摘要:

INORGANIC ANALYSIS 251 INORGANIC ANALYSIS. Estimation of Ammonia in Soils. R. S. Potter and R. S. Snyder. (J. hzd. and Brig. Chem., 1915, 7, 221-22G.)-Several known methods were examined and found defective, and a new one, believed to be satisfactory, is described. Schloesing’s method fails because dilute hydrochloric acid does not extract the whole of the ammonia from soils. Of ammonia added as ammonium sulphate, not more than 70 per cent.can be recovered. For the same reason Baumann’s method, which also depends on extraction with hydrochloric acid, must fail. Russel’s later method ( J . Agric. Sci., 1910, 3, 233), depending on distiIIation with a very weak alcoholic potash, also fails to return all ammonia added to the soil as sulphate. His earlier method, and all methods depending on distillation with magnesia, lead to the decomposition of organic nitrogenous compounds.The new method is a modification of Folin’s method for physiological liquids. The soil (25 grms.) is introduced into a 500 C.C. Kjeldahl flask with 50 C.C. of water and a few drops of heavy oil to prevent foaming, The flask is fitted with a doubie- bored rubber stopper, carrying two tubes, one just penetrating the stopper to connect to a 16 oz.bottle containing 20 C.C. of =& sulphuric acid and about 200 C.C. of water ; the other-a Folin tube (Zeitsch. Physiol. Chem., 1902, 37,16I)-extending to within +inch of the bottom of the flask. A dozen or more of these sets can be run in series with one pump, the entering air being of course washed by passing through dilute sulphuric acid.Before starting the pump and finally tightening the conneotions, about 2 grms. of sodium carbonate are added to the contents of each flask. The pump is operated for fifteen hours at such a speed that about 4 litres of air are aspirated per minute. The apparatus is then disconnected, and the excess of acid remaining in the bottles titrated in the usual manner.Steel’s modification (J. Biol. Chem., 1910, 8, 365) of Folin’s method, though apparently an improvement where urine has to be analysed, is quite unsuited to soils. His reagent-weak caustic alkali in saturated brine-has the merit of decom- posing crystals of magnesium ammonium phosphate, which always separate on adding alkali to urine ; but the concentration of ammonia and water-soluble phosphate in soils is so low that no such crystals are likely to form in the course of soil analysis ; and, moreover, Steel’s reagent brings about very serious decomposition of the organic nitrogenous constituents of soil, so that the ammonia in some cases is over-estimated 200 per cent.The view that soils, when treated by the authors’ method, do not form triple phosphate crystals, with corresponding under-estimation of ammonia, is supported by the fact that seven very different samples gave identical results whether treated by their method or by Folin’s modification, in which potassium oxalate is used to prevent the formation of magnesium ammonium phosphate.G. C. J. Estimation of Soil Carbonates. W. H. MacIntire and L. G. Willis.(J. Ind. and Ey. Chenz., 1915,7, 227-228.)-The authors have previously shown that 100 mesh limestone and finely ground dolomite are completely decomposed by 6 per cent. phosphoric acid in the cold with very much less aotion on the organic252 ABSTRACTS OF CHEMICAL PAPERS matter of soils than is brought about by the use of hot sulphuric or hydrochloric acid (Tennessee Sta.Bull. 100). A single soil, of high magnesia content, has since been encountered which resisted this treatment but yielded to 6 per cent. hydro- chloric acid, also in the cold, with thirty minutes agitation by a current of air which sweeps the carbon dioxide into the absorption apparatus. The use of phosphoric acid had the advantage over hydrochloric acid, when employing gravimetric methods of estimating carbon dioxide, that silver sulphate absorption tubes could be dispensed with.I n view of the occasional failure of the method, however, the authors now recommend for general work with unknown soils a modification of their cold aeration method, using hydrochloric acid in conjunction with Ames’ double titration method of estimating carbon dioxide (J. Agric.Sci., 1908, I, 322) which is unaffected by the carrying over of hydrogen chloride with the carbon dioxide. The flask is fitted with a two-hole rubber stopper, carrying a globular tap funnel with long stem reaching nearly to the bottom of the flask, and a short exit tube, which is connected by rubber tubing to a Camp’s bead tower. The latter, which is more effective as an absorption apparatus for a rapid stream of carbon dioxide than is a Folin absorption tube is charged with about 25 C.C.of approximately sodium hydroxide and enough water to cover the beads. On its outlet side the Camp tower is connected to a pump or exhaust fan. The tap funnel of the decomposition flask is charged with 60 to 80 C.C. of dilute (1 : 10) hydrochloric acid, and its tubulure connected to an apparatus for washing the current of air with caustic alkali solution. The acid is run in, the pump or fan set in operation, and the air-entrance to the decomposition flask so far checked by screw pinchcocks on the rubber connections that tbe pressure in the flask is about six-sevenths that of the atmosphere. At the end of thirty minutes the apparatus is disconnected, the contents of the Camp tower and washings are nearly neutralised to phenolphthalein with approximately acid, exactly neutralised with weaker acid, and the sodium hydrogen carbonate then titrated with methyl orange and standard acid usually of strength, stronger acid being more convenient for soils of high carbonate content. The soil (usually 20 grms.) is decomposed in a 300 C.C.conical flask. G.C. J. Estimation of Copper in Steel. W. D. Brown. ( J . Ind. and Eng. Chem., 1915, 7, 213.)--The method depends on precipitation of copper as thiocyanate, treatment of the washed precipitate wiih a measured quantity of potassium iodate solution of known titer, and estimation of the excess of iodate by addition of potassium iodide and titration with thiosulphate.The steel (5 grms.) is dissolved in a mixture of 40 C.C. dilute (1 : 1) nitric acid and 25 C.C. dilute (1 : 1) sulphuric acid, and the solution evaporated to fumes to expel all nitric acid. When cold, 50 C.C. hot water are added and the solution boiled, transferred to a beaker, and diluted to 400 C.C. with hot water. When all the ferric sulphate is in solution, 50 C.C. strong ammonium bisulphite solution is added, with stirring, and followed by 25 C.C.of 5 per cent. potassium thiocyanate. The solution is boiled until precipita- tion is complete (five minutes), filtered by suction through an 11 cm. filter, and the precipitate washed with cold 1 per cent. sulphuric acid. Paper and precipitate are transferred to a beaker and treated with 20 C.C. dilute (1 : 1) hydrochloric acid,INORGANIC ANALYSIS 253 and about twice as much of the standard iodate solution as is expected to be required to react with the cuprous thiocyanate.The paper is well macerated with a glass rod, and water added to bring the volume of solution to about 500 C.C. Potassium iodide is added, in quantity about five times as great as that of the iodate previously added, and the liberated iodine is titrated with thiosulphate.The latter should be added slowly, stirring well, and starch used towards the end. The relation 7KI0, = 6Cu is all that is necessary to calculate the results, but the reactions involved are rather intricate, and may be stated as follows : 4CuCNS + 7KIO,+ 14HCl= 4CuS0, + 7IC1+4HCN + 7KC1+ 5H20 7ICl+ 7KI = 141 + 7KC1.(1) (2) (3) KIO, + 5KI + 6HCl= 6KC1+ 3H,O + 61. Equations (1) and (2) show that 7KI0, oxidise 4Cu, with formation of 7IC1, which, on dilution and treatment with potassium iodide, liberate 141, or KIO, = 21, whereas each molecule of iodate in excess of that required by the copper liberates 6 atoms of iodine, in accordance with the familiar equation (3). Therefore, one-third of the oxidising power of the potassium iodate taking part in reaction (1) is reclaimed on addition of iodide, and the net consumption of iodate by copper is given by the relation 4Cu = Q of 7KIO,, or 6Cu = 7KI0,.The potassium iodate solution is most conveniently made by dissolving 20 grms, of the salt and diluting to 1,000 C.C. The best commercial salt usually having about 97 per cent.of the oxidising power of pure potassium iodate, 1 C.C. of this solution will be almost exactly equivalent to 0.005 grm. copper. An equivalent thiosulphate solution contains 137 grms. per 1,000 C.C. Both solutions are standardised by means of permanganate solution, standardised in its turn by means of sodium oxalate. On standard steel the results agree closely with those obtained by electrolysis and other approved but tedious methods.G . C. J. On pure copper solutions the results are exact. Method of Estimating the Volume of Solid Matter in Muds. W. H. Coleman. ( J . SOC. Chem. Id. 1915,34,209-210.)-1n recovering cyanogen from coal- gas by passing the gas through a mud obtained by adding ferrous sulphate to gas liquor, some of the cyanogen was present in the solution as ammonium ferrocyanide, and some in the solid form as a complex double ferrocyanide of iron and ammonia, I t was found impossible to filter off and dry the mud without altering its composition, so the following method wa8 adopted for ascertaining the soluble and insoluble cyanogen: A measured quantity (50 c.c.) of the well-shaken muddy liquid was allowed to settle, and the ammonium ferrocyanide estimated in the clear liquid; this amount was termed A .To another similar portion of the liquid 50 C.C. of water were added, the mixture allowed to settle, and the ammonium ferrocyanide again estimated in the clear liquid (B). The total quantity of ammonium ferrocyanide was also esti- mated in the original muddy liquid (C). If x is the number of C.C.of liquid in the 50 C.C. mud taken for B before dilution, then, as 50 C.C. of water were added, 5 0 - x is the number of C.C. of liquid in the 100 C.C. after dilution, and this would contain the same total amount of ferrocyanide as was contained in the x C.C. before dilution,254 ABSTRACTS OF CHEMICAL PAPERS provided, of course, none of the insoluble ferrocyanide dissolved on dilution.Therefore ( x x A ) = ( 5 0 + ~ ) B , or x= ___ 50B C.C. Then 50 - x C.C. is the volume of solid in 50 C.C. of the original mud. A - B The method is applicable to a number of cases. W. P. S. Colorimetric Estimation of Nitrous Acid. G. Romijn. (Chem. Weekblad, 1914, 11, 1115-1116.) -The reagent consists of a powdered mixture of 1 part of a-naphthylamine chloride, 10 parts of sulphuric acid, and 89 parts of tartaric acid, and can be kept unaltered for a long time.The water must not contain more than 0-15 mgrm. of nitrous acid (NO,) per litre, since otherwise precipitation of the colouring matter formed in the reaction takes place. Should the coloration appear too rapidly, the water must be diluted with distilled water and the test repeated.C. A. M. Method of Determining Sulphurous Acid, Thiosulphates, and Polythio- nates. A. Sander. (Zeitsch. angew. Chem., 1915, 28, 9-12; through J. Xoc. Chem. Ind., l915,34,225.)-Polythionates, thiosulphates, and sulphurous acid may be deter- mined in presence of each other by titrating the thiosulphate and sulphurous aiid with & iodine solution (a c.c.), the polythionate being unacted upon, and determining the sulphuric acid formed by the oxidation of the sulphurous acid by titrationwith6 caustic soda ( b c.c.).Then g C.C. is the measure of the iodine reacting with the sulphurous acid and ( b -$) that reacting with the thiosulphate. In a fresh portion of the original solution the sulphurous acid is converted into bisulphite by means of & NaOH in the presence of methyl orange, and the neutralised solution is poured into an excess of a cold saturated solution of mercuric chloride. In forty-five minutes, with frequent shaking, the following reactions are complete : Na,S,O, + 2HgC1, + H,O = Na,SO, + Hg,CI, + 2HC1+ S.Na2S40, + SHgCl, + 2H20 = Na,SO, + Hg,Cl, + H,SO, t 2HCl+ 2s. 2NaHS0, + HgCI, = Hg(SO,Na), + 2HCl. The acidity is titrated with & NaOH, as above, and that due to the known amount of thiosulphate and bisulphite computed.The remainder is due to poly- thionates, and is expressed in terms of grm-mols. NaOH. One-fourth of this result represents the grm.-mols. of polythionates present. Rapid Method for Estimating Antimony and Tin in Mattes, Soluble Furnace Products, Chilled Slags, etc., containing much Iron, Copper, and Arsenic.F. A. Stief. (J. Ind. a7zd Eng. Chem., 1915, 7, 212.)-To 0.5 grm. of the substance contained in a covered 250 C.C. beaker, 10 C.C. sulphuric acid is added. If high in silicon, 15 C.O. water are added before the acid. The contents of the beaker are boiled for fifteen minutes in all if no water was added, or if water was added, for fifteen minutes after fumes first arise.To the cooled solution 10 C.C. water and 10 C.C. hydrochloric acid are added, and the mixture is boiled two minutes. About 1.5 grms. potassium chlorate is then added cautiously, and the mixture heated until fumes arise to expel all chlorine compounds. The oxidation with chlorste might be attended with danger if a flask were used, but with a beaker, and proceedingINORGANIC AXALYSTS 255 cautiously, nothing worse than the loss of the clock-glass cover need be feared.About 0.1 grm. sulphur is next added to reduce antimony and arsenic, and the mixture boiled for thirty minutes, when the sulphur will have almost disappeared. The mixture is cooled, and 6 C.C. water and 20 C.C. concentrated hydrochloric acid are added, as well as about 0.5 C.C.of granulated pumice. The arsenic is expelled by boiling, and antimony and tin are estimated as described in the following abstract. If preferred, the boiling to expel arsenic may be conducted in a flask, but 20 C.C. or more hydrochloric acid and no water must be used to rinse the beaker in such a case. The amount of sulphur should not be much more or less than stated, too little leading to incomplete reduction, too much tending to retain antimony and tin. Nitric acid may be used instead of potassium chlorate to oxidise the metallic salts, and its use is generally necessary when much carbon is present.In such cases more sulphur must be used for the subsequent reduction, and the aim should then be to use enough sulphur to reduce arsenic and antimony, but not to have more than 0.1 grm.excess. Having suacient potassium or sodium present to form double salts with the tin and antimony while evaporating the solution until fumes are given off prevents any volatilisation of these metals as chlorides. Slags or ores containing insoluble stannic oxide or silicate must be previously fused with caustic alkali for the tin estimation.The results obtained by the author during six years check well against those obtained by other chemists daily engaged in analysing similar materials by more troublesome methods. A warning is issued, however, that the method now described requires considerable experience to operate it successfully, and is not suited to occasional work. G. C. J. Rapid Analysis for Tin, Antimony, and Arsenic in Alloys.F. A. Stief. (J. Ind. and Ertg. Chm., 1915, 7, 211-212.)--The finely divided alloy (0.5 grm.) is dissolved by boiling with exactly 8 C.C. sulphuric acid in a 300 C.C. Florence flask. The solution is cooled, diluted with exactly 5 C.C. of water, and cooled again. Granu- lated pumice (0.5 grm.) and exactly 20 C.C. of concentrated hydrochloric acid are added, and the mouth of the flask is closed with a double-bored rubber bung, carry- ing a thermometer and an exit tube.The bulb of the thermometer should be about 1 inch above the level of the liquid, whilst the exit tube, which just penetrates the bung internally, is bent twice at right angles externally. The outer end is connected by a short piece of rubber tube to the end of an N-shaped piece of tubing, which serves as a condenser. This tube is made by bending an 18-inch length of $-inch (internal) tubing, and is drawn out to 2 inch to connect to the exit tube from the flask and to Q inch at the other end, which dips into a 300 C.C.beaker containing about 100 C.C. of water, The v portion of the N-tube rests in a, beaker of cold water, and is half filled with water.The contents of the flask are heated for ten to fifteen minutes, taking care that the thermometer never registers above 108' C., but is as high as 107' C. for at least five minutes. The N condenser is then rinsed into the 300 C.C. beaker, to which 2 grms. sodium bicarbonate are added and enough water to make the volume about 200 C.C. The arsenic is then titrated at about 27" C.with256 ABST.RACTS OF CHEMICAL PAPERS iodine and starch, controlling the results by a control experiment, which usually consumes about 0.15 C.C. of & iodine. To the cooled solution in the flask, 130 C.C. of water are added, and the antimony titrated with permanganate, again controlling the results with a blank experiment, which usually constimes 0.05 to 0.1 C.C.of & permanganate. If the percentage of antimony in the alloy is found to be less than 14, enough antimony chloride solution is added to make the solution contain approximately 0-07 grm. antimony. Exactly 6 C.C. sulphuric acid, 60 C.C. concentrated hydrochloric acid, and 6 inches of 14-gauge iron wire are added, and the mixture boiled for thirty minutes. More iron wire (4 to 6 inches) is added, and boiling continued for thirty minutes.The sides of the flask are rinsed down, the mouth loosely stoppered for about two minutes to allow air to be expelled by hydrogen, steam, and hydrogen chloride, after which the stopper is made fast and the flask cooled in cold water. When cold its contents are transferred to a 500 C.C. beaker, the flask rinsed out with 150 C.C.cold, recently boiled water, and the tin titrated with iodine and starch. Under these conditions, the control approximates 0.3 C.C. +"a iodine, and must be allowed for. Copper does not interfere with the antimony titration, nor with the tin titration, if the alloy contains over 70 per cent. of tin. With small percentages of tin and more than 3 per cent. of copper, the latter tends to interfere, but its interference may be wholly eliminated by adding 1 grm.of potassium iodide immediately before the titration with iodine. G. C. J. Precipitation of Zinc and Manganese by Ammonium Sulphide. F. See- ligmann. (Zeitsch. anal. Chem., 1914, 53, 594-595.) - The following procedure is recommended for obtaining zinc and manganese sulphides in a condition in which they may be filtered without difficulty. The neutral solution, containing about 0.5 grm. of the metal per 200 c.c., is rendered strongly ammoniacal (10 to 20 C.C. of 25 per cent. ammonia per 100 C.C. of solution), heated to 60' to 80" C., and treated with a slight excess of ammonium sulphide. The mixture is then boiled for a few minutes, the precipitate collected on a filter, washed with dilute ammonium sulphide solution, and ignited. The ignited residue is treated with 5 C.C. of con- centrated sulphuric acid, and the excess of this is removed by heating. Zinc sulphate may be heated to dull redness without undergoing decomposition, and manganese sulphate is somewhat more stable. I n a subsequent paper (ibid,, 1915, 54, 104) the author points out that ammonium salts interfere with the precipitation of manganese as sulphide, but do not affect the corresponding precipitation of zinc. I n the case of manganese, a few drops of hydrogen peroxide solution should be added before the excess of ammonia is introduced. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9154000251

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

256 ABST.RACTS OF CHEMICAL PAPERS APPARATUS, ETC. Determination of Very Weak Acids and Bases by Means of Electrolytic Conductivity Measurements. S. Horiba. (Mem. CoZZ. Sci., Imp. Univ., Kyoto., 1914, 1, 35-47; through J. SOC. Clzenz. Ind., 1915, 34, 223.)-From data obtained by measuring, at 25" C., the conductivities of (1) a mixture of aniline (weak base) withAPPARATUS, ETC. 257 an excess of hydrockloric acid, and (2) a mixture of phenol (weak acid) with an excess of sodium hydroxide, the following empirical formula were deduced and found satisfactory as a basis for the determination of weak bases and acids, respectively, under similar conditions : (a) 0.2985 C= -x-x,, where C is the concentration of the weak base (aniline), x and xu the specific conductivities of the mixture and acid respectively, the con- centration of the latter being between & and c5.x77z - x, 0.154 + 0.0433 x C,, ’ (b) c,= - where C, and C, are the concentrations of the weak acid (phenol) and sodium hydroxide respectively, x, and x, the specific conductivities of the mixture and the sodium hydroxide respectively, C, being between & and Tc, and C less than half C,. The constants of the hydrolytic dissociation of aniline hydrochloride and sodium phenoxide were also calculated.Measurement of the Freezing-Point Depression of Dilute Solutions. L. H. Adams. (J. Amer. Chem. SOC., 1915, 37, 481-496.)-For calculation of the mol. number and corresponding ionisation value, the depression of the freezing-point was observed by means of a thermo-element indicating the difference of temperature between a solution of the substance and water when both were in equilibrium with solid ice, the concentration of the equilibrium solution being then determined by means of a Zeiss interferometer.The .temperature difference was measured with an error not exceeding O.OO0lo C. by means of a 50-junction copper constantan differential thermo-element (giving 2,000 microvolts per degree) and a potentio- metric system, which enabled the electromotive force to be read to 0.1 microvolt.The apparatus consisted of two similar vacuum-jacketed vessels arranged side by side in a bed of ice contained in an insulated jar with a lid filled with ice. The two vessels were charged each with about 500 grms. of ice and the same quantity of water.By means of special stirrers in each vessel acting as circulating pumps, the water was circulated over the ice, being drawn from the bottom and discharged over the top until perfect equilibrium was attained. This stage afforded a “zero” reading for the thermo-element, and a portion of 50 c.c., withdrawn from one of the vessels by a pipette, afforded a sample of 6‘ zero ” concentration for the Zeiss inter- ferometer.An exactly equal quantity of a concentrated solution of the substance to be examined was then introduced to replace the sample of water taken from the vessel. Circulation was again set up until equilibrium was again attained and the thermo-element showed a constant reading, at which point a sample of the equilibrium solution was withdrawn for comparison in the interferometer. The interpretation of the results was then only a matter of accurate calibration.The degree of sen- sitiveness of the interferometer was found to be 2 parts per million. Experimental results are given for the non-electrolyte mannitol, and for potassium nitrate and chloride, at concentrations ranging from 0.004 to 0.1 formula-weights per litre, showing that the method is susceptible of the degree of accuracy claimed.J. F. B.258 ABSTRACTS OF CHEMICAL PAPERS Filter Pipette for Ether. J. M. Pickel. (J. Ind. and Eng. Che% 1915, 7, 236-237).-The illustration shows a device for filtering ether without waste, and simultaneously delivering it in requisite measure into fat-extraction flasks. The ether is forced by the rubber bulb G, through the filter C , up the tube E, into the pipette B, which delivers it into the flasks.The bulb has only one valve. The small hole in its side is to be closed by the thumb during compres- sion, and to be uncovered the instant the ether begins to overflow into the tube, i. The filter is an ordinary fat-extraction thimble, fitting the tube D tightly, fastened to it with thread, and extending 1 inch beyond the end of D to provide sufficient filtering surface. The siphon pipette, to deliver about 25 c.c., is made from 4 inches to 6 inches of 1-inch glass tube, B, into which is fused a, about 3 or 4 mm. in diameter and 60 mm. long above its union with B. The cap j is about 8 mm* internal diameter and 55 mm. long, and is supported on i, the upper end of which should be notched as shown. I t is most convenient to make the pipette fully large, and reduce its capacity to that desired by introducing glass beads. G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9154000256

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

258 ABSTRACTS OF CHEMICAL PAPERS REPORTS. Reports to the Local Government Board. On the Freezing-Point of Milk considered in its Relation to the Detection of Added Water. G. W. Monier-Williams. (Food Reports, No. 22, 1914.)-During recent years papers have been published calling attention to the fact that the freezing-point of milk varies within comparatively narrow limits, and claiming that the value observed for the freezing-point affords a more certain and accurate indication of the presence and relative amounts of added water in milk than can be obtained from the results of chemical analysis alone (cf.ANALYST, 1908, 33, 279 ; 1911, 36, 345 ; 1912, 37, 307 j 1913, 38, 368 ; 1915, 55). An investigation was, therefore, undertaken with a view of ascertaining whether the method is capable of being used with advantage.In determining the freezing-point of an aqueous solution within a degree of accuracy approaching -t.O.O0lo C., it is necessary to take into consideration a, number of possible sources of error which may influence the determination. The sources of error inherent in a mercury thermometer are-inaccuracy of the scale; slight alterations in the volume of the bulb, by which the zero-point may be raised or lowered; the heat capacity of the bulb in thermometers with a very open scale; the resistance offered to the movement of the mercury in a very fine capillary, and the temperature of the emergent column of mercury, The most reliable method of controlling the scale is by means of a careful comparison of the freezing-points ofREPORTS 259 ’ cane-sugar solutions of known strength with the very accurate values given by Raoult (Zeitsck.physik. Chem., 1898, 27, 617); a table showing these values is given in the Report. The second source of error may be eliminated by taking the freezing- point of water both before and after each daily series of determinations, and the “lag” of the mercury in the capillary may be overcome by the use of a small .. ... 10 electric hammer which gives a succession of sharp taps to the thermometer. If the temperature of the room does not vary during the time occupied in the determina- tions of the freezing-points of water a d of the solution, the correction for the emerging column of mercury will apply only to the length of the column correspond- ing with the difference between the two melting-points; in the case of milk, and a room temperature of 20Q C., the correction will be - 0*0015°.Should the room260 REPORTS iemperature vary, however, the total length of the emerging column of mercury must be taken into account. Other sources of error are introduced by the mechani- cal production of heat by the stirrer and too low a temperature of the freezing-bath, but these may be eliminated if the temperature of the bath is so regulated that the freezing-point of the solution coincides with the so-called '( temperature of conver- gence"-ie., the point at which the solution is in exact heat-equilibrium with its surroundings, the amount of heat abstracted from the solution in unit of time by the freezing-bath being exactly equal to the heat imparted by the stirrer, by radia- tion from the outside, etc.The convergence temperature varies with the apparatus, and must be determined by experiment; in the apparatus described below it was found to be 0-24" C. above the bath temperature. For a solution freezing at - 0.50" C. the temperature of the bath had to be - 0.74' C.The error due to increase of con- centration of the solution owing to separation of ice (super-cooling error) may be very large, and would appear to have been overlooked by most investigators. The true freezing-point of a dilute aqueous solution is that temperature at which it is in exact equilibrium with ice. If a solution is cooled below its freezing-point, and a minute fragment of ice is then introduced, formation of ice occurs in the liquid, and the temperature immediately rises to a point which approximates to the true freezing-point.Owing to the separation of the ice, the observed freezing-point mill be that of the more concentrated solution. Raoult has shown that the effect of super-cooling may be expressed by the equation : K = E, where C' is the observed cs depression of the freezing-point, C the true depression, S degrees of super-cooling, and K a constant.The latter is found by determining the freezing-point for different degrees of super-cooling; if the values found are plotted as ordinates and the degrees of super-cooling as abscissae, an approximately straight line is obtained from which the true freezing-point for super-cooling nil may be found.K is then calculated from the above formulae. For cane sugar solutions K=0*015, and for milk K = 0.017. The apparatus used in the determinations is shown in the illustration. A Dewar vacuum vessel (l), of 10 cm. internal diameter and 16 cm. internal depth, was closed with a large cork disc (2), about 1 inch thick, glued to a metal plate; the outer edge of the plate was soldered to a metal ring (3), and the cover thus formed could be made air-tight by a rubber ring (4).Through the middle of the cork disc passed a glass tube (5) of 3.8 cm. internal diameter, an air-tight junction with the metal plate being effected with glue cement. The cork disc also carried a copper inlet-tube for ether and air (6), the lower end of which formed a perforated ring; an outlet tube (7) ; a thermometer (8) graduated into O*0lo C.; and a siphon (9) connected with the lower end of the tube (5), and so designed that ether could be admitted or withdrawn from the Dewar vessel as desired. The freezing tube (10) was a thin glass test-tube, 3.5 cm. internal diameter; it was closed by a, cork, 1 inch in thickness, carrying the thermometer (ll), a spiral glass stirrer (12), and a small opening (13) provided with a stopper. I t also carried another thermometer, not shown in the figure, graduated to 0.1' C., to indicate the degree of super-cooling.The freezing-point is determined in the following manner : The outlet tube (7) isREPORTS 261 connected with a water-pump, and ether, dried previously with calcium chloride, drawn into the Dewar vessel until the latter is full.About 60 C.C. of the liquid of which the freezing-point is to be determined are introduced into the freezing tube (lo), which is closed with the cork and placed in the tube (5). Ether is allowed to flow from the Dewar vessel through the siphon (9) into the space between the tubes, and the stirrer is connected with the rotating spindle (14), driven by an electric motor.The supply of ether is shut off, and a rapid current of air is drawn through the Dewar vessel. As the ether evaporates it is replenished by shutting off the air-supply and opening the tap connecting with the ether-supply. In this way the temperature of the ether bath can be lowered to about -4" C . in fifteen to twenty minutes.The ether in the space between the tubes (5) and (10) serves as a, heat-conducting medium, and the temperature of the solution is lowered far more rapidly than would be the case if the space contained air. The stirrer should be rotated at constant speed (about 1,300 revolutions per minute in the case of the form of stirrer shown). When the solution has reached the desired degree of super-cooling-Le., about 0-5' C.below the expected freezing-point-the air-supply is shut off, and the tap of the siphon tube (9) opened. The ether in the space between the two tubes (5) and (10) is thus replaced by air. The tap on the siphon tube is closed, and ether at room tempera- ture drawn into the Dewar vessel until the temperature of the bath has risen to a point approximately 0.25" C .below the expected freezing-point. The degree of super- cooling is observed, and a minute fragment of ice introduced through the opening (13). A small electric hammer (15) is set in motion, and the point to which the mercury of the thermometer (11) rises observed through a telescope at a distance of a few feet, the temperature of the bath being kept constant by drawing ether or air through it as required.The thermometer (11) had a total range of about 1' C., divided into intervals of 0.005' C . ; each 0*005O division occupied a length of about 0.4 mm. With this instrument the correct reading in the determination was reached in less than a minute, and the observed freezing-point remained constant for an indefinite period, provided that the bath temperature and the speed of the stirrer did not alter.For practical purposes the process may be simplified by dispensing with the determination of the zero-point given by distilled water, and comparing the freezing- point of the milk sample with that of a solution of 9.495 grms. of pure sucrose in 100 grms. of water ; this solution freezes at exactly - 0.5345' C., the average freezing- point of normal milk.If the two determinations are carried out in precisely the same manner, they will both be affected to a similar extent by the various sources of error mentioned, and the difference between the two results will indicate fairly accurately the true freezing-point of the milk in question, The bath may be of ice and salt, and the temperature as low as - 5' C., the important point being that the temperature be kept approximately the same in both determinations.The same degree of super-cooling must be employed, and the rate and manner of stirring must be alike in both cases. The freezing-point of milk is not appreciably affected by the removal of the fat, but the development of acidity in the milk has a considerable influence. The increase of acidity, however, is very slow during the preliminary stages of souring, and in262 REPORTS practice it is found that the taste and smell of the sample are a very good guide as to whether or not the freezing-point method is applicable.A sample has to smell and taste distinctly sour before the freezing-point is depressed by as much as 0*002° C. Pasteurisation for twenty minutes at 60° C.raises the freezing-point by about 0.002O c. The average freezing-point of 141 samples of genuine milk was found to be - 005345~ C., the values found ranging from - 0*558’ to - 0-514O ; these values have been subjected to all the necessary corrections, and are probably accurate to about +,0*002O C. The freezing-point appears to be the most constant of any of the pro- perties exhibited by milk.Although unaffected by the removal of fat from or the addition of separated milk to genuine milk, it is raised by the addition of water to the milk. The method may, in certain circumstances, be applied with advantage, as a confirmatory test, to the detection of added water and to the approximate estimation of the amount present.Owing, however, to the experimental difficulties involved in obtaining reliable results, it is somewhat doubtful whether the method is capable of general application for purposes of milk control. w. P. s. Standards for Whisky in Western Australia, under “The Health Act, 1911-12.’’ (Government Papers, pp, 39, January 5, 1915; through J . Soc. Chem. Ind., 1915.)-The following standards have been ratified by the Governor in Council : Scotch whisky shall be spirit distilled from barley, malt, or other grains (which as regards pure pot still whisky shall be distilled at a strength not exceeding 35 per cent.over proof), matured by storage in wood for not less than two years, and shall be sold under one of the following designations and conform to the corresponding standards: (a) Standard pot still whisky shall contain not less than 45 grms.of compound ethers, 3.5 grms. of furfural and 180 grms. of higher alcohols, per 100 litres of absolute alcohol, these ingredients to be determined by the methods laid down in Schedule A of the Regulations (not included in the present papers) ; (b) Blended whisky containing at least 75 per cent. of standard pot still whisky shall contain not less than 40 grms.of compound ethers, 2.6 grms. of furfural, and 140 grms. of higher alcohols; (c) Blended whisky containing at least 50 per cent. of standard pot still whisky shall contain not less than 35 grms. of compound ethers, 1-76 grm. of furfural, and 110 grms. of higher alcohols; (d) Blended whisky containing less than 50 per cent.of standard pot still whisky shall be that which fails to comply with any of the above standards. Irish whisky shall be spirit distilled from barley, malt, or other grains, matured by storage in wood for not less than two years, and shall be sold under one or other of four designations identical with those for Scotch whisky, but with different standards, as follows (no standards at present as regards furfural) : (a) Not less than 35 grms. of compound ethers and 200 grms.of higher alcohols; ( b ) not less than 30 grms. of compound ethers and 160 grms. of higher alcohols ; (c) not less than 25 grms. of compound ethers and 130 grms. of higher alcohols ; ( d ) less than 25 grms. of oompound ethers or 130 grms. of higher alcohols. All other kinds of whisky shall conform to the standards for Scotch whisky.The four classes of whisky-((a), (b), (c), (d)-must bear distinctive labels of prescribed colouriag. These regulationsINSTITUTE OF CHEMISTRY 263 are based on a report made by the Government analyst for Western Australia, E. A. Mann, after visits to, and analysis of the products of, more than fifty distilleries in Scotland and Ireland. The standards prescribed for ( ( standard pot still whisky ” (Scotch) are only slightly lower than the averages of the values obtained in the analysis of all the investigated Scottish whiskies (117 samples) produced with pot stills, so that about one-half of the number of samples analysed would not conform to the standards, whilst nearly all the products obta,ined with more or less modified types of still, and all those obtained with patent stills, would be excluded. It is pointed out in Mr. Mann’s report, however, that as the whiskies imported into Australia are usually blends of a large number of products, their composition would tend to approximate to the standards laid down. The papers include, besides the reports mentioned, a memorial of protest from the Scottish Whisky Exporters’ Association, supported by reports by P, Schidrowitz and R. R. Tatlock.

ISSN:0003-2654    

DOI:10.1039/AN9154000258

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

INSTITUTE OF CHEMISTRY 263 INSTITUTE OF CHEMISTRY. GLASS RESEARCH. The Council have published a short report summarising the work of the Glass Research Committee appointed in October last to conduct investigations with a view to arriving at suitable formulas to be freely available to manufacturers willing to assist in maintaining the continued supply of laboratory glassware. The import- ance of this work to numerous industries, particularly those concerned with the production of war material, will be apparent.The Committee consisted of Professor Raphael Meldola (then President of the Institute), Messrs. B. Blount, 0. Hehner, H. Jackson, W. C. Hancock, and T. R. Merton. The chief aims of the research were-(1) To produce working formulas for all glasses used in laboratory work, and (2) to ascertain the influence of various ingredients on the physical and chemical properties of glasses.The work was extended to include glass for miners’ lamp-glasses, at the suggestion of the Home Office ; and also glass for ampoules, to meet the needs of wholesale pharmaceutical chemists engaged in the production of army medical requirements. The Committee have also examined and reported on samples of British and French laboratory glass- ware, produced since the beginning of the war, a number of the specimens being made from formulas similar to, and in some cases almost identical with, those recommended by the Committee.The Committee have had before them many specimens of glasses used for various purposes, of which analyses have been made by Messrs.Blount, Hancock, and Hehner. It has been found, however, that mixtures prepared in accordance with the analytical results were not always satisfactory; but the analyses were helpful in suggesting synthetic experiments.264 INSTITUTE OF CHEMISTRY Up to the present time, the Research Committee have reported eleven formulas for glasses for various purposes based on the results of about 400 experimental melts on a scale large enough for drawin6 rods and blowing small vessels.I n addition, a number of experiments have been made in order to study the influence of the various constituents employed. No formula has been issued without sub- mitting the specimens made to rigorous tests to prove their suitability for the purposes for which they are intended.Moreover, by varying the experimental working Fonditions, it can be said with reasonable confidence that the mixtures will prove equally satisfactory under the actual working conditions of a glass furnace. The question of workable temperatures has been carefully considered, and, so far as it is possible to judge, the melts on a small scale indicate that even better results will be obtained on the industrial scale.This view has been justified by the samples already received from manufacturers who have tried some of the formulas. In deciding the formulas it has been found necessary to pay special attention to the proportions of basic and acidic substances in respect of the action of glass mixtures on clay crucibles during fusion, and it has been shown by careful investiga- tion that the formulas proposed give melts in which the influence of the ingredients of the crucibles is very slight, and in some cases practically inappreciable.The following formulas have been communicated to a number of manufacturers who have expressed their interest in the progress of the investigation, and to scientific workers who are conducting similar experiments : Soft GEasses, suitable for ordinary chemical laboratory ware : 1.Parts. Sand ... ... ... 67-0 Sodium carbonate (NA,CO,) ... 34.2 Calcium carbonate ... ... 11.6 Alumina (A1,0,) ... ... ... 6.5 A soft glass which does not give up alkali readily to water, works well in the blowpipe, and does not devitrify readily, 2. Parts. Sand ... ... ... 67.0 Sodium carbonate (Na,CO,j ...29.0 Calcium carbonate ... ... 9-6 Ca1ciu.m fluoride ... ... 1.6 ... ... Alumina (Al,O,) ... ... 8.3 Boric anhydride (B,O,) ... ... 2.0 A soft glass of higher quality. Does not give up alkali under severe tests. A kindly working glass before the blowpipe, and very difficult t o devi trify. A Besistant Glass suitable for pharmaceutical purposes, ampoules, etc. : 3.Sand ... ... ... ... ... ... ... ... Calcium carbonate ... ... ... ... ... ... Potassium nitrate ... ... ... ... ... ... ... ... ... ... ... Alumina (A1,0,) ... Magnesia, ... , .. ... ... ... ... ..* ... Sodium Carbonate (Na,CO,) ... ... ... ... ... Boric anhydride (B,O,) ... ... ... ... ... Parts. 67.0 10.0 12.5 0.5 1 *o 17.0 8.0 This glass is intermediate in hardness between soft glass and combustion tubing, is highly re- sistant t o chemical action, withstands changes of temperature well, and should be a very suitable glass for high-class beakers, flasks, etc.INSTITUTE OF CHEMISTRY 265 Glasses for Combustion Tubing : Sand ...*.. ... ... 60*2 Barium carbonate ... ... ... 843 Calcium carbonate ... ... 13-0 Potassium nitrate ... ... ... 4.3 Sodium carbonate (Na,CO,) ...5.5 Calcium fluoride ... ... ... 1.0 4. Parts, Alumina (A1,0,) ... ... ... 6.2 Boric anhydride (B,O,) ... ... 5.5 This glass resembles Jena combustion tubing very closely indeed. It has practically the same fusing-point. It fuses on to Jena glass perfectly, and is indistinguishable from it before the blow- pipe and in its behaviour on prolonged heatin below its fusing-point. The presence of the smal? quantity of calcium fluoride facilitates the incor- poration of the ingredients.The sodium carbonate can be reduced to 1'34 parts,. provided 7.93 arts of anhydrous borax be used in the place of %oric anhydride. Miners' Lamp-Glasses : Sand ... ... ... ... Alumina (Al,O,) ... ... Calcium carbonate ..- Antimony oxide (Sb,O,) ... Potassium nitrate ...Sodium carbonate (Na,CO,) Boric anhydride (B,O,) ... 6. ... Arsenious oxide (As,O,) ... Parts. ... 65.0 ... 1.0 '-. (36 ... 2.0 ... 1.0 ... 3.0 ... 14.0 ... 24-0 A colourless and fusible glass, withstanding rapid changes of temperature exceptionally well. 5. Sand ... ... ... ... Barium carbonate ... ... ... Calcium carbonate ... ... ... Potassium nitrate ... ... Sodium carbonate (Na,CO;) ... Alumina (Al,O,) ...... ... Boric anhydride (B203) ... ... Parts. 68.2 6.2 8.8 14.2 4.3 5.5 5.5 This glass is practically of the same composition as No. 4. It is not so easy to make or to work, but it does not become so opaque as Jena combus- tion tubing on prolonged heating. As in No. 4, the proportions given for sodium carbonate and anhydrous borax can be substituted for the figures for sodium carbonate and boric anhydride.7. Sand ... ... ... ... Calcium carbonate ... ... Alumina (Al,O,) ... ... ... Arsenious oxide ( As,O,) ... Antimony oxide (Sb,O,) ... ... Anhydrous borax (Na,B,07) ... Boric anhydride (B,O,) ... ... ... Potassium nitrate.. . ... ... Parts. 65.00 1.00 0.60 2.00 1.00 3.00 26-60 5.50 The same alass as No. 6, but the ingredients lave been vazed to avoid the use of so much boric mhydride, which is at present apparently difficult ;o obtain on a commercial scale.Resistance Glass : 8. Parts. Sand ... ... ... ... ... ... ... ... 65.5 Alumina (A1,OJ ... ... ... ... ... ... ... 2.5 Magnesia (MgO) . . I ,.. ... ... ... ... ... 5.0 Zinc oxide (ZnO) ... ... ... ... ... ... 8.0 Sodium oarbonate (Na2C08) ..... ... ... ... 10.2 Anhydrous borax (Na,B,O1) ... ... ... ... ... 13.0 A glass almost identical in its general behaviour with Jena resistance glass ; withstands changes of temperature well, but, like Jena, is not suitable for working before the blowpipe. It darkens and tends t o devitrify ; operations-such, for instance, as sealing side tubes into ffasks-are difficult, if permanent and neat joints are required.Formula No. 3, recommended for pharmaceutical purposes, ampoules, etc., may be substituted for the resistance glass with advantage, as the ampoule glass lends itself very well to blowpipe-work, and is also especially resistant chemically.266 INSTITUTE OF CHEMISTRY Alternative for Combustion Tubing : 9. Parts. Sand ... ... ... ... ...... ... 72.0 Alumina (A1,0,) ... ... ... ... ... ... ... 10.0 Calcium carbonate ... ... ... ... ... ... 11.0 ... ... ... ... ... 0-5 Magnesia (MgO) . . , Potassium nitrate (KNO,) ... ... ... ... ... 3.0 Sodium carbonate (Na,CO,) ... ... ... ... ... 11.2 Anhydrous borax (Na2B,0,) ... ... ... ... ... 7.2 ... ... This glass is capable of withstanding high temperatures and rapid changes of temperature ; works well before the blowpipe, and is free from the chief defect of Jena glass-namely, the readiness with which it becomes cloudy, and finally quite opaque, after prolonged use.By slight modifications of this formula, almost any degree of hardness can be obtained. In formulas Nos. 8 and 9, substances such as magnesia (MgO) and zinc oxide (Zn0) can be added in the form of carbonates, if the actual percentages of MgO and ZnO respectively present in the carbonates are known.Soft Soda-Glasses suitable for tubing and X-ray bulbs : 10. Parts. Sand ... -.. ... ... 68.0 Calcium carbonate (CaCO,) ... 12.8 Sodium carbonate (Na,CO,) ... 26.0 Alumina (A1,0,) . . . . . . ... 4-0 Potassium nitrate (KNO,) ... 14.5 11. Parts. Sand ... f . . ... 68.0 Calcium carbonate ...... 12.8 ... Alumina (Ai20s) ... ... 4.0 ... Potassium carbonate (K,CO,) ... 10.0 Sodium carbonate (Na,CO,) ... 26.0 These glasses do not lose their easy working qualities after repeated heating and blowing, and are plastic over a long range of temperature. They require a temperature of a t least 1,400 to 1,500" C. for complete incorporation of the ingredients, in order t o obtain that homogeneity which is necessary for resistance to rapid changes of temperature and ease of working before the blowpipe. No. 10, containing potassium nitrate, is considered the better of the two, and is more easily incorporated. The committee consider that the formulas they have obtained, and the work they have done on the various glasses, justify them in the opinion that there is now information available for the manufacture of all the important glasses used in the laboratory and for industrial purposes, which have hitherto been mainly obtained from abroad.

ISSN:0003-2654    

DOI:10.1039/AN9154000263

出版商:RSC    

年代:1915

数据来源: RSC

摘要:

REVIEWS 267 REVIEWS. THE MANUFACTURE OF ORGANIC DYESTUFFS. By A N D R ~ WAHL. Translated by F. W. ATACK. London: G. Bell and Sons. 1914. Pp. xiv+338. Price 5s. net. Twenty-five years have elapsed since the translation of Benedikt’s “ Chemistry of the Coal-Tar ColourA,” by Professor Knecht, facilitated the study of this branch of chemical synthesis for English-speaking students. This convenient textbook has long since become obsolete owing to the rapid development in the manufacture of new synthetic dyes, and although two or three larger treatises on thia subject have appeared subsequently, the present volume represents the only recent attempt to bring the matter up to date in a manual of moderate size.I t is therefore quite appropriate that the translator of Benedikt’s earlier handbook should contribute a, benedictory preface to the English edition of Professor Wahl’s work, ‘( L’Industrie des Matidres Colorantes Organiques.” The treatise appears in its English form at an opportune time when the question of (‘ a place in the sun ” for the British dye industry is being vigorously debated.I n this connection it is interesting to note what, in the author’s opinion, was the reason why, after a period of expansion in France, the synthetic colour industry crossed the frontier and became established in Germany and Switzerland.He attributes this migration to the opposition of eminent French chemists of that, day to the modern theories of valency and structural organic chemistry. These views were accepted with enthusiasm in Germany, and furnished the industrial chemist with a firm scientific basis for his researches in this branch of organic synthesis.The first part of the book consists of tbree short chapters dealing with the distillation of coal-tar. The second part is devoted to an outline of the prooesses involved in the conversion of the comparatively few industrially important distilla- tion products of coal-tar into the large number of intermediate products which form the raw materials of the colour industry.A chapter is given to each of the important operations of nitration, sulphonation, and alkali fusion. I n regard to the last of these, it may be mentioned that as synthetic phenol (p. 35) ia used not only in dye formation, but also in the manufacture of the important military explosive, melinite, one could wish, for the sake of our gallant French allies, that the yield of phenol in France was likely to be quite so high as ‘( 80 to 90 per cent.of the weight of sulphonate used.” An inexorable principle, however, demands that 94 parts of phenol shall be the maximum output from 180 parts of dry sodium benzene-sulphonate. The greater part of the book deals with the synthetic dyes, divided into fifteen chemical groups.These chapters contain references to the most recent develop- ments. Some of these items have become known since the publication of the French268 REVIEWS edition in 1911, and are introduced for the first time into the present translation. The last three chapters, dealing with indigoid dyes, thiazole and sulphur dyes, and aniline black, are among the most interesting sections.In some instances the lack of orientation numbers will render difficult the students’ task of identifying the dye components. Although the expert will know which of the ten possible dihydroxynaphthalenes is employed in preparing diamond black P.V., there is nothing in the context (p. 114) to suggest the 1 : 5-isomeride.These omissions are, however, very trifling, and the whole treatise can be strongly recommended as a useful and readable manual which, on account of its copious references to patent and other original literature, may wellusewe as a stepping-stone to a more intimate acquaintance with the organic colouring matters. G. T. MORUAN. NUCLEIC ACIDS : THEIR CHEMICAL PROPERTIES AND PHYSIOLOGICAL CONDUCT.By WALTER JONES, Ph.D., Professor of Physiological Chemistry in the Johns Hopkins Medical School, London. 1914. New York : Longmans, Green and Go, Price 38. 6d. net. This is one of the series of gg Monographs on Biochemistry,” and consists of a small book of 118 pages, including a bibliographical list and an index, Nucleic acids are polybasic acids, the constitution of which is at present unknown.The first member of the series was discovered in 1874 in the spermatozoa, of the salmon, thus, as the present author remarks, at a time when the chemistry of the proteins was little understood. The fact that nucleic acids are obtained from the hydrolysis of the nucleo-proteins, of which they form the characteristic prosthetic group, was first demonstrated by Kossel, to whose work we are mainly indebted for our present knowledge of this subject.Dr. Jones is to be congratulated for the clear and concise manner in which he has epitomised our knowledge of a branch of chemistry which has only within recent years been rescued from a chaotic condition. I t must be remembered that we are only at present at the beginning of our knowledge of the proteins, and that of the whole class, the nucleo-proteins are the most complex and least understood.The monograph is, of course, complementary to others of the series dealing generally with the proteins, and the text will only be appreciated by those having a knowledge of protein chemistry. The importance of this branch of chemistry to those engaged in the analysis of foods is sufficient to justify us in recommending to them the present monograph written by one who has added to our knowledge of the subject by his own researches.Not the least valuable portion of the monograph is the biblio- graphical list, which appears to be complete. ARTHUR R. LING. A MANUAL OF CHEMISTRY. Adapted to the Requirements of Students of Medicine, By ARTHUR P.LUFF, M.D., B.Sc. (Lond.), F.R.C.P., F.I.C., and HUGH C, H. CANDY, B.A., B.Sc. (Lond.), F.I.C. Fifth Edition, Enlarged. Messrs. Cassell and Go., Ltd. Pp. xix-t-660. Price 8s. 6d. net. In textbooks written specially for elementary students it is essential that the A author should in no way obscure the main facts by a mass of unnecessary detail.RXVIEWS 269 due recognition of this truth has been one of the chief merits of the manual under review, and the present edition, whilst affording evidence of most careful revision, has in no sense been needlessly elaborated.The general arrangement remains practically the same, and although mainly based upon the curriculum of work required by medical students reading for the Preliminary Science Examinations of the University of London and of the Conjoint Board of Physicians and Surgeons, yet the syllabus is by no means slavishly adhered to.Nothing but praise can be accorded to those chapters devoted to chemical theory, a subject that usually bristles with difficulties to a beginner, and the book as a whole can be safely recommended for the purpose for which it is intended.Parts I. and 11. are devoted to non-metallic elements, and Part 111. to metals, whilst organic chemistry is dealt with in Part IV., and the mathematics of chemical problems in Part V. The practical chemistry of Part VI. embraces elementary qualitative and quantitative analysis on the lines of the examinations referred to above. A feature that should be noted is that special sections have been inserted describing various organic compounds that have recently come into prominence in medical practice. The account here given of the constitution of these substances, together with their chemical formulte, will doubtless appeal as much to the qualified practitioner as the rest of the book does to the medical student.P. A. E. RICHARDS. THIRD INTERNATIONAL CONGRESS OF TBOPICAL AGRICULTURE.1915. London : John More than 150 papers, contributed by authorities in fifty different countries, were presented to the Congress, and abstracts of most of them are printed in the Proceedings, together with the address delivered by the President of the Congress, Professor Wyndham R. Dunstan. Amongst the subjects dealt with in the Proceedings are Technical Education in Tropical Agriculture, Organisation of Agricultural Departments in relation to Research, Agricultural Credit Banks and Co-operative Societies, Sanitation and Hygiene on Tropical Estates, Legislation against Plant Diseases and Pests, Fertility of Soils in the Tropics, Variation in Plantation Rubber, Cotton and Cotton Cultivation, Jute and Hemp Fibres, Cereals, Cocoa, Tobacco, Oils and Oil Seeds.In all cases where the original paper or discussion was in a foreign language a translation is appended. None of the papers includes any details of special analytical interest, the treatment being in all cases technical and agricultural ; but contributions dealing with the production of Jute and Hemp Fibres, Cereals, Sugar, Cocoa, Tobacco, and Oil Seeas will be found of value to those whose interests lie in such directions. Bale, Sons and Danielsson.Price 10s. net. H. F. E. HULTON.270 RE VIEWS RUSSIAN EQUIVALENT TABLES. 1914. Central Translations Institute, 265, Strand, Though Russian scientists use the metric system and many Russian engineers the British foot and inch, the data of any Russian technical problem are nearly always presented, even to an Englishman, in terms of Russian weights and measures.The present publication, timely in view of the probable closer intercourse between the two countries, may consequently prove useful to some British chemists. The tables, which are printed on stout cardboard, about 12" x 10" and folding in three, include everything of practical importance in the way of weights and measures, as well as tables of exchange for six different values of the rouble.The tables are conveniently arranged and apparently free from error. The transliteration of Russian words is a vexed question, but the writer would enter a mild protest against the words '( archine " and Arsheen " and " sajen " conform more nearly to the Russian spelling, and suggest more closely to an Englishman the sound of the Russian words. G. CECIL JONES. W.C. Price 1s. net. sagene." @ + T + % @ * INSTITUTE OF CHEMISTRY. PASS LIST : APRIL (1915) EXAMINATIONS. OF five candidates who presented themselves for the Intermediate Examination, two passed: T. L. McEwan, B.Sc. (St. Andrews), and E. Mendoza. Of ten candidates who presented themselves for the Final (A.I.C.) Examination, eight passed. In the Branch of Physioal Chemistry : E. K. Rideal, B.A. (Cantab.), Ph.D. (Bonn). In the Branch of Organic Chemistry : W. S. Allen and Gilbert Herding. In the Branch of the Chemistry (and Microscopy) of Food and Drugs, Fertilizers and Feeding-Stuffs, Soils, and Water: A. S. Carlos, B.Sc. (Lond.), R. H. Hopkins, BSc. (Birm.), D. A. Legg, A. R. Pearson, B.So., A.R.C.S. (Lond.), and G. A. Stokes.

ISSN:0003-2654    

DOI:10.1039/AN9154000267

出版商:RSC    

年代:1915

数据来源: RSC