摘要:

JULY, 1909. Vol. XXXIV., NO. 400. THE DETERMINATION OF THE “OXYGEN ABSORBED?’ OF SEWAGE AND EFFLUENTS BY A MODIFICATION OF KUBEL’S METHOD. BY W. CARTER. (Read at the Meeting, April 7, 1909.) IN a, paper by Dunbar ( J . Sanitary Inst., 1904, 25), a determination of the oxygen absorbed of sewage and effluents by a modification of Kubel’s method is described. This method, as well as Kubel’s, gave results too high for comparison with the ordinary four -hour B digestion method. In some determinations of the oxygen absorbed of sewage and effluents at Bury,302 THE ANALYST. it was found that, if the mixture of permanganate, acid, and water, to be examined is raised to a temperature of 60" C., and maintained between 55" and 60" C. for a period of ten minutes, comparable results are obtained.EXPERIMENTS WITH SEWAGE AND EFFLUENTS. Method I.-Titration at 55" to 60" C. A blank experiment was carried out as follows: A mixture of 50 C.C. KMnO, (1 C.C. =0.0001. O.), 10 C.C. dilute H,S04 (1 : 3), and 70 C.C. of distilled water, con- tained in a clean flask, was raised to 60" C. as quickly as possible (a minute sufficing as arule), with constant stirring, and maintained between 55" to 60" C. for a period of ten minutes. A measured and sufficient quantity of potassium iodide solution to reduce the permanganate was added, and sodium thiosulphate rapidly run into the hot mixture until the yellow colour was just discernible. A measured quantity of starch solution was now added, and the titration concluded. The experiments with sewage and effluents were carried out similarly.If the temperature of the mixture on adding the starch solution should be above 40" C., the blue colour will not develop, and the contents of the flask must be cooled. In the following experiments (except in those with tap-water) the quantity of sodium thiosulphate added reduced the temperature below 40" C. ; the quantity of starch and iodide added was the same in all cases. !Method II.-Titratioiz i ? ~ the Cold. The procedure is similar to that just described, with the exception that the mixture is cooled to the room temperature before titration with thiosulphate ; eight to nine minutes are allowed for cooling under the tap. Method III.-Titration at 55" to 60" C. with Oxalic Acid. I n this case oxalic acid is used instead of sodium thiosulphate, the other con- ditions being the same as those of Method I.The blank, after standing ten minutes at 60" C., is used to estimate the strength of the oxalic acid in the usual way. After heating the sample, the requisite quantity of oxalic acid (as determined bythe b1ank)is run into the hot mixture, and the excess titrated with permanganate. The results are slightly higher in comparison with the four-hours digestion than with Methods I. or 11. RESULTS OBTAINED BY METHODS I., II., III., AND COMPARED WITH THE FOUR-HOURS DIGESTION AT 16" C. Filtered effluents ... Tank effluents ... 35 $ 9 ,? 9 , 70 C.C. taken with 50 C.C. KMnO, and 10 C.C. acid. Crude sewage ... 35 9 , 100 C.C. KMnO, and 20 C.C. acid.THE ANALYST. Method I. 303 Filtered Effluents.~ 1.42 0.79 0.45 0-39 0.24 0.42 0.41 069 1.45 1.85 0.31 0.20 1-31 0.72 0.40 0.38 0.24 0.35 0.41 0.69 1.32 1 -83 0.30 0.18 4.34 3.68 4-24 2.93 3.25 3.47 Four Hours. 4.37 3.79 4.40 3.00 3.24 3.43 Method II. 2.09 3-50 4.00 3984 5-28 3.84 2.15 3 -10 4-24 4-32 5.57 3-90 Method IIL 2.30 3.74 4.10 3.20 3.64 3-38 2.15 3 *88 3.93 3-00 3.43 3.24 Crude Sewage. 9-80 11.30 10.86 7.66 8-99 3.16 8.50 6.70 13-26 11-24 3.98 7-61 3.75 8.70 7.80 11 -00 7.80 11-30 Four Hours. 9-60 11.10 10.20 7.48 8-71 3.50 8.30 7.00 13-60 11.10 3.68 7.73 3.32 8.30 7-00 10.64 7.50 10.20 Ferrous sulphate was tried, and gave results which agreed fairly well with the above. RESULTS OBTAINED WITH TOWN SUPPLY BY METHODS I., II., IIT., AND COMPARED WITH THE FOUR-HOURS METHOD AT 16OC. The quantities used were : tap-water 250 c.c., KMnO, 50 c.c., and H,SO, 10 C.C. Methad I. Method 11. Four-Hours Digestion. 0.140 1.. 0.134 ... 0.123 0.131 ... 0.129 ... 0.127 0.087 ... ... 0.052 0.095 ... ... 0.074 0,120 ... ... 0.116 Method 111. Four-Hours Digestion. In conclusion, I wish to acknowledge my indebtedness to Mr. W. Scott for his assistance throughout the experiments.

ISSN:0003-2654    

DOI:10.1039/AN909340301b

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

304 THE ANALYST, AN ABNORMAL SAMPLE OF BUTTER FROM A CHESHIRE HERD OF COWS. BY ALFRED SMETHAM, F.I.C. (Read at the Meeting, May 5, 1909.) THE following case furnishes another instance of the well-known fact that, under some conditions, even a herd of a considerable number of cows may yield abnormal butter. A sample of butter, taken early in December, 1908, having been condemned as containing an admixture of foreign fat, a portion of it was, a month later, referred to me, with information from which it appeared improbable that adulteration had taken place. For comparative examination I obtained a sample of butter direct from the farm in Cheshire from which the suspected sample was originally supplied, and also, from the same farm, a sample of milk, from which I myself churned some butter.The three samples gave the following results : Original Butter taken Butter churned Suspected Sample, at Farm, from Afternoon Milk, December 3. January 5. January 8. Reichert-Wollny figure . . . 18.8 17.9 17.9 Iodine number . . . ... 44.6 39.6 - I understood that the cows still left in milk on January 8 were two barren COWS, three late calvers, and about ten cows just going off milk and milked only in the morning. On January 11 I examined butter churned by myself from the mixed milk of all these cows, obtaining a Reichert-Wollny figure of 17.4. Two other analysts to whom the milk was forwarded found 17.8 and 17.1 respectively. Two further samples of butter churned in the ordinary way on the farm gave Reichert-Wollny figures of 18.6 and 18.1. The farm, I should say at once, was a cheese-making farm, and, as it seemed to me probable that this case might be typical of other cases in Cheshire (where it is the custom when the cows are going off milk-and only then-to make butter instead of cheese), I thought it would be interesting to inquire further into the circumstances, and to this eud I asked the owner of the cows for full particulars of his herd, mode of feeding, etc.. At the time (the beginning of December) when the original sample of butter was taken there were fifty cows still in milk, but rapidly going off. Of these, forty had calved in February and March, eight in April, one in May, and one in June. As far as recollection served, the suspected sample was made from a, mixture of whey cream from the last cheeses and cream from the milk yielded after cheese-making had ceased, the two creams being mixed and churned together.So long as cheese was being produced (that is to say, up to the time just before the taking of this sample), the cows were fed with corn in addition to grass; and they were at that time in “fair” condition-that is to say, in about the same condition in which average cheese- making herds in Cheshire would be at that time of year. When cheese-making ceased the corn was dropped, and the feed consisted of hay of somewhat inferior The inquiry elicited the following facts :THE ANALYST. quality (ad libitum) and what grass the animals could get when they were turned out in the middle of the day. This change of diet was made because it was desired that the cows should ‘( dry off.” On February 7, learning that some of the cows had calved, I asked their owner to supply me with some of the milk from these, as well as from his barren cows and late calvers.By this time, it may be observed, the use of corn had been resumed, a mixture of equal parts of Indian corn meal, decorticated cotton-cake, and bran, being given, in addition to prime upland hay ad libitum. The milk from the freshly calved cows was obtained from two cross-bred dairy Shorthorns, which had been fifteen and sixteen days in milk, and were yielding from 26 to 28 quarts per day. The mixed corn, etc., given to these cows amounted to 6 to 8 pounds per head per day. I n the same shed were one of the barren cows and two late calvers, being part of the five which yielded the milk of January 11.One of the barren cows had been disposed of, and one of the late calvers had dried off com- pletely. The quantity of milk yielded by these three cows was only 8 to 10 quarts daily, and the feed was the same as that given to the two freshly calved cows, except that, as the yield of milk was lower, only 3 to 4 pounds of the mixed corn and cake were given. The three cows consisted of one cross-bred dairy Shorthorn, one Alderney-Ayrshire, and one Welsh-Shorthorn cross. The two samples of milk were churned separately in the laboratory and the butter examined, with the following results : Milk from Freshly Calved Cows taken on the Morning of Milk from Barren Cow and Late Calvers drawn on Morning Febniary 23. of February 23.Reichert-Wollny figure . . . ... 36.3 19.8 Iodine number ... ... ... 36-9 38.2 On March 13 I received from the farm three samples of butter-one from the milk of the same cows which on the previous occasion were described as freshly calved, one a, sample of whey butter from the whole of the cows then in milk, and the third a sample made from a mixture of whey cream and “beestings.” These yielded the following results : Recently Whey Bntter Bntter from Whey Calved from All Cream and co\\.s. co\\?3. ‘ ‘ Beestings. ” Reichert-Wollny figure . . . 34.4 30.4 30 *9 Iodine number . . . ... 39.9 38.4 36.9 Saponification value . . . 224.0 224.0 226.8 Another sample of butter produced on April 4, 1909, from the mixed morning and evening milk from thirty cows, gave a Reichert-Wollny figure of 29.4. The conclusion I came to was that, taking into account the whole of the circumstances, the abnormality appeared to be due to the lateness of the period of lactation, and not to bad condition of the cows, such as might have been brought about by defective feeding.

ISSN:0003-2654    

DOI:10.1039/AN9093400304

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

306 THE ANALYST. THE ESTIMATION OF IRON BY PERMANGANATE IN PRESENCE OF HYDROCHLORIC ACID. B Y G. CECIL JONES, A.C.G.I., F.I.C., AND JOHN H. JEFFERY. (Read at the Meeting, June 9, 1909.) IN most textbooks of analytical chemistry, two methods are described for the estima- tion of iron by permanganate in presence of hydrochloric acid-namely, the method of Fresenius and that of Zimmermann-Reinhardt. Within the last year or SO doubt has been cast on both these methods, Harrison and Perkin (ANALYST, 1908, 33, 47), as a result of their experiments with the Zimmermann-Reinhardt method, expressing the view that ‘‘ for exact titrations permanganate cannot be employed in presence of hydrochloric acid,” whilst Birch (Chem. News, 1909, 99, 61 and 73) was unable to confirm the results of Fresenius.Had we felt that Harrison and Perkin were justified in their conclusion, this paper would never have been written; but their work certainly showed that very inaccurate results might be obtained by following Treadwell’s description of Reinhardt’s method, and suggested that the excellent results published by earlier authors might have been due to a happy balance of opposing errors. On the other hand, it remained possible that the other workers had, in their experiments, secured constancy of certain conditions, the importance of which they did not realise, or at least failed to emphasise. We set ourselves the task of determining whether any set of conditions, reasonably attainable, would render the Zimmerrnann-Reinhardt metliod of universal application, whilst we were led to study Freoenius’s method by the recommendation given to it by Hehner during the discussion of Harrison and Perkin’s paper.I t will be convenient to review briefly, in the light of our present knowledge, the history of these methods, more especially as that of Fresenius, though supported for a generation by his great name, finds little or no support in the experiments which he describes. When Marguerite (Aizn. Chim. Phys., 1846, 18, 244) first recommended the use of permanganate for the volumetric determination of iron, it was supposed that the reaction proceeded quantitatively in accordance with the equation (1) 10Fe0 + Mn207 = 5Fe20, + 2Mn0, whether the titration was conducted in presence of sulphuric acid or of hydrochloric acid. Lowenthal and Lenssen (Zeit.anal. CTzern., 1862, 1, 329) were the first to show that, in the presence of hydrochloric acid, the consumption of permanganate was excessive, and that this was due to its being used up in oxidising hydrochloric acid in accordance with the equation (2) lOHCl+ Ma,07 = 5C1,+ 2Mn0 + 5H20, a reaction which proceeds but slowly in pure dilute solutions, but which is greatly accelerated by the presence of iron salts. There is some evidence to-day that theTHE ANALYST. 307 reaction may be less simple than is indicated by equation (2), but the net result of the possible series of reactions is reduction of permanganate and liberation of chlorine, some of which escapes reduction by the ferrous iron, the exact amount of such escape depending on the conditions of the experiment.From a study of the results of Lowenthal and Lenssen, which he repeated and confirmed, Fresenius (Zeit. anal. Chem., 1862, 1, 361) was led to recommend the method known by his name. His experiments were of this kind : He found that 25 C.C. of & ferrous solution, diluted to a litre with water containing some 30 C.C. of hydrochloric acid (specific gravity 1*1), required the addition of something like 26 C.C. of & permanganate before the pink tint of the latter became permanent. If then a further 25 C.C. of ferrous solution was added to the contents of the flask or basin and the titration continued, not much more than 25 C.C. of permanganate was usually necessary to restore the pink colour, whilst a third addition of ferrous solution almost invariably required exactly 25 C.C.of permanganate. On the strength of these experiments, Fresenius recommended that, where titration in presence of hydrochloric acid was unavoidable, the iron solution should be made up to 250 c.c., 50 C.C. of this diluted with EI, large volume of water, and permanganate added until a permanent pink resulted, when a, further 50 C.C. of the iron solution was to be added and titration continued, and so on. When two consecutive and closely concordant numbers were obtained, the mean of these was to be taken as the true reading for 50 C.C. of the iron solution. According to Fresenius, the third and fourth numbers should always, and the second and third usually, agree well together, but he gives no practical example of the application of this, his first, method.A second method, where but a small quantity of the ferrous solution was available, was to add to a considerable volume of water, acidified with hydrochloric acid, some 25 C.C. of & ferrous solution and just sufficient permanganate to produce a permanent pink tint, and then to pour into this mixture the liquid to be analysed, when titration with permanganate was said to give a fair result. Two examples of this method were given, but we show later that an important condition was realised in these experiments which would never be the case in any practical attempt to apply the method. Kessler (Pogg. Aizn., 1863, 119, 225) recorded the fact that in the presence of much sulphuric acid, and still more in that of manganese sulphate, the disturbing influence of hydrochloric acid is greatly reduced; but it remained for Zimmer- mmn (AmaZen, 1882, 213, 305; also Ber.deut. chem. Ges., 1881, 14, 779) to recommend the use of manganese sulphate as an aid to accuracy of analysis. He stated that, if at least 1 gram of the crystallised salt were taken for each 15 C.C. of hydrochloric acid (specific gravity 1-1) supposed to be present, iron might be titrated as accurately in hydrochloric as in sulphuric acid solution. Reinhardt (Chem. Zeit., 1889, 13, 323) replaced the simple manganese sulphate solution of Zimmermann by a solution made by dissolving 200 grams of the crystallised salt in 1,000 C.C. of water, and adding to this a cooled mixture of 400 C.C. concentrated sulphuric acid, 600 C.C.water, and 1,000 C.C. phosphoric acid (specific gravity 1.3). The use of this solution, of which Reinhardt took 60 C.C. for each experiment, renders the assay liquid practically colourless until the permanent pink tint due to permanganate announces the completion of the titration. In the absence of phosphoric acid, theTHE ANALYST, yellow colour of ferric chloride renders the end-point less clear. The addition of phosphoric acid to the manganese sulphate appears also to increase slightly the efficiency of the latter as a retarder of chlorine evolution. Reinhardt says nothing concerning the accuracy of the method. Since the introduction of Reinhardt’s modification of Zimmermann’s method, it has been usual to speak of titrations conducted in absence of hydrochloric acid, and in which Marguerite’s equation (1) is strictly fulfilled, as being carried out according to Marguerite, and the use of the expression ‘‘ Marguerite’s method ’’ in this restricted sense will save much verbal repetition in the paragraphs which follow.Treadwell (“ Analytical Chemistry,” vol. ii., English edition, 483)’ who makes use of Reinhardt’s solution, states that the amount of manganous salt present should not exceed the amount of iron to be estimated. We have been unable to discover any publication of his in which he gives grounds for this statement, but possibly it was the result of an experience similar to that of Harrison and Perkin. These authors (Zoc. cit.) found that Reinhardt’s solution itself may exert an oxidising action on ferrous solutions, and so reduce the permanganate consumption ; and that this oxidising power is not even constant, but is in some way dependent on the age of the solution.The results they obtained by following Treadwell’s directions varied considerably, but were all too high, and the best of them were found to owe their relative accuracy to the oxidising power of the newly prepared Reinhardt solution. Working with older manganese solutions, they found the over-consumption of permanganate as much as 0.8 C.C. with only 15 C.C. of hydrochloric acid (specific gravity 1.1) present, and the over-consumption increased with increasing concentra- tion of hydrochloric acid. On the other hand, Brandt (Chem. Zeit., 1908, 32, 812, 830, 840, and 851) gives tables showing that in his hands the method of Reinhardt yields results which, if not wholly independent of the amount of hydrochloric acid present, are at any rate not greatly influenced by much larger quantities than those employed by Harrison and Perkin.The main purpose of his paper is the recommendation of pure ferric oxide as a standard for determining the titre of permanganate solutions intended for use in estimating iron by the Zimmermann-Reinhardt method, and, if this substance be adopted as the standard, dissolved in hydrochloric acid and reduced by stannous chloride precisely as an ore would be treated, he says that method leaves nothing to be desired. His experiments show that, under the conditions which prevail in his practice, and with iron equivalent to about 50 C.C. of a decinormal solution present, the permanganate consumption is almost exactly 0.2 C.C.greater than is required by Marguerite’s equation, For routine analysis, where approximately the same reading-40 to 50 c.c.-can be obtained in every experiment, no correction is necessary if ferric oxide be adopted as the standard. His paper provides no answer to the criticisms of Harrison and Perkin concerning the alterability of Reinhardt’s solution, and it is strange that he did not think to vary the amount of iron in his experiments, which give one no hint as to the interpretation to be placed on a, reading of a different order of magnitude, say, 2.5 C.C. If 0.498 gram of pure ferric oxide, reduced and titrated by Reinhardt’s method, gives a reading of 50 c.c., to how much ferric oxide does a reading of 2.5 C.C.correspond? One-twentieth of 0.498 isTHE ANALYST: 309 0.0249, or, say, 0.025 ; but Brandt tells us that the error of the method, as compared with that of Marguerite, is 0.2 C.C. when there is ferrous iron present equivalent to 0.498 gram of ferric oxide, and the error will surely not be less when the concentra- tion of iron is reduced, and that of hydrochloric acid maintained constant. It would seem more reasonable to suppose that 2.5 C.C. was equivalent to 0.023 gram ferric oxide, and without experiment no one would care to assume that it had a value even so high as this. Now, the difference between 0.025 and 0.023 is a, matter of 10 per cent., far too large an amount to be left in doubt. He can insure a reading of 40 to 50 c.c., and, moreover, is too expert in the use of bichromate to heed our results or Brandt’s ; if, indeed, he has not as a rule a method of his own for applying permanganate. He is called upon to estimate widely varying quantities of iron in materials, as to the com- position of which he knows very little in advance ; and there is no doubt that he would as a, rule prefer to use permanganate were he sure that it would give him accurate results, and it is to such a8 he that this paper is addressed.To the iron and steel worker these considerations will have no weight. With the general worker it is far otherwise. EXPERIMENTAL. We have reduced our experimental record to just so much as is necessary to support our conclusions and to enable anyone to repeat our more instructive experi- ments.The following tables are compiled from experiments made within the last few days with the special object of saving our readers’ time. The results published here find confirmation in many other series of experiments, made with solutions not exactly equivalent, and therefore requiring closer inspection to learn their bearing than the busy reader can well spare. Needless to say, many of our early series of experiments, made when our knowledge was less complete, are less regular ; but our purpose is to show how permanganate can be used in presence of hydrochloric acid, and not how we obtained this knowledge. The following solutions were used : Mangancse Solution .- Reinhardt’s solution, the preparation of which has already Stannous Chloride .- 50 grams of the crystallised salt and 100 C.C.of concentrated Mercuric ChZoride .- A cold saturated solution. Hydrochloric A c i d : 6-normal, that is to say, acid of specific gravity 1.1, or SuZphuric A c i d .- Also, for convenience of comparison, about 6-normal. In each of the experiments recorded in Table I., the quantity of water stated in column B was mixed in a capacious basin with the Reinhardt solution, where this was used, and tinted with permanganate, of which 1 drop sufficed in every case; 25 C.C. of a freshly prepared solution of ferrous ammonium sulphate was then added, and simultaneously the acid, hydrochloric or sulphuric, as the case might be. Where stannous chloride or mercuric chloride were used, these were added with the acid as follows: Ten minutes before each titration was made, the requisite amount of been described.hydrochloric acid made up to 1,000 C.C. about the strength of the mixture which exhibits a constant boiling-point.310 THE ANALYST. hydrochloric acid was placed in a flask, and the stannous chloride and mercuric chloride added. This mixture was added to the contents of the titration bowl simultaneously with the ferrous solution. The permanganate was then allowed to fall drop by drop into the bowl with constant stirring, each titration occupying about four minutes. All the numbers in the table in columns A to H represent cubic centi- metres. TABLE I. No. of Experi- ment. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. A. teinhardt’r Solution. - 25 25 50 -- - - - 25 25 50 10 25 25 25 50 25 25 25 25 25 25 B.Water. 425 400 425 400 400 150 425 415 400 390 365 405 340 390 365 340 405 390 390 900 1400 90 D. 6N.HC1. - - - - -- - 25 25 25 25 25 25 25 25 50 50 10 25 25 25 25 25 E. SnC1, Solution. - - - - - - -- 0.5 0.5 0.5 0.5 0-5 0-5 0.5 0.5 1.0 2.0 0.5 0.5 0.5 - - P. HgCI2 Solution. - -. - - - - - 10 10 10 10 60 10 10 10 10 10 10 10 10 10 - G. Final Volume. 500 500 500 500 500 500 500 500 500 500 500 500 500 500 500 500 500 500 500 1000 1500 200 H. Perman- ganate Consump- tion. 2505 25.0 25.0 25.0 25.0 25.0 25.5 25.7 25-05 25.1 25.1 25.2 25.1 25-05 25.15 25.1 25.05 25.15 25.25 25.1 25.15 25-05 Experiments 2 and 3 compared with 1 appear to confirm the observation of Harrison and Perkin that Reinhardt’s solution exerts an oxidising action on the iron solution; but the solution used in this particular series of experiments had no such action as experiment 4 shows, where doubling the volume of Reinhardt’s solution does not affect the result.Had the sulphuric acid contained ferrous iroD, as it frequently does, experiments 5 and 6 would have shown higher results than experiment 1. That they give identical numbers, higher than that found in experiment I, only illustrates the fact to which Treadwell has already drawn attention, that to obtain accurate results by Marguerite’s method, it is necessary to have much sulphuric acid present, the minimum allowable strength being about half-normal. Larger quantities of sulphuric acid are without influence on the result-THE ANALYST.311 Experiment 7 may appear a surprisingly good result to some who have studied the influence of hydrochloric acid on permanganate titrations of iron. Harrison and Perkin record an excess consumption of permanganate of 0.6 c.c., with only one- fourth as much hydrochloric acid present. The difference between their results and ours is, we believe, due to difference in manner of adding the permanganate. By running this in in a continuous stream up to 23 C.C. and then proceeding by drops, we have obtained results practically identical with theirs. Experiment 8 shows that either stannic or mercuric or mercurous chloride, all of which are present in practical titretions, reinforce the disturbing action of the hydrochloric acid. Experiment 9 shows that 25 C.C. of Reinhardt’s solution reduces the error introduced by 25 C.C. of hydrochloric acid to 0.05 c.c., whilst experiment 10 shows that it does not wholly neutralise the action of the tin or mercury salts.Experiments 11 and 12 show that, while no advantage is gained by increasing the proportion of Reinhttrdt’s solution, it is not wise to diminish it greatly below that used in experiment 10. Experiment 13 shows that no advantage attends the use of large quantities of mercuric chloride, such as the 60 C.C. used by Reinhardt and by most workers since his time. Experiments 15 and 16 show that doubling the amount of hydrochloric acid, whilst. preserving unaltered all the other conditions, increases the over-consumption of permanganate from 0.1 to 0.15, but that this can be prevented from exceeding 0.1 by taking more of Reinhardt’s solution. Experiment 17 shows how the over- consumption of permanganate falls when the amount of hydrochloric acid is greatly reduced.Experiment 14, compared with No, 9, shows that mercuric chloride, as might be expected, has no influence on the titration, whilst Nos. 18 and 19 show that either stannic or mercurous chloride has a notable influence. Experiment 20 shows that dilution considerably beyond 500 C.C. is without influence, whilst Nos. 21 and 22, like the figures of Zimmermann, Harrison and Perkin, and Birch, directly challenge the recommendation to be found in all the textbooks from the time of Fresenius that the titration is best conducted in highly dilute solution. The greater the dilution, the wider the divergence from Marguerite’s equation.In practice, however, a final volume of about 500 C.C. is preferable, since comparatively wide variations from this volume have no measurable influence on the result. In a bulk of 1,500 c.c., such as Reinhardt recommended, one drop of permanganate is scarcely enough to produce a distinct pink tint, whilst in small bulks, under 200 c.c., though with great care the absolute error may be very slightly reduced, it is more difficult to get closely concordant duplicates, especially if the amount of hydrochloric acid is large. A number of the experiments of Table I. were next repeated with the following modification : The measured 25 C.C. of ferrous solution was completely oxidised, mixed with the quantity of hydrochloric acid stated in column D, heated to boiling, and reduced by stannous chloride, which towards the end was added 2 drops at a time.When 2 drops of stannous chloride produced no further change of tint, a measured excess of the reagent was added, the solution cooled, and subsequently mixed with mercuric chloride. After ten minutes, the contents of the flask were emptied into a bowl containing the Reinhardt solution and water previously tinted by 1 drop of permanganate. The results of experiments 10 to 13 and 15 to 19 were312 THE ANALYST. confirmed in every case. Since the experiments of this series differed from those in Table I. by the presence of some 25 C.C. of FG stannic chloride, it may be taken that this reagent has, as might be expected, no influence on the course of the titration.On the contrary, it seems to be conclusively proved that mercurous chloride has a marked influence if present in large amount. The excess of stannous chloride can easily be kept below 0.25 c.c., and the results differ inappreciably when the excess is varied from 0.1 to 0.5 C.C. The interval of ten minutes between the addition of the mercuric chloride and the commencement of the titration is the result of our observa- tion that, when the excess of stannous chloride is purposely kept very small, the precipitate of mercuric chloride takes an appreciable time to appear. From this we were led to suppose that the reaction SnC1, + 2HgC1, = SnC1, + 2HgCl might require an appreciable time to approximate completion, and this we find to be the case.Titration of the liquid immediately after the addition of the mercuric chloride leads to high results, due to the presence of unoxidised stannous chloride. We find that Reinhardt knew that the reaction SnCl, + 2HgC1, = SnC1, + 2HgCl never even approximated completion in dilute solutions, and he insisted on the addition of the mercuric chloride before diluting largely, but even in a bulk of 100 C.C. the reaction is slow. Probably ten minutes is an unnecessary allowance, but it has been found to be both ample and safe, since no appreciable oxidation of iron takes place in a much longer time, identical results being obtained after thirty minutes’ standing. In a further series of experiments, recorded in Table II., varying quantities of ferrous solution were titreted with permanganate under the conditions indicated in experiment 10 of Table I.Here, again, two methods were followed-namely, (1) Simple mixture of the ferrous solution with hydrochloric acid, mercurous and mercuric chloride, followed by titration in presence of Reinhardt’s solution ; and (2) titration of the ferrous solution by permanganate in presence of a little sulphuric acid, reduction of the resulting ferric solution by stannous chloride in presence of 25 C.C. of hydrochloric acid (specific gravity 1*1), treatroent with mercuric chloride, and re-titration by Reinhardt’s method. Had we contented ourselves with one of these methods only, our conclusions might perhaps have dissatisfied some ; but, fortunately, the two methods give identical results. Table 11.shows the permaa- ganate consumption ( a ) in half-normal sulphuric acid solution, and ( b ) by Reinhardt’s method. TABLE 11. Consumption of permanganate. & Ferrous Solution. ( a ) In H,S04 Solution. 50 50 20 20 10 10 6 5 2 2 1 1 ( b ) By Reinllardt’s Nethod. 50.1 20-1 10.1 5.1 2.1 1.1 We think these results show plainly that the small by hydrochloric acid, even in presence of Reinhardt’s unavoidable error introduced solution, is a constant one,THE ANALYST. 313 independent of the amount of iron present, and therefore easily corrected for. The correction, though small, cannot be omitted, as on a small amount of iron it represents a notable percentage. We have made many preparations of Reinhardt’s solution, and, though we have occasionally found them to possess oxidising power when first made, this has never been so great as that observed by Harrison and Perkin. Moreover, before the solutions are a week old this oxidising power becomes so small as to be un- measurable.It is true that we used the purest chemicals procurable, but since we have found it possible to cut down the quantities to be used in each experiment to less than half those proposed by Reinhardt, the extra expense involved by this is not great. I t is impossible to lay too much stress on the importance of adding the permanganate slowly, drop by drop. We were led to this discovery by differences between ourselves, which by a process of elimination were ultimately traced to the difference in the speed at which we ran in the permanganate. We have since found that this point has been dealt with very fully by Skrabal (Zeit.anal. Chem., 1903, 42, 359). We think the results of Birch and of Harrison and Perkin are evidence that they, too, were ignorant of the work of Skrabal, and this is perhaps not surprising, since the literature of the subject these authors were studying is immense, and in the course of his fifty-page paper Skrabal records but one experiment with Reinhardt’s solution, and makes no reference at all to the method of Fresenius. Some of the earliest authors-Lowenthal and Lenssen, for instance-speak of the addition of permanganate ‘‘ drop by drop slowly ” as the custom in their time, but there is no evidence whatever that they realised that such procedure was of vital importance. On the contrary, their own poor results suggest that they themselves disregarded the custom.For the estimation of iron in ferric oxide, or other substance most easily got into solution in hydrochloric acid, we recommend solution in 25 C.C. of hydrochloric acid (specific gravity l-l), reduction by stannous chloride, using as small an excess of this as is reasonably possible, and addition of 10 C.C. of mercuric chloride solution when cold. Into a capacious bowl we bring 25 C.C. of Reinhardt’s solution and some 400 to 500 C.C. of tap-water, and tint the mixture by the addition of permanganate, of which 1 drop should suffice. Ten minutes after the addition of the mercuric chloride to the ferrous solution, we pour the latter into the bowl, rinse the flask or beaker, and add the rinsings to the contents of the bowl, which are then titrated with permanganate, drop by drop, with constant stirring.From the burette reading we deduct 0.1 c.c., and calculate the amount of iron present by reference to the known titre of the permanganate as determined by titration against a ferrous solution free from hydrochloric acid. With the above-mentioned quantities we believe the method capable of giving results equal in accuracy to those obtained by any volumetric method, and it is not difficult to keep all the quantities sufficiently near those named. A final dilution of from 400 to 1,000 C.C. is without measurable influence on the result, and tap-water-that supplied to our laboratory, at any rate -may replace distilled water without disadvantage. This has saved us the trouble of boiling and cooling out of contact with air the large volumes of water required by314 THE ANALYST.our experiments. The amount of acid need never be much less than 25 c.c., for after solution of the iron oxide it can always be made up to its original volume with acid of constant boiling-point. If, on the other hand, it is necessary to use fuming acid, this will be down to the strength of constant boiling-point acid by the time solution is complete ; and if its volume much exceeds 25 c.c., all that is necessary is to add an equal volume of Reinhardt’s solution instead of the usual 25 C.C. The tin solution recommended by Treadwell is too strong, having regard to the great influence of relatively small amounts of mercurous chloride. Of our tin solution, it is immaterial whether the excess used is 1 drop or 10-a sufficiently wide margin for anyone.Provided the amount of hydrochloric acid is not less than about 20 C.C. (specific gravity 1.1), and that the volume of Reinhardt solution is at least equal to that of hydrochloric acid, the consumption of permanganate will in every experiment be almost exactly 0.1 C.C. in excess of that demanded by Marguerite’s equation. In our hands it averages a little less than this, but is much nearer 0.1 than 0.05, and we do not feel justified in splitting drops. There is much to be said for Brandt’s proposal to adopt pure ferric oxide as a standard for determining the titre of permanganate solutions ; but if this is done, it is preferable to record the true and not the apparent titre on the label, if the solution is to be used for general purposes and not merely for the analysis of ores.For example, if 0,3194 gram pure ferric oxide, by Reinhardt’s method, requires exactly 40.0 C.C. of our permanganate, we do not label the solution ‘‘ exactly decinormal,” as gram ferric oxide, or 0.3194 Brandt would do, but calculate the true titre as 1 c.c.= ___ Provided that 0.1 C.C. be always deducted from the observed permanganate consumption, the solution can then be used for the estimation of widely varying quantities of iron by Reinhardt’s method. If the use of freshly made manganese solution is unavoidable, the oxidising power of this can be determined in ten minutes by two experiments, like 3 and 5 in Table I., and allowed for if a measurable quantity.Unlike Birch, we found no difficulty in repeating the experiments of Fresenius, and even obtained better results than Fresenius himself, due no doubt to the slow speed at which we added the permanganate. When, however, we came to apply Fresenius’s recommendations practically, we were scarcely surprised to find the method break down. For in his experiments, after the first titration, Fresenius contented himself with adding more ferrous solution, and made no further addition of acid. Now, the analyst, with his ferrous solution in one flask and hydrochloric acid in the other, would presumably never mix them, and in any practical application of Fresenius’s method each addition of ferrous solution would be accompanied by the addition of more acid, and, as a rule, of mercurous chloride, stannous chloride being infinitely more convenient to use than zinc.The following experiments represent an attempt to apply Fresenius’s method under test conditions : 125 C.C. of =& ferric chloride, containing hydrochloric acid equivalent to 75 C.C. of oonstant boiling-point acid, was reduced by stannous chloride, and made up to 250 C.C. with mercuric chloride solution. Successive portions of 50 C.C. were then added to 1,000 C.C. of water and titrsted slowly with permanganate. 0,2234 39.9 gram iron. 39.9THE ANALYST. 315 1st 50 C.C. required 25.7 C.C. permanganate 3rd 9 , ,, 25-75 ,, I , 2nd 9 , 9 , 25-7 1 , 9 , 4th 9 , , I 25.8 ,, 9 , Twenty-five C.C. of the same decinormal ferric chloride, reduced and titrated by Reinhardt's method, required 25.1 C.C.permanganate. In order to give the method of Fresenius every chance, the ratio of acid to iron in these experiments was kept as low as we find it can be kept in practice. As has been said in the introduction, Fresenius gave no practical example of this method, but of his second method he gave two examples which he believed to be practical. But here, again, he dissolved iron in sulphuric acid, and added the resulting ferrous solution, without any simultaneous addition of hydrochloric acid, to the contents of the vessel in which the preliminary experiment had been made. CONCLUSIONS. The method of Fresenius gives erroneous results, and appears to have been founded on a misconception, and never until now put to a practical test.The method of Reinhardt, though empirical and dependent for its successful application on somewhat rigid uniformity of procedure, is yet capable of yielding results little, if at all, inferior in accuracy to those given by the best volumetric methods. Our work was undertsken with a practical object, and, though theoretical considerations helped us in the choice of experimental methods, we do not propose to add to the mass of theory which has been woven around this subject. We may, however, point out that our results are consistent with the theory of Manchot and Wilhelms (Amalen, 1902, 325, 93), and that those recorded in Table 11. appear to lend additional support to their view. We take this opportunity of expressing our thanks to Mr. R. F. Easton for much useful help in the conduct of the large number of experiments which were found necessary to the completion of this work.DISCUSSION. Mr. W. C. BIRCH said he had had occasion to work on this subject, and the results might perhaps be interesting, as bearing on the action of the manganous sulphate, which was an essential constituent of the Zimmermann-Reinhardt reagent. I n titrating with that reagent there was a distinct, though slight, evolution of chlorine, and a brown colour was produced in the solution even by a quite small excess of permanganate over the quantity required to oxidise all the iron present. These brown solutions were very similar iu appearance to those described by Pickering ( J . Chem. SOC., 1879, 42, 654), which were produced by the action of hydrochloric acid on any of the higher oxides of manganese.Unfortunately, it was not possible to isolate this brown colouring matter from such dilute solutions as were met with in volumetric analysis; but, by blowing hydrochloric acid into a concentrated solution of potassium permanganate, and cooling the solution with316 THE ANALYST. ice and salt, it was possible to isolate a crystalline double salt having the formula MnC1,2KC1.H2O. The reaction which caused the formation of this compound could perhaps be represented by the equation K2Mn208 + 16HC1= 2KC1+ 2MnC1, + 8H,O + 4C1,. I t had been shown by Rice (J. Chenz. Xoc., 1898, 74, 260) that manganous chloride reacted, though but slowly, with free chlorine at the ordinary temperature to produce MnCI,. He thought it fair to assume that under the conditions of the Zimmermann-Reinhardt titration the chlorine liberated would be in a nascent state, and would therefore be more active chemically than chlorine in the free state; and if that were so, it was to be expected that the reaction between the manganous sulphate or manganous chloride and the chlorine would go on more quickly than under the conditions of Rice’s experiments.The Zimmermann-Reinhardt reagent, therefore, provided every chance for the chlorine to enter into combination before escaping from the solution, and to remain in the solution in a state in which it was able to oxidise the remainder of the ferrous iron. This waB shown by the following simple experiment which he had made : About 10 C.C. of concentrated hydrochloric acid, with a few C.C. of potassium permanganate, were placed in one flask, and in another flask the same quantities of these reagents, with an excess of manganous sulphate, a current of air being aspirated through both flasks, and the evolved chlorine collected in potassium iodide, and titrated with thiosulphate. The chlorine evolved from the flask not containing manganous sulphate was equivalent t o 313.1 C.C. of decinormal thiosulphate solution, while that from the flask containing manganous sulphate required only 0.5 C.C. The aspiration of air was carried on for two hours in the c a ~ e of the first solution and two and a half hours in the cage of the second. This might enable a mental picture to be formed of the part played by the manganous sulphate in the Zimmermann-Reinhardt reagent. Rlr. CHAPMAN said that palladium-hydrogen was preferable to stannous chloride as a reducing agent. One of its advantages was that nothing was introduced t o interfere with the indicator. The initial expense of the palladium was certainly somewhat large, but not so large as to be of really serious moment. THE CHAIRMAN (Mr. RICHMOND) remarked that it seemed clear, from the work of the authors and of Mr. Birch, that what happened when ferrous solutions were titrated with permanganate in presence of hydrochloric acid was that, while some of the permanganate was used up in oxidking the iron, a portion of it also was used in oxidising some of the oxides of manganese, to form higher oxides, which then formed unstable chlorides, and the speed of the former reaction was greater than that of the latter. That being so, the precaution which the authors recommended of adding the permanganate drop by drop, so as to keep the concentration of the permanganate in all parts of the solution very low indeed, was obviously a wise one. He thought that the difliculty of using bichromate was not so great as had been suggested, especially if the titration was made by artificial light, a practice which he personally much preferred.

ISSN:0003-2654    

DOI:10.1039/AN9093400306

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 317 THE ESTIMATION OF THE ALKALINITY OF BLEACHING POWDER SOLUTIONS. BY KENNEDY J. P. ORTON, PH.D., M.A., F.I.C., AND W. J. JONES., B.Sc. (‘ISAAC ROBERTS RESEARCH STUDENT). (Read at the Meeting, June 9,1909,) THE usual method of estimating the free alkali hydroxide in bleaching solutions- for example, bleaching-powder solution -is that devised by Blather (Bull. SOC. Chim., 1891, 1, 116). I t is based on the fact that alkaline bleaching solutions colour phenolphthalein. When the solution is titrated with standard sulphuric acid, the colour is discharged, not, however, by the excess of acid, but by the chlorine set free by the interaction of the hydrochloric and hypochlorous acids, when the excess of alkali has been neutralised. Addition of alkali does not in consequence restore the colour of the indicator.Owing to the extensive hydrolysis of hypochlorites, the destruction of the indicator tends to occur before the neutralisation of the alkali, and hence leads to an estimate of the latter which is below the actual value. I n addition to this possible objection, Blather’s procedure is not readily applicable to solid basic hypochlorites, such as are present in ordinary bleaching powder, or separate from bleaching powder solutions (Orton and Jones, J. Chem. SOC., 1909,95, 751)) inasmuch as it is not possible to dissolve these compounds entirely except in inconveniently large quantities of water. We have devised a method which we find highly accurate for solutions of bleaching powder, and easily applied to the direct estimation of the calcium oxide or hydroxide in basic hypochlorites.In such bleaching solutions as those prepared from sodium hydroxide (or Eau de Javelle), which may contain some carbonate, this method gives the hydroxide and carbonate together, and does not directly distinguish between them. The method is as follows: A known volume of approximately -& hydro- chloric acid is placed in a Drechsel bubbler, and then a given volume of the bleaching powder solution is run in. A fairly rapid current of air, freed from dust, is now drawn through the liquid, the bubbler being carefully shielded from light. Aspiration for three-quarters of an hour suffices to free the liquid from chlorine, a fact which can be very easily tested by adding 1 drop of a 0 0 1 per cent. solution of methyl orange.The indicator is bleached if any chlorine remain. The excess of acid is then titrated with I n the case of solid basic hypochlorite (or compounds of calcium chloride and hypochlorite) the procedure is identical, except that it is more convenient to intro- duce the solid into the bubbler before the acid. The alkalinity of the solutions or solid is calculated from the following equations : Ca(CiO), + 4HCl= CaCI, + 2H,O + 2C1, ; and Ca(OH), + 2HCl= CaCl, + 2H20. The thiosulphate or arsenite titre (&) of the bleaching solution gives directly the volume of q0 hydrochloric acid reacting with the hypochlorite. sodium carbonate.318 THE ANALYST. For this method to give trustworthy results, it is necessary that certain con- ditions hold. I t must entirely react with the hydrochloric acid.(2) All the chlorine must be evolved as gas, and none reduced to hydrochloric acid. (3) The hydrochloric acid must not react with chlorate at the dilutions used and at the ordinary temperature. A number of separate experiments devised to test these requirements for accuracy have been made, with the result that all are found to hold rigidly under the conditions used. The following analysis of a test solution, made up by passing chlorine into a standard solution of sodium hydroxide, demonstrates the accuracy of the method. One hundred C.C. of the solution of sodium hydroxide contained 0.5476 gram. (1) No hypochlorous acid must pass over during the aspiration. NaOH found as NaCl and NaClO = 0.4125 gram. 9 , ,, as NaC10, =0.0098 ,, 9 , ,, by determination of the alkalinity=0.1247 ,, Total NaOH found =0.5470 ,, Estimations of the alkalinity of a large number of bleaching-powder solutions by this method have shown that such solutions are saturated with respect to calcium hydroxide, containing 1.6 to 1.7 grams per litre. As the concentration of the bleaching powder rises (active chlorine above 2N), the alkalinity falls, owing, doubt- less, to the depression of the solubility of the calcium hydroxide by the high concen- tration of calcium chloride and calcium hypochlorite. Comparison of ours with Blather's method shows, as was foreseen, that the latter gives a somewhat lower estimate of the alkalinity.

ISSN:0003-2654    

DOI:10.1039/AN9093400317

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

318 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. Estimation of Benzaldehyde in Almond Flavouring Extract. W. Denis and P. B. Dunbar. ( J . Ind. and Eng. Chem., 1909, 1, 256-257 ; through J. SOC. Chem. I d . , 1909, 28, 488.)-The method described depends on the precipitation of benzaldehyde as its phenylhydrazone by means of a reagent consisting of 1 C.C. of phenylhydrazine, 1-5 C.C. of glacial acetic acid, and 20 C.C. of water, prepared immediately before use. Two portions of 10 C.C. each of the almond extract are treated respectively with 10 C.C. and 15 C.C. of the reagent in stoppered flasks, and, after shaking, the mixtures are allowed to stand overnight; 200 C.C. of water are then added to each flask, the precipitates collected on asbestos filters, washed with cold water and then with 10 C.C.of 10 per cent. alcohol, and dried in vacuo over sulphuric acid, or for three hours at 70" to 80" C. in a, vacuum oven. The method gives results corresponding to 97 to 99 per cent. of the theoretical, and the presence ofTHE ANALYST, 319 benzoic acid on nitrobenzene is without influence. The reason for using different quantities of reagent for the two portions is that most almond extracts contain only abouh 1 per cent. of benzaldehyde, but occasionally samples occur containing as much as 6 per cent. A. G. L. Theobromine-Content of Cocoa Beans. A. Kreutz. (Zeit. Untersuch. Nahr. Genussm., 1909, 17, 526-527.)-The author has carried out a number of experiments the results of which confirm his previous statement (ANALYST, 1909, ZO), that a portion of the theobromine present in cocoa beans is directly soluble in chloroform, whilst the remainder goes into solution only after the cocoa has been subjected to hydrolysis ; that this portion of the theobromine exists in combination as a glucoside could not be ascertained definitely.A nine-hours extraction with chloroform is sufficient to obtain the whole of the free theobromine, whilst a, further extraction for about six hours after the cocoa has been boiled with sulphuric acid as described (loc. cit.) gives the combined alkaloid. About one-half of the total theo- bromine exists in the free state, as will be seen from the following results, but there i s no reason to believe that there is a, deiinite border-line between the two states in which the alkaloid occurs in the beans : Theobromine.Free. Combined. Kind of Cocoa. Srtmana .. ... ... Venezuela, St. Rosa ... Bahia ... ... ... Per Cent. 2-38 1.54 1.54 Per Cent. 2.75 1-29 1.58 w. P. s. Estimation of Fat in '' Charcuterie " and in Other Products containing Water. G. Perrier. (BwZZ. SOC. Chim., 1909, [IV. 3, 5, 569-571.)-The following rapid method of estimating fat in oharcuterie, etc., obviates the tedious drying of the substance and consequent alteration of the fat. Ten grams of the sample are triturated in a mortar with 3 to 4 grams of coarse sand which has been previously washed and dried. From 20 to 25 grams (or more if necessary) of anhydrous sodium sulphate are then gradually added, and the pounding continued until a dry friable mass is obtained, After standing for thirty minutes this is placed in a paper cartridge and extracted with ether.The extraction of fat is complete in about two hours, and the perfectly limpid ethereal solution is then distilled, and the residue of fat dried for about ten minutes at 110' C., or at the ordinary temperature invacuo over sulphuric acid. C. A. M.320 THE ANALYST. Composition of the Fat contained in Egg Yolk. R. Paladino. (Biochem. Zeit., 1909, 17, 356-360.)-This fat was found to consist of olein, palmitin, and stearin ; it also contained a considerable quantity of phosphorus Compounds, and sulphur and iron were present. The author employed the lead method for the separation of the oleic acid, whilst the presence of stearic acid was ascertained by converting the lead salts insoluble in ether into the corresponding barium salts, extracting the latter with hot alcohol, and recrystallising the fatty acid liberated from the insoluble barium salt.On steam-distilling a portion of the mixed fatty acids, an acid distillate was obtained which, when partially neutralised and again distilled, yielded a volatile acid which was identified as formic acid. The oil itself, when allowed to stand for some time, separates into two portions : the one is a dark orange-coloured oil, and the other a light yellow solid fat. The liquid portion, when examined with the spectroscope, shows a broad band in the green, blue, and violet part of the spectrum. By crystallisation from chloroform, the author has obtained the colouring matter of egg yolk in the form of yellow crystals.w. P. s. New Method for the Chemical Assay of Ergot. H. C. Wood, Jun. (Amer. J. Pharm., 1909,81,215-218.)-The author observed that a liquid extract which was completely inert physiologically gave practically no precipitate with water, and experiments on various extracts showed that the precipitated' (( resin " was greater in amount as the physiologicsl activity of the extract under examination rose. The following results are of interest : Physiological ' ' Resin " Preparation. Test. per Cent. 33 0.68 0.39 0-58 0.3'7 0.48 0.34 The " resin " was determined by diluting the extract with two volumes of water, and repeatedly shaking out the mixture with benzene, evaporating the solvent on the water-bath, and drying the residue at 40' C.The physiological activity was determined by the method of Hofer and Wood (Univ. Penizsyl. Med. Bull., February, 1909). Each pair of the above samples was from the same extract ; those marked 1, which retained their potency, had been kept in hermetically sealed bottles, while those marked 2 had lost in potency and had been exposed to the air. In each case the amount of benzene extract diminished with the physiological activity. Benzene extracts the greater portion, but not the whole, of the active principle of ergot in fairly pure condition; but another active substance (possibly an alkaloid) appears to be also present in ergot. The benzene extractive had the physical and chemical properties of a resin-acid, and is probably identical with the sphacelotoxin of Jacobi (1897). That benzene extracts the greater part of the pure active ingredient of ergot is shown by comparing the dose of the resultant pure extractive required to produce a certain amount of physiological effect with that theoretically necessary. For instance,THE ANALYST, 321 0*00061 gram per kilo of the extract caused a rise of 10 mm.in the blood-pressure, and 0*00105 gram of 32 mm. Extract B2,0*17 gram per kilo of which gave a rise of 10 mm., contains 0.37 per cent. extractive = 0.00063 gram per dose (theory), as against 0.00061 gram found experimentally. A. R. T. Detection of Small Quantities of Capsicum in Ginger Preparations. C. H. La Wall. (Amer. J. Pharm., 1909, 81, 218.)-The author gives the following amended method for the detection of capsicum, based on that of Garnett and Green (Brit.and Col. Druggist, 1907). The ginger ale or other aerated liquid is poured from one vessel to another to expel carbon dioxide, or is warmed on a water-bath. If alcohol be present, this is driven off by evaporation, and the residue diluted. I t ie then acidified with dilute sulphuric acid, and shaken with 50 C.C. of ether for one minute. If the residue from the ether, which is allowed to evaporate spontaneously, weighs 10 mgm. or less it is treated with 2 C.C. of half-normal alcoholic caustic potash, and the solution transferred to a test-tube provided; with a reflux tube ; should the residue exceed 10 mgm. in weight, 1 C.C. more alkali is added for each additional 10 mgm. The solution is gently boiled in the test-tube in a water-bath for half an hour, the alcohol allowed to evaporate, and half a test-tube of water added to the nearly dry residue to dissolve it, then half its volume of ether, and the mixture shaken.A portion of the ethereal liquid is evaporated, and the residue tasted. Capsicum is indicated by the pungency of the residue, but only a slight oamphoraceous taste is noticeable in the presence of even large quantities of ginger in the original preparation. One part of capsicum in 10,000 parts of water may thus be detected. A. R. T. Steeping of Harieot Beans, their Injurious Properties, and the Dis- guising of Poisonous Foreign Varieties. A. Barill& ( J . de Pharm. et de Chim., 1909, 29, 422-428.)-1t has been known for some time that certain varieties of haricot beans (PhaseoZus Zzmatus) (ANALYST, 1906, 31, 249) imported from India and Burmah have been the cause of poisoning, owing to the cyanogenetic glucoside which they contain-so much so that the importation of the Javan beans has been prohibited in France.Certain traders have, however, succeeded in placing these dangerous foreign beans on the market by modifying their characteristic shape by boiling them, after which they have the same appearance as the edible variety. The same modification may also be effected by prolonged steeping in water. The practice of steeping ” has been somewhat largely followed for reviving the appearance of old haricot beans of the edible variety. This rejuvenation is of short duration ; the beans soon become wrinkled again, and are particularly subject to fermentation.When old beans are steeped they become green like the freshly shelled beans, but this coloration is not due solely to the chloroleucites ; the development of mould fungi also contributes. Whereas young haricots contain reserve materials in a healthy state of recent formation, old haricots rejuvenated contain similar materials in a state of degradation. Moreover, whilst the former are practically aseptic, the latter, having previously been dried, are invaded by all kinds of micro-organisms and fungi, French haricots absorb 83 to 86 per cent. of moisture after steeping forTHE ANALYST. twenty-four hours in the cold ; certain hard-skinned Swiss varieties absorb only 42 per cent., whilst the toxic Javan variety absorbs 96 per cent.in the same time. The steeping water removes about 3 per cent. of soluble matters from the beans, and is extremely liable to putrefaction. This liquid, besides being full of micro-organisms, has been ascertained to possess mildly toxic properties, possibly due to the break- down products of the proteins or the ptomaines derived from incipient putrefaction. Steeping is an objectionable practice, and when used for disguising the toxic foreign beans it amounts to a dangerous fraud. J. F. B. Estimation of Dirt in Milk. G. Fendler and 0. Kuhn. (Zeit. U?ztersuclz. Nahr. Genussm., 1909, 1’7, 513-526.)-The following method for the estimation of dirt in milk is recommended, it having been found that filtration through ordinary filter- paper leads to erroneous results on account of the paper retaining fat, etc.Briefly, the method consists in submitting the milk to centrifugal action, separating the sediment, and washing the latter with ammonia, alcohol, and ether. This treatment does not materially decrease the weight of ordinary dirt, such as cow-dung, etc., which may be present in the milk. At least 100 C.C. of the milk should be taken for the estimation, and the vessel in which the milk is submitted to centrifugal action should be drawn out at the bottom to form a narrow stem, which may be graduated SO that the volume of the sediment may be ascertained. The fluid portion is then poured off, and the sediment is shaken with 15 C.C. of 10 per cent. ammonia, the mixture being diluted after the lapse of one hour with water, and again submitted to centrifugal action.The opalescent liquid is decanted, the sediment is washed with a, little water into a weighed Neubauer crucible (a platinum Gooch crucible containing spongy platinum as the filtering material), and washed successively with water, alcohol, and ether. The crucible and its contents are then dried at 100’ C. until constant in weight. Any sample of milk which yields more than 1 mgm. of sediment per 100 C.C. must, in the author’s opinion, be considered as dirty. w. P. s. Composition and Nature of the Membrane surrounding Fat Globules in Milk. E. Abderhalden and W. Voltz. (Zeit. physiol. Chenz., 1909,59,13-18.) -The membrane was isolated by means of the method proposed by Lehmann and described by Voltz (Pjiiger’s Archiv, 1904, 102, 373).This method consists in introducing the milk, treated previously with about 0.1 per cent. of sodium fluoride or thymol, into the bottom of a vessel containing a column of water about 50 cm. in height. The milk globules rising and collecting on the surface of the water are collected, placed on a filter, and when most of the water has run away, the filter and its contents are heated at a temperature of about 70’ C. The remainder of the water and the larger proportion of the fat are thus removed, the residue on the filter being then dried thoroughly, powdered, and extracted with ether. The membrane was found to vary widely in composition, according to the milk from which it was obtained. This is seen from the following results obtained on the analysis of two specimens isolated from two different lots of cow’s milk :THE ANALYST, 333 Milk 1.Milk 2. Yield of dry membrane per 50 litres of milk Ash ... ... ... ... ... Organic matters ... ... ... ... Nitrogen ... ... ... Containing : ... The membrane, when subjected to hydrolysis, yielded, amongst other products, considerable quantities of glycocoll, showing that it does not consist of casein or milk albumin. I t is still open to doubt whether the membrane consists of any definite substance. w. P. s. 17.768 grams. 9,342 grams. 10*807 .. 0.689 gram. 6.961 ,, 8.653 grams. 0.732 gram. 0.558 gram. Estimation of Quinine in Cinchona Bark. N. H. Cohen. (Pharnz. J., 1909, 82, 670.)-The author describes experiments made to test the accuracy of Duncan's method of precipitating quinine as sulphate from a neutral sodium sulphate solution (ANALYST, 1909, 220). These show that, except under the most favourable conditions (a low temperature and relatively high concentration of the pure alkaloid salt), the yield of crystals from a solution of quinine sulphate does not correspond to the solubility. When sulphates of quinine, cinchonine, and cinchonidine are also present, the precipitate of quinine sulphate is invariably impure, and it cannot be freed from the sulphates of the other alkaloids by a second precipitation. The conclusion is therefore arrived at that Duncan's method cannot be used for the estimation of quinine, although it may be found useful as a rapid means of obtaining a, rough idea of the proportion of that alkaloid, or of separating the greater part of it in an approximately pure condition.C. A. M. Composition of Shea Butter. J. E. Southcombe. ( J . Soc. C h m . In& 1909, 28, 499.)-The fruits of the two varieties of Bassia Parkii are known afi shea nuts and kariti nuts. The latter invariably yield a smaller quantity of fat (with lower melting-point and higher iodine value) than the former. Thus from two samples of kariti nuts from the Soudan the author obtained 35 and 32.7 per cent. of fat, melting at 25' and 27' C., and having iodine values of 66 and 67.1, and saponification values of 175.3 and 177.1 respectively. The yield of fat from three Nigerian samples of shea nuts ranged from 49.8 to 53.6 per cent., and the fats had the following constants : Melting-point, 27' to 30' C.; iodine value, 54.8 to 57.5; and saponification value, 173.9 to 183.4. A specimen of shea butter prepared by the natives contained 0.6 per cent. of moisture and 2 per cent. of foreign matter (sand, fibre, etc.). It gave the following analytical values : Specific gravity at 98" to 99" C., 0.861; melting-point, 29" C.; solidification-point, 20' to 21' C. ; acid value, 26.17 ; saponification value, l(8.7 ; iodine value, 57.6 ; Hehney value, 93-8 ; and Reichert-Meissl value, 1.15. By fractional crystallisation of this fat triskarin in fairly pure condition was obtained, but no quantitative separation could be effected. The liquid " fatty acids separated by Ruggieri and Tortelli's324 THE ANALYST. lead-ether method had an iodine value of 90.6.They yielded only dihydroxystearic acid on oxidation with alkaline permanganate. The 6' solid " fatty acids (iodine value, 3.2) melted at 52" to 5 7 O C., and by fractional crystallisation of their magnesium salts from alcohol were found to consist of 4 to 5 per cent. of lauric acid and 90.5 per cent. of stearic acid, contaminated with oleic acid. The mixed fatty acids thus consisted approximately of 60 per cent. of oleic acid, 30 to 35 per cent. of stearic acid, and 3 to 4 per cent, of lauric acid. The fat also contained 3.8 per cent. of a fragrant resinous unsaponifiable matter. The native method of extraction leaves a, considerable proportion of nitrogen ia the fat, and this probably accounts for the liability of imported samples of shea butter to become oxidised and rancid.The volatile fatty acids in the butter increase in the stored butter. Thus the Reichert- Meissl value of a sample of crude fat increased from 1-10 to 1.56 in two months and to 1.8 in six months, whilst in the case of the purified fat the corresponding values were 0.75, 0.90 and 0.90 respectively. C. A. M. Identification of Inosite in Natural Wines. G. Perrin. (Afifi. de Chinz. Anal. AppZ., 1909, 14, 182-183.)-The fact that all natural wines contain inosite affords a simple means of distinguishing them from artificial products. For the identification of inosite, 200 C.C. of the wine are treated with 20 C.C. of basic lead acetate solution and a few drops of an alcoholic solution of tannin, and filtered. The filtrate is freed from lead by means of hydrogen sulphide, and the filtrate from the lead sulphide decolorised with animal charcoal, and concentrated to about 10 to 20 C.C. on the water-bath. The following tests are then applied to this liquid: (1) Two drops are heated on platinum foil with 1 drop of a 10 per cent. solution of silver nitrate, and the residue carefully ignited. I n the presence of inosite a violet- rose coloration is obtained. This disappears on cooling, but reappears on again heating the foil. (2) Two drops of the solution are heated on platinum foil with 1 drop of nitric acid, and the carbon incinerated as before. The residue is then treated with a drop of ammonia solution, and the liquid again evaporated. A rose coloration, which is less pronounced than that obtained in the first test, indicatea that the wine contained inosite. C. A. M.

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年代:1909

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324 THE ANALYST. BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Behaviour of Atoxyl in the Body. J. Igersheimer and A. Rothmann. (Zeit. physiol. Clzenz., 1909, 59, 256-280.)--Atoxyl~ when injected into the blood, is excreted for the greater part in an unchanged condition in the urine, and there is consequently reason to assume that it exerts its influence (curative and antiseptic) without undergoing any decomposition. Whilst, however, atoxyl itself is relatively non-poisonous, chronic atoxyl poisoning can take place, and the symptoms are analogous to those in arsenical poisoning. Having found that atoxyl combines to a certain extent with the cells of the various organs, that some change or decomposition of the substance takes place, and that arsenic, as such, is set free in the body, the authors conclude, that poisoning by atoxyl is due, not only to the substance itself, butTHE ANALYST4 325 t o the toxicity of its decomposition products and to the arsenic liberated (cf.ANALYST, 1909, 152). w. P. s. Occurrence of p-Oxyphenylethylamine in Emmentaler Cheese. E. Win- terstein and A. Kiing. (Zeit. physiol. Chem., 1909, 59, 138-140.)-The authors have isolated small quantities of p-oxyphenylethylamine from ripe, abnormal Emmentaler cheese. Whether this substance is formed by bacterial or enzymic action could not be ascertained, but from the experiments of Fischer and Abder- halden, who found that neither pancreatic nor peptic digestion produced similar bodies, it may be concluded that its formation is due to the action of bacteria. w. P.s. The Quantity of Lime and Magnesia in Various Seeds. E. Schulze and C. Godet. (Zeit. physiol. Chem., 1909, 58, 156-161.)-The following quantities of iime and magnesia were found in various seeds; the mount of total ash, potash, and phosphoric acid is also given, and the figures express percentages calculated on the dry seed kernels : Seeds of Siberian pine . . . ... ... Blue lupine . . . ... ... Pumpkin ... ... ... ... Castor-oil plant . . . ... ... Sunflower . . . ... ... ... Hazel ... ... ... ... Almond ... ... ... ... Walnut ... ... ... ... Total Ash. 2-90 3-78 3.67 3-64 3.66 3.09 2-86 2 a40 K20. CaO. 0.19 0.19 0-04 0-15 0.18 0.30 0.37 0.08 MgO. 0.27 0.40 0.70 0.72 0.66 0.48 0.38 0.28 p205. 1.16 1.53 2-10 1.16 - - - _- The husks of some of the seeds were examined, and found to contain less magnesia than lime.As the magnesia is present in larger amount than the lime in .the kernels, the authors conclude that magnesia plays a more important part in the growth of the embryo plant than does lime. R. Willstatter (ibid., pp. 438-439) has collated the results of analyses which show t'hat, in the case of wheat, rye, barley, oats, rice, maize, and buckwheat, the magnesia is also present in larger quantity than the lime. w. P. s. A Criticism of Staining Methods for Determining the Dead Cells of Yeast. E. Schlichting and H. Winther. (Commuiaicated to the Seventh Znternatioiaal Congress of Applied Chemistry.)-After a survey of the literature per- taining to the staining methods for determining the dead cells of yeast, the authors show, by means of a series of texts, that : (1) The methods at present prescribed and most generally followed in commercial laboratories for the determination of dead cells in yeast samples are not sufficiently accurate for technical purposes.(2) The stain- ing methods described and adopted in their own practice give sufficiently accurate336 THE ANALYST. and compardble results. (3) Different concentrations of stain are liable to give erroneous results. (4) The most appropriate dilution for the yeast is in the propor- tion of about 40,000 cells per 1 c.m. (5) Of all the staining media employed in their experiments, the authors prefer a solution of sulpho-indigotate in the dilution of 1 : 30. H. F. E. H. Estimation of the Total Sulphur in Urine. E. Abderhalden and C.Funk. (Zeit. physiol. Chem., 1909, 58, 331-333.)-The authors confirm the statement made by Osterberg and Wolf (ANALYST, 1908, 33, 364) that oxidation with fuming nitric acid yields too low results in the estimation of the total sulphur in urine, and they propose a modification of the sodium peroxide method for this purpose. Ten C.C. of the urine are evaporated to dryness in a nickel crucible after the addition of a little sodium carbonate and 0.4 gram of lactose; 6.4 grams of sodium peroxide a10 then mixed with the residue in the crucible, and the latter is stood in a porcelain basin containing sufficient water to immerse about three-quarters of the height of the crucible. The contents of the crucible are next ignited by insert- ing a red-hot iron wire through a small hole in the lid. The basin is then covered, and the crucible, when cold, is overturned in the water, the sulphuric acid in the solution being afterwards estimated in the usual manner. The results obtained by the method agree well with those found when the urine is ignited in the presence of sodium carbonate and potassium nitrate. w. P. s.

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年代:1909

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336 THE ANALYST. ORGANIC ANALYSIS. Analysis of Commercial Acetate of Lime. T. S. Gladding. (J. I d . and Eng. Chem., 1909, 1, 250-252; through J. SOC. Chem. Ind., 1909, 28, 467.)-Two grams of the sample are distilled with 30 C.C. of water and 10 C.C. of phosphoric acid (specific gravity 1.70) in a long-necked flask of 300 C.C. capacity. Distillation is con- tinued for one and a half hours, the volume being kept constant by the continuous addition of water free from carbon dioxide. The distillate is collected in standard alkali solution. Concordant results are obtained with solutions containing calcium acetate and phosphoric acid in varying degrees of concentration. I t is pointed out that Fresenius and Griinhut, who condemned the method, introduced a current of steam instead of water into the distilling-flask ; the faultiness of this procedure had been shown previously by the author and by Grosvenor.A. G. L. A Reaction of Acetone. B. Bardach. (Chem. Zeit., 1909, 33, 570.)-The property possessed by proteins and groups capable of forming anhydrides, of com- bining with iodine in presence of acetone, may be used conversely for the detection of acetone. The test is carried out in the following manner : 5 C.C. of the solution supposed to contain acetone, in an approximately neutral condition, are treated with 1 C.C. of a 3 per cent. solution of purified peptone and a sufficient quantity of Lugol’s reagent (4 grams of iodine, 6 grams of potassium iodide, and 100 C.C. of water) to give a deep red-brown colour ; finally, 3 C.C. of ammonia axe added.The brown colour should persist after this for at least ten minutes; if it disappears too rapidly, theTHE ANALYST 327 quantity of iodine was insufficient. After about one hour a precipitate will have formed, and the liquid may be decanted oflf. The residue is acidified with hydro- chloric acid, which dissolves the phosphates, and if nothing remains, the absence of acetone may be inferred. Any precipitate which remains in the acidified liquid should be examined under the microscope, the liquid being decolorised, if necessary, by a few drops of sodium thiosulphate: The characteristic precipitate differs from iodoform in the fact that it crystallises in the form of yellowish-coloured fine needles or filaments. If the acetone be present in large quantities, the crystals form rapidly, and may be identified by the naked eye, but if only traces be present, it may be necessary to allow one and a half hours for their separation.The test is a very delicate one ; liquids containingonly 0.01 per cent. of acetone give a bulky crystal- line precipitate. Alcohol and bodies containing the less readily oxidisable groups, -CH,OH and -CH(OH)- in juxtaposition to a methyl group, do not react, but the test seems to be quite general for the group CH,-CO-C-. I t possesses the great advantage of being applicable to highly coloured liquids. J. F. B. The 6 c Hydrogen Value ” of Unsaturated Carbon Compounds : A New Analytical Constant. S. Fokin. (Zeit. anal. Chem., 1909, 48, 337-348.)- The ‘‘ hydrogen value ” of unsaturated compounds has been proposed (ANALYST, 1908, 33, 407) as EL new analytical constant comparable with the ‘‘ iodine values ”* of Hub1 and Wijs.It is deter- mined by hydrogenation at the ordinary temperature by means of gaseous hydrogen in presence of reduced platinum as a catalyst. The I ‘ hydrogen value” is defined as the number of C.C. of hydrogen, measured at 0” C. and 760 mm. pressure, which combine with 1 gram of the substance under in- vestigation. The apparatus used for the determination is shown in the accompanying diagram. The reaction is carried out in the flask A, of 50 to 100 C.C. capacity, with a small tube, a, fused to the bottom. The substance itself is placed in the flask; the catalyst, consisting of 0.1 to 0.02 gram of reduced platinum, is placed in the tube a, and moistened with 0.25 to 0.5 C.C.of water in order to avoid. direct contact with the hydrogen gas. Twenty or thirty C.C. of alcohol are. then introduced into the flask, and the latter is closed and connected with the pressure tubing, b, through which the air is exhausted from the flask and..328 THE ANALYST from the alcohol as completely as possible. Meanwhile the gas burette B, of 200 C.C. capacity, is filled with mercury and a supernatant layer of alcohol, which latter is caused to ascend until it fills the connecting tubes c, d, and g, up to the tap K of the gasometer D ; it is also sucked by the mouth into the tube e. When the reaction flask is fully evacuated, the end of the tube b is pinched and connected with the gas burette. The cocks F and K are opened, the mercury reservoir being lowered, and the alcohol in the connecting tubes is drawn into the gas burette.The pinchcock on b is now opened, the hydrogen in the gasometer is allowed to flow into the flask A and the burette B, and the level in the latter is read oft', the cock K being closed. The mercury reservoir having been raised to its highest level, the flask A is shaken by a mechanical arrangement, cgre being taken not to allow the mercury to splash over from B into A. The velocity of the reaction depends on the quantity of catalyst used, but certain substances, owing to their property of coagulating the platinum, react soniewhat slowly. It is desirable that the quantity of hydrogen left in the burette at the end of the reaction should be as small as possible, the volunie finally read being corrected for temperature and pressure and the vapour tension of alcohol.Electrolytic hydrogen is used for the experiment, its oxygen contents being determined by means of pyrogallol. Further corrections are then necessary for the hydrogen taken up in combining with this oxygen and for that absorbed by the alcohol alone, as determined by a blank experiment. Unsaturated bodies of the aliphatic series show '' hydrogen values " in good concordance with those calculated from their '' iodine values." Cyclic compounds with double bonds do not react with hydrogen as a rule, but in special cases, such as cinnamic acid and nitrobenzene, a partial reduction of the benzene ring is observed, due to the nature of the substituting groups, Rosin and other terpene derivatives, as well as phenols, which absorb iodine by substitution, show no hydrogen absorption.J. F. B. Testing the Reaction of Lubricating Greases. W. Normann. (Chem. Rev. Fett.- '16. Ha~x.-I?zd., 1909, 16, 99-100.)-Por the determination of free fatty acids in thick lubricating greases, a solvent, boiling above 100" C., such as toluene, xylene, or butyl alcohol, is preferable to the light petroleum spirit used by Marcusson. The grease is heated with 100 C.C. of one of these solvents with the addition of 10 C.C. of absolute alcohol placed on the water-bath, and the insoluble matter allowed to settle. The liquid is then decanted from the deposit of lime, etc., and filtered, and the filtrate cooled and titrated with standard alkali solution.C. A. M. New Constants for the Valuation of Mineral Lubricating Oils. R. Kissling. (Chem. Zeit., 1909, 33, 521-522.)-The method described previously (ANALYST, 1908, 33, 432) by the author for the estimation of the carbonised matters in heated mineral oils yields too high results, owing to the retention of sodium hydroxide by the carbon. After the oil has been removed by treatment with benzene, the filter and carbonised matter must be washed thoroughly with water until all the alkali has been removed. I t is also recommended that the aqueous alkaline extractTHE ANALYST, 329 of the oil be acidified with hydrochloric acid before the tarry matters are extracted with benzene. The following average results were obtained with various mineral oils : Kind of Oil.Heavy Russian machine oil (four samples) Pennsylvanian machine oil (four samples) ... ... Turbine oil A, before use ... ... ... ?, after use ... ... ... Turbine oil BJ before use ... ... ... ) J after use ... ... ... " Illinois " lubricating oil (three samples) ~. . ... ... Tarry Matter. 0.54 0.54 0.59 0.80 0.91 1.64 0.92 Carbonised Matter. ~ 0.36 0.36 0.39 0.89 1-07 2-67 0.95 w. P. s. Commercial Analysis of Manufactured Caoutchoue. Pontio. (Bull. Xoc. Chim., 1909, 5, 428-442.)-The author proposes a scheme for the analysis by means of solvents of manufactured rubbers, the various constituents being classified as follows : A bsohte Alcohol Group-Free sulphur, resin, paraffin, fatty substances. Alcoholic Soda Group-Rubber substitutes, and the sulphur combined with them.Lavendar Oil and Acetone Group - Mineral oils and bituminous products. Chmeize Group-Caoutchouc gum and sulphur combined with it, mineral matters, and free carbon. I n many cases the constituents are not freely soluble (e.g., sulphur in alcohol), and a prolonged extraction is necessary. For this purpcse the author has devised an apparatus (see Fig.) in which six or twelve samples can be treated simultaneously. The lower extraction vessel holds about 700 C.C. of solvent, and is pro- vided with a wide mouth with a, ground-in stopper. From this is suspended a cage carrying six perforated funnels, in which the samples are placed in such a position that the lower portions of the funnels dip below the surface of the liquid, and the samples may be digested for six hours with the boiling solvent.After the digestion the samples and the funnels are transferred to the upper portion of the extraction vessel, where they are washed by the condensed vapours of the solvent, whilst another set of six may be undergoing digestion in the lower portion. For the washing operation, the passage from the condenser is divided into six branches, each of which is immediately over a funnel. The solvent used for the third group consists of a mixture of 40 per cent. of oil of spike (dextrorotatory lavender oil) and 60 per 7 cent. of acetone. The digestion of the samples lasts for six hours with the first three solvents, and for twelve hours with the cumene. In the last case the digestion must330 THE ANALYST. be effected on tared paper filters, of which the loss of weight in the operation has been determined by a blank experiment.Thefoldingof these filters is of the highest importance. I n order to avoid creeping " by capillarity, no fold must touch the next one. The paper is moistened with a few drops of cumene; 2 grams of ignited kaolin are poured into the bottom of the cone, and the powdered rubber placed on the top. The filter and support are then adjusted in such a way that the whole is suspended to a depth of 1 cm. in the boiling cumene. The residue from the extraction is washed first with benzene, then with alcohol, and when dry it represents the quantity of mineral matter and carbon in the sample. The mineral loading matters in indiarubber may be estimated with sufficient accuracy for commercial purposes by direct incineration of the sample in a, muffle at a very low temperature, provided the loading does not comprise free carbon or mercuric sulphide; the error introduced by the changes undergone by the usual metallic oxides and sulphates is hardly appreciable.The total sulphur is best determined by heating in a covered crucible with manganese dioxide and fusion mixture. Free sulphur and sulphur combined with substitutes are estimated in the respective alcoholic extracts by oxidation with alkaline hydrogen peroxide. The sulphur in the minerals is estimated in the residue from the extraction with cumene. The sulphur of vulcanisation is estimated by difference. Analysis of Gutta-percha by Solvents.-The gutta-percha is first treated by digestion with boiling 96 per cent.alcohol in the manner indicated above for twelve hours. This extracts the resins. The residue is then similarly exhausted with ether ; the residue from this treatment then contains the natural impurities of the gutta and 62 per cent. of any bitumen which may be present. This residual bitumen is extracted by boiling carbon bisulphide or toluene, and there remain only the inert impurities, whence the original quantity of bitumen may be calculated. J. F. B. Horse-chestnut Oil. Stillesen. (Chenz. Zeit., 1909, 33, 497-498.)-Ether extracts from the dry and finely divided seeds of the horse-chsstnut, ~3!3sculz~s hippocastanurn, from 1.5 to 3 per cent. of yellowish-brown somewhat viscid fatty oil, which has the following chemical and physical constants : ...Specific gravity at 15' C. ... ... ... 0.9260 Saponification number ... ... ... ... 194.5 Acetyl number ... ... ... ... ... 13.5 Insoluble fatty acids ... ... ... ... 92.9 Refractive index at 20' C. ... ... ... ... 1.4747 Iodine number ... ... ... .. ... 95.4 Reichert-Meissl number ... ... ... ... 1.54 The oil begins to solidify at - 20" C., and is a wax-like d i d at - 37" C. It contains 0.53 per cent. of unsaponifiable matter. The principal constituent of the oil is olein, with small quantities of linolein, palmitin, and stearin. The oil appears to be on the border-line between the semi-drying and non-drying oils. w. P. s.THE ANALYST. 331 Determination of the Acid Value of Resins. J. Marcusson and G. Winterfeld. (Chern. Rev.Fett.- a. Hurx-Ind., 1909, 16, 104-107.)-1n the ordinary direct method of determining the acid value of resins, long-continued boiling with alcohol is necessary to extract the whole of the free acids. A mixture in equal parts of chloroform and alcohol is a much better solvent, but, owing to the action of the alkali on the chloroform, the end-point of the titration is usually not sharp enough. On the other hand, a mixture in equal parts of benzene and alcohol has not this drawback. It dissolves many resins readily, and even in the case of hard resins, such as amber, dammar, and Zanzibar copd, where complete solution is not obtained, its use enables the whole of the free acids to be titrated. From 3 to 4 grams of the resin are heated for a short time beneath a reflux condenser, with 200 C.C.of the mixture of absolute alcohol and benzene. The contents of the flask are then cooled, and, without separation of any insoluble matter, titrated with & alkali solution, with phenolphthalein as indicator. The results thus rapidly obtained are in close agree- ment with those found by exhausting the resin with boiling alcohol. The presence of potassium or sodium soaps has no influence on the results ; but if ammonium resinate is present, as in many of the so-called L 4 soluble ” resin oils and mineral oils, it is best to make a separate estimation of the ammonia by distillation, in order to find the amount of alkali consumed in the liberation of ammonia during the titration. Calcium soaps form basic soaps during the titration, and the latter are not dissociated in the mixture of benzene and alcohol, and therefore do not react with phenolphthalein. This is obviated by the addition of water as follows : From 5 to 10 grams of the substance containing the calcium resinate are boiled for a short time under a reflux condenser with about 50 C.C.of a neutral mixture of 90 parts of benzene and 10 parts of absolute alcohol. Any insoluble matter is filtered off from the hot liquid and washed, and the filtrate mixed with 30 C.C. of neutral 50 per cent. alcohol, and titrated with & sodium hydroxide solution, with phenolphthalein as indicator, the flask being meanwhile constant€y shaken until the lower layer remains pink. I n the presence of resinates of aluminium, iron, manganese, and other heavy metals, notably lead, it is necessary to determine the amount of acid required to neutralise the soaps, and, on the other hand, the amount of alkali required to neutralise both the originally free resin acids and those liberated by the hydrochloric acid.From 10 to 12 grams of the sample are treated with 50 C.C. of benzene, and filtered from any insoluble matter. The filtrate is then mixed with 30 C.C. of water containing methyl-orange, and titrated with hydrochloric acid until the aqueous layer becomes pink. This layer is now drawn off, mixed with the washings of the benzene layer, and with neutral alcohol, and titrated with & sodium hydroxide solution, with phenolphthalein as indicator. The difference between the amount of alkali required and that corresponding to the hydrochloric acid gives the quantity of alkali neutralised by the free resin acids.C. A. M. Saccharification and Polarimetric Estimation of Starch in Barley. F. Schubert. (2. Spiritzisind., 1909, 32, 157 ; through J. SOC. Chem. Ind., 1909,28, 487.)-The author has modified Geschwendner’s and Parow and Neurnann’s methods (ANALYST, 1908, 33, loo), and claims that the modified method gives concordant and832 THE ANALYST. satisfactory results for siarch, none of the dextrose produced undergoing decomposi- tion. The method consists in treating 20 grams of barley grist in a 200 C.C. graduated flask with 100 C.C. of a reagent which contains 100 grams of salt and 10 grams of hydrogen chloride per litre. The whole is heated for five hours (not necessarily continuously) at 100" C., either in a vigorously boiling water-bath provided with a comtant-level arrangement and means for preventing superheating, or else in an oil-bath provided with a thermo-regulator working at 98" to 100" C.After cooling, the contents of the flask are made up to the mark, filtered without clarification, and polarised. The reading so obtained should be checked after the liquid has stood for some little time. One degree Ventzke corresponds to 0-2941 gram starch, and one circular degree to 0-8514 gram starch, with the 200 mm. tube. A. G. L. Note on the Hydrochloric Acid Extraction Method for the Polarimetrie Estimation of Starch. L. T. Thorne and E. H. JeRers. (CommzLnicated to the Seventh Internatioizal Congress of Applied Chemistry.)-The authors triturate 5 grams of the very finely powdered material with small amounts of water, using less than 20 C.C.in all. About 40 C.C. of hydrochloric acid of specific gravity 1.15 are then very gradually added, the whole becoming a viscous liquid. The mixture, after standing ten minutes, is transferred to a 200 C.C. flask containing 10 C.C. of 4 per cent. phosphotungstic acid and 20 C.C. of hydrochloric acid (specific gravity 1-15), The whole is made up to 200 C.C. with hydrochloric acid (specific gravity l - l ) , and then thoroughly shaken in a wide-mouthed bottle or centrifugalised till the pre- cipitate separates from the clear solution, which is then filtered and the polarimetric. reading taken. With a 200 mm. tube, Schmidt and Haensch scale, and white light, R x 40 the percentage of starch is found from P= -- 1TiF E.F. E. H. Determination of Starch in Cereals by Means of the Zeiss Immersion Refractometer. L. M. Lalin. (2. ges. Brauzu., 1909, 32, 231-233; through J. SOC. Chem. I72d., 1909, 28, 617.)-By means of the Zeiss immersion refractometer, the author has measured the refraction of starch conversion products in different stages of saccharification by diastase. I t is found that the coefficient of refraction of a solution of soluble starch is not altered by diastatic conversion of the starch up to the point where the products give no reaction with iodine. Starches from various cereals were employed, in addition to Lintner's soluble Btarch, and the conversions were effected by diastase precipitated from the aqueous extract of a well-grown malt by the addition of ammonium sulphate.The concentration of the starch varied from 1 to 5 per cent. One gram of starch was found to correspond with four divisions on the refractometer scale. The following method is given for the determination of starch in cereals: Two to three grams of the, finely powdered material are pounded in a mortar with a small quantity of water, and introduced into a 100 C.C. flask, the volume being made up to about 80 C.C. 0.2 C.C. of a 1 per cent. solution of diastase is then added, and the flask heated for five minutes in a boiling water-bath, and then cooled to the ordinary temperature.THE ANALYST. 333 35 After the addition of a further quantity of 0.2 to 0.3 C.C. of the 1 per cent. diastase solution, the flask is kept at 55" to 60" C.for half an hour, after which it is cooled and the liquid made up to 100 c.c., well shaken, filtered, and the filtrate examined in the refractometer at 17.5" C. To correct for the refraction of the soluble con- stituents of the cereal, 2 to 3 grams of the latter are finely powdered, pounded in a mortar with a little water, the whole being then introduced into a 100 C.C. flask, and the volume made up to 100 C.C. After being well shaken, the liquid is filtered, and its refraction determined at 17.5O C. With cereals like rye, which contain a large proportion of diastatic enzymes, the cold water extract should not be allowed to stand for long. Measurements of the proportions of starch in a number of different cereals show that this method gives results in close agreement with those obtained by the polarimetric method (Lintner, ANALYST, 1907, 32, 179), the greatest difference found being 0.37 per cent. 10.1 194.6 64.2 94.3 1.00 Oil from the Seeds of " Symphonia globulifera." J. E. Southeombe, (J. Xoc. Chem. Ind., 1909, 28, 499-450.)-The seeds of the South American plant, Ehynzphonia globulifera, are ovoid in shape, and from 1 to 2 inches in length and 2 to 1 inch in breadth. The fat, which the natives extract by treating the crushed seeds with hot water, is a dark reddish-coloured mass, which contains a white unsaponifiable resinous substance (1.1 per cent.) having a fragrant odour resembling hhat of vanilla, and yielding, on distillation, a small quantity of a volatile oil. The fat extracted from the seeds with petroleum spirit by the author had the following analytical characteristics : 0.891 Specific Gravity at 99°-1000 C 48-50 46 64.8 0.8849 FAT. I I I I I I I I I FATTY ACIDS. I I I

ISSN:0003-2654    

DOI:10.1039/AN9093400326

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 333 INORGANIC ANALYSIS. Estimation of Ammonia without a Condenser. R. 0. E. Davis. ( J . Anaer. Clzem. SOC., 1909, 31, 556-558.)-The author has 'modified Kober's method, which in the amended form is shown to give accurate results. Thirty C.C. of sulphuric acid are used for the digestion of 0.5 gram of substance, and 100 C.C. of water are added after the oxidation is complete. The Kjeldahl flask is connected on one side with a vessel containing a solution of caustic soda to render the acid solution alkaline, while on the other side a tube connects the flask with a Folin tube, which is immersed in standard acid to absorb the ammonia, and the vapours also subsequently pass through a bulbed tube containing glass beads wetted with the standard acid. From this tube connection is made with a suction pump, which draws the caustic soda solution over into the334 THE ANALYST.digestion flask after the dilution water has been added and all connections made, The tube carrying the soda solution dips below the surface of the acid solution in the flask. Air is then drawn through the apparatus by the continued action of the pump for fully one hour, and the ammonia is absorbed in the standard acid. The digestion flask is placed in an asbestos box, which keeps the solution warm (from the heat of neutralisation) for one and a half hours. Scrap aluminium is added to the digestion flask, which results in a steady stream of hydrogen being evolved. If more than 0.5 gram of substance be employed, it is best to keep the liquid hot by means of a burner while drawing air over it.If aluminium and acid be employed for the digestion, the same results are obtained as when mercury and salicylic acid are used. The results are comparable with the ordinary distillation method. A. R. T. Influence of Small Quantities of Arsenic and Antimony on Copper. A. H. Hiorns and S. Lamb. (J. SOC. Chem. I d . , 1909, 28, 451-457.)-Small ingots of copper containing arsenic show a slight elevation of the surface up to 0.1 per cent. of arsenic; from 0.2 to 0.4 per cent. the surface is level, and above 0.5 per cent, a distinct furrow appears. From 0 to 0.2 per cent. the ingots show blowholes. The colour becomes lighter with increasing content of arsenic; with 2.9 per cent. the colour is that of gun-metal. The metal also files better as the percentage of arsenic is increased.Tested with the scleroscope and intensifier hammer, pure copper shows 7" of hardness; with 0.05 per cent. of arsenic, 8'; with 0.382 per cent., 9"; with 1.395 per cent., 10"; and with 2.893 per cent., 11". Wires drawn from pure copper always break at a blowhole; with 0.05 to 0.382 per cent. of arsenic good wires are easily drawn; above this amount, up to 1 per cent., the wires break or are weak owing to small surface cracks; from 1 to 2.24 per cent. good wires are again obtained. On rolling cold, ingots with up to 0.2 per cent. fray slightly at the edges, probably due to enclosed oxide; between 0.2 and 0.5 per cent. the metal stands the test well; from 0.5 to 1-74 per cent. the metal again shows cracks at the edges; from 1-74 to 2-89 per cent.the metal rolls well, no large edge-cracks being produced; pure copper stands this cold rolling test well. The electrical conductivity varies in a fairly regular manner, being 100 for pure copper, 79.4 for 0.05 per cent. arsenic, 69.5 for 0.098 per cent., 59.5 for 0.22 per cent., 42.7 for 0.471 per cent., 33.2 for 0.701 per cent., 16.5 for 1-74 per cent., and 12.6 for 2.581 per cent. The ingots described above were prepared by melting electrolytic copper con- taining 0-02 per cent. of iron with a rich copper-arsenic alloy containing 32.7 per cent. of arsenic, or with a copper-actirnony alloy containing 67.1 per cent. of anti- mony. The arsenic or antimony found by analysis in the finished ingots was usually somewhat lower than the calculated amount, especially for the richer alloys.Oxygen was not estimated in any case. All ingots of copper containing antimony show blowholes, even with 3.5 per cent. On rolling cold, cracks are always produced in a plane at right angles to the rolls. With more than 0.6 per cent. of antimony, wires cannot be drawn. Antimony and arsenic lighten the colour of the ingot to about the same extent. The hardness increases only from 7" for pure copper to 8' for copper with 1 per cent. of antimony, and 9" for 2 per cent. The electrical conductivity decreases from 100 for pure copperTHE ANALYST. 335 to 76 for 0.098 per cent. of antimony, 70 for 0.203 per cent., 58.4 for 0.392 per cent., 48.9 for 0.461 per cent., and 42.4 for 0.605 per cent. Microscopical examination showed the probable presence of Cu,As and Cu,Sb in the two series of alloys.A. G. L. Rapid Volumetric Method for Determining Cerium in Presence of Other Rare Earths. F. J. Metzger. ( J . Anzer. Chem. Soc., 1909, 31,583-525.)-Cerous salts in sulphuric acid solution are quantitatively oxidised by sodium bismuthate to ceric salts, and the latter can then be again reduced by means of ferrous sulphate added in known amount, the excess of this salt being determined by titration with permanganate. The permanganate solution is approximately one-fortieth normal, and is prepared by dissolving 10 grams of potamium permanganate and 50 C.C. of strong sulphuric acid in water, and making up to 1 litre. The value of this solution in terms of Fe, x 3,08415, gives the equivalent of CeO,.To 50 C.C. of the solution, containing about 0.2 gram of the rare earths, is added 20 C.C. of strong sulphuric acid, and the liquid evaporated until fumes of sulphur trioxide are evolved, (This treatment is unnecessary if the salts are already in the form of sulphates, when 1 : 4 sulphuric acid is added to the salts to dissolve them.) The liquid is cooled, when 2 grams of ammonium sulphate are added, to prevent the precipitation of basic bismuth salt, and 80 C.C. of water. One gram of sodium bismuthate is next added, and the liquid boiled, when it is cooled somewhat, diluted with 50 C.C. of 2 per cent. sulphuric acid, filtered through a Gooch crucible, and the residue washed with 100 to 150 C.C. of 2 per cent. sulphuric acid. Standard ferrous sulphate is run into the solution in excess (colour changes from yellow to colourless), and this is titrated back with permanganate. The method is not invalidated by the presence of salts of Th, La, Nd, Pr, Y, Er, Zr, Sm, Gd, and Ti.The method is being applied to the examination of minerals, monazite sand, and incandescent. mantles. The method is accurate, as shown by the following results: CeO, taken. (1) 0.1901 gram (determined by oxalate precipitation) ; found, ( a ) 0.1897, (b) 0.1907 gram CeO,. Taken (2) 0,2102 gram; found, (a) 0.2103, (b) 0,2104 gram CeO,. (3) Taken, 0.1928; found ( a ) 0.1927, and (b) 0.1922 gram CeO,. A. R. T. The Influence of Bromides and Iodides on the Estimation of Nitrates in Water. L. Farey. (Bull. SOC. Chim., 1909 [iv.], 5, 563-566.)-Experiments made on similar lines to those described in the case of chlorides (ANALYST, 1909, 174) have shown that bromides and iodides also exert a disturbing influence upon the estima- tion of nitrates by the colorimetric msthod of Grandval and Lajoux.In each instance the decolorisation produced by these salts is to be attributed to the libera- tion of the respective halogen acids, which then form derivatives, the ammonium salts of which have little or no colour. The coefficient of decolorisation varies with the nature of the halogen salt, the action of iodides being intermediate to that of chlorides or bromides. Reference to the following table, which summarises the author’B results, enables a correction to be applied for the amount of the halogen336 THE ANALYST, salts present in a water.amount of nitrate, R, to that of the apparent amount estimated colorimetrically. The coefficient of decolorisation is the ratio of the real M m s . of NaCl or A R Coefficient of Decolorisatioii - = D. Chlorides. EqniGIent Quantities of NH,Br or KI per Litre. 0 100 200 300 400 500 1,000 Average increase per 100 mgm. ... 1.0 1.15 1-30 1.45 1.60 1.75 2.3 0.15 Bromides. 1.0 4.5 7.7 10.8 14.0 1 6 .6 ::: - 3.1 Iodides. 1.0 1.7 2.3 2.9 3.5 4.0 6.9 0.6 Thus in the case of a water containing 735 mgm. of sodium chloride and an ap- parent quantity of 45 mgm. of nitrate per litre, the coefficient of decolorisation in the table is 2-05. The real amount of nitrate in the water is therefore 45 x 2.05 = 92.25 mgm. The objection that in the presence of iodides the coefficients would be falsi- fied by the formation of nitrogen iodide is answered by the results of the experiments of Cavalier and Artus (ANALYST, 1905, 30, 319j, who showed that the dark coloration produced by nitrogen iodide faded in the course of two or three minutes.C. A. M. Detection of Chlorides in Presence of Complex Cyanides and Other Halogenides. W. Bottger. (Zeit. anal. Chem., 1909, 48, 356-368.)-Complex, sparingly soluble cyanides are decomposed on heating for a short time with mercuric oxide, yielding mercuric cyanide, which is practically non-dissociable, and which consequently gives no precipitate with silver nitrate. Mercuric nitrate decomposes the complex cyanides more rapidly than the oxide, but excess must be used, and the excess of soluble mercury salt seriously interferes with the delicacy of the subsequent test for chlorides.I t is therefore necessary to remove the mercury and heavy metal derived from the complex cyanide from the solution before testing with silver nitrate. This can be done by sulphuretted hydrogen, but if mercuric nitrate has been used there is a production of thiocyanate under the action of the nitric acid, which again interferes with the test for chlorides. Finally, the author found a satisfactory method by the use of mercuric oxide and dilute sulphuric acid, which is illustrated by the following example: 0.5 gram of a mixture of 1 part of copper ferrocyanide and 3 parts of mercuric oxide were boiled for a few minutes with 20 C.C. of water and 10 C.C. of 2N-sulphuric acid, to which had been added 0.1 gram of potzssium chloride.The cooled solution was saturated with a current of well-washed sulphuretted hydrogen and filtered. The filtrate was warmed, and a * Colour too dark for very accurate estimation.THE ANALYST. 337 stream of washed carbon dioxide was passed through until all the hydrocyanic acid and sulphuretted hydrogen were expelled, an operation lasting for twenty minutes. Before titrating the chloride by silver nitrate according to Volhard's method, it was necessary to oxidise the iron present in the solution from the ferrous to the ferric state by means of permanganate. The loss of chlorine, due chiefly to volatilisation of hydrochloric acid during the expulsion of the sulphuretted hydrogen, amounted to about 3 per cent.When bromide or iodide was substituted for the chloride, the losses of halogen were considerably greater, owing to the action of the permanganate. This circumstance can be made use of for the detection of chlorides when bromides are also present, by treating the liquid, after the removal of the hydrocyanic acid and sulphuretted hydrogen, with an excess of permanganate and heating for about twenty-five minutes to expel the bromine, then reducing the excess of permanganate by alcohol, filtering off the manganese dioxide, expelling the alcohol by a current of carbon dioxide through the warm liquid, and finally re-oxidising the iron by a trace of permanganate. The losses of chloride through all these operations are very considerable, and amount to nearly 50 per cent., but the method is still useful.J. F. B. Gravimetric Molybdate Method for the Determination of Phosphoric Acid for the International Trade of Raw Phosphates. Ullmann. (Conz- muizicated to the Seventh International Congress of Applied Chenzistry, 1909 ; through J. Xoc. Chenz. I d , 1909, 28, 616.)-The following reagents and solutions are required : (1) Aqua regia-three parts of hydrochloric acid of specific gravity 1.12, mixed with one part of nitric acid of specific gravity 1.2. (2) Ammonium wzolybdate solution-150 grams of ammonium molybdate are dissolved in 500 C.C. of hot water, and the solution is mixed with 400 grams of ammonium nitrate, also dissolved in water, the mixture being then diluted to 1 litre; this solution is added to 1 litre of nitric acid of specific gravity 1.2, the whole is allowed to stand for twelve hours at a temperature of 60" C.(or for twenty-four hours at the ordinary temperature), and then filtered. (3) Solution for washing the nzolybdate precipitate-thirty-two parts of nitric acid of specific gravity 1.2 and 50 grams of ammonium nitrate (free from phosphate) are diluted to 1 litre with water. (4) 2.5 per cent. ammonia solution. (5) Neutral mugnesia so~zbtioit-~0 grams of magnesium chloride (MgCl,,H,O) and 150 grams of ammonium chloride are dissolved in 1 litre of water. Nethod.-Five grams of the sample are treated in a 500 C.C. flask with 50 C.C. of q u a regin, and the mixture is evaporated to the consistency of a syrup in order to eliminate silica. The residue, which when cold is almost solid, is boiled with R mixture of 10 C.C.of nitric acid of specific gravity 1.2 and 50 C.C. of water, cooled, diluted to a volume of 500 c.c., and filtered. Fifty C.C. of the filtrate (equivalent to 0 5 gram of the substance) are mixed with a sufficient quantity of the molybdate solution (at least 100 C.C. of the latter for each 0.1 gram of phosphoric anhydride present), and kept at a temperature of 50' C. for one hour. The precipitate is then collected on a small Elter, and the filtrate is treated with a further quantity of molybdate solution, and allowed to stand for twelve hours at 60' C. in order to ascertain whether all the phosphoric acid has been precipitated. The precipitate is338 THE ANALYST. washed with the acid ammonium nitrate solution until the filtrate is free from calcium salts-at least five washings, using 20 C.C.each time, being necessary. The test for calcium is made by adding a little sulphuric acid and 2 C.C. of alcohol to 1 C.C. of the wash-water ; the mixture remains clear in the absence of calcium salts. The yellow precipitate is then dissolved in about 80 to 100 C.C. of 2.5 per cent. ammonia, and the filter is washed five or six times with hot water. The volume of the solution and washings should not exceed 150 C.C. The solution is heated to between 60° and 80' C., and the phosphoric acid is precipitated by the addition to the hot solution of 20 C.C. of neutral magnesia solution drop by drop, and with constant stirring. At the end of four hours the precipitate is collected on a filter and waahed with 2.5 per cent. ammonia, until free from chlorine. The filter and precipitate are then heated in a platinum crucible until the filter is charred completely (care being taken that no flame is produced during the ignition of the filter), and the ignition is continued over a, blast lamp until the weight is constant. The ignited residue should be quite white. Factors.-From Mg2P,07 to P,O,, 0.63780; from P20, to Ca,P,O,, 2-185. Volumetric and Gravimetric Estimation of Thallium by Means of Potassium Ferricyanide in Alkaline Solution. P. E. Browning and H. E. Palmer. (Zeit. awrg. Chem., 1909, 62, 218-220.)---To a solution of thallous nitrate an excess of potassium ferrizyanide solution is added, followed by potassium hydroxide. The precipitate of brown thallic hydroxide is filtered off on asbestos, and carefully washed, preferably with hot water. The filtrate is acidified with sulphuric acid, and the ferrocyanide formed estimated by titration with standard potassium permanganate solution, a correction being made for the amount of the latter required to produce a pink colour in the ferricyanide solution. The results obtained are accurate to within 0.5 per cent. Equally accurate and generally slightly high values are obtained by weighing the thallic hydroxide obtained as above after drying to constant weight at 200" C. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9093400333

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

338 THE ANALYST. APPARATUS, ETC. Improved Laboratory Apparatus. A. Hahn. (Chem. Zeit., 1909,33,472.)- Rejux Condenser to be m e d f o r distilling of the Solvent.-The improved reflux condenser consists of an ordinary straight Liebig’s condenser with a side-branch fused at a, convenient angle to the tube above tho jacketed portion. This branch is of the same dimensions as the lower point of the condenser, and fits the same cork. When the digestion under the reflux condenser is finished, the condenser is withdrawn from the cork, and the side-branch at the upper end is inserted, so that the solvent can then be distilled off through the inclined condenser. A thermometer is inserted through the upper mouth of the condensing-tube, with the bulb at the base of the branch-tube. Dish j’or treating Fats and Other Viscous a d Greasy Substances.--In weighing out greasy and sticky substances it is often necessary to wipe the spatula on the edges of tho dish, and thus to incur risk of losses.In order to avoid this inconvenience aTHE ANALYST. 339 dish is constructed, either of porcelain or platinum, which has a ridge rising froin the bottom to a sharp edge, against which the spatula may be wiped. J. F. B. A New Absorption Apparatus. H. Wolbling. (Chm. X e d . , 1909, 33, 499.)-As is seen from the figure, the apparatus is a combination of a Volhard flask with a Winkler’s absorp- tion spiral, and it is particularly useful for the absorption of such gases as chlorine, etc. The current of gas is converted by the jet at the commencement of the spiral into a stream of small bubbles, which are absorbed by the solution in the spiral.The bulb arrangement placed on the exit end of the spiral insures complete absorption of the gas. I n the case of gases, such as ammonia, which are readily absorbed by a solution placed in the flask, the exit end of the spiral may be bent dowilwards, so that the liquid collecting in the flask may overflow into a beaker or other receptacle. w. P. s. An Extraction Apparatus for Plant Products, etc. S. J. M. Auld and (Chem. News, 1909, 99, 242.)-The extraction apparatus shown in S. S. Pickles. the figure consists of ~t large flask, A, fitted with a double-bored stopper. Through one of the holes passes a fairly narrow tube, enlarged at its lower extremity to a thistle-funnel, firmly packed with cotton-wool and covered with a, piece of fine muslin or cotton cloth.Outside the flask this tube is bent twice at right angles and forms a siphon, the lower arm of which passes through a second double-bored stopper into a flask, B, at a lower level than the first flask. Through the second hole of the stopper in the upper flask passes a wide tube leading to a reflux condenser, and carrying a side-tube, which passes through the second hole of the stopper of the lower flask. A tap, C, is fitted on the wide tube, between the side-tube and the upper flask. The material to be extracted and the solvent are placed in the upper flask. The contents are then heated to boiling, the tap C being open. When the solvent has become saturated, the tap C is closed for an instaut, when the solution in A is forced to pass through the filter and siphon into B. On heating the lower flask, with C open, the solvent distils back into A, and the whole process is repeated.With many solvents, the tap C may be replaced by a short rubber connection, which is momentarily closed by pressure with the fingers. The advantages of the apparatus are that large quantities of material can be dealt with, that extraction is effected at the boiling-point of the solvent, and that the solvent is recovered in the same apparatus. The extraction is, however, not quite automatic. A. G. L.340 THE ANALYST. Simple Apparatus for Extraction in the Cold and for Determination of Solubilities at the Ordinary Temperature. J. Schroeder. (Zeit. anal. Clzenz., 1909, 48, 351-352.)-The author has devised an apparatus for avoiding the evaporation of the solvent during the filtration of solutions at ordinary temperatures, serving for the extraction of substances by means of volatile solvents at the ordinary temperature, and for the preparation of saturated .solutions for the determination of solubilities.The apparatus consists of three main parts (see Fig.) : A cylindrical separator, C ; a double funnel, B, with the upper half ground in to fit the lower half; and a graduated cylindrical receiver, A. The substance to be extracted is placed in the separator C, together with the solvent, and the funnel, being disconnected from B, is shaken vigorously. It is then placed in position in the double funnel, B, the lower half of which contains a filter.When fine powders have to be extracted, it is advantageous to plug the lower end of C above the tap with asbestos wool. Vessels C and A are connected by a piece of rubber tubing, in order to equalise the pressure during filtration, The same tubing serves to plug the upper end of the double funnel 13, in case the separating funnel C has to be withdrawn for a second extraction. J. F. B. A Modification of Hempel’s Gas-Burette. J. F. Spencer. (Bey. deut. chem. Ges., 1909, 42, 1786-1787.)-1n working with the ordinary Hempel burette it is very difficult to displace the air from the tube connecting the burette with the absorption pipette. This inconvenience may be completely overcome by the use of the special tap illustrated in the figure.This tap is a 4-way tap, having one lower limb, c,fused to the top of the burette, two upper limbs, a and b, pointing vertically upwards, and one side-limb, d, at right angles to the others. The two tubes a and b can each be put into communication with the tube c, so that they may be used either for the introduction of gas samples, or for their transference to an absorption pipette. Both these tubes may be connected with the side-tube d, but the latter can never be connected directly with the burette. The use of d is twofold: first, it serves for the removal of air from the connections between the burette and pipette, and, secondly, it may be used for sweeping out the air from the connections when taking samples of gas. The manner in which the special tap is used is as follows : The absorption pipette is connected with the burette in the ordinary way.Then the tap is turned SO that the pipette is in communication with the side-tube d, and the absorption liquid is forced up so that it fills the tubes and drips out from d, thus expelling the air. The tap is then turned, and the absorption of the gas is effected in the ordinary manner. In order to take a sample of gas, the other vertical tube is employed in an exactly similar way. J. F. B.THE ANALYST. 341 A Mercury Pump. M. Guichard. (Bull. SOC. China. 1909 [iv.], 5, 571-574.)- The mercury pump shown in the diagram has the advantages of simplicity of con- struction, cheapness, and of being easily disconnected for cleaning. I t is here represented on a scale of one-sixth of the actual width and one-twentieth of the height. In order to get good results it is essential that the measurements of the different tubes should not vary by more than about 1 cni.from those given. The external glass tube a is about 0.2 cm. in thick- ness, and has a diameter of 2.5 cm., and a length of 100 cm. I t is closed at the bottom by an indiarubber cork, in which is a hole. The tube b is 1 cm. in diameter and 120 cm. in length, and (for convenience) is bent at a right angle at about 108 cm. from the base. The extremity d of this tube is drawn out so that its diameter is slightly greater than that of the leaden tube c, which is cemented into it at d. Any apparatus in which it is desired to produce a vacuum is connected with the tube c. The tube e has an exterior diameter of 0.5 em.and an interior diameter of 0.15 cm. It passes through the hole in the rubber cork in a, and its upper opening is fixed at about 94 cm. above that cork. Its lower extremity ends in a hook, which dips into the mercury trough h, consisting of a small basin 8 cm. in diameter by 5 cm. in depth. The tube f, through which the mercury enters the apparatus, is narrow, and 100 cm. in length. It is open at its lower extremity, while the other end is connected by means of indiarubber tubing with the mercury reservoir g, which holds about a litre. A pinch-screw fixed on the indiarubber tubing enables the flow of mercury to be regulated. The apparatus is clamped to a stand, or to the wall, by means of the clamps m and j , and the rubber cork in a is supported by a wire, the ends of which are fixed at 2 1.As a rule the sound made by the falling drops of mercury will indicate that the vacuum is sufficient. When the sound of the shock is very sharp, the pressure within the apparatus is less than & mm. of mercury. It will sometimes be found advantageous to use this pump in connection with a water-pump that will rapidly lower the pressure down to 2 cm. of mercury. C. A. M. Simple Method of Filling Toluene Thermo-Regulators. J. P. McGowan. (Chem. News, 1909, 99, 181.)-The author avoids the difficulties and possible breakages in filling regulators of this class by drawing out to a capillary, with a constriction near the bulb, the upper end of the toluene bulb, this capillary being parallel with the limb of the regulator and equal to it in length.acorn knob ” is provided at the upper end of the capillary, and to this knob is attached a rubber tube, which connects it with a test-tube, fitted with wash-bottle tube fittings. To use this contrivance, the side-tube of the regulator is closed, and suction made on the mouth-tube of the wash-bottle fitting, toluene being at the same time poured An342 THE ANALYST. into the regulator. When the regulator is full, and a little toluene has been drawn over into the test-tube, the salt solution is poured into the regulator limb, followed by the required amount of mercury, each in turn being drawn over into the bulb by suction. The tube fitting is then detached, and the capillary sealed off at the constriction. The limb of the regulator is filled by pouring mercury in, placing the bulb in fairly hot water, and tapping the limb at intervals.A. R. T. Apparatus for Determination of Solubilities at the Boiling-Point of B the Solvent. J. Schroeder. (Zeit. anal. Chenz., 1909, 48, 349-350.)-The author has devised the apparatus here illus- trated for the determination of solubilities of substances at the boiling-point of the solvent. The graduated boiling-tube rl has an internal diameter of 3 cm., and a ground-in stopper, a, in which is placed a triangular rod from which a short thermometer, with a scale of about 20" C., divided into tenths, is suspended by a platinum wire, and is totally immersed in the vapour of the boiling liquid. A reflux condenser is fitted into the upper part of the stopper. A siphon-tube, c, is fused into the upper part of the side of the boiling-tube, and its end is ground so as to fit tightly into the removable outer limb of the siphon d.In use, a measured quantity of the solvent is placed in the boiling-tube, together with an excess of the substance, and the solution is boiled until it is saturated. Then a pressure-ball is attached to the top of the condenser, and a quantity of the boiling liquid is expelled through the siphon into a weighing-bottle for analysis. In order to prevent the passage ol particles of solid through the tubes c and d, a filtering plug of floss-silk or asbestos is in- serted at the point where they are joined. The same apparatus serves for the determination of the boiling-points of saturated solutions, and for molecular weight determinations. J. F. B. Safety Wash-Bottle. J. Mauthner. (Chem. Zeit., 1909, 33, 412.)-The wash-bottle shown in the figure, which is made by Paul Haack, Vienna, is constructed without any ground-glass joints or corks. The entry tube for the gas is cut off obliquely at the end, and simply rests on the bottom of the wash-bottle, which is filled to a point a little above the end of the inner tube. If a stoppage occurs at a, point beyond the wash-bottle, the liquid in the latter is forced up into the reservoir until the gas can escape into the air, whilst if absorpoion is too rapid, air is drawn in the reverse way. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9093400338

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 343 NEW BOOKS. THE NATURE OF ENZYME ACTION. By W. M. BAYLISS. Octavo volume. 90 pp. This is one of a series of monographs on biochemistry, edited by R. H, A. Plimmer and F. G. Hopkins. An attempt is being made to place physiological chemistry, or biochemistry, in a more accessible position, by issuing a series of monographs upon the various chapters of the subject, each independent of and yet dependent upon the others, so that from time to time, according to demand, a new edition of each monograph can be published, without reissuing the whole series. The present volume deals with Catalysis in General; Enzymes as Catalysts; Chemical and Physical Properties of Enzymes ; General Methods of Preparation and of Investigation ; Reversibility of Enzyme Action ; the Velocity of Reaction, and the Various Conditions affecting it ; the Nature of the Combinations between Enzyme and Substrate ; Co-Enzymes and Anti-Enzymes ; Zymogens ; Oxidation ; Processes and certain Complex Systems ; General Conclusions ; Supplementary Notes ; List of Literature referred to ; Index.London : Longmans, Green and Go. Price 3s. net. THE CHEMICAL CONSTITUTION OF THE PROTEINS. Part I. By R. H. A. PLIMMER. Octavo volume, 100 pp. London : Longmans, Green and Go. Price 3s. net. The text is divided as follows: I. Chemical Composition of the Protein Mole- cule. 11. Chemical Constitution of its Units, or the Discovery and Syntheses of the Amino-Acids-(a) Mono-Aminomonocarboxylic Acids ; ( b ) Mono- Aminodicarboxylic Acids ; (c) Diaminomonocarboxylic Acids ; (a) Heterocyclic Compounds ; (e) The Optically Active Amino-Acids.Part 11. Octavo. 70 pp. Price 2s. 6d. net. The text is divided as follows : I. The Condensation together of Amino Acids. 11. The Biuret Base. 111. The Linking together of Amino-Acids-(a) Combinations of Amino-Acids with Carbonic Acid ; (b) with Ammonia; IV. The Polypeptides- (a) Syntheses ; (b) Structure ; (c) Configuration ; ( d ) Properties ; ( e ) Action of Enzymes ; (i.) Trypsin ; (ii.) Pepsin ; (iii.) Other Enzymes. V. Polypeptides present in Proteins. THE RISE AND PROGRESS OF THE BRITISH EXPLOSIVES INDUSTRY. Edited by E. A. 13. Hodgetts. Published under the auspices of the Seventh Inter- national Congress of Applied Chemistry by its Explosives Section, Small quarto. ix+418 pp. London : Whittaker and Co.Price 15s. net. The first part comprises the History of Gunpowder ; Researches on Gunpowder ; Nitrocellulose ; Nitro-glycerine and Nitro-glycerine Explosives ; Researches on Nitro-glycerine ; Permitted Explosives ; Percussion Caps ; Bickford’s Safety-fuse ; Military Fire- This volume is divided into two parts, historical and descriptive.344 THE ANALYSTo works ; Pleasure Fireworks ; Legislation ; Bibliography ; Chronology (1242-1700) ; List of Gunpowder-makers up to 1800. The descriptive part deals with existing Government and private establishments. TECHNICAL METHODS OF CHEMICAL ,~NALYSIS. Edited by G. LUNGE; English translation from the latest German edition, adapted to English conditions of manufacture, edited by C. A. Keane (see ANALYST, 1909, 251).Volume I., in two parts includes : General Methods used in Technical Analysis, by G. Lunge, English translation revised by C. 9. Keane. Technical Gas Analysis, by F. Fischer, English translation revised by C. A. Keane; Fuel Analysis, by F. Fischer, English translation revised by T. L. Bailey; Sulphurous Acid, Nitric Acid, and Sulphuric Acid, by G. Lunge, translated by J. T. Conroy ; Saltcake and Hydrochloric Acid, by G. Lunge, translated by J. T. Conroy; Sodium Carbonate, by G. Lunge, translated by J. T. Conroy; The Chlorine Industry, by G. Lunge, translated by J. T. Conroy; Potassium Salts, by L. Tietjens; Cyanogen Compounds, by H, Freudenberg, English translation revised by J. T. Conroy ; Clay, by P. Kreiling, English translation revised by W. Burton ; Clay Wares, Earthenware, and Glazes, by K. Dummler, English translation revised by W. Burton; Aluminium Salts and Alumina, by G. Lunge; Glass, by E. Adam, English translation revised by W, Thomason ; Calcareous CementR, by C. Schoch, English translation revised by W. F. Reid; Drinking Water and Water Supplies, by L. M. Winkler, English translation revised by G. J. Fowler; Feed Water for Boilers and Water for other Technical Purposes, by G. Lunge ; Sewage and Effluents, by E. Haselhoff, English translation revised by G. J. Fowler; Soils, by E. Haselhoff, English translation revised by A. D. Hall; Air, by K. B. Lehmann, English translation revised by C. A. Keane.

ISSN:0003-2654    

DOI:10.1039/AN9093400343

出版商:RSC    

年代:1909

数据来源: RSC