The introduction contains some very sound remarks on the confusion that arises from the employment of varying forms of expressing analytical results, and the author expresses the wish (which will be echoed by many) that certain standard methods might be adhered to in official work, and a stop be put to the unceasing stream of new and often doubtful methods which swells the already large literature of this subject. The chapter on expression and interpretation of results is distinctly good and is illustrated by many useful tables foundeil on the methods described, but the author rightly remarks that figures obtained by the actual investigator are of more use to him than published figures.At least half the volume is devoted to butter, and the sections dealing with lard, margarine, and tallow are consequently very condensed ; and whilst the details of examination given are sound and practical, they will not be of much use to those D’ANALYSES CHIMIQUES.) Paris : Ch.BQranger. 1912. Price 6 f.REVIEWS 403 who are not fairly well acquainted with the subject, and might well have been treated more fully. The book, whilst in every way excellent, is not suitable for those who desire guidance in the occasional examination of butter, etc.At the same time, those whose work lies principally in this direction will probably find much to interest them. The various laws and regulations concerning these products, which are and have been in force in France are fully set out, together with a synopsis of the regulations in force in practically every civilised country.These appendices will be of consider- able value to those who have constantly to examine the produce of other countries, and it is to such, as has been said, that the work will be of chief interest. CECIL REVIS. THE QUALITATIVE ANALYSIS OF MEDICINAL PREPARATIONS. By H.C. FULLER. New York : John Wiley and Sons; London : Chapman and Hall, Ltd. 1912. Pp. ix+132. Public Analysts and other analytical chemists who, from following the proceedings of the Select Committee of the House of Commons on Patent and Proprietary Medicines, or from other causes, have realised the enormous difficulty of analysing, even qualitatively, complicated mixtures of vegetable extracts and other preparations of drugs, will be inclined to turn hopefully to any new work promising assistance in the analysis of medicinal preparations.I n the case of the small volume under review disappointment will follow hope. The book is by an American writer for American readers, and relates apparently to American Patent Medicines. I t is a vast collection of “ facts ” largely relating to bodies many of which are but rarely met with, in this country, at all events.Alphozone, Chinaphenin, Coronillin, Oxaphor, Periplocin, and Spirosal, are half a dozen selected at random. Among the long list of substances enumerated, the occurrence of many of which must be rare, the limit of unlikelihood surely being reached with skatol, the reviewer failed to find mention of several commonly occurring and important medicinal chemicals, as, for instance, formates and glycerophosphates.Throughout the classified lists of substances where italics are used to call attention to the commoner substances, the use of italics does not appear to have been made with much discretion. The author’s style is abbreviated to breaking-point, and frequently leaves some- thing to be desired, as instance the statement on p.3, that lead acetate is LLpaTtZy Boluble in alcohol,” and this sentence on p. 86: “Be sure the lime and magnesia are free from arsenic, or decompose with nitric and sulphuric acids.” Throughout the work the names of alkaloids are denied the terminal ‘‘ e,” which is irritating to English readers, while split infinitives and errors of syntax are not wanting.The first portion of the book (pp. 1 to 78) is concerned with the scheme of analysis for the separation and detection of substances in medicinal products, and consists largely of long lists of such ‘( substances.’’ Crude drugs, resins, extracts, oils, and other mixtures are designated (‘ substances ” in this book. The tests given for identifying the 6 L substances ” are very largely colour reactions.In some cases Price 6s. 6d. net.404 REVIEWS melting-points are given; but information as to how the “substances” are to be isolated in order that the colour reaction may be applied, or the melting-point determined, is not forthcoming. Thus, on p. 86, the reader is instructed to “ remove a portion and test for sucrose, citrates, tartrates, acetates, albuminous material, hypophosphites, hypochlorites, peroxides, and for substances which may become altered by heat,” without any guidance as to how these operations are to be performed.I t is well known that colour reactions are only to .be relied upon when the substance is free from admixture, such as usually occurs, unless great precautions are taken, in the case of separation from complicated organic mixtures.This interference the author recognises in the Introduction, but not in the body of the work, except that on p. 35 he frankly remarks that “the colour reactions given with sulphuric acid are usually only characteristic when the substances are pure and alone.” Similarly, in order that the melting-point may be used zts an analytical factor, the substance-which may be a minute quantity of an alkaloid or glucoside- has to be separated and purified, an operation frequently of extreme difficulty. Aconitine is ineptly stated on p.36 to melt at ‘( 182’ to 186’ slow heating.” Now, the melting-point of aconitine varies according to the rate of heating, the alkaloid being decornposed by slow heating; but by no means can a distinctive melting-point be obtained within the range given in this book.On p. 56 a test is given for aconitine which deserves strong condemnation, the reader being instructed as follows : “ Aconitiiz.-Dissolve residue in water containing a few drops of acetic acid and take 1 to 2 C.C. in the mouth, rolling it round with the tongue, and then expectorate.If aconitin is present, the tingling sensation will soon appear. If sufficient alkaloid is present, prepare the aurochloride,” etc. For the personal safety of some readers it seems expedient to remark that, if suffi- cient aconitine is present, there would hardly be time to prepare the aurochloride before death supervenes, even though the analyst exhibit transatlantic facility in expectora- ting.The author continues : “If sufficient alkaloid is present, prepare the aurochloride, which is a well- defined crystalline salt, wash, dry, and take the melting-point, which, in the case of the pure salt, is 135’,” Inasmuch as aconitine aurochloride exists in three modifications, each having its distinct melting-point, these instructions are scarcely adequate for the identification of aconitin.In fact, the treatment of the alkaloids cannot be said to be at all satisfactory. No reliable instructions, for instance, are detailed for the separation and identifica- tion of so important an alkaloid as morphine, nor, indeed, for any other alkaloid. Among such tests, other than colour reactions and melting-points, as are to be found, there is a lack of thoroughness and accuracy which prevents the acceptance of this book as a safe analytical g,uide.Thus, on p. 15, the development of a blue colour with ferric chloride as proof of the presence of epicarin, even when salicylic acid arid vanillin have been excluded, appears to lack finality. On the same page reduction of ammoniacsl silver nitrate is stated to indicate either chloral or dormiol ;REVIEWS 405 and a subtle colour test for subcutin is applied to a residue regardless of the interference of other substances. On p.24 aspirin is stated to give a violet coloration with ferric chloride, a result which is not obtained unless the acetyl- salicylic acid (aspirin) contains a11 impurity-q., salicylic acid. On pp. 78 and 79 there is detailed a procedure for examining preparations for arsenic which is superfluous to the expert analyst, and an unsafe guide for others; while on p.25 the author himself apparently tires of the long list of tests, for he naively remarks : “ If this scheme does not Berve to identify the substances present, proceed according to Mulliken’s scheme for the identification of organic bodies.” Pp.81 to 108 are devoted to methods of analysis of certain classes of pharrna- ceutical products. Of these special sections that on L c Elixirs ” is probably the best, the subject being treated systematically and in such a manner as to be of real use to non-pharmaceutical analysts. One regrets that other sections in the book are not treated on similar lines. The “ Extracts ’’ form one of the most important classes of pharmaceutical preparations, and their analysis presents, perhaps, the greatest diBculty; yet this is at once one of the briefest and weakest sections in the book.One looks in vain for mention of such common and important extracts as those of ergot, opium, nux vomica, belladonna, Indian hemp, liquorice, senna, cinchona, rhubarb, and male fern.Under this section, on p. 93, the author’s nalveth once more asserts itself and prompts him to state (of extracts) that 6 L they often take part in the preparation of pharmaceuticals, but alone one is seldom called to analyse them, and when they are sold in this way they are usually labelled so that an identification is not difficult.” Ointments, on p. 102, are stated to contain, besides “ alkaloidal bodies dissolved as oleates in suspension,” also (‘ flavouring agents,” which excites one’s curiosity as to whether in the author’s view ointments merit the same treatment as aconitine.Pills are stated to contain gypsum (an unlikely constituent), but no mention of French chalk, which forms the coating of ‘‘ pearl-coated ” pills, is to be found. To systematise the qualitative analysis of drugs and I L substances ’’ used in medicine is a task of such extreme difficulty as to be virtually an impossibility, and to say that the author has not succeeded is not to deny utility to his book.To work out a qualitative analysis of even the mixtures and compounds mentioned in this book would occupy a lifetime, and it may be said with little fear of contradiction that a life could easily be better and more profitably spent.C. A. HILL. CHLORIDE OF LIME IN SANITATION. By ALBERT H. HOOKER. New York : John Wiley There is little matter of analytical interest in this book, but there is a large amount of information which will be useful to chemists engaged in the control of water and sewage purification, and in disinfection work generally.The first one-third of the book con- sists of an account of the use which has been made of chloride of lime in tbe sterili- sation of drinking-water, in the treatment of sewage, in the watering of streets, in surgical practice, on the farm, and in the destruction of house-flies. These chapters are written in a style which can be followed by the ordinary reader, as it appears to be and Sons.1913. Pp. v+231. Price 12s. 6d. net. The book is divided into two distinct parts.406 INSTITUTE OF CHEMISTRY part of the author’s object to encourage the more general use of disinfection processes. The following two-thirds of the book is the more important part to the technical reader. I t consists of a bibliography of the literature of the matters treated in the first part, extending to 442 entries, and classified according to subjects.In nearly all cases an abstract of the reference quoted is given. Many of these abstracts are those of official and annual reports, the contents of which frequently fail to become generally known ; and for thus drawing attention to them the author deserves the un- stinted thanks of workers in the subject.There is an index to subjectsand authors, and the names of the authors mentioned in the bibliography are included. J. H. JOHNSTON. INSTITUTE OF CHEMISTRY. PASS LIST : JUNE-JULY (1913) EXAMINATIONS. LONDON AND GLASGOW. OF thirty-three candidates who presented themselves for the Intermediate Examina- tion, sixteen passed: R. L. Amoore, R. 0. Bishop, A. Dingwall, J. W. Donaldson, B.Sc. (Edin.), J. G. Duncan, A. Dunsmore, J. S. Frith, Peter Kerr, B.Sc. (Edin.), K. G. Lochhead, J. W. Lorimer, H. V. Parker, B.A. (Cantab.), H. C. Reynard, F. Smith, F. W. Snelgrove, B.Sc. (Lond.), A. R. Steele, and A. F. Weiss, B.Sc. (Lond.). Of forty-five candidates who presented themselves for the final examination, twenty- four passed; in the Branch of Mineral Chemistry: B. Campbell, B.Su. (Lond.), J. A. Pickard, B.Sc. (Lond.), A.R.C.S. (Lond.), E. A. Rayner, B.Sc. (Lond.), and E. W. Skelton, B.Sc. (Lond.) ; in the Branch of Metallurgical Chemistry : R. J. Dunn, B.Sc. (Birm.) ; in the Branch of Physical Chemistry : (Miss) G. Thompson, B.Sc, (Lond.) ; in the Branch of Organic Chemistry : J. S. Bainbridge, B.Sc. (Leeds), A. L. R. Clarke, B.Sc. (Lond.), A. Cunningham, B. B. Dey, M.Sc. (Calcutta), J. R. Gray, G. N. Grinling, E. S. Hawkins, B.Sc. (Birm.), P. C. R. Kingscott, A.R.C.S. (Lond.), D. E. Sharp, B.Sc. (Aberdeen), T. F. Smeaton, E. W. Smith, B.8c. (Lond.), and R. Wheatley, B.Sc. (Leeds); in the Branch of the Chemistry of Food and Drugs, and of Water : (Miss) D. J. Bartlett H. B. Brown, D. W. Kent-Jones, B.Sc. (Lond.), H. A. Phillips, H. V. Potter, and S. H. Stroud.

ISSN:0003-2654    

DOI:10.1039/AN9133800399

出版商:RSC    

年代:1913

数据来源: RSC