摘要:

SEPTEMBER, 1912 Vol. XXXVII., No 438. THE ANALYST. OBITUARY. BENJAMIN EDWARD REINA NEWLANDS. BENJAMIN EDWARD REINA NEWLANDS, youngest son of the Rev. William Newlands, was born in Southwark on January 23, 1842. On his mother’s side he was of Italian descent. Both he and his brother John received their early education at home with their father, and subsequently at St. Saviour’s Grammar School. The brothers studied chemistry under Professor A.W. Hofmann, and at an early age ratarted an analytical practice in Great St. Helen’s, London. Benjamin became assistant to Professor C. W. Heaton at Charing Cross Hospital, in 1862, and to Professor Way, of the Royal Agricultural Society, in 1863. His bent was always, however, towards technology, and at the end of 1863 he was appointed chemist to Messrs.James Gibbs and Go., manure makers, Victoria Docks, and from 1869 to 1873 he was manager at these works. In the latter year, he was made manager of Mr. James Duncan’s Sugar Refinery, Clyde Wharf, Victoria Docks. This refinery was contiguous to Messrs. Gibbs’s works, and while at the latter Newlands had had the entrde, and from time to time had given Mr.Duncan advice. He remained as manager, with his brother John as chemist, until the refinery, then the largest in the United Kingdom, closed in 1887, when the brothers once more embarked upon a, professional career as analytical and consulting chemists at 27, Mincing Lane, London, and subsequently at 2, St. Dunstan’s Hill, London. Well known as they were in the sugar trade, the brothers Newlands soon built up a good practice, mostly connected with sugar technology.Their consulting work was not confined to this country, their services being retained in India and the Colonies. A new edition of their treatise on ‘‘ Sugar ” has just been published. After the death of John Newlands in 1898, the writer was in partnership with Benjamin for five years. Benjamin Newlands was a Fellow of the Institute of Chemistry of Great Britain and Ireland, and had served on its Council and as a Vice-president.He was also a Fellow of the Chemical Society, and a member of our own Society. Of all scientific societies, he cared most for the Society of Chemical Industry, of which he was an original member, and served from the first on its Publication Committee, and, with a few intervals, on its Council.He was several times elecfed a Vice-president of the Society of Chemical Industry, and was Chairman of the London Section from 1895-96. He will be remembered by his professional brethren, not only by his wide praotical knowledge, but no less by his sound common-sense, which was tempered by a characteristic geniality of manner. His fund of humour was wellnigh inexhaustible, and earned for him the reputation of the best raconteur in chemical circles. He died at his residence at Hayling Island on August 7.ARTHUR R. LING.392 A. G. LEVY: PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE ESTIMATION OF CARBON IN STEEL. BY A. G. LEVY, B.Sc., F.I.C. THE direct combustion method for determiningcarbon in steel is now used so largely --many analysts using this method to the exclusion of all others, except for checking purposes-that it may not be amiss to point out one source of error hitherto appar- ently overlooked.Whenever the direct process has been compared with the solution methods, it has been noticed that, except in cases where combustion appears to have been not quite complete, there is a tendency to slightly high results.Thus, many of the values quoted by Blount and Levy (ANALYST, 1909, 34, 94) show a small excess over those obtained by the solution method. I n the discussion on this paper, L. Archbutt (ibzd., p. 97) mentioned this tendency ; and, more recently, Helen Isham (J. Id. and Eng. Chem., 1911, 3, 577) states that the values given by the direct method are usually 0.007 per cent.higher than those obtained by the use of the solution method. She also shows that there is no loss of carbonaceous gases during the dissolution of the steel in acidified potassium cupric chloride solution at ordinary temperatures. It is obvious that if the sample of steel contains dissolved carbonaceous gases, such as carbon monoxide and dioxide, their carbon content will be included in its entirety in the values given by the direct combustion method ; whilst it seems almost equally certain that it will not affect the solution process, since, even if the gases liberated are not expelled from the solution, they will pass with this into the filtrate from the insoluble carbonaceous residue, and leave the latter free from all but a possible trace of the double compound of cuprous chloride and carbon monoxide, At first sight one might think that the quantities of gases involved are too small to affect the carbon determination. During the last few years, however, a good deal of work has been done on the amount and composition of the gases dissolved in steel, and it appears that errors of up to 0-02 per cent., or even more, may easily be due to this source. For the present purpose, by far the most valuable is a paper by E.Goutal (Rev. MdtaElurgie, Mhmoires, 1910, vol. vii., p. 8). Goutal’s method consisted in dissolving the sample in carefully boiled out acid potassium cupric chloride solution in a, current of nitrogen, finally raising the solution to the boiling-point, and de- termining carbon monoxide, carbon dioxide, and sometimes other gases, in the gases evolved, and carbon in the residue.Proceeding in this way, he obtained the following results :THE ESTIMATION OF CARBON IN STEEL 393 co ,. Per Cent. Soft steel ... ... 0.0254 Medium steel ... ... ... 0.0210 Hard steel ... ... 0.0678 Extra hard steel' ... 0.0792 Nickel steel (Ni, 2.04 per cent.) 0.0530 Chrome steel (Cr, 5-10 per cent.) 0.0510 Basic open hearth iron ...0.1890 c o . Per Cent. 0.0063 0.0120 0.0137 0.0142 0*0060 0-0115 0.0132 C in Residue. Per Cent. 0.160 0.295 0.596 1.334 0.340 0.360 4.110 C (corresponding to Carbonaceous Gases). Per Cent. 0.0096 0.0108 0.0244 0.0277 0.0170 0.0188 0.0571 The values in the last column are not given by Goutal.He also shows that, if the solution contains not more than 10 per cent. of HCI, and the temperature is not raised above 45O C., the CO, remains wholly in the liquid, whilst the GO is partly disengaged. Thus, working with 10 grms. of a steel con- taining 0.95 per cent. carbon, he found : C (corresponding to cop co. Carbonaceous Gases). Per Cent. Per Cent. Per Cent.During dissolution . . . ... o*oooo 0.0068 0.0029 In filtrate (on boiling) ... 0.0075 0~0070 0.0050 In residue (boiled with very dilute HCl) ... ... 0.0751 0.0015 0.0211 Total ... ... ... 0.0826 0.0153 0.0290 -- -- Check by first method ... 0-0829 0.0153 - The carbon dioxide here found to remain with the residue would probably be largely, if not wholly, expelled during the drying usual before burning the residue, and hence would be lost in the solution method.In another series of experiments he obtained the following values : Medium Steel. Hard Steel. Extra Hard Steel. Per Cent. Per Cent. Per Cent. C in residue . . . ... ... 0.2950 0.5960 1,3340 C in GO, ... ... ... 0-0057 0.0185 0.0216 C in CO ... ... 0.0051 0-0059 0.0061 c in cases not iientise'd' ...O*OOO~ 0.0171 0.0158 c total .. ... ... ... 0.3067 0.6375 1.3775 As far as my reading goes, Goutal is the only author who mentions the influence of the dissolved gases on the two methods of estimating carbon. Thus, on p. 13 (op. cit.) he states quite incidentally that he prefers his own method of determining carbon (to the direct combustion method), because it enables one to distinguish between two forms of carbon (that in the residue and that evolved as gas), which influence the properties of the steel in quite different ways.This general silence is all the more striking when one reflects that the same consideration applies to all the numerous wet methods of combustion. Further proof of the existence of appreciable quantities of dissolved mrbonaoeous gases in steel and iron is found in several other papers by different authors, a,ll of394 A* GO LEVY: THE ESTIMATION OF CARBON IN STEEL 1.36 - 2'89 -- 2'81 - 5-22 - 0.76 -- 0.67 - 1-35 - 0.41 - whom determined the gases evolved on heating the samples in vucuo.A number of recent determinations are collected in the table following, in which I have calculated in the last column the percentage of carbon corresponding to the carbonaceous gases evolved : - - - - 0-18 0.32 0.25 2-67 0 B 2 2 Nature of Sample.8 36'43 33.70 78'75 06'00 25.43 11.09 16'74 11.46 1 Wire, 1 mm. diameter .. 1 Wire, 0'5 mm. diameter 1 Foil, 1 mm. thick .. 1 Filings ... ... .. 2 Planings, mixed ... .. 2 Planings, surface .. 2 Planings, half-way .. 2 Planings, centre ... .. 7.010 20.33 7-83 6.220 12-70 11.89 5.050 53-46 17'40 5.160 66.45 29.17 3-690 13-49 7-31 0.590 3'84 5.67 1-400 10.37 3.67 0,880 2'72 4.78 { Planings, 45 per cent. { nickel steel - - - - - - - - - 4 Piece without blowholes 4 Piece with blowholes ...0.150 0-004 0.220 0.690 0.020 0.020 0.010 0.220 0.950 Planings, baaic Bessemer 5 { steel 5 Electric furnace steel ... Crucible steel, 0'24 per { cent. wide 5 Rail steel ...... 5 Swedish pig-iron ... C. % 0.074 0.042 0*13C 0.09s 0.120 0.120 0.120 0.120 0.150 0.150 0.900 0-810 0.050 to 0.080 0.150 0-400 0.400 0.400 3.650 - d a m w 8, B" w ." B Grms. LO-000 14-000 12-500 :6*000 '5*000 '5.000 5.000 - o*ooo o*ooo 9'310 3'261 - - - - - - - - Qascs evolved on Heating in VLLCUO. Gases in ver Cent. of Total Gas. Gases in C.C. as measured at 0" and 760 mm.Gases in C.C. at 0" and 760 m 2-36 0.91 1.63 1 '49 2 '45 1.31 1 #07 4 *45 5.80 0-20 0'13 0-30 0'22 0.18 0.35 0.11 0-51 0.91 0.07 0.66 0.20 I 0'73 I 1 . per C.C. of Metal. 0.55 0.16 0.35 0.10 0 *35 0.22 0.31 0'92 0.56 0 * m bog 3 8 ~ SG $20 E V 2 x 0-037 0.030 0-038 0.084 0.003 0.008 0.003 - y078 3.058 1.034 1.016 )*017 1.006 1.013 p015 p017 1.009 1.007 1.031 1.046 REFERENCES TO TABLE, 1.0. Bondouard, Rev. MktaZlurgie, MBm., 1908, 6, 73. 2. G. Relloc, Rev. Mktallurgie, MBm., 1908, 6, 479 and 482. 3. G. Belloc, Rev. Mktallurgie, MQm., 1908, 6, 573 and 574. 4. T. Baker, J. Iron and Steel Inst., Carnegie Schol. Mem., 1909, 1, 225. 5. P. Goerens, Rev. MPtaZZwrgie, 1910, 7, 392. With the exception of the two results due to Baker, all the determinations were carried out on planings or thin wire and foil.Hence, gas evolved from large blow- holes is excluded, and the results apply directly to samples as usually taken for direct combustion. It will be seen that plus errors of 0.03 per cent. carbon, due to this source alone, &re easily possible, even if four higher values (up to 0.08) are rejected as abnormal. Incidentally, the presence of small quantities of hydrogen in the metals supplies a reason for the insertion of a drying tube between combustion tube andTHE BACTERIOLOGY OF AERATED WATER 395 potash bulbs, which precaution is occasionally omitted. Regarding the accuracy of the determinations quoted, it may be mentioned that Baker found a small furnace blank of about 3 C.C. total gas, consisting largely of hydrogen and nitrogen, due probably to the walls of the heated porcelain tubes not being perfectly impervious to gases at high temperatures under the high vczcua used. Finally, to sum up, when working to a close carbon specification, it may not be t~ matter of indifference to the maker of the steel whether the analyst uses a solution or a direct combustion method.

ISSN:0003-2654    

DOI:10.1039/AN9123700391

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

THE BACTERIOLOGY OF AERATED WATER 395 THE BACTERIOLOGY OF AERATED WATER. BY G. D. ELSDON, B.Sc., A.I.C., AND NORMAN EVERS, B.Sc., A.I.C. DURING the past few years attention has been drawn to the bacteriological examina- tion of commercial soda-water, and a number of results have been published by Public Analysts and others--e.g., Klein, Report of the Medical Officer of Eealth for the City of London (ANALYST, 1911, 36, 16).Thirty-seven samples of commercial soda-water have recently been completely analysed in this laboratory, with the following bacteriological results : In no case has typical B. coli (flagniac) been found in 50 C.C. In two cases fermentation was obtained in glucose taurocholate with 50 c.c., in two cases with 10 c.c., and in 1 case with 1 c.c.; but in all these casee further examination showed that these were not typicd B.coli. The number of organisms growing on jelly in three days, found in twenty-five samples stored in siphons, varied from 1 to 150 per c.c.; whilst the number found in waters stored in bottles, all precautions being taken to prevent the access of bacteria during opening, was found to be in some cases 1,000 to 3,000 per C.C.I t seemed desirable to find out how far these bacteriological results, obtained in many cases probably several days (and possibly weeks) after bottling, are of vdue as an indication of the purity or otherwise of the original water, for it seemed probable that the presence of carbon dioxide under pressure would have a dele terious action on the micro-organisms present in the water. For the purpose of carrying out these experiments, the apparatue known as the '' Prana Sparklet " siphon was used.The siphons were thoroughly cleaned and steamed for one hour, with careful hqating and cooling to prevent breakages, on each of two syzessive days, the siphon-head being plugged with wool. The water to be experimented upon was then run in by means of a sterile funnel, and carbonated in the usual manner.Small quantities were withdrawn from the siphon from time to time for the purpose of bacteriological examination, estimations being also carried out on the water itself as a control. Such experiments were carried out on-(1) the number of organisms growing on jelly at 2 1 O C., counting after three days; (2) the number of organisms growing on neutral-red lactose taurocholate agar (Rebipel agar) at 37' C., counting after two days ; and (3) the power of fermenting glucose taurocholate broth.396 ELSDON AND E.VERS: After Three Days.1. The Number of Organisms growing on Jelly at 21° C.-Various samples of water were taken and aerated as described above, and the number of organisms per C.C. growing on jelly at 21O C.estimated after various lengths of time in both the caxbonated and nncarbonated water. The results obtained are given in the following table : After Seven Days. TABLE I. Original- Water. 63 7,000 Number of Bacteria growing on Jelly in Three Days at 21" C. After Three Days. After Seven Days. After Fourteen Days. Control. Carbonated. Control. Carbonated. Control.Carbonated. 62 58 57 25 46 5 -_ - 6,200 38 6,100 5 Source of Water. Original Water. Filtered river . . . ... ... Filtered upland surface.. . - 1 . Unfiltered upland surface . . 9 9 9 , 9, ... 9 , 9 , 9 9 ... $ 9 9 , 9 9 ... Deep well ... ... ... 950 19 391 3,400 290 10,000 Liq. Control. Carbonated. Control. Carbonated. I I I 910 845 Liq . 7,300 2,650 36,800 240,000 125 15 3 53 63 397 950 867 4,200 5,500 7,400 1,700 33,900 - 93 1 1 44 51 142 - These results, obtained from different types of water, show that the total number of organisms is rapidly reduced by carbonation, and in well-filtered waters, where the number of organisms is small originally, carbonation prevents these organisms from multiplying.In the case of the polluted water, it will be observed that the number of organisms was very rapidly reduced.2. Number of Bacteria growing on Rebipel Agar at 37" C. i.n Two Days.-Sterile tap-water was in two cases inoculated with a small number of B. coli (flsginac) grown in peptone water for two days. Part of the water was aerated, and the effect of aeration observed as before. TABLE 11. Experiments were then undertaken on the number of organisms growing on Rebipel agar which are naturally present in waters.The method used was similar to the one used under Section I. The results were as follows :THE BACTERIOLOGY OF AERATED WATER 275 108 347 397 - - 1,820 66 44 19 8 7 714 23 905 2 TABLE 111. Source of Water. Deep well water ... ... ... River water ... ... ... ... ... 9 9 Y, Yt -.. I Number of' Bacteria growing on Rebipel Agar at 37" C.Original Water. 3. Efect of the Addition of Sodium Bicarbonate on the Fermentation of Taurocholate. -Fifty C.C. of sterile carbonated water were added to taurocholate, and then inoculated with a little cultivated B. coli (flaginac) and incubated at 37' C. After twenty-four hours a vigorous acid and gas production was observed. Fifty C.C. of sterile carbonated water containing 10 grains per pint of sodium bicarbonate were added to taurocholate and inoculated as above.After twenty-four hours a, vigorous growth was observed. Fifty C.C. of a well-water known to contain B. coli were taken, and sufficient sodium bicarbonate added to make the alkalinity equal to 10 grains per pint. The water was then added to taurocholate, and after incubating at 37" C.for twenty-four hours, a similar growth was obtained to that given by the original water. Fifty C.C. of carbonated water containing sodium bicarbonate equal to about 5 grains per pint were put into taurocholate; after twenty-four hours a vigorous growth was observed. These results show that the growth of bacteria in glucose taurocholate is prevented neither by an alkalinity of 10 grains per pint of sodium bicclrbonate, nor by carbonation, nor by both together.4. Organisms producing Acid and Gas in Glucose Taurocholate.-The results given below were obtained by growing natural waters in gluoose taurocholate with and without carbonation. In the table, (a) signifies the carbonated water, whilst (b) signifies the uncarbonated or control water.TABLE IV. Well Water A. 50 C.C. 10 C.C. 1-0c.c. 0.1 C.C - Original ... ... ... + + + - .- + + - - ( ( a ) + ... \(b) i- After four days .. ria) + "'\(b) + After seven days ...398 THE BACTERIOLOGY OF AERATED WATER Original ... ... After four days .. . After seven days ... After twelve days ... Original ... ... After four days ... After seven days ... After twelve days ...Well Water C. 50 C.C. ... + . * .{ { (4 . . . { [$ ... ( b ) 10 C.C. + + + + + + - 10 C.C. + + + + + + + 1'0 C.C. 0.1 C.C. - + + + + + + - 1'0 C.C. 0.1 C.C. + + + 4- + -b + + + + + + +- + It will be seen that except in the case of the well water B the carbonation did not sensibly affect the organisms fermenting glucose taurochobte in the time given. Conclusions.-The general conclusions to be drawn from these experiments seem to be the following : (a) The total number of organisms growing on jelly at 21" C.is considerably reduced by carbonation, and a water containing originally a large number of organisms may, after a week's standing under pressure, contain only a number such as would be found in a very good water. (b) B. coli are not so rapidly reduced as other organisms, but die off rather more rapidly than in ordinary water.(c) The number of organisms growing on Rebipel agar are much reduced by carbonation, especially those which do not produce the typical B. coli red appearance. This latter fact was shown by the appearance of the plates after incubation. (d) Ten grains per pint of sodium bicarbonate does not affect the growth of organisms in glucose taurocholate ; neither does excess of carbon dioxide, such as is- found in carbonated waters. I t follows, therefore, that bacteriological results obtained on a water which has been carbonated for more than twenty-four hours are of little value as an indication of the source or purity of the original water, except in the case of growth in glucose taurocholate. In this latter case correct results may probably be obtained for a week after carbonation. CITY ANALYST'S LABORATORY, BIRMINGHAM.

ISSN:0003-2654    

DOI:10.1039/AN9123700395

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

SOLUBILITIES OF LEAD SALTS IN ETHER AND PETROLEUM ETHER 399 SOLUBILITIES OF THE LEAD SALTS OF THE HIGHER FATTY ACIDS IN ETHER AND IN PETROLEUM ETHER." BY G. B. NEAVE, M.A., D.Sc. OWING to the fact that the solubility of lead oleate in ether is employed in estimating the amount of oleic acid in a mixture, and the possibility that errors may arise from the solution of the lead salts of saturated acids, the latter were prepared and their solubilities in ether and petroleum ether determined.Preparation of the Lead Salts,-The pure acid was neutralised with ammonia, and the lead salt precipitated by addition of a saturated solution of lead acetate. The lead salt was filtered, washed, and recrystallised from alcohol. Lead caproate m.pt. Lead heptylate ,, Lead caprylate ,, Lead nonylate ,, Lead myristate ,, Lead palmitate ,, Lead stearate ,, Lead caprate 9 , Lead laurate $ 9 73-74" C.P b found 47-23 % Pb calculated 47.37 % 90*5-91*5' C. ,, 44.27 % ,, 44-51 % 83-5-8495" C. - - 100" c. ,, 37-59 % ,, 37.70 % 103-104" C. ,, 34.16 % ,, 34.21 % 107" C. ,, 31.34 % ,, 31.32 % 112" c. - - 125' C. - - 94-95" c. ,,. 39.68 % ,, 39.73 % Lead 0leate.-This salt was obtained as a white powder, m.pt.45-50" C., which is considerably lower than that quoted by Gottlieb (Annalen, 1845, 57, 38). Other preparations were made, but all the specimens gave approximately the same m.pt. The lead oleate thus obtained was extremely soluble in ether and in petroleum ether. Attempts were also made to prepare the lead salts of other unsaturated acids.These, however, were very rapidly oxidised on exposure to the air. Determination of Solubilities of the Lead Salts.-The ether employed was purified by distillation over sodium ; the petroleum ether was the fraction collected from 40-60" C. ,The flask containing the lead salt and the solvent was placed in a thermostat maintained at a temperature of 20" C., and was fitted with a stirrer driven by a small motor. Since filtration by the ordinary method was slow and involved a loss of solvent, a special pressure-filtering apparatus was used.The flask containing the solution and excess of lead salt was closed with a cork, through which passed, in addition to the stirrer, two tubes, one terminating just below the cork, the other at the bottom. The second tube, communicating with a weighed flask, was widened at the end, on which was the filter, consisting of two layers of Swedish filter-paper, with an outer layer of thin silk.After the solution was saturated, dry air was forced into the flask, and any convenient volume collected in the weighed flask and evaporated to complete dryness. The solubilities at the boiling-points of the solvents were determined in the same manner, the first flask being attached to an efficient con- dehser.* This work was carried out under the conditions of the Analytical Investigation Scheme.400 SOLUBILITIES OF LEAD SALTS IN ETHER AND PETROLEUM ETHER solution : The solubilities in the following table are expressed in grms. per 100 C.C. practically Lead caproate .. . Lead heptylate .. . Lead caprylate . . . Lead nonylate ... Lead caprate ... Lead myristate . . . Lead laurate ... Lead palmitate.. . Lead stearate ... practically Ether. 20" c. - 0.2397 0.0938 0*1115 0.0290 practically insoluble prac tically insoluble practically insoluble Boiling-Point. 1.3640 1.4900 0.5460 0.2404 0.4285 0.0555 0.0205 0.0261 Petroleum Ether. 20" c. - 0.0200 practically insoluble practically insoluble practically insoluble practically insoluble practically insoluble prac t ically insoluble practically insoluble Boiling- Poin t. 0.0608 0.0528 0.0384 0-0450 0-0170 0.0210 practically in soluble practically insoluble 0-0170 It will be seen from the table that the solubilities are very small, while that of I desire to thank Messrs. E. Anderson. A.I.C., A. P. Clark, D. Hamilton, A.I.C., lead oleate, as stated previously, is very great. and J. Porter, A.I.C., for their assistance in this work. THE ROYAL TECHRICAL COLLEQE, GLASGOW.

ISSN:0003-2654    

DOI:10.1039/AN9123700399

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

400 SOLUBILITIES OF LEAD SALTS IN ETHER AND PETROLEUM ETHER ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. ANALYSIS OF FOOD AND DRUGS. Micro-Chemical Tests for the Identification of Some of the Alkaloids. E. B. Putt. (J. Ind. and Eng. Chem., 1912, 4, 508-512.)-1n the method described, a fragment of the alkaloid was dissolved on a microscope slide in a drop of dilute hydrochloric acid, a drop of the reagent was added, and the nature of the precipitate examined under the microscope.In many cases distinct types of crystals were formed successively by the same precipitate. Some forty different alkaloids and other substances were thus tested, and a, description is given of the crystalline or amorphous precipitates obtained. The paper is illustrated with photo-micrographs. w.P. s.FOOD AND DRUGS ANALYSIS 40 1 New Method of Estimating Caffeine. G. Costes. (Ann. Chim. anal., 1912, 17, 246-249.)-The method is based upon the fact that caffeine is not destroyed by three hours' heating with sulphuric acid, and after the destruction of the bulk of the accompanying organic matter, the alkaloid may be extracted from the neutralised solution with chloroform. Twenty grms.of the ground coffee (or more in the case of samples containing only about 0.1 per cent. of caffeine) are mixed little by little with 15 to 20 C.C. of pure sulphuric acid (sp. gr. 1.835), and the flask placed for ten to fifteen minutes on the water-bath at 100' C., after which the mixture is extracted with three successive portions (about 200 c.c., 150 c.c., and 100 c.c.) of boiling water, the extraction being continued about ten minutes the first time and five minutes the second and third time.After each extraction the liquid is filtered into a porcelain basin containing a little sodium hydroxide (insufficient to neutraliee the whole of the acid). The united filtrates are rendered slightly alkaline with sodium carbonate, concentrated to about 200 c.c., filtered if necessary, and extracted three times with chloroform (50 c.c., 35 c.c., and 30 c.c.).The chloroform extracts are united and distilled, and the residue of caffeine purified by heating it for ten minutes with 2 C.C. of sulphuric acid on the water-bath, and adding just sufficient water to render filtration possible. The filter is washed five or six times with a little boiling water, and the filtrate and washings rendered slightly alkaline with ammonia, cooled, and extracted with three successive portions of chloroform (25 c.c., 20 c.c., and 15 c.o.).The extracts are evaporated in a tared basin on the water-bath at about 80" C., and the residue is dried for thirty minutes at 100" C. and weighed. However white the crystals appear, the residue will not contain more than about 93 per cent.of pure caffeine, and it is therefore advisable to estimate the nitrogen by Kjeldahl's method, and to calculate the corresponding amount of caffeine. For industrial purposes results in close agreement with those given by the methods of Granval and Lajoux and of Helger and Juckenack may be obtained by omitting the neutralisation of the liquid after the initial treatment with sulphuric acid and filtration, extracting the caffeine with (1) 100 c.c., (2) 100 c.c., and (3) 75 C.C.of chloroform, evaporating the extracts, and weighing the residue. C. A. M. Comparative Value of the Catalase, Reduetase, and Leucoeyte Tests in Detecting Mastitis. 0. Gratz and A. Naray. (Milchwirtschaftl. Zentralb., 1912, 41, 225-232, 257-263, 289-303 ; through Chern.Xentralb., 1912, II., 287.)-The milk of 153 individual cows was examined, re-examined after ten or twelve days, and the examination repeated several times in all doubtful cases. As a result the reductase test, whether in Barthel's original form or Schardinger's modification of it, is declared to be too uncertain to be of value.The catalase test is said to be five to ten times as sensitive as the leucocyte test, but the latter is necessary to control the results of the former in cases where the abnormal catalase number is due to blood. In such cases the blood will usually be detected by the reddish colour of the sediment in the capillary of the tube used for collecting the sediment for a leucocyte count.For the catalase test the authors use Koestler's apparatus, 10 C.C. of milk, and 5 C.C. of 1 per cent. hydrogen peroxide solution, and allow two hours at 22" to402 ABSTRACTS OF CHEMICAL PAPERS 24' C. to twenty cows, only one of which is suffering from mastitis. They find that the test readily fixes suspicion on the mixed milk of ten G. C. J. Estimation of Husk in Cocoa Powders. L.Kalusky. (Zeitsch. Untersuch. Nahr. Genussm., 1912, 23,654-661.)-The method proposed depends on the difference between the sp. gr. of the cell tissue of the inner portion of the cocoa bean and that of the husk. The sp. gr. of the cell tissue of the inner portion (obtained by treating .the fat-free substance with diastase, and subsequently with hydrochloric acid) varies from 1.1131 to 1.3503, and is usually less than 1.25; whilst that of the husk lies between 1-4324 and 1.9337, and in the majority of cases is upwards of 1.50.The authoress found that it was possible to separate the two tissues by means of a mixture consisting of chloral hydrate, glycerol, and water, and having a sp. gr. of 1.415 at 17" C., and to estimate within narrow limits the quantity of husk which had been added to cocoa powders, when both the powder and the husk had been prepared by herself from cocoa, beans.When commercial cocoa powders were examined it was found, however, that the sp. gr. of the cell tissue of the inner portion was somewhat higher than the above-mentioned figures, and it was found necessary to employ a medium having a sp. gr. of 1.5 in order to separate the two kinds of tissue.The details of the process as applied to the estimation of added husk in cocoa, powder are as follows : About 5 grms. of the cocoa are extracted with ether until the fat has been removed completely. One grm. of the fat-free, dry powder is boiled for five minutes with 500 C.C. of water, then cooled to 65" C., and maintained at this temperature for one hour after the addition of a small quantity of diastase.Twenty- five C.C. of 25 per cent. hydrochloric acid are next added; the mixture is boiled for thirty minutes, when the insoluble tissue is collected on a weighed filter, washed with hot water, dried for two hours at 100' C., and weighed. The dry tissue is detached from the filter, ground as finely as possible in a mortar, again dried, and a weighed portion of it mixed in a suitable tube with 20 C.C.of the medium, and submitted to centrifugal action for five minutes. The medium is prepared by mixing 210 grms. of chloral hydrate, 50 grms. of glycerol, and 35 grms. of water, and should have a, sp. gr. of 1.50 at 17" C. ; if this is not the case, more chloral hydrate or water is added, as required.The portion of tissue which is at the bottom of the tube is now separated, mixed with 100 C.C. of water, collected on a filter, washed with hot water, dried, and weighed. A convenient form of tube for use in the centrifugal operation is described; it consists of a glass tube which is drawn out to a narrow point at the lower end, a small opening in this end being closed by a glass rod passing down the centre of the tube.The end of the rod is ground to fit the opening, and the sediment may be discharged from the tube by raising the rod slightly. The weight of heavy tissue thus obtained is calculated as a percentage quantity of the original cocoa, and the result is multiplied by 3 in order to give the percentage of husk present. This factor is obtained as the result of estimations of heavy tissue in samples of cocoa husk, the latter yielding on an average 30 per cent.of the tissue. When husk is absent, the whole of the tissue is found floating on the surface of the medium w. P, s. after the mixture has been submitted to centrifugal action.FOOD AND DRUGS ANALYSIS 403 Detection of Formic Acid in Fruit Products. F. L.Shannon. (J. I d . and Eng. Chm., 1912, 4, 526-528.)-The authors find that numerous substances, known to be free from formic acid, yield, when submitted to steam distillation, a distillate which reduces both silver nitrate and mercuric chloride. From none of these substances, however, could forniic acid be isolated and identified as such. For the identification of formic acid the authors recommend that the acid be converted into formaldehyde by means of magnesium and dilute sulphuric acid ; the acid may also be neutralised with lead hydroxide, when characteristic crystals of lead formate are obtained. In testing fruit juice or fruits, about 500 grms.of the sample are submitted to steam distillation, until the distillate ceases to give an acid reaction towards litmus (usually about 2,500 C.C.must be collected). The distillate is then neutralised, evaporated to 50 c.c., transferred to a flask provided with a long tube, to act as an air-condenser, and treated at the ordinary temperature with magnesium and sulphuric acid. The mixture is now distilled, and the first 10 C.C. of distillate tested for the presence of formaldehyde. Another portion of the sample may be distilled as before, and the distillate collected in a flask containing lead-cream (prepared by treating lead nitrate solution with potassium hydroxide until the mixture is faintly alkaline to phenolphthalein). The distillate is then evaporated to 50 c.c., filtered, and the filtrate set aside to crystallise.Any crystals obtained are washed with alcohol, to remove lead aoetate, and then examined for formic acid by the usual tests (reducing reactions, conversion into formaldehyde, etc.).w. P. s. Bromine Absorption of Certain Vegetable Oils and Fats. B. Sprink- meyer and A. Diedrichs. (Zeitsch. Untersuch. Nahr. Genussm., 1912, 23, 679-687.) -The following percentage quantities of insoluble bromine compounds were obtained on subjecting various oils and fats to the process described by Hehner and Mitchell (ANALYST, 1898, 23, 315): Linseed oil, 28.9; candlenut oil, 8.8; hempseed oil, 8-82; walnut oil, 2.22 ; soja bean oil, 3.62 ; sesame oil, 0.14 ; mustard oil, 1.30 : rape oil, 1.92.Poppy-seed oil, sunflower-seed oil, maize oil, cottonseed oil, castor oil, tea oil, earthnut oil, cocoanut oil, palm oil, palm-kernel oil, cacao butter, stillingia tallow, tulucuna fat, dika fat, and rnalukang butter, did not yield an insoluble bromine compound. In the case of shea butter, different specimens of the fat yielded from 5.2 to 8.6 per cent. of bromine compound, whilst mowrah butter gave 0.82 per cent., enkabang tallow 0.17 per cent., and adjab fat 2-2 per cent. As regards the four last-mentioned fats, the bromine compound appears to be formed from the unsaponi- fiable matters present, the fatty acids derived from the fats yielding no bromine compound after they have been freed from unsaponifiable matter. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700400

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

FOOD AND DRUGS ANALYSIS 403 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Estimation of Laetie Acid in the Presence of Proteins. J. Mondsehein. (Biochem. Zeitsch., 1912, 42, 105-123.)-Lactic acid is an important constituent of animal organs, but the greater part of this acid found in extracts of the organs is404 ABSTRACTS OF CHEMICAL PAPERS produced by post-mortem changes in the tissue, only a small quantity being a constituent of the living organ.Experiments carried out by the author show that when animal tissue is boiled with water only about two-thirds of the quantity of the lactic acid passes into the aqueous solution, the remaining third combining with the coagulated albumin. The following method is proposed for the estimation of the total amount of lactic acid present in an animal tissue or serum : In the case of muscular tissue, 50 grms.of the finely-divided substance are suspended in about 80 C.C. of water, the mixture is heated to boiling, and the coagulum is collected on a filter and washed with hot water until free from acidity. The filtrate is then titrated with & alkali solution, using phenolphthalein as the indicator, and the acidity is expressed in terms of lactic acid.The coagulum is now removed from the filter, mixed in a beaker with 50 C.C. of water and 10 C.C. of a 10 per cent. sodium hydroxide solution, and the mixture is heated until fluid. One hundred C.C. of saturated sodium chloride solution are then added, the whole is again heated to boiling, and the hot mixture is saturated with sodium chloride.The precipitated proteins arecollected on a filter and washed with hot saturated sodium chloride solution ; the filtrate is rendered slightly acid with sulphuric acid, diluted to 500 c.c., filtered through a dry filter, and the lactic acid estimated in 250 C.C. of the filtrate by the method described by von Furth and Charnass (ANALYST, 1910, 35, 445). The quantity of lactic acid thus found is added to that obtained by titration in the first part of the process, in order to give the total amount of the acid present in the substance under examination. Before applying von Furth and Chamass's method, i t is advisable to boil the acid filtrate for ten minutes, in order to expel any hydrogen sulphide which may be present.The small quantity of protein which is precipitated on the addition of the sulphuric acid does not interfere with the estimation.w. P. s. Application of the Quantitative Precipitin Reaction in Honey Analysis -11. J. Thoni. (Mitt. Lebensmitteluntersuch. u. Hyg., 1912,3, 74-94 ; through Cham Zentralbl., 1912, II., 151-153; cf. also ANALYST, 1911, 36, 456.)-The author has studied the effect of heating the honey on the results of the precipitin reaction. Honey may be heated for various reasons-e.g., for removing air-bubbles (tempera- ture 35" C.), melting the honey out of the combs (temperature 50" C.)-and comparatively high temperatures are used in clarifying foreign crude honeys. The precipitin reaction depends on protein constituents which only begin to change at temperatures above 50" C., so that only such temperatures come into account.Experiments made at 60° to 98" C. showed that only temperatures a few degrees below 100" C. caused a diminution in the quantity of the precipitate, and then only if maintained for a certain length of time (ten to sixty minutes). Complete absence of the precipitate is only observed when the honey has been heated for longer than one hour at looo C.At such a temperature the aroma and enzymes are destroyed, and such honey could not be regarded as normal. In the quantitative precipitin reaction the values obtained have only a relative significance, since they may vary according to the equivalent of the antiserum ; only results obtained at the same time with the same serum are comparable among themselves.With a large number ofBACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 405 samples of genuine honey of different origins no considerable differences in the variations of the precipitate values were established ; these variations amounted to about 2 40 per cent. of the mean value. In the case of abnormal samples the serological method permitted an accurate identification of the honey.For the esti- mation of the catalnse value of honey, 7.5 C.C. of honey solution (50 per cent.) were mixed with 7-5 C.C. of a 1 per cent. solution of hydrogen peroxide, and the volume of oxygen was observed after twenty-four hours, The author agrees with Witte that the catalase value alone is only of use in extreme cases as an indication of large adulteration, or incipient fermentation, or strong heating.As regards the effect of heating on the diastase value, the author considers that the original honey should, be heated, not its solution, and in such cases a deficiency in diastatic activity only occurs at temperatures above 90° C., a higher limit than is found when the diluted honey is heated. For carrying out Fiehe's reaction, about 7 or 8 grms. of honey are dissolved in an equal quantity of water, extracted with ether; the clear, filtered ethereal solution is evaporated in a porcelain dish at 40" to 45' C., and the residue tested in the usual manner.Genuine honey does not give Fiehe's reaction; adulterated honey does; so that this is a reliable test for certain kinds of adultera- tion (cf. ANALYST, 1911, 36, 456). J. F. B. Determination of the Digestive Value of Papain.J. R. Rippetoe. (J. Ind. and Eng. Clzem., 1912, 4, 517-518.)-Graber (ANALYST, 1912, 57) described a method for testing the digestive value of papain, using finely-ground steak suspended in 0-3 per cent. hydrochloric acid, and criticised the use of egg albumin in an alkaline medium. The author describes a process he has long employed for testing papain, in which 10 grms.of egg albumin is subjected to the action of 0.1 and 0.2 grm. of papain in 40 C.C. of 0-1 per cent. sodium hydroxide solution for six hours at 52' C. in a, stoppered bottle, shaking every ten minutes. The whole is then washed into a graduated cylinder, made up to 70 c.c., and the volume of the deposit read at the end of one and sixteen hours. The following figures show the com- parative effects of acid and alkali on the same sample of papain : Deposit in C.C.aftcr standing. One Hour. Sixteen H&w. Blank ... ... ... ... 52 43 0.2 Y7 Y Y 0.1 $ 9 ... ... 8 8 0.2 9 9 2, 0.2 Y, ... ... 30 30 0.1 grm. papain, 0.1 per cent.' N ~ O H ... ... 26 18 0.2 Y7 ,, 0.1 per cent. Hc~ ... ... 16 20 7 9 0.2 Y9 ,9 0.3 9 , 9 , 0 ' . ... 32 30 The inhibitory effect of the acid on proteolysis is clearly shown.H. F. E. H. Laboratory Studies of Rennin. A. Zimmerman. (J. Ind. and Eng. Chem., 1912, 4, 506-508.)-Rennin precipitated with sodium chloride at 40" C. is sold in powder form mixed with lactose, and so prepared gives a much smaller yield than with sodium sulphate, but its activity is from five to six times greater.It has, when thus diluted, an activity of 1 : 30,000 or 40,000 within twelve minutes, contains more or less albumose, and is acid in reaction. Scale rennin is prepared by406 ABSTRACTS OF CHEMICAL PAPERS scaling the whole clarified rennet solution a t a temperature of 43.5’ C., and has a, strength of 1 : 30,000 or 40,000. Scale rennin contains peptones and albumoses formed during the process of the digestion of the rennets with hydrochloric acid which it retains, having thus an acid reaction.The former product is the less permanent, this quality being apparently dependent on phosphoric acid, originally present in the rennets as the calcium salt, and set free by the hydrochloric acid when employed. The scale preparation, but not the sodium chloride product, gives the reaction of phos- phoric acid, and the addition of this acid in the proportion of -075 per cent.to new milk greatly accelerates the action of rennin. As milk gets older, rennin acts more readily. The curd in milk four to eight hours old forms very gradually, and when complete is not nearly so firm as that produced in the presence of phosphoric acid which materially reduces the time of action.Lactic acid has about one-fifth, and hydrochloric and oxalic acids one-tenth, the activity of phosphoric acid in this con- nection. Milk which is slightly acid curds more readily, and can be modified to require a longer time by addition of small quantities of alkali. To control the vari- ability of milk for the assay of rennin, a standard rennin is required to show whether the milk is fast or slow.The action of the rennin is tested in not less than twelve different samples of milk. If the rennin is standardised to 1 : 30,000 in eight minutes, its use as a control with the rennin to be assayed shows whether the milk is fast or slow, and allowance is made accordingly. The rennin should be added to the milk as soon as the temperature is 40’ C.Aqueous solution of rennin of sp. gr. 1.010 and containing 0.20 per cent. by volume of hydrochloric acid lost 30 per cent. of its activity in twenty-four hours at 2 1 O C. Stronger solutions with more acid proved more permanent. The author’s results point to the use of granular scale rennin and phosphoric acid in place of lactic acid in the preparation of essence of pepsin.H. F. E. H. Trommer’s Test for Sugar in Urine. E. Salkowski. (Zeitsch. physioZ. Chem., 1912, 79, 164-170.)-The author agrees with the statements by Schulz (cf. ANALYST, 1912, 264) regarding the behaviour of urine when treated with copper sulphate and sodium hydroxide solutions, but points out that urine containing sugar behaves some- what differently from urine free from sugar when the two are treated with copper sulphate and then rendered alkaline, and that it is still possible to detect sugar in urine by Trommer’s test when the order of adding the reagents is reversed.The following manner of carrying out the test is, however, recommended : Five C.C. of a 30 per cent. sodium hydroxide solution and 8 drops of a 10 per cent. copper sulphate solution are mixed and heated to boiling; a clear blue solution is thus obtained con- trtining a few particles of black copper oxide which do not interfere with the test.To the hot solution are now added 2 C.C. of the urine, and the mixture is again boiled. Urine containing as little as 0.2 per cent. of sugar reduces the copper much more than does urine free from sugar. The test is rendered more sensitive by allowing hydro- chloric acid to flow on the surface of the hot mixture; in the presence of sugar a yellow zone of hydrated cuprous oxide is obtained.The urine may also be clarified by means of mercuric acetate before being tested. Twenty C.C. of the sample are treated with a 20 per cent. mercuric acetate solution,ORGANIC ANALYSIS 407 this being added drop by drop as long as a precipitate is formed, but: a large excess is to be avoided. The mixture is then neutralised with sodium carbonate, filtered, the filtrate acidified with hydrochloric acid and warmed gently after the addition of a quantity of zinc-dust. When all the mercury has been precipitated, the mixture is again filtered, and the filtrate tested for sugar by Trommer’s test, the sodium hydroxide being added before the copper sulphate. I n the caee of normal urine the solution retains its blue colour, but becomes bright yellow if 0.2 per cent. of sugar is present. Subsequent addition of hydrochloric acid also renders this test more sensitive. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700403

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

ORGANIC ANALYSIS 407 ORGANIC ANALYSIS. Colour Reaction of Alcohols and Alcoholic Hydroxyl Groups, L. Rosen- thaler. (Chem. Zeit., 1912, 36,83O.)-A red coloration is obtained when an alcohol is heated with its own volume of a 0.5 per cent. sodium nitrite solution and 4 volumes of a 0.5 per cent. sulphanilic acid solution (prepared by dissolving 1 grm. of sulphanilic acid in a mixture of 5N hydrochloric acid and 150 grms.of water). With 0.25 grm. of ethyl alcohol or glycerol, the colour develops within thirty seconds ; it fades after a time and is discharged on the addition of an acid. The reaction is not very sensitive, but may be obtained with 2.5 mgrms. of ethyl alcohol or 0.01 grm. of glycerol. The coloration develops slowly at the ordinary temperature ; this is especially the case with malic acid, whilst citric and tartaric acid yield but a slight reaction even when the mixture is heated, Other acids containing a hydroxyl group or groups give the coloration, as do also the higher alcohols, certain carbohydrates, etc.W. P. S. Differentiation between Natural and Petroleum-Residue Asphalts. J. Marcusson. (Chem. Zeit., 1912, 36, 801-803.)-As an approximate means for diiferentiating between natural and petroleum-residue asphalts, the proportion and nature of the oily constituents afford a guide, but is not in itself a conclusive test.If an asphalt on distillation yields over 34 per cent. of oil of a thick, ointment-like consistence, it is probably a petroleum residue ; the oily matters from natural asphalt are relatively thin, but it must be borne in mind that many petroleum residues yield less than 34 per cent. of oil.Further, if the oil contains over 2 per cent. of paraffin- wax, the presence of petroleum residues is very probable, but certain petroleum residues yield oils poor in paraffin-e.g., from Roumanian petroleum 3.1 to 3.6 per cent. and from Californian 2.2 to 2.9 per cent. Further methods of differentiation have been investigated by the author.For instance, natural asphalts, on distillation, yield distillates with a comparatively high acid value. A quantity of the sample representing 30 grms. of bitumen is distilled in a small retort and two fra&ions of 4 to 5 C.C. each are collected. These are dissolved in ether and shaken with water to remove any mineral acid.Neutral alcohol is then added and the acid value of both fractions determined, using alkali-blue as indicator. In the case of natural asphalt the acid value of the first fraction is over 1, and the second fraction still shows a distinct acid value, whereas the acidity of the distillates from petroleum residues is very small, generally niZ in the second fraction. The separation of solid408 ABSTRACTS OF CHEMICAL PAPERS paraffin from the distillates is also an indication of petroleum residues.A further criterion is the saponification value of the bitumen soluble in benzene : 5 grms. of the soluble bitumen are dissolved in 25 C.O. of benzene free from thiophene and boiled for an hour with 25 C.C. of $-alcoholic potassium hydroxide, cooled, diluted with 200 C.C.of alcohol and titrated with repeated heating until all the alkali is extracted from the precipitate of pitch. Natural asphalts show saponification values of 28.5 to 34 for the extracted bitumen ; petroleum residues show values from 7.6 to 13.5. J. F. B. Bromine and Iodine Methods for the Volumetrie Estimation of Cresol. C. M. Pence. (J. Ind. and Eng. Chem., 1912, 4, 518-520.)-The usual bromine methods for the estimation of cresol depend upon fixed conditions (cf.ANALYST, 1900, 25, 78), and whilst they may be of service they do not satisfy the demand for a suitable method. Tribrorno-o- and p-cresol bromides cannot be formed in a manner analogous to the production of tribromophenol bromide (cf. ANALYST, 1910, 35, 218) ; dibromocresol bromide compounds are formed and finally tribromo- phenol bromide, but o- and p-cresols cannot be estimated volumetrically by con- version into these compounds.m-cresol may be estimated by conversion into tribromo-m-cresol ; if the m-cresol solution is in contact with bromine for 1.5 hours and potassium iodide is then added and the mixture allowed to stand for two hours, all the cresol is converted into tribromo-m-cresol.0- and p-cresols form di-iodo compounds, and this reaction is made the basis of a method for their estimation. Five grms. of the cresol are dissolved in water, 10 C.C. of sodium hydroxide solution being added to aid in the solution, and the mixture is diluted to 1 litre. Twenty-five C.C. of this solution are treated with 9 grms. of sodium acetate and 50 C.C.of TG iodine solution. After the lapse of one hour, 100 C.C. of water are added and a few C.C. of chloroform to dissolve the precipitated di-iodocresol, and the excess of iodine is titrated with thiosulphate solution. As m-cresol does not yield di-iodo compounds under the same conditions, a mixture containing this cresol cannot be analysed by a volumetric iodine method.w. P. s. Compounds of Ferric Salts with Albumoses. F. Rohmann and T. Shmamine. (Biochem. Zeitsch., 1912, 42, 250-254.)-When an aqueous solution of Witte’s peptone is treated with either ferric chloride or ferric sulphate, a pre- cipitate containing primary albumoses is obtained, which may be collected on a filter and washed without difficulty. I t contains sulphuric acid in addition to iron, when ferric sulphate is used, but the ratio of Fe : SO, is greater than in the precipitant.When the precipitate is suspended in water and an alkali is added cautiously, complete solution is obtained, but on the addition of an excess of alkali ferric hydroxide is precipitated and the albummes remain in solution. If barium hydroxide be used as the alkali, the sulphuric acid is also precipitated.After removing the excess of barium hydroxide by means of carbon dioxide, the barium-albumose compound may be decomposed with dilute sulphuric acid ; a portion of the albumoses remains in solution whilst the remainder separates out together with the barium sulphate. The insoluble portion is soluble both in alkali solutions and in very diluteW A N I C ANALYSIS 409 sulphuric acid.This behaviour of the albumoses recovered from the iron precipitate indicates the presence of a mixture of proto- and hetero-alburnose. w. P. s. Estimation of Lactic Acid and P-Hydroxybutyrie Acid in Mixtures of the Same. J. Mondschein. (Biochem. Zeitsch., 1912, 42, 91-104.)-When lactic acid in 1 per cent. sulphuric acid is heated to boiling and & potassium permanganate solution is added drop by drop, the lactic acid is converted quantitatively into acetaldehyde, carbon dioxide, and water, according to the equation : CH, CHOH.COOH + 0 = CH,.CHO + CO, + H,O.On the other hand, P-hydroxybutyric acid in 4 per cent. sulphuric acid solution is converted into acetone, carbon dioxide, and water, by adding to the boiling solution a 0-5 per cent.potassium bichromate solution; in this case the reaction proceeds according to the equation : CHrCHOH.CH2.COOH+ 0 = CH,.CO.CH,.COOH + H20 = CHrC0.CH3 + CO,+ H20, the acetoacetic acid being an intermediate product. Should both lactic acid and p- hydroxybutyric acid be present together in a solution, the former yields a small quantity of aldehyde when the mixture is oxidised with bichromate, and the latter acid a small quantity of acetone during the permanganate oxidation, the conditions necessary for the complete oxidation of one acid not being suitable for the complete decomposition of the other.The two acids may, however, be estimated separately by a combination of these methods,‘ the oxidations being carried out in an apparatus described previously by von Furth and Charnass (ANALYST, 1910,35,445).A definite volume of the solution containing the two acids is oxidised with permanganate as described (Zoc. cit.), and the distillate obtained, measuring 400 c. c., is divided into two equal portions, and the total aldehydic content is estimated in one portion by means of potassium bisulphite as described by Ritter (ANALYST, 1901, 26, 131).The other portion of the distillate is then boiled under a reflux condenser after the addition of hydrogen peroxide and sodium hydroxide in order to destroy the aldehyde. The mixture is now distilled, and the distillate again examined by Ritter’s method. The difference between the results of the two estimations corresponds with the amount of aldehyde present, from which the lactic acid may be calculated.Another portion of the original solution is then oxidised with potassium bichromate, and distilled. The distillate in this case contains the whole of the acetone derived from the P-hydroxybutyric acid together with a quantity of aldehyde from the lactic acid. After this aldehyde has been destroyed by boiling the solution with sodium hydroxide and hydrogen peroxide under a reflux condenser, the solution is again distilled and the acetone estimated in the disfillate by Messinger’s iodoform method (cf.ANALYST, 1908, 33, 98). Experiments with solutions containing known quantities (about 0.2 grm. each) of the two acids show that the method is trust- worthy, 99.2 per cent. of the amount lactic acid, and 97.8 per cent.of the P-hydroxy- butyric acid actually present being obtained. w. P. s.410 ABSTRACTS OF CHEMICAL PAPERS Method of Examining Chinese Wood Oil. P. C. McIlhiney. (J. Ind. and Eng. Chem., 1912, 4, 497-498.)-The following method of estimating the proportion of this oil which is solidified when treated with iodine is proposed in the hope that the estimation may be of value in distinguishing between genuine oils and those which have been adulterated with other oils.The author refrains from giving any figures at present, as he has not been able to obtain authenticated specimens of Chinese wood oil, and has only applied the method to commercial samples. Broadly speaking, Chinese wood oil yields only a small fraction of liquid oil when subjected t o the process, whilst other oils remain entirely liquid and soluble in petroleum spirit. The details of the method are as follows : Five grms.of the oil are heated with 10 C.C. of 99.5 per cent. acetic mid until a clear solution is obtained, and 50 C.C. of a 1.5 per cent. iodine solution in 99.5 per cent. acetic acid are added. This iodine solution should be warmed so that it does not cool the oil solution.After the lspse of thirty minutes, 50 C.C. of petroleum spirit are added, mixed thoroughly with the mass, and then decanted into s separating funnel; the extraction with petroleum spirit is twice repeated, and the united extracts are washed with water until free from acid, then with potassium iodide solution to remove free iodine, and finally with water.The petroleum spirit is next evaporated and the residue weighed in order to obtain the portion of the oil which is not solidified by the action of iodine. w. P. s. Heat Test for Chinese Wood Oil. F. Browne. (Chem. News, 1912, 106, 14-15.)-The author advocates a standardised form of apparatus and method of working for the observation of the time required to produce g ' setting " or jelly forma- tion on heating the oil to 540' to 560' F.The addition of 10 per cent. of other vegetable, or of mineral, oils causes an appreciable lengthening of the time required, which for 5 C.C. of a, genuine wood oil is about eleven to twelve and a half minutes under the stated conditions of the experiments. If the time required is thirteen minutes or more, the author employs the iodine and chloroform test (ANALYST, 1898, 23, 43).The following range of constants is given: Sp. gr. at 15.5" C., 019402 to 0.9431; saponification number, 191 to 194; iodine number (Wijs), 173 to 174. A. R. T. Genuine oils u set" in from forty to fifty-five seconds. Refractive Index of Chinese Wood Oil. L. E. Wise. (J. ITzd. and Eng. Chem., 1912, 4, 497-498.)-The refractive indices of fifteen samples of commercial Chinese mood oil were found to lie between 1.5099 and 1.5186, the values being determined at a temperature of 25" C.Gross adulteration of the oil with other drying oils can be detected readily by means of the refractometer as the refractive index is lowered. w. P. s. Effeet of Free Fatty Acid on Specific Gravity of Some Fatty Oils.A. 0. Ransome. (J. SOC. Chem. Ind., 1912,31, 672.)-The author's results support the statement of Allen (" Commercial Organic Analysis," 11,, part i., pp. 126-127) that in the case of olive oil the presence of free fatty acids lowers the sp. gr. Each 5 per cent. of free acid was found by the author to diminish the gravity byORGANIC ANALYSIS 411 Neutral Sp. Gr. 0*00082, Allen's figure being L L about 0.0007." From a consideration of the results of other observers, the author shows that the sp.gr. of the fatty acids of various oils is invariably lower than that of the oil itself, the differences being from 0.0037 to 0.0258. It is further shown that the iodine number of Menhaden oil is increased by the presence of free fatty acids, and it is assumed that many or all constants of an oil will vary progressively with the proportion of free acids present.In the case of oils containing a sufficient quantity of free acids to vitiate the constants, it is thus considered desirable to isolate the fatty acids and make the analysis on them instead of on the original oil. The following figures may be quoted : Free Acid as Oleic, per Cent. ANALYSIS OF SIX AUTHENTIC SPECIMENS OF OLIVE OIL.- __ - __ 0.91800 0.91872 Malaga, No. 1 ... ... ,, No. 2 ... ... ,, No. 5 ... ... Calabria, fino ... ... ,, aino-verde ... ,, aino-giallo ... 2.24 2.79 3.22 1-38 25.87 36.38 Sp. Gr., 15.5" C. 0.91572 0.91554 0.91528 0.91654 0.91374 0.91280 Decrease due t o 5 per Cent. Free Acid. - - - - 0*000820 0.000825 ANALYSIS OF A SAMPLE OF MENHADEN OIL CONTAINING 4-03 PER CENT.GLYCEROL** Sp. gr. at 15.5" C. ... Iodine value (Wijs) ... Free fatty acids, per cent. Acid value ... ... Saponification value . . . (.== oleic) . . . ... Sample. 0.9257 185.27 47.99 - - Glycerides. 0.9309 180.39 0.22 - 192.9 Acid. 1 Corrected Acids. _I I 0-9161 192.02 - 187.42 200.80 0.9149 192.9 Three Menhaden oils showed a decrease of sp. gr., for each 5 per cent.of free fatty acid, of 0*00054, 0*00084, and 0*00063. A. R. T. Glyeerides Occurring in Fats and Oils: Heptadecoic Acid and its Glyceride. A. Bomer and R. Limprieh. (Zeitsch. Untersuch. Nahr. Gewssm., 1912, 23, 641-653.)-Considerable doubt having arisen as to the actual presence of a glyceride of heptadecoic acid in fats and oils (cf. ANALYST, 1904, 29, 259; 1905, 30, * The acids contained about 7 per cent.of glyceride calculated on the difference between the neutralisation and saponification values. The figures for acids were corrected on this basis.412 ABSTRACTS OF CHEMICAL PAPERB 212), the authors have prepared this acid and its glyceride synthetically for the pur- pose of comparison with the acid isolated from fats and oils ; the results of this com- parison mill be published later, the present paper dealing with the preparation and properties of the acid.Krafft's method (Ber., 1879, 12, 1668) was used for this purpose; it consists in distilling a mixture of barium stearate and barium acetate under reduced pressure, separating the resulting ketones by fractional solution in alcohol, oxidising the heptadecyl ketone with bichromate and sulphuric acid, and crystallising the heptadecoic acid repeatedly from alcohol.The pure acid obtained melted at 60.5" C., and boiled, in an absolute vacuum, at 143.6" C. One hundred C.C. of absolute alcohol dissolve 1.15 grms. of the acid at 0" C., and 3.48 grms. at 15" C. The zinc salt is practically insoluble in cold alcohol. The triglyceride of the acid was prepared by heating the potassium soap for two hours with the theoretical quantity of tribromhydrin, extracting the mass with ether and evaporating the ethereal solution ; the residue obtained was dissolved in benzene, and the glyoeride precipitated by the addition of alcohol.After crystallisation from ether it yielded masses of needle-shaped crystals which melted at 62.7" C.One hundred C.C. of anhydrous ether dissolve 0.0288 grm. of the glyceride at 0" C., and 0.322 grm. at 15' C. w. P, s. New Oxygen Absorption Method for Oils. L. P. Wilson and G. S. Heaven. (J. SOC. Chem. Ind., 1912, 31, 565-568.)-About 0.2 grm. of the oil is mixed in a flask with 1 grm. of kieselguhr, and, after the flask has been cooled to a definite temperature, a side-tube provided on the neck of the flask is sealed. The flask is now heated to 100" C.for one hour, again cooled, and the side-tube is con- nected with graduated levelling tubes filled with water; the height of the water is noted and the seal is broken, the resulting difference in the water-level (after the water surfaces have been brought to the same level) being a, measure of the amount of oxygen absorbed by the oil.The volume of oxygen absorbed is then calculated into a percentage quantity on the oil. The side-tube of the flask may be provided with a bulb to prevent water entering the flask. The following percentage amounts of oxygen were absorbed by various oils examined : Linseed oil, 17.2 to 21-2 ; poppy- seed oil, 17.4 ; cottonseed oil, 11.1 ; sesame oil, 5.8 ; olive oil, none.w. P. s. Notes on Serger's Reaction for Vegetable Oils. Utz. (Chem. Rev. Fett.- 21. Harx.-Ind., 1912, 19, 128-131; 151-153.)-Serger has suggested the use of a solution of 0.1 grm. of sodium molybdate in 10 C.C. of strong sulphuric acid as a means of distinguishing between vegetable and animal oils, the former when dissolved in ether giving colorations varying from yellow to blue or green, whilst in the case of the latter no colorations are produced in less than thirty to forty-five minutes.Comparative tests here described show that the reaction is slower and no more sensitive than Bellier's test, whilst treatment of the oils with bleaching agents such as benzoyl peroxide ("lucidol") or the action of heat prevent the appearance of the colorations.Oils giving only faint reactions in this test may be mixed with lard without risk of detection by Serger's test, and the phytosterol test is then the only method of proving the addition of vegetable oils. C. A. M.ORGANIC ANALYSIS 413 Comparison of Methods for Determining the Viscosity of Pitch. €3. Weinberg and H. Smirnow. (J. Russ. Phys.-Chem. Soc., 1912, 44,3; through Chem.Zentralbl., 1912, II., 4.)-The investigation was confined to methods in which the motion reaches a limit, and in which alteration of form, but not of volume, takes place (cf. Weinberg, J. Russ. Phys.-Chern. Soc., 1907, 38, 202). The torsion method, the Legel method, and the strata-displacement method, were particularly examined. The torsion method is the best for substances having viscosities of the order of 108 --&--* it may be used for substances from 10'3 to 1O1O, but the external friction of the apparatus must be accurately determined.The Legel method possesses the advantage of direct transmission of the force to the examined substance, but secondary phenomena must again be taken into account. The third method has a low degree of accuracy, and for substances of viscosity below lOQ requires the appli- cation of the law of Archimedes; this applies also to the first method when the cm.sec. ' viscosity is below 1010 L- cm. sec. 0. E. M. Separation and Estimation of Pyridine and Ammonia. A. Bayer. J. f. Gasbeleuehtung, 1912, 55, 513-514 ; through Chm. Zentralbl., 1912, II., 281.) -In the titration of pyridine and ammonia, ferric thiocyanate is a better indicator than methyl orange or ferric chloride.The solution of pyridine or ammonia is acidified with & hydrochloric acid, ferric chloride and ammonium thiocyanate are added, and then & caustic alkali, until the red-brown liquid becomes quite colour- less. For the estimation of pyridine in presence of ammonia, the pyridine is first concentrated by distilling the solution after the addition of sulphuric acid until it is almost neutral to litmus.The whole of the pyridine, with very little ammonia, passes over with the first third of the distillate. The ammonia, is titrated with +$, hydrochloric acid, using litmus as indicator, excess of acid is then added, and the pyridine estimated in the manner already described.Where the utmost accuracy is desired, the ammonia is best eliminated as ammonium magnesium phosphate. G. C. J. Detection of Pyridine Bases in Ammonia and Ammonium Salts. A. Wohlk. Ber. deutsch. pharm. Ges., 1912, 22, 285-288 ; through Chem. Zentralbl., 1912, II., 286-287.)-1f an ammonium salt containing pyridine bases be triturated in a mortar with twice its bulk of borax, the impurity may be detected by its odour, which is pronounced if so little as 0.4 mgrm.be present. For the examination of liquid ammonia, the latter is mixed with a small excess of acid and evaporated to dryness on the water-bath, the dry residue being used for the test. Ammonium salts can be freed from pyridine by dissolving them in water and leading a current of pure ammonia gas through the solution.G. C. J. A Critical Study of Sugar Analysis by Copper Reduction Methods. A. W. Peters. (J. Amer. Chem. SOC., 1912,34,928-954.)-The investigation described by the author arose from the need for a rapid and accurate method of determining414 ABSTXACTS OF CHEMICAL PAPERS sugar in urine, and led to his standardising a volumetric method applicable to any sugar.No new principle is involved, the experimental work recorded mainly dealing with the effect produced by variations in the rate of heating the alkaline copper solution with sugar. To an aliquot portion of the residual copper solution after filtration sulphuric acid and excess of potassium iodide are added, and the liberated iodine titrated against thiosulphate. This '6 residual " method the author considers very rapid and accurate. An examination in detail is described of the rate of reduction with pure dextrose under varying conditions of time and heating, and curves are given showing the percentage of the total sugar reduced for each interval of time at different temperatures.It is important to employ a mechanical heating device to insure uniformity in this connection, and the standard heating power arbitrarily selected was such as to produce a rise from 36' to 90" C.in 120 seconds, when acting on 60 C.C. of distilled water. The duration of heating was always calculated from the moment the temperature of 90" C. was reached,-and was fixed at exactly 20 seconds. Reasons are given and figures quoted supporting the contention that this is the best length of time for the reduction process, the much longer period usually taken being without justification.The total volume of the solution employed is 60 c.c., 20 C.C. of '' Fehling-Soxhlet " copper sulphate solution, 20 C.C. of '' Allihn alkaline tartrate solution," containing 346 grms. of Rochelle salt and 250 grms. caustic potash per litre, and 20 C.C. of sugar solution. The heating is conducted in an Erlenmeyer flask, closed with a doubly-bored stopper, a thermometer passing through one of the holes, the other being left free for the escape of steam The flask stands on an asbestos plate, which must be 3 to 5 cm. away from the burner. At the end of the 20 seconds' heating, the whole is cooled for a, few seconds under the tap to just below the boiling-point, and then filtered through a Gooch crucible packed very heavily with two layers of asbestos containing pure talcum powder between them. The total volume of filtrate, including washings, must not exceed 75 to 80 C.C. ; and the thiosulphate finally employed should have a value between 12.5 and 13 mgrms. of copper per C.C. The dextrose-copper ratio so obtained falls from 0.833, when 1 mgrm. of dextrose is employed, to 0.522 for 25 mgrms. dextrose, at which point it remains constant till 110 mgrms. of dextrose is reached, when it rises to 0.572 at 200 mgrms. dextrose. From 1 to 10 C.C. of urine may be employed, 2 C.C. being usually taken in the case of urine from diabetic subjects. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9123700407

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

414 ABSTXACTS OF CHEMICAL PAPERS INORGANIC ANALYSIS. Separation of Arsenic from Antimony and Other Metals by Means of Methyl Alcohol in a Current of Air. L. Moser and F. Perjatel. (Monatsh., 1912, 33, 797-820.)-The authors have worked out a method for the estimation of arsenic by distillation in presence of methyl alcohol and strong hydrochloric acid with a current of air at the temperature of the water-bath (cf.Friedheim and Michaelis, Ber., 1895, 28, 1414; S. W. Collins, ANALYST, 1912, 229). A portion of the arsenic distils as the trichloride, and a portion as methyl arsenite, which is immediately hydrolysed by the water in the receiver. If the arsenic is present in theINORGANIC ANALYSIS 415 pentavalent form, it must be reduced before distillation, preferably by means of a ferrous salt.The methyl alcohol has no reducing action under the conditions adopted. The usual method of oxidising the arsenious acid, in preparing ores for analysis, by potaesium chlorate and hydrochloric acid is unsatisfactory, and leads to a loss of arsenic ; but oxidation by means of chlorine in alkaline solution is complete. Arsenic acid is not volatilised with hydrochloric acid.The general arrangement of the apparatus used for distillation is similar to that described by Thaddeeff for the estimation of boric acid with methyl alcohol. I t consists of a wide-necked Aask, with rubber stopper having three holes. Through one passes a tube for the intro- duction of air, extending to some height ; through the other a dropping funnel; and through the third a simple bulb distillation-head, To this is joined a tube 60 cm.long, bent at one end, and dipping to the bottom of a beaker cooled by water. The flask is immersed in a water-bath; the current of air is regulated by a screw-clip, and passes through drying towers. About 200 C.C. of water are placed in the beaker. For the separation of arsenic from antimony, etc., the quantity of arsenious acid taken must not exceed 0.22 grm.If the substance has to undergo a preliminary treatment, this may be carried out in the flask, and any residues of nitric acid or water must be removed ; small quantities of sulphuric acid are immaterial. In the case of penta- valent arsenic, 5 to 8 grms. of ferrous sulphate are added; then 40 to 50 C.C. of hydrochloric acid, sp.gr. 1.19, and the contents of the flask are brought to the boil in the water-bath, and kept at the boil for five to ten minutes. By that time the reduction of the arsenic acid is complete, and the first addition of 30 C.C. of methyl alcohol is made, air being passed through for a few seconds to prevent the sucking back of water in the beaker. The liquid is then boiled for a quarter of an hour with- out the air-current, and for half an hour with a vigorous current.Next, a further 20 C.C. of methyl alcohol are added, and boiled for a quarter of an hour ; the same operation is repeated, and the liquid boiled for another quarter of an hour. The total time of boiling is one and a half hours, of which one hour is with the air-current. The separation of the arsenic is complete, and this element is estimated in the distillate either gravimetrically or volumetrically by iodine or permanganate.Th antimony and other metals are estimated in the residue ; the method is not applicable for the separation of arsenic from mercury, since the latter ia also volatile as chloride. J. F. B. Estimation of Arsenic. E, Rupp and F. Lehmann.(Arch. Pharm., 1912, 250, 382-389.)-The following method has been devised more especially for the rapid estimation of arsenic from salvarsan in animal tissue. I t depends upon the destruction of the organic matter by means of potassium permanganate or persulphate and sulphuric acid, and the distillation of the arsenic as trichloride in a current of hydrochloric acid gas evolved from the solution itself.From 5 to 20 grms. of divided moist material are intimately mixed with 10 grms. of powdered potassium permanganate (or persulphate) and 10 C.C. of dilute sulphuric acid, and the mixture heated for fifteen minutes, with continual stirring, on the water-bath, after which it is gradually treated with 25 C.C. of concentrated sulphuric acid, followed by 30 C.C.of hydrogen peroxide solution. As soon as frothing has stopped, the liquid is transferred416 ABSTRACTS OF CHEMICAL PAPERS to a Kjeldahl flask, into which is also introduced 5 grms. of anhydrous (or 10 grms of crystalline) ferrous sulphate to reduce the arsenic acid, and 50 grms. of sodium chloride, the flask then connected with a receiver containing 40 grms. of sodium bicar- bonate and 100 C.C.of water, and heated on a sand-bath. The receiver is frequently shaken, and as soon as the whole of the bicarbonate has dissolved the distillation is stopped, and the distillate cooled, rendered alkaline, if necessary, with sodium bicarbonate, filtered, and titrated with standard iodine solution, 0.05 C.C. of & solution being deducted as a correction. C .A. M. Electrometrie Determination of the Reaction of Liquids containing Carbon Dioxide. K. A. Hasselbalch. (Compt.-rend. des Travaux du Lab. de Carlsberg, 1911, 10, 69-84.)-The exact electrometric determination of the re- action of liquids containing carbon dioxide is rendered difficult by the tendency of the solution to part with some of its dissolved gas, and become appreciably more alkaline before the de- termination can be completed.Michaelis and Rona (Biochem. Zeitsch., 1909, 18, 317) have proposed to obviate this difliculty by superimposing an atmo- sphere of hydrogen above the liquid, and by preventing the electrode from dipping in the liquid any more than is necessary to make contact. Their method has advantages, but does not give exact results, and it is now shown that an atmosphere of hydro- gen does not prevent lose of carbon di- oxide, and that the increased accuracy of their results compared with those of earlier workers is entirely due to the electrode not being submerged in the liqlsid. The author has adopted this principle of slight immersion of the electrode, and has evolved a method which makes it possible to obtain exact results in a very short time (half an hour).The method depends on putting some of the solution in equilibrium with hydrogen in an appropriate apparatus, and then, since the liquid has lost carbon dioxide in the process, replacing it by a fresh portion of liquid, and proceeding to the electrometric measurement. The illustration shows a convenient form of apparatus. The electrode is seen just touching the surface of the liquid, which half fills a vessel of about 15 C.C.capacity. A current of hydrogen is passed through the empty vessel for half an hour to saturate the hydrogen electrode at the prevailing barometric pressure. The liquid is then introduced through the funnel and pinchcock, and the apparatus rocked from the vertical to a horizontal position I]INORGANIC ANALYSIS 417 and back again some 200 times.Blood may require nearly three times as much agitation. The liquid, which has lost carbon dioxide, is now run out of the apparatus and replaced by a fresh portion, and the E.M.F. determined in the usual manner. G. C. J. Estimation of Arsenious Acid with Permanganate in Presence of Hydrochloric Acid. L. Moser and F, Perjatel, (Monatsh., 1912, 33, 751-758.) -The titration of arsenious acid by permanganate in acid solution sometimes presents difficulties, owing to the fact that reduction to the manganous stage is only complete and rapid under certain conditions.If the permanganate be added too quickly to a too concentrated solution of arsenic, yellow to brown colorations, due to the intermediate stages of reduction of the manganese, occur, and the titration is spoilt; the concentration of free acid is also an important factor.The authors have worked out the following generally satisfactory method: 0.1 to 0.3 grm. of arsenious acid is dissolved in not very concentrated caustic soda lye, containing about 1 grm. of solid sodium hydroxide, in a porcelain dish, and the solution is diluted with 100 to 200 C.C.of water. The liquid is acidified by the addition of 10 to 15 C.C. of hydrochloric acid, sp. gr. 1.19, per 1 grm. of sodium hydroxide used. Permanganate is then added drop by drop in the cold with continuous stirring. Under these conditions no brown coloration ensues, and the end-point is sharply recognisable by a pink colour lasting for two to three minutes.The volume of the arsenious chloride solution should be between 50 and 200 C.C. If the solution to be tested is already acid, it is advisable to neutralise it first exactly with sodium hydroxide, and then to add 5 to 10 C.C. of concentrated hydrochloric acid. If a yellow coloration develops on titration, the addition of the permanganate has been too rapid. The results are accurate.J. F. €3. Reaction of Hydrazine and Hydroxylamine with Ferricyanides, and New P. R. Rky and (Zeitsch. amrg. Chem., 1912, 76, 380-386.)-Hydrazine and potassium Methods for Estimating Hydrazine and Ferricyanides. H. K. Sen. ferricyanide in alkaline solution react as follows : N,H, + 4K,Fe(CN), + 4KOH = N, + 4K4Fe(CN), + 4H20. In presence of excess of alkali, the reaction is quantitative until either the whole of the hydrszine or the whole of the ferricyanide has disappeared.The reaction proceeds rapidly at room-temperatures, and is unaccompanied by any secondary reaotions. I t therefore affords a basis for the estimation of hydrazine or ferricyanide. For the estimation of hydrazine, the substance for analysis is weighed out from a weighing bottle into the cup of a Crum’s nitrometer, and washed into the latter by means of a little water and 4 to 5 C.C.of 15 per cent. caustic potash. A solution of the substance may be used, since considerable dilution has no influence on the course of the reaction; but the presence of a deep aqueous layer above the mercury in the nitrometer reduces the space available for gas, and the larger the gas volume, the less the percentage error of the method.A large crystal (an excess) of potassium ferricysnide is introduced by the open end of the nitrometer, which is418 ABSTRACTS OF CHEMICAL PAPERS immersed in the mercury bath, and the tube is shaken to hasten the reaction, which is complete in three or four minutes. Since Stolle’s iodine method (J. Pralct.Chem., 1902, 66, 332) for the mtimation of hydrazine leaves nothing to be desired, the new method is recommended rather for the estimation of ferricyanide, especially in presence of ferrocyanide. In this appli- cation, a ‘‘ pill ” of hydrazine sulphate (an excess) is introduced into the nitrometer from below, and the ferricganide is weighed out into the cup of the nitrometer, covered with water, and drawn in.Caustic potash solution is then added through the cup, and the analysis completed as before. The accuracy of the method is limited only by the accuracy with which the gas volume can be read. The test numbers show that the authors make no attempt to read this volume more closely than 0.05 c.c., and their greatest error corresponds exactly to a misreading of the gas volume of 0.05 C.C. The excess of hydrezine always present in ferricyanide determinations keeps the mercury clean, but mercury which has been exposed to excess of ferricyanide in hydrazine determinations needs purification with dilute nitric acid before being used for other purposes.Phenyl-hydrazine reacts with ferricyanide similarly to hydrazine, but hydroxyl- amine gives rise to a mixture of nitrogen, ammonia, and nitrous oxide, the proportions of which depend on the exact conditions under which the reaction is brought about.G. C. J. Determination of Iodine in the Presence of Other Halogens and Organic Matter. E. C. Kendall. (J. Arner. Chem. SOC., 1912, 34, 894-909.)-For the determination of iodine, when present as a soluble iodide or in the uncombined form, the author employs a modification of Hunter’s method (ANALYST, 1910, 35, 483), in which about 200 C.C. of the cold neutral or slightly alkaline solution, containing the iodine to be estimated, is treated slowly with sodium hypochlorite in slight excess in the presence of 5 C.C.of 42 per cent. phosphoric acid. Any iodine present is oxidised to iodic acid. To prevent loss of iodine, if more than 0.1 grm.is present, a few C.C. of benzene are floated on the surface of the liquid. Ten C.C. of a colourless 5 per cent. solution of phenol are then rapidly and forcibly blown into the flask. This removes all traces of chlorine without the formation of coloured compounds. The whole is now made just alkaline with 30 per cent. sodium hydroxide, and then acidified by the addition of 10 C.C.of 50 per cent. phosphoric acid. Potassium iodide is next added in excess, about eight times the weight of the iodine originally present being required ; and the liberated iodine, of which one- sixth part is that originally present, is titrated with thiosulphate. Working with quantities of iodine lying between 5 and 350 mgrms., over fifty results are recorded, showing a maximum error of -0-76 per cent., a minimum error of + 0.02 per cent., and an average error of about f0-1 per cent.Bromine or bromides, if present, do not interfere, and there is no oxidation of the bromine. Hydrobromic acid, when present in large amount, will reduce iodic acid, but all the former may be removed by the addition of sufficient hypochlorite.The procedure is that already described, except that 10 C.C. of benzene are added, sufficient hypochlorite being used to liberate all the bromine and oxidise the iodine.INORGANIC ANALYSIS 41 9 A little pumice is added, and the solution is boiled. The benzene reacts with the hypobromite and hypochlorite, forming bromo- and chloro-benzene. The free bromine is boiled out of the solution.A precipitate of bromo-benzene may form, but does not interfere. When colourless, the solution is cooled, and potassium iodide is added directly, no neutralisation and acidification being necessary, The presence of chlorides has no effect, and there is no need to boil the solution. To remove organic matter, enough material to contain about 60 mgrms. of iodine is fused with special precautions, at a temperature below dull redness, in a nickel crucible, with 5 grms.of solid caustic soda. Potassium nitrate is finally added in small quantity, and the melt, which should be clear, is cooled and extracted with water. At this stage, silver, copper, iron, or mercury, if present, are removed, and the solution, which contains sodium hydroxide, carbonate, and iodide, potassium nitrite and nitrate, is acidified slowly with 10 C.C.of 50 per cent. sulphuric acid, after the addition of 2 C.C. of a 10 per cent. solution of sodium bisulphite, to prevent loss of iodine with the escaping carbonic acid, and a few C.C. of chloroform. The iodine, which is now present as hydriodic acid, is oxidised with hypochlorite to iodic acid, as already described, phenol and potassium iodide being added as before.If bromine is present, the modifications required in its presence mentioned above are introduced. The author was unable to modify Hunter's method (Zoc. cit.) satis- factorily for the estimation of iodine in such small quantities as those present in preparations of thyroid gland. A better method is the fusion treatment already described, but with numerous detailed modifications, gallic acid being added after the potassium nitrate to effect the reduction of the excess of nitrate and nitrite.Bromine is next added in slight excess, and then removed with sodium salicylate. When this method is employed with all the refinements described, as little as 0.005 mgrm. of iodine can be detected with certainty, 1 grm.of thyroid gland substance and 10 grms. of caustic soda being suitable amounts to employ for the preliminary fusion. Three commercial samples of thyroid gland preparation con- tained respectively 1.899, 1.950, and 1.716 mgrms. of iodine per grm. of material. H. F. E. H. Electrolytic Estimation of Manganese and its Separation from Iron. H. Golblum and H. Gunther.(Compt. rend., 1912, 155, 166-168.)-The presence of iron in a solution from which manganese is to be deposited as MnO, is a positive advantage, as the deposit is then much more adherent. In solutions containing iron and manganese, the latter may be deposited completely as MnO, as follows : The solution, which may conveniently contain 0.1 grm. of manganese and 10 grms. of ammonium oxalate in 100 c.c., is placed in a platinum Classen dish, which serves as an anode, the rotating cathode consisting of a smaller slotted dish suspended from the rotating device by a platiniridium rod of sufficient rigidity.The cathode is rotated at about 700 revolutions per minute, and a current of 2 amperes at 3 volts employed, the solution being maintained at 80" C. An hour suffices for the deposition of the whole of the manganese as MnOZ on the anode, and, under the above conditions, the deposit will contain not more than 0.5 mgrm.nor less than 0.9 mgrm. of iron. The exact correction corresponding to any particular conditions may be readily determined420 ABSTRACTS OF CHEMICAL PAPERS by solution of the weighed deposit and colorimetric determination of the iron.Lower current densities reduce the amount of iron deposited on the anode, but a, current of at least 0.5 ampere is necessary to make the deposition of manganese quantitative. Some iron, but comparatively little, is deposited on the cathode, which may be weighed, and the solution freed from manganese may then be electrolysed in other suitable apparatus for the estimation of the iron.G. C. J. Electrolytic Estimation of Molybdenum. Part I. A. Fischer and J. Weise. (Zeitsch. anal. Chem., 1912, 51, 537-550.)-The authors are unable to confirm the statement of Earner (ANALYST, 1903, 28, 328) and of Wherry and Smith (ibid., 1907, 32, 341) that molybdenum is deposited quantitatively from a molybdate solution as hydrated sesquioxide when following the directions of those authors.On the other hand, the quantitative deposition of molybdenum is found to be practicable under the following conditions : When speed is no object, or the com- plication of a, rotating anode is undesirable, the molybdate solution is acidified with 0.15 C.C. sulphuric acid, diluted to 120 C.C. in a platinum dish with matte surface, heated to an initial temperature of 75" C., and electrolysed for fourteen hours with a current of 0.02 to 0.03 ampere at 1.8 to 2 volts.The deposit is converted quanti- tatively into MOO, by heating for two hours in an electrically-heated furnace maintained at 400' C. For rapid work, hydrochloric acid must be substituted for sulphuric acid and, with from 0.05 to 0-2 grm. MOO, present, the amount of hydrochloric acid should not be much less than 0.2 c.c., nor more than 0.25 C.C.of concentrated acid (sp. gr. 1-19). If no more than 0-13 C.C. of acid be present, the deposit is not adherent, whilst high concentrations lead to incomplete deposition. With as much as 0.33 C.C. acid present, the results are always low but never more than 0-5 mgrm, low ; but two or three times this amount of acid gives rise to errors of from 10 to 50 per cent.A current of 3-5 to 4 amperes is employed, the voltage varying from 18 to 30 according to the temperature of the electrolyte and the speed at which the anode is rotated. Deposition is complete in less than twenty-five minutes. The deposit is transformed into MOO, in the manner already described. A current of 2.5 amperes gives equally good results, but thirty-five minutes are required for the deposition of 0.2 grm.The authors have been unable to get good results when working with larger quantities than correspond to 0.2 grm. MOO,, and they show that the error depends mainly, if not entirely, on the difficulty of oxidising large deposits quantitatively to MOO,. The success of this operation, even with small deposits, is shown to depend on precise regulation of the temperature.At temperatures much below 400" C., the conversion of Mo,O, to MOO, is never complete, whilst higher temperatures may result in loss by volatilisation. G. C. J. A convenient speed is 600 to 800 revolutions. Analysis of Platinum Alloys. H. Arnold. (Zeitsch. anal. Chem., 1912, 51, 550-554.)-The analysis of platinum alloys can be accomplished more quickly by the following method tihan by methods which depend on the separation of platinum as metal or as sulphide.The method depends on the separation of platinum as potassium plstinic chloride. The alloy (1 grm.) is dissolved in aqua regia, and theINORGANIC ANALYSIS 421 solution evaporated to dryness three times with hydrochloric acid.The soluble chlorides are taken up in 10 C.C. of hydrochloric acid (sp. gr. 1*12), 1 grm. of caustic potash dissolved in a little water is added and the solution evaporated to dryness on a not too vigorously boiling water-bath. The residue of silver chloride and potassium platinic chloride is washed four or five times by decantation with 50 C.C. of alcohol, and, the bulk of the precipitate is dried in the evaporating basin whilst the filter is ashed.The dried precipitate is next transferred to the crucible containing the ash, and the potassium platinic chloride decomposed by ignition in a current of hydrogen. The contents of the crucible are then transferred to a beaker and heated successively with dilute nitric acid and dilute ammonia. The platinum is filtered off, washed with hot dilute ammonia and then with hot water, and the filter ashed and the residue ignited, treated with hydr ofluoric acid to eliminate silica derived from glass vessels, re-ignited and weighed.In the filtrate from platinum, silver is precipitated -preferably as sulphide, since silver chloride is appreciably soluble in solutions of alkali chlorides-and is finally weighed as chloride.The alcoholic filtrate is evaporated to dryness, the residue moistened with dilute hydrochloric acid and the solution again evaporated. The residue is then taken up in 5 to 10 C.C. of hydrochloric acid (sp. gr. 1.1) transferred to a Rothe separator and iron removed by Rothe's ether process (Mitt. Kgl. Techrz. Versuchs- anstalt, 1892, 123). The iron is obtained in aqueous solution by shaking the com- bined ethereal extracts with water, and is determined in any convenient manner.The acid aqueous layers from the separator are united, warmed to expel dis- solved ether and taken down to fuming after addition of 0.5 c . ~ . of sulphuric acid. The cooled residue is taken up in dilute sulphuric acid, the solution made alkaline with ammonia and any trace of ferric hydroxide filtered off, re-dissolved, and its solution added to the main solution of ferric chloride separated by the ether process.The solution of copper and nickel freed from the last trace of iron is next acidified so that it contains about 5 per cent. of sulphuric acid, and copper is precipitated by passing hydrogen sulphide through the hot (80" C.) solution.The copper is finally obtained as oxide or as copper, and usually carries a weighable trace of nickel which is best determined by the dimethylglyoxime method. The copper may also be accompanied by a trace of platinum, but this never exceeds 0.5 mgrm. The filtrate from the copper sulphide is evaporated to small bulk, mixed with a saturated solution of ammonium sulphate and 50 C.C.of 25 per cent. ammonia and electrolysed for nickel, preferably using Frary's apparatus (Zeitsch. Electrochem., 1907,13,308). G. C. J. Estimation of Radium in Minerals and Rocks. E. Ebler. (Zeitsch. Eectro- chem., 1912,18, 532-535.)-This paper includes an illustration and fuller description of the apparatus already described by the author (ANALYST, 1912, 323).The parts of the apparatus from the platinum boat a to the ground connection f can be identi- fied by reference to the abstract of the earlier paper. The drying tube v is charged with sodium and not with phosphoric anhydride, which absorbs notable amounts of niton and sometimes gives off lower oxides of phosphorus which make the air a con- ductor. The use of the pump g to transfer the air and emanation to the vessel F, is422 ABSTRACTS OF CREMICAL PAPERS obvious from the drawing. Their further transference from h to Z is effected by means of the balance vessel m, the tubulure of which is connected to that of I by flexible tubing not shown in the drawing.The gas is left in I some minutes to allow time for the complete decomposition of any possible thorium emanation and is then transferred to the ionisation chamber n, where the measurement of the maximum Zum Eleklrorneier 9 saturation current is made after four hours.The ionisation chamber carries a mano- meter, 4, and rests on the ebonite supports ss, inside the metal casing r , which is earthed. The ionisation chamber itself consists of a double-walled brass vessel, the space between the walls being filled with tin. Its inner wall is galvanised with zinc.G. C. J. Study on the Acidity of Soils. A. Gregoire. (BUZZ. SOC. Chinz. de BeZg., 1912, 26, 336-342, 362375.)--The estimation of the acidity of a, soil is a necessary preliminary for gauging its requirements in lime. The acid constituents of the soil exist largely in a condition in which they are not readily extracted, and the author gives an account of the principal methods which have been proposed for%heir estima- tion, and discusses the interpretation of their results in relation to the necessity of liming.H e further proposes a method for the estimation of acidity based on the liberation of iodine from a mixture of iodide and iodate as applied by Kjeldahl for the estimation of feeble organic acids.The reagent employed contains 55.3 grms. of potassium iodide, 14.3 grms. of potassium iodate, and 99.2 grms. of crystallised sodium thiosulphate, per litre. The solution of iodine employed for titrating back the excess of thiosulphate contains 17 grms. of iodine and 25 grms. of potassium iodide per litre, and the solutions are staadardised against each other by adding 20 C.C.of acid to the first, and titrating back with the iodine. The solution of iodide, iodate, and thio- mlphate is called Kjeldahl’s solution; it keeps very well. For the estimation, 10 grms. of soil, passed through a sieve with holes of 1 mm., are placed in a stop- pered flask with 15 C.C. of the Kjeldahl reagent. After a sufficient time, the volume is made up t o 105 c.c., the solution is filtered, and 100 C.C.are drawn off for titratingINORGANIC' ANALYSIS 423 back the thiosulphate. If the soil be digested with the diluted Kjeldahl solutioq the action is very much weaker than with the undiluted reagent. The action of the reagent upon the soil is not, instantaneous, but iodine continues to be liberated for a very considerable time, so that it seems difficult to arrive at a final point.The results obtained in several experiments with the same soil are, however, very regular, and it appears desirable to neglect the slow ulterior action of thereagent, possibly on certain mineral constituents of the soil, and to confine the observations to the iodine liberated by the more pronounced organic acids in a period of twenty-four hours.Experiments have shown that the temperature of the digestion within moderate limits has no influence on the results. Further tests have also shown that a large number of inorganic substances behave as acids towards the Kjeldahl reagent ; for instance, aluminium sulphate and chloride react with the whole of their acid, and in the case of ferrous ammonium sulphate about half of the sulphuric acid reacts, corre- sponding to that which is in combination with iron.J. F. B. Estimation of Total Manganese in Soils. R. A. Gortner and C. 0. Rost. (J. Ind. and Eng. Chem., 1912, 4, 522-524.)-As repeated treatment with hydro- fluoric acid and sulphuric acid is required in order to obtain in solution all the man- ganese present in soils, the author recommends the following method 8s being more rapid.One grm. of the soil is fused with 4 grms. of sodium carbonate, the melt is dissolved in 100 C.C. of water, acidified with 130 C.C. of 35 per cent. sulphuric acid, and diluted to a volume of 250 C.C. Should a precipitate of silica separate at this point it must be removed by filtration, but a slight opalescence does not interfere.One hundred C.C. of the solution are then treated with from 0.25 to 1 grm. of sodium bismuthate, and boiled until the manganese has been oxidised to permanganate. If there is any red coloration the boiling has not been continued long enough. The solution is now cooled, and the coloration compared against a standard perman- ganate solution which has been prepared by reducing a potassium permanganate solution (in 20 per cent.sulphuric acid) with sulphurous acid and reoxidising the mixture with sodium bismuthate. This standard solution should contain about 0.2 mgrm. of MnO per 10 C.C. Sodium bismuthate is preferred to ammonium per- sulphate as an oxidising agent as it gives a better oxidation, always giving the true permanganate tint whilst persulphate is liable to produce a reddish tint. w.P. s. Quantitative Estimation of Thorium, especially in Monazite Sand, by Means of Sodium Hypophosphate. A. Rosenheim. (Chem. Zeit., 1912,36,821.) -The sample (100 grms. in the case of a 5 per cent. monazite sand) is decomposed with concentrated sulphuric acid at 180' to 200" C. in the usual manner, the sulphate dissolved in cold water, and the solution made up to 1,000 C.C.When the undissolved matter has settled, 1OOc.c. of the clear solution is pipetted off and mixed with 50 C.C. of concentrated hydrochloric acid and about 180 C.C. of water, and heated to boiling. A cold saturated solution of sodium hypophosphate is then added as long as continued addition gives rise to any further precipitate, and the thorium hypophosphate is filtered off and washed with water acidified with hydrochloric acid until the wash-424 ABSTRACTS OF CHEMICAL PAPERS ings no longer give any precipitate (ceria, etc.) on addition of oxalic acid (or hydrogen peroxide! and ammonia.The precipitate of thorium hypophosphate always contains titanium, and zirconium if present in the sample, but onlytraces of cerium and other rare earths.Tetravalent cerium gives rise to a very insoluble hypophosphate, but the high acid concentration in which the above precipitation is made ensures the absence of tetravalent cerium. To free the thorium from titanium, zirconium, and traces of other earths, the precipitate and filter-paper are digested with sulphuric acid in capacious platinum basin or a Kjeldahl flask with occasional addition of a crystal of nitre to hasten the oxidation of the paper.The acid is mostly boiled away, and the cooled mass taken up with water. Since anhydrous thorium sulphate dissolves with difficulty, it economises time to make the solution faintly alkaline with ammonia. When the finely-divided suspension of anhydrous thorium sulphate has given place to a flocculent precipitate of hydroxide, the mixture is made strongly acid with hydrochloric acid, boiled, and the solution of thorium chloride filtered from any trace of silica.In the hot filtrate, thorium is precipitated as oxalate, which is filtered off after twelve hours and washed with dilute hydrochloric acid until free from the last traces of cerium, zirconium, and titanium.The precipitate is finally ignited, and weighed as oxide as usual. For purposes of works control, useful information may be obtained by igniting the original precipitate of Th(PO,), and weighing it as pyrophosphate, ThP,07. Apart from the fact that the hypophosphate precipitate is never pure, this abbreviated method has another source of inaccuracy in that the oxidation of hypophosphate to pyrophosphate is never quite complete.As a check on manufacturing operations, however, the method is useful. Sodium hypophosphate is not yet readily procurable, but it can be prepared by the method of Rosenheim and Pinsker (Ber., 1910, 43, 2003). It will shortly be obtainable in commerce, since a process for working up monazite sand on the large scale by its use has been described, G. C.J. Analysis of High-Grade Tungsten Alloys. T. Knezynski. (Anzeiger Akad. Wiss. Krakau., 1911, 542-544 ; through Chem. Zentralbl., 1912, II., 283.)- When the other constituents of the alloy form readily volatile chlorides, the alloy is conveniently opened up by heating in a current of chlorine. It need not be finely powdered. When the reaction is complete, and the tube in which it is conducted has cooled (in a current of chlorine), this tube and the Peligot tube are washed out successively with dilute hydrochloric acid and dilute ammonia. Excess of hydro- chloric acid and about 5 C.C.of nitric acid are added to the liquid, which is heated to boiling, concentrated to about 60 c.c., and then allowed to cool. The separated tungstic acid is filtered off and washed, and the filtrate evaporated to dryness, to throw out of solution the last traces of tungstic acid.The residue is heated to 120' C., to render insoluble the tungstic acid, which is moistened with dilute (1 : 5) hydrochloric acid, filtered off, and washed. The combined tungsten precipitates are redissolved in ammonia, separated from a trace of iron, and the solution evaporated to dryness.The tungstic acid is transferred to a quartz crucible by the use of a little ammonia, excess of nitric acid is added, the liquid evaporated, and the residueINORGANIC ANALYSIS 425 ignited and weighed as WO,. This method is especially useful when a determination of carbon has to be made simultaneously. If only metals have to be estimated, decomposition of the alloy by means of nitric and hydrofluoric acids is quicker.The fragments of alloy, contained in a platinum dish, are covered with 5 C.C. of nitric acid, and 0-5 grm. of ammonium fluoride is added in small pieces at a time. The reaction, violent at first, needs the heat of a water-bath to sustain it towards the end. To the clear solution 2 or 3 C.C. of sulphuric acid are added, and the solution taken down to fuming. The cooled residue is diluted with water and 20 C.C.of hydrochloric acid, and the tungsten separated as already described. G. C. J. Measurement of Concentration of Hydrogen Ions in Sea Water. S. Palitzsch. (Compt.-rend. des Travaux du Lab. de Carlsberg, 1911, 10, 85-98.) -The concentration of hydrogen ions in sea water usually lies between 10-7'95 and In a series of measurements made during a cruise from the Baltic to the Black Sea, the only exceptions to this generalisation were certain samples taken from great depths in the Black Sea, which contained hydrogen sulphide, but were still slightly more alkaline than pure water, the highest hydrion concentration noted being 10-7'25, a number for which a lesser degree of accuracy is claimed than for the others given in the paper.The method adopted was that of Sorensen (ANALYST, 1903, 34, 498), in which comparison is made with a series of standard solutions, using an appropriate indicator. For the narrow range of concentrations covered by this inquiry, only two of Sorensen's fundamental standards are needed-namely, & hydrochloric acid and a borate solution made by dissolving 0.2 gram-molecules (12.404 grma.) of boric acid in 100 C.C.of sodium hydroxide, free from carbonate, and diluting to 1,000 C.C. with boiled water. These two solutions are then mixed in varying proportions, to obtain a series of substandards. A mixture of 5.25 C.C. of the borate solution with 4-75 C.C. of the hydrochloric acid corresponds to a hydrion concentration of LO-7-62, whilst 8 C.C.of borate and 2 C.C. of acid correspond to 10-891. The paper includes a table showing the hydrion concentrations corresponding to many intermediate mixtures, together with the corrections to be applied for the influence on the indicator of the high saline concentration of sea water. For hydrion concentrations from 10-8.91 to 10-8'29, phenolphthalein is used as indicator ; for higher concentrations up to 10-7'62, a-naphtholphthalein is preferred, and is, indeed, necessary, when the concentration exceeds lO-*'OS, since water less alkaline than this is without influence on phenol- p ht halein.As a general rule the hydrion concentration increases with the depth from which the sea is sampled, A series of samples taken at one spot in the Atlantic showed concentrations varying from lO--S22 at the surface to 10-7'95 at 750 and 1,000 fathoms, and samples collected similarly in other seas yielded very similar results.G. C. J. Estimation of Zinc in Ferruginous Minerals. E. Beyne. (BUZZ. Soc. Chim. de Bely., 1912, 26, 355-361.)-The method generally used for the assay of zinc ores in industrial laboratories is that of Schaffner.The mineral is opened up with426 ABSTRACTS OF CHEMICAL PAPERS nitric acid and hydrochloric acid, the metals of the copper and arsenic group are re- moved by sulphuretted hydrogen, the filtrate is collected in a 500 C.C. flask, the excess of sulphuretted hydrogen is removed by boiling, and the iron is oxidised by nitric acid. On cooling, 100 C.C. of ammonia (sp. gr. 0.92) are added, and 5 C.C. of hydrogen peroxide if manganese be present. The whole is shaken and allowed to settle until the next day, when it is filtered. Meanwhile a control solution is prepared containing approximately the same amount of pure zinc, the same amount of acid and ammonia, as the solution to be analysed. The titration of the two liquids with sodium sulphide is then conducted simultaneously, until a drop of each produces the same effect upon a strip of lead paper. The principal source of error in this procedure is caused by the co-precipitation of an appreciable amount of zinc with the ferric hydroxide, in spite of the large excess of ammonia employed. The amount of the error increases with the amounts of the two metals present. Various means have been recommended to avoid this error, and the author finds that the simplest consists in adding a com- paratively large excess of ammonium chloride before precipitating the iron, a similar quantity of the salt being also added to the control solution. The actual quantity of ammonium chloride necessary has not yet been worked out for minerals containing various proportions of zinc and iron. The extent to which the error is eliminated under given conditions increases with the quantity of ammonium salt added. Thus, with a solution corresponding to 2.5 grms. of a mineral containing 40 per cent. of zinc and 20 per cent. of iron in 250 c.c., an addition of 35 to 40 grms. of ammonium chloride, before precipitating with ammonia and diluting to 500 c.c., gave the theoretical result in the titration for zinc. The addition of more than 40 grms. would begin to interfere with the sharpness of the end-point of the titration. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9123700414

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

426 ABSTRACTS OF CHEMICAL PAPERS APPARATUS, ETC. Porcelain Bunsen Burners. E. Beckmann. (Zeit. angew. Qhem., 1912,25, 1515-1518.)-Various forms of Bunsen burners with porcelain tubes are described and recommended for use in spectroscopic work. They may be obtained from Altmann, Luisenstrasse, 47, Berlin. C. A. M. Apparatus for the Detection of Carbon Monoxide. M. A. Guasco. (Compt. rend., 1912, 155, 282.)-Two bulbs, one of which is platinised, are carried at the extremities of a, vertical U-tube, and are enclosed in a gas-tight envelope, to which the gas to be examined is admitted through a porous septum.The portion of the U-tube outside the envelope contains a, coloured liquid, and is so arranged that very small differences of level, produced by differences in temperature of the bulbs due to occlusion of inflammable gases by the platinum, are readily observed.With the apparatus used, the difference in tbe levels in the two limbs produced by 1 volume of carbon monoxide per 1,000 was 13 mm., and by 2 in 1,000, 26 mm. The smallest quantity giving a distinct indication was 1 in 10,000. If mercury is substituted for the coloured liquid, the apparatus can readily be arranged to close a circuit, and thus release an alarm signal.0. E. M.APPARATUS, ETC. 427 Extraction Apparatus. H. J. Cary-Cum. (J. Ind. and Eng. Chem., 1912, 4, 535-536.)-The apparatus described is for the determination of the constituents of rubber insulation material on wire or cord, and consists of a conical flask 6 inches high, fitted with a metallic spiral tube condenser, passing through a metal plate which forms the cover of the flask, The sample is placed in the suspended Gooch crucible, at the base of which is a disc of filter-paper.The whole is placed on a hot plate or other convenient heater, and works without need of attention, the solvent condensing at the base of the coil and dripping directly into the crucible.The increase in the weight of the conical flask is the weight of matter extracted. H. F. E. H. Use of the Zeiss Interferometer in the Technical Analysis of Flue Gases. 0. Mohr. (Zeitsch. angew. Chem., 1912, 25, 1313-1317.)-Haber and Lowe (Zeitsch. anqeu?. Chem., 19L0, 23, 1393) have described a new interferometer by means of which Rayleigh’s principle may be applied to problems of technical gas analysis.They confined themselves, however, to relatively simple problems, such as the deter- mination of methane in mine air and the examination of technical hydrogen. The analysis of flue gases is complicated by the fact that they are not a mere mixture of carbon dioxide with air, nor are they air in which so much oxygen has been replaced by an equivalent amount of carbon dioxide.The sum of the percentages of oxygen and carbon dioxide is always less than the percentage of oxygen in normal air, mainly on account of the hydrogen in the fuel, and there is always the possibility that carbon monoxide may be present. The authors show, however, that the new method of analysis may be extended to flue gases. After being dried by means of sulphuric acid, the gas is passed through the interferometer chamber and a reading taken.I t is then passed through a soda-lime tube to deprive it of carbon dioxide, and again through the interferometer, and another reading, which will be lower than the first, is taken. The difference between these first two readings is the measure of the carbon dioxide. With the Zeiss instrument used by the authors a difference of 0.01 scale division corresponds to 0.186 per cent.carbon dioxide. In the absence of carbon monoxide, the second reading also gives the relative proportions of oxygen and nitrogen, which are read off by reference to a straight line curve constructed from readings obtained with mixtures of oxygen and hydrogen in known proportions. From these values for oxygen and nitrogen, which together total 100 per cent., the percentage of oxygen and nitrogen in the original gas is calculated by reference to the percentage of carbon dioxide found.If the percentage of oxygen thus found plus the percentage of carbon dioxide is notably less than it should be, the presence of carbon monoxide is nearly certain. The authors have constructed several tables to428 ABSTRACTS OF CHEMICAL PAPERS facilitate the calculations.The final table is for determining whether carbon monoxide is present or not, and it gives the totals to which the percentages of carbon dioxide and oxygen should sum for four grades of fuel (from coke to brown coal), and with varying excesses of air above that necessary for combustion. G. C. J. Determination of Melting-Points with the Aid of the Microscope.M. P. Cram. (J. Amer. Chem. Soc., 1912, 34, 954-956.)-1n toxicological investiga- tions the m.pt. of a substance too small in amount to be introduced into a capillary tube may be determined within a few degrees by the use of a compound microscope fitted with a &inch objective and magnifying 100 diameters. The diaphragm is removed, and beneath the table is clamped a, section of brass tube, 3.1 cm.in diameter and 2.4 cm. long, fitted with glass windows at the end, and wound with a beating coil of '' nichrome " wire through which is passed an electric current. The heating wire is impregnated with Bakelite varnish No. 2. Four yards of asbestos-covered 020 nichrome wire are wound on, and the outside wrapped with four layers of asbestos paper.Squares of asbestos board with a hole in the centre are used above and below the tube to prevent loss of heat. The thermometer is introduced through a side-tube, the centre of which is 8 mm. above the bottom of the main tube, and the bulb is entirely within the centre of the coil, the stem extending horizontally to one side. Above the bulb of the thermometer is a, wire bridge, upon which the micro- scope-slide which is to hold the substance is placed.Round cover-glasses 2 cm. in diameter are best adapted to hold the material to be tested. The temperature of the thermometer is not exactly tbat of the substance on the slide, but the true m.pt. can be found by noting the thermometer reading with substances of known m.pts.A current of 0.6 ampere gave a, reading of 64" C., while a, temperature of 200" C. was obtained with a current of 1.25 amperes. H. F. E. H. New Sublimation Apparatus and its Application in Food Analysis. E. Philippe. (Matt. Lebe72smittelluntersuch. 16. Hyg., 1912, 3, 41-53 ; through Chem. Zentralbl., 1912, IT., 82.)-The apparatus consists of a metal capsule of 7 cm. diameter, serving as a condenser, inverted with its lower edge resting on the convex surface of a wstch-glass of 11 cm.diameter, with the interposition of a soft rubber ring about 12 mm. wide and 6 to 7 mm. thick, and held in position by three spiral spring clips. Through the top of the capsule pass two tubes of 8 mm. diameter, serving for the circulation of the cooling water. The watch-glass is placed with its concave side on a flat glass dish with a ground edge, having a height of 3 cm.and a diameter slightly smaller, or at any rate not larger, than that of the capsule. The arrangement rests on a tripod with a double wire gauze. The apparatus is intended for quantitative sublimations, and is applicable for the estimation of salicylic and benzoic acids in foods.Tests made with various sublimable substances showed a yield generally of over 95 per cent. The greatest loss was experienced with vanillin -viz., 5.5 per cent. After each estimation the previously tared watch-glass is wiped on its under side, and the sublimate is dried in the desiccator for half an hour before weighing. In the estimation of salicylic acid in milk an error of about 33 per cent.was found, owing to the fact that some of the sa,licylic acid was carried downAPPARATUS, ETC. 429 in the precipitation of the milk with copper sulphate and sodium hydroxide; in the estimation of benzoic acid in milk the yield 96.41 per cent. In fruit preserves and fruit juices the estimation of salicylic acid by sub- limation of the ethereal extract gave results agreeing well with the bromine titration method.For the estimation of salicylic acid in a coffee substitute preparation, 10 grms. were freed from fat by petroleum spirit, treated with 10 C.C. of ammonia, extracted with chloroform, and the chloroform extract was submitted to sublimation. The results were in good concordance with the estimation by the Trillich- Gockel met hod.J. F. B. Beckmann Thermometer with a Modi- fied Arrangement for setting the Mercury Thread. A. Kuhn. (Chem. Zeit., 1912, 36, ,843.)-The construction of the thermometer is shown in the illustrations. The excess of mercury is brought into the two side limbs by simply inclining the thermometer, and the capillary may be filled by a reverse movement, the lower reservoir of the instrument being at the same time warmed until the mercury thread reached the elongated point a of the capillary (Fig.3). The opening at the point a is of such size that each drop of mercury flowing from i t measures 1’ C. on the scale. It is not necessary to tap the thermometer during these operations. w. P. s. FIG. 1. ranged from FIG. 3. New Hand Photometer. W. J. Dibdin. (J. SOC. Chm. Id., 84-81 to F J G , 2.1912, 31, 624-625.)-The present instrument is a development of the author’s radial photometer described in 1884. I t is a portable instrument, weighing 6 pounds, and measuring 17 x 5 x 5 inches, and may be used for comparison of lights in rooms, streets, etc. The instrument is designed to embrace three conditions : (1) Maximum open scale readings ; (2) convenience and accuracy in comparing lights of different colours ; (3) reliability, by reason of the facility with which its indications can be checked.The open scale readings are obtained by the employment of an electric incandescent lamp, the current to which (from a storage cellj is regulated by means of a rheostat giving an unusually lengthy movement of the contact-point, the position of which is read on a scale graduated in terms of LLfoot-ca,ndles.” This arrangement allows of more delicate measurements than by direct readings of the voltmeter, which is also fitted in the instrument to check the working of the storage cell.The comparison430 ABSTRACTS OF CHEMICAL PAPERS of lights of different colours is secured by means of the author’s improved form of Leeson’s star-disc. Readings of this instrument compared simultaneously with those of a standard photometer show it to give accurate results, the figures differing by +Om01 to - 0.04 foot-candles, with an average of - 0.01 for twelve readings. To ascertain the “illuminating power” of any radiant, the square of the distance in feet from the photometer disc is multiplied by the ( 6 foot-candle ” power observed.As the instrument indicates up to 12 footcandles, a light at 25 feet distance giving that degree of illumination would have an intensity of 7,500 candles ; while if the power at the same distance was only 0-001 candle (loFest observable), the initial intensity would only be 0.625. The range of the instrument is thus wide enough for all ordinary purposes.A. R. T. Easily Adjustable Vapour Thermostat. J. Fletcher and D. Tyrer. (Proc. Chem. Xoc., 1912, 28, 189-192.)-TThe authors describe a vapour-bath which can be maintained constant with very little trouble to 0.005O C., and can be fixed at any desired point (say, between 30” C. and 130° C.) with the greatest ease. I n principle it consists of a pure liquid boiling under a constant and adjustable pressure, - - - - - I b M which is controlled and maintained constant by an efficient manostat. Practically any liquid of suitable boiling-point may be used.The boiling liquid is contained in the flask A (see diagram). The vapour passes into the compartment B, which may be of any particular form suitable; B also contains a thermometer, as shown. The vapour is then condensed in C, and returns as liquid to the boiling flask A .The end of the condenser C is connected, as shown, with an air reservoir, D, of about 10 to 20 litres capacity (the larger the size of this reservoir the greater is the efficiency of the apparatus), and then to the manostat E. The manostat, being the most important part of the apparatus, is desoribed at some length, and for the sake ofAPPARATUS, ETC.431 dearness has been drawn in the diagram on a rather large scale. The tube Fis attached to an efficient water-pump. The degree of exhaustion is first roughly adjusted by allowing air to enter by the side-tube and pinch-cock G. The mercury rises into the bulb Hout of the reservoir I until the level reaches the end of the tube J, when it stops and remains constant.If it passes this point, it closes off the rest of the apparatus from the pump ; and as air is entering through the side-tube G, the pressure increases, and the level of the mercury in the manostat fall8 again. As soon as the end of the tube J becomes uncovered, the pump again comes into play, and rapidly reduces the pressure, causing the mercury level to rise again.When equilibrium is reached, the level of the mercury remains constant, and a continual current of air and mercury passes up the tube J into the compartment K, from whence the mercury faHs back into the bulb H by the tube L, and the air passes off through the pump. I t will be clear that the difference in the levels of the mercury in H and I represents the pressure in the apparatus, and the adjustment of this pressure is merely made by altering the height of the reservoir.For the proper working of the manostat it ie necessary to have a large air- supply to draw from, otherwise the mercury level in H rises and falls irregularly. This is the purpose of the air reservoir D. Although the level of the mercury in H may fluctuate slightly, the pressure recorded by the manometer M remains perfectly constant.In order to raise the temperature in B, the mercury reservoir I is raised, and to lower the temperature it is merely necessary to lower I. For the efficient working of the apparatus the author insists that attention should be paid to the following dotails : The reservoir should be shallow, so that if the vessel K partly fills with mercury, as sometimes happens, the difference in the mercury levels in H and I is not appreciably altered.The end of the tube J should be a narrow slit not wider than 0-5 mm., and bent horizontally. The width of this slit insures that the greatest possible variation in the pressure is 0.5 mm., although the actual variation need not exceed 0.1 mm. In order to accelerate the initial exhaus- tion of the apparatus, the tap T is provided as a by-pass, which at all other times must be closed.The connecting tubes should be of wide bore, so that the pressure at all parts of the apparatus is absolutely the same. The boiling liquid used must be pure, and must boil quietly without bumping. It is found that bumping is prevented, however low the pressure, by placing in the flask A a layer of mercury as indicated.I t is better to boil the liquid over a small free flame shielded from draughts. If the efficiency of the water-pump varies considerably, and if it is desired to have a very constant temperature, it is better to use two manostats connected together with an air reservoir and air inlet tube between them. The temperature can, however, be maintained constant to about 0*01" C. with one manostat. If rubber stoppers are used, an alcohol should be employed as the boiling liquid, but with ground-glass connections lubricated with glycerol-dextrose mixture any liquid can be used. For temperatures ranging from 30° to 65' C. the authors recom- mended methyl alcohol, from 40" to 70' C. ethyl alcohol or benzene, and for higher temperatures toluene or xylene. In experiments made with a Beckmann thermometer in €3, and with a double manostat, it was found that for short periods of time the temperature remained con-432 GOVERNMENT REPORTS stant to O*O0lo C. For longer periods the variation is greater; but 80 long as the atmospheric pressure remains unchanged, the temperature remains constant to about OgO05" C. It is claimed that this form of thermostat has many advantages over Ihe usual large water-bath. I t is more quickly adjustable, and need not be left going for long periods of time, as it is only a matter of a few minutes to start it again.

ISSN:0003-2654    

DOI:10.1039/AN9123700426

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

432 GOVERNMENT REPORTS ,GOVERNMENT REPORTS. Regulations under the Public Health (Regulations as to Food) Act, 1907.-S1~,-1 am directed by the Local Government Board to advert to the Public Health (Regulations as to Food) Act, 1907 (7 Edw. VII., c. 32), under which the Board are empowered to make regulations authorising measures to be taken for the preven- tion of danger arising to public health from the importation, preparation, storage, and distribution of articles of food or drink (other than drugs or water) intended for sale for human consumption. In connection with the powers thus conferred the Board have for some time had under consideration and inquiry the danger to health which may be entailed by the addition of preservatives and other foreign substances to milk and cream and the importance of controlling such additions, and they have now made Regulations under that Act entitled “The Public Health (Milk and Cream) Regulations, 1912.” In making these Regulations due regard has been had to representations which the Board have received from local authorities under the Sale of Food and Drugs Acts, from representatives of the trades affected and from others concerned.The Regulations are designed to secure that no preservatives shall be added to milk, or to cream containing less than 35 per cent. by weight of milk fat, at any stage from the place of production to that of delivery to the purchaser. In the case of cream containing over 35 per cent. of milk fat, the addition of boric acid, borax, or a mixture of these preservative substances, or of hydrogen peroxide, is not prohibited by the Regulations, but is subject to a system of declaration which is required to be Followed by all persons dealing with such cream for the purpose of sale for human consumption.By this system (Part 11. of the Regulations) it is intended that preserved cream as an article of commerce shall in all stages be differentiated from cream to which no preservative has been added.Further, Article IV. (a) prohibits the addition of any thickening substance to cream or preserved cream. It will be seen that except as regards Part 111. the duty of administering she Regulations has been placed upon those authorities in England and Wales who are Looal Authorities under the Sale of Food and Drugs Acts.Existing arrangements for the collection and examination of milk eamples under the Sale of Food and Drugs Achs can readily be extended so as to enable the Council to receive such reports from the public analyst as are requisite. Arrangements will Copies of an Order containing these Regulations are enclosed.GOVERNMENT REPORTS 433 be required for the periodical examination of samples of cream for the purpose of ascertaining whether the requirements of the Order are being duly complied with. In the case of any contravention of the Regulations, steps should be taken to ascertain the circumstances in which the default has arisen, with a view to any necessary action.Article VI. requires that before the Local Authority institute proceedings against any person for contravention of any of the Regulations in Part 11.of the Order, the Local Authority shall afford him an opportunity of furnishing an explanation, and shall consider such explanation and all the oircurnstances of the case. I t should be observed that the proceedings here in question are those authorised by the Public Health (Regulations as to Food) Act, 1907, and the enactments referred to in the Notice at the foot of the Order.It will be desirable that the Medical Officer of Health should be instructed to exercise general supervision over the action taken in pursuance of these Regulations, and that the officer of the Council who directs sampling under the Elale of Food and Drugs Acts, should be instructed to confer with the Medics1 Officer of Health and with the Public Analyst as to the details of procedure necessary to secure the observance of the Regulations in the area over which the Council has supervision.The Regulations will as regards their main provisions take effect on and after October 1 next, and as regards Article V. (1) on January 1, 1913. The Board are anxious to secure uniformity in the administration of the Regulations, and will be glad to have their attention drawn to any cases of difficulty which may hereafter arise.Copies of the Regulations and of this Circular are enclosed for transmission to the Medical Officer of Health and Public Analyst. The Regulations and this Circular will be placed on sale, so that copiers may shortly be obtained, either directly or through any bookseller, from Messrs.Wyman and Sons, Limited, Fetter Lane, London, E.C. I am, Sir, Your obedient Servant, IT. C. MUNRO, Secretary. THE TOWN CLERK or THE CLERK TO THE COUNTY COUNCIL. The draft of the Regulations was published in the ANALYST, 1912, 109-115. In Page 110 (March issue of the ANALYST), line 7 from bottom, for “40 ” read Page 110, line 4 from bottom, delete “in amount not exceeding 0.1 per cent.by Page 111, line 13, for (‘ June ” read ‘‘ October.” Page 111, lines 22 and 24, for (‘ 40 ” yead “ 35.” Page 111, line 27, delete “ in amount not exceeding 0.1 per cent. by weight.” Page 111, delete last 8 lines of page, and substitute : ARTICLE V.41) Every seller of preserved cream shall, in every advertisement, price list, or trade list which is used in connection with the sale of preserved cream for human consumption, describe that article as preserved cream, and in no such the final form the following alterations have been made : “ 35.” weight.”434 GOVERNMENT REPORTS Capacity of Reccptacle. document shall any words be contained which might imply that the preserved cream is cream to which a preservative substance has not been added.Page 112, line 13 from bottom, after 6c Act ” insert r 6 (as amended by subsequent legislation).” Page 112, line 7 from bottom, after ‘‘ officer ” insert (‘ or to any officer of the Local Government Board.” Page 113, lines 1 and 3, for 40 ” read ‘‘ 35.” Page 113, line 6, delete ‘( in amount not exceeding 0.1 per cent. by weight.” Page 114, line 20, delete Labels I.and 11. and what follows to line 5 from bottom and substitute : LABEL I. LABEL 11. 1 Size of Label. PRESERVED CREAM BORIC ACID CONTAl N I N G PRESERVED CREAM NOT EXCEEDING ( PE ROX I D E) . 3. The size of the declaratory label shall be determined as follows : Not exceeding 1 pint ... ... ... ... Exceeding 1 pint ... ... ... ... ... 1 Inches. Inches. 2 by 19 3 by 5 Circular to Local Authorities in England and Wales for the Purposes of the Sale of Food and Drugs Acts, 1875 to 1907.-S1~,-1 am directed by the Board of Agriculture and Fisheries to enclose herewith a copy of the Sale of Milk Regulations, 1912.These Regulations amend the Sale of Milk Regulations, 1901, in so far as they relate to skimmed or separated milk, and replace the limit of 9 per cent. of total milk-solids on which, under Article 3 of those Regulations, a presumption that the milk is not genuine is based, by a limit of 8.7 per cent.of milk-solids other than milk-fat. Representations have been received from time to time from Local Authorities of districts where there is a trade in skimmed and separated milk that considerable practical difficulties arise in instituting proceedings in cases in which water has been added to skimmed milk, but, owing to the fact that the milk has been im- perfectly skimmed, the total solids have not fallen below 9 per cent.Thus a sample containing 1.5 per cent. of fat and 7.5 per cent. of milk-solids other than milk-fat would probably contain over 12 per cent. of added water, but the total solids are upREVIEWS 435 to the limit of 9 per cent.The present Regulations are intended to obviate these difficulties and to facilitate the prevention of the adulteration of skimmed milk with water. The fixing of the percentage at 8.7 may result in some hardship in cases where the milk is imperfectly skimmed. Thus, if milk containing 3 per cent. of milk-fat and 8-5 per cent. of milk-solids other than milk-fat is imperfectly skimmed, SO that 1-5 per cent. of milk-fat remains, the proportion of milk-solids other than milk-fat will rise only to 8-63 per cent., and the Board would suggest that this point should be taken into account by your Local Authority in considering the question whether they should institute proceedings on the presumption of adultera- tion based on the Regulations in cases where the deficiency of milk-solids other than milk-fat is slight and the skimmed milk contains a considerable proportion of milk-f at.I am to enclose duplicate copies of this Circular and of the Begulations for transmission to the Public Analyst, and to say that the Board will be glad to supply .further copies of the Circular for distribution amongst the members of your Local Authority and the officers concerned in the administration of the Acts on being informed of the number you require.I am, Sir, Your obedient Servant, T. H. ELLIOTT, Secretary. THE CLERK TO THE LOCAL AUTHORITY. BOARD OF AGRICULTURE AND FISHERIES, August 20, 1912. Statutory Rules and Orders, 1912, No. 687 : Adulteration (Sale of Food and Drugs Acts) -The Sale of Milk Regulations, 1912.(Dated June 29, 1912.)-The Board of Agriculture and Fisheries, in exercise of the powers conferred on them by Section 4 of the Sale of Food and Drugs Act, 1899, do hereby make the following Regulations : Skimmed or Separated NiZk.-(1) Where a sample of skimmed or separated milk (not being condensed milk) contains less than 8.7 per cent. of milk-solids other than milk-fat, it shall be presumed for the purposes of the Sale of Food and Drugs Acts, 1875 to 1907, until the contrary is proved, that the milk is not genuine, by reason of either the addition thereto of water or the abstraction therefrom of milk-solids other than milk-fat.Revocation of Existing ReguZntion.-(2) Regulation 3 of the Sale of Milk Regula- tions, 1901, is hereby revoked, but not so as to affect the validity of any certificate of analysis given before the commencement of these Regulations or any legal proceedings in respect of any sample to which any such certificate relates. Commeacement.-(3) These Regulations shall come into operation on the First day of September, One thousand nine hundred and twelve. Eztent.-(4) These Regulations shall extend to England and Wales. Short Title.-Theae Regulations may be cited as the Sale of Milk Regula- tions, 1912.436 REVIEWS In witness whereof the Board of Agriculture and Fisheries have hereunto set their official seal this twenty-ninth day of June, One thousand nine hundred and twelve. (L.S.) T. H. ELLIOTT, Secretary.

ISSN:0003-2654    

DOI:10.1039/AN9123700432

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

436 REVIEWS REVIEWS. PRINCIPES THEORIQUES ET PRATIQUES D’ANALYSE MINERALE. G. CHESNEAU. The author describes this book as a guide for engineers to the analysis of industrial minerals, but it is more truly a comprehensive treatise on inorganic analysis; and though written from the standpoint of the works manager or the mining engineer, it will be of considerable value to the professional chemist.The first part, which deals with theoretical principles and general methods of analysis, is exceptionally good. I t sets forth the ratwnaEe of analytical manipulation with a completeness and lucidity all too rare in professedly ‘‘ practical ” handbooks. The theory of washing precipitates is fully discussed, and the relation of solubility to size of particles is considered, and the reason why digestion usually diminishes the fineness of a precipitate is indicated. Gelatinous precipitates and the precautions necessary in dealing with them receive full consideration.The equilibrium con- ditions of the reactions suitable for analytical purposes are discussed with a view to the elucidation of the two fundamental problems-to produce a, precipitate as little soluble as possible, and to dissolve insoluble bodies.Qualitative analysis is next considered ; general methods and 8 complete scheme for the detection of metals are given. The first part doses with an excellent chapter on the general processes of quantitative analysis. The degree of accuracy attainable in volumetric processes is discussed, and emphasis is laid upon the advantages of the comparative me’thod, in which a cc standard ” is treated in exactly the same way as the sample.The principal sources and uses are first given for each element and its industrially valuable compounds ; then its distinguishing characteristics and the analytical properties made use of for its detection and estimation are described. This is followed by an account of selected methods for the separation and estimation of the element in question, ctnd the application of these methods to minerals and manufactured products.On the whole, the methods chosen are authoritative and reliable, though some are rather unfamiliar to English practice. All are very carefully described, with due attention to such points as concentration of solutions, temperature, strength of acid, etc.Following the treatment of hydrogen, the general question of acidity is dealt with and the theory of indicators outlined. A section is also devoted to water analysis. Phosphorus and phosphoric acid are well treated. Under Arsenic ” the method of Fresenius and Babo is given. This allows of the detection of one- thousandth of a milligram of arsenious acid, and its differentiation from antimony.The consideration of carbon is followed by methods for the estimation of common Ch. Beranger, Paris. 1918. Price 25 francs. In the second part the elements are studied separately.REVIEWS 437 hydrocarbons, elementary organic analysis, and the analysis of fuels. The chapter on the iron group opens with a clear discussion of the conditions necessary for the separation of the metals as sulphides and acetates.Somewhat surprising is the absence of any mention of the bichromate method for iron estimation. The analysis of iron and steel is treated in considerable detail. Besides the usual dry and wet combustion methods for carbon, a volumetric method is described. The apparatus appears to be rather complicated, and, as only one determination can be made in two hours, its advantages are not very obvious.The Eggertz colour method is reviewed, with due warning as to its limitations. For sulphur, the only oxidation process described is the c‘Arnold” method, in which aqua regia is used together with bromine and potassium chlorate, and the precipitation with barium chloride is made in the cold. The molybdate method described for phosphorus, involving two precipitations of the phosphomolybdate, is decidedly tedious and complicated.No magnesia method is given. Several colour methods for manganese are described, including the persulphate process, which is certainly the simplest and most expeditious. I n dealing with the ‘‘ rare” elements, a preliminary treatment by the ether method of Rothe is recommended.This accomplishes a nearly complete separation of the iron from all the other elements except molybdenum. The estima- tion of nickel by means of dimethylglyoxime is described, but the cyanide titration in presence of ammonium citrate is not mentioned. The metals of the copper and tin groups are well treated, and methods for the analysis of their alloys are given.Like most French publications, the book lacks an index, but there is an alphabetical list of minerals of which the analysis is given. The printing is good, and the diagrams are clear and well chosen. F. W. HARBORD. THE ANALYST’S LABORATORY COMPANION. Fourth Edition. By ALFRED E. JOHNSON, London : J. and A. Churchill. As a small work of reference for chemical and physical data, this edition of Mr.Johnson’s book deserves commendation. The numerous tables have been revised where necessary, and some further tables have been added, the International Atomic Weights for 1912 being adopted. Considering, however, that refractometric methods of analysis are being employed to an increasing extent, it is rather surprising that space has not been found for tables showing the relation between refractive index and percentage content of solutions of various substances.The notes on analysis have also been revised and amplified, some very useful additions being the standards for sewage effluents recommended by the Royal Commission on Sewage Disposal (Fifth Report, issued in 1908), and the chief provisions of the Draft of The Public Health (Milk and Cream) Regulations, 1912,” issued by the Local Government Board.I n the section dealing with the cupric reducing power of the carbohydrates, a method for the gravimetric estimation of reducing sugars is described, but no mention is made of the volumetric method now so generally used. B.Sc. (Lond.), F.I.C., A.R.C.Sc.1. 1912. Pp. ix + 164. Interleaved with blank pages.438 INSTITUTE OF CHEMISTRY Considerable space is devoted to chemical calculations.At p. 36, Mr. Johnson justly condemns the calculation of analytical results to an unwarrantable number of decimal places, but falls into the same error himself at p. 107, where the percentages of dextrose and maltose in a commercial 1‘ glucose ’’ are given to the second decimal place. On the whole, however, the revision has been done very carefully, the errors observed are few, and for the most part trivial, and the new material has been judiciously selected.The book is of a convenient size, and should prove very useful in the laboratory. LEWIS EYNON. INSTITUTE OF CHEMISTRY. PASS LIST : JULY EXAMINATIONS, 1912. OF thirty-five candidates who presented themselves for the Intermediate Examina- tion, eighteen passed : C.A. Adams, I3.Sc. (Lond.), Miss D. J. Bartlett,, L. 0. Brekke, B.Sc. (Leeds), H. B. Brown, F. G. Conyers, E. D. Goddard, B.Sc. (Lond.), J. R. Gray, F. A. Hatoh, M. Howie, D. W. Kent-Jones, E. Marsden, Miss E. G. Mocatta, B.Sc. (Lond.), E. A. Rayner, B.Sc. (Lond.), W. S. Ritchie, B.Sc. (Lond.), W. G. Saunders, D. E. Sharp, B.Sc. (Aberdeen), T.F. Sineaton, and W. A. Storey. Of thirtyseven candidates who presented tpemselves for the Final Examination, twenty-eight passed. I n the branch of Mineral Chemistry : C. R. Chown, A.R.C.S. (Lond.), B.Sa. (Lond.), H. Gilmour, W. P. Harmsworth, J. G. King, H. Knight, P. G. Knapman, B.Sc. (Lond.), and R. H. Truelove, B.Sc. (Lond.), A.R.C.S. (Lond.). I n the branch of Metallurgical Chemistry : E. 0. Jones, B.Sc. (Lond.), A.R.C.S. (Lond.), W. A. C. Newman, B.Sc. (Lond.), A.R.C.S. (Lond.), and E. W. Yeoman, B.Sc. (Lond.), A.R.C.S. (Lond.). In the branch of Physical Chemistry : J. I. Crabtree, B.Sc. (Vict.), and Miss A. M, Finney, B.Sc. (Birm,), In the branch of Organic Chemistry: J. L. S. Allan, J. Crawford, G. J. Eastburn, J. H. Naylor, M.Sc. (Maw.), F. G. Rawling, M.Sc. (Leeds), S. Robertson, A. Wilson, T. A. Wilson, and T. Wright. I n in the branch of the Chemistry of Food and Drugs, and of Water : S. W. Bunker, B.Sc. (Lond.), D. H. B. Cowman, B.Sc. (Lond.), A. Gemmell, B.Sc. (Edin.), C. L. Hinton, H, Raistrick, B.Sc. (Leeds), M. J. Robb, B.Sc. (Aberdeen), and 5. B. Tallantyre.

ISSN:0003-2654    

DOI:10.1039/AN9123700436

出版商:RSC    

年代:1912

数据来源: RSC