摘要:

THE ANALYST. JAN UARY, 1898. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. THE monthly meeting of the Society was held on Wednesday evening, Dccember 1, in the Chemical Society’s Rooms, Burlington House, the President (Dr. Bernard Dyer) occupying the chair. The minutes of the previous meeting were read and confirmed. The President read the following list of officers for the ensuing year, as proposed Preside7zt.-Bernard Dyer, D. Sc. Vice-Presidents (who have filled the office of President).-M. A. Adams, F.R.C.S. ; A. H. Allen ; Sir Chas. A. Cameron, M.D., F.R.C.S. ; A. DuprB, Ph.D., F.R.S. ; Otto Hehner ; Alfred Hill, M.D., F.R.S.E. ; J. Muter, M.A., Ph.D., F.R.S.E. ; Thos. Stevenson, M.D., F.R.C.P. Vice-Presidents (who have not filled the office of President).-A. P. Aitken, D.Sc., F.R.S.E.; W. W.‘li’isher, M.A. ; J. A. R. Newlands. Hon. Twaszwer.-E. W. Voelcker, A.R. S.M. R o n . Secretaries.-E. J. Bevan, Charles E. Cassal. Other Members oj’ CozmciZ.-Bertram Blount, Sidney Harvey, C. G. Moor, M. A., F. Wallis Stoddart, Walter J. Sykes, M.D., John White, W. C. Young. The names of those members of the Council who do not retire this year are R. Bodmer, A. Wynter Blyth, M.R.C.S., A. C. Chapman, S. Rideal, D.Sc., .J. E. Stead, J. A. Voelcker, M.A., B.Sc., Ph.D. Mr. Leonard K. Boseley, analyst to Messrs. James Keiller and Sons, of Silver- town, was proposed for election as a Member of the’society, and Mr. - O’Shmgh- neesy, assistant to Mr. R. Droop Richmond, as an Associate. by the existing Council for election at the annual meeting : The following papers were read : “ Milk Analysis and Certification.” ‘( A Method of Estimating Tannic Acid by ;Means of the Polarimeter.” ( ( A Butter Eighteen Years Old,” ‘( Note on Mineral Matter in Commercial Bleached Ginger.” The following gentlemen were elected members of the Society: Mr.S. H. Collins, F.I.C., Assistant Agricultural Chemist to the Indian Government ; Pro- fessor James Hendrick, B.Sc., F.I.C., the University, Aberdeen; Mr. W. H. Jackson, Analyst to the West Yorkshire Coal and Iron Company; and Mr. E. H. RQberts, Analyst to the Dairy Supply Company, Ltd. By James Edmunds, M.D. By R. F. Wood-Smith. By E. G. Clayton. By E. J. Bevan.2 THE ANALYST. On the proposal of Mr. HEHNER, seconded by Mr. CHAPMAN, Mr. John Hughe8 and Mr. Bertram Blount were appointed auditors of the Society’s accounts for the year. The PRESIDENT announced that, although the Annual Dinner would take place on Tuesday, January 18, the Annual Meeting, far the election of officers, etc., would not take place until February, when it would be held in conjunction with the ordinary meeting.

ISSN:0003-2654    

DOI:10.1039/AN8982300001

出版商:RSC    

年代:1898

数据来源: RSC

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2 THE ANALYST. AN IMPROVED MILK-SCALE. BY H. DROOP RICHMOND. (Read at the Meeting, NOV. 3, 1897.) WHEN determining the density of milk, it is frequently a matter of convenience to make the estimation at the temperature at which the milk happens to be, instead of adjusting it to the normal temperature. When this is done, it is necessary to make a correction to ascertain the value at 60" F. Vieth has published a set of tables (ANALYST, x. 70) founded on those of Fleisch- niann, and these I have found correct ; numerous experiments have shown that the difference between the density at 60" F. shown by Vieth's tables, and that actually determined, very rarely exceeds 0.0002. Seeing the favour with which slide rules are regarded at the present time, it ha8 long been my desire to incorporate a corrector of specific gravity with the '( milk- scale." On the body of the instrument the temperature is engraved, each degree of temperature being of dimensions corre- sponding to the increase of speoific volume (specific volume of milk at 32" F.= 1) ; on the slide the scale of specific gravity is marked, each degree having a value inversely proportional to the increase of expansion with the specific gravity. To use the instrument, the specific gravity found (i.e., the apparent specific gravity deter- mined in glass vessels) is placed against the line 60" F. (marked with an arrow) ; thO true specific gravity is read off against the temperature at which the determinatiozl was made. The ( ( milk-scale " is now made by Messrs. Baird and Tatlock, London, with the: addition of the specific gravity corrector.I have now succeeded in doing this. DXSCUSSION. The PRESIDENT said that very many analysts were already much indebted to Mr. Richmond for the time saved in calculation by the use of his milk-scale, and the introduction of the modification now described would add to their obligation. Mr. A. W. STOKES said that the working of the scale was greatly facilitated by the use of a simple index, made by bending a flat piece of metal, a plan which he had found to answer better than any of the other devices made, which were more or less complicated. The PRESIDENT said that an ingenious little apparatus of a nature somewhat similar to that mentioied by Mr. Stokes had been introduced some time previouslyTHE ANALYST. 3 by Mr, Cassal. Among the advantages of such a device was that it prevented the temptation to make inlscmarks on the scale. [NoTE.-As the question of pointers was raised in the discussion, I may point out that the first was used by Mhnnheim nearly fifty years ago on the slide-rule. It was first applied to the milk-scale by A. E. Johnson, the most recent improvement being the use of a vernier instead of a pointer, as proposed by Sykes.] H. D. R.

ISSN:0003-2654    

DOI:10.1039/AN8982300002

出版商:RSC    

年代:1898

数据来源: RSC

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THE ANALYST. 3 NOTE ON THE GRADUATION OF LEFFMANN-BEAM BOTTLES. BY G. E. SCOTT-SMITH AND A. B. SEARLE. (Read at the Meeting, Nov. 3, 1897). IN estimating the amount of fat in milk, we have recently been much perplexed by the occurrence of a great discrepancy between the results of the Leffmann-Beam and Werner-Schmid processes. This was the more surprising 8s the two methods had given us very concordant results in the past. The amylic alcohol was purified by shaking with brine to remove any ethylic alcoho1,which might be present. It was then allowed to stand for twenty-four hours over potassium carbonate, and was then distilled. That portion distillingbetween 128" C. and 131" C. was used for the experiments. The sulphuric acid was found to be of the specified strength as calculated from the specific gravity (1.843).Using these purified reagents no better results were obtained. A mixture of amyl alcohol and hydrochloric acid some weeks old was compared with a mixture prepared from the same reagents a few minutes before use. Experi- ments were made at the same time in wbich the quantity of sulphuric acid used was slightly varied, a constant volume of 15 C.C. of milk being used in each case. The volume of fat thrown up was noted after whirling one, two, three, four, and five minutes respectively, with the following results : We first directed our attention to the reagents used. Using 0 C.C. H2S0, and '( old " amyl ahohol mixture . . . ... ... Using 9 C.C. H,SO, and '( new " amyl alcohol mixture . -. ... Using 10 C.C. H,SO, and" o l i " amyl alcohol mixture .. . , .. . ... Using 10 C.C. H,SO, and (' new " amyl alcohol mixture ... ... ... In one minute. 3.7 3.7 3.7 3-7 Fat ; per Cent. In two minutes. 3.3 3.3 3.3 3.3 In three minutes. 3.3 3-3 3.3 3.3 In four minutes. 3.3 3.3 3.3 3.3 In tive minntes. 3.3 3.3 3.3 3.2 After whirling for one minute the separation was not sharp, as the layer of fat contained a large quantity of flocculent matter. After two minutes' whirling the separation of the fat was almost complete, and after three minutes the separations were always sharply defined. These results are satisfactory, in RO far as they show4 T-HE ANALYST. that the amount of sulphuric acid can be varied to a moderate extent without affecting the accuracy of the results. Being convinced that our reagents were pure and that our method of procedure was correct, we attempted to find whether the source of error lay in the graduations of the bottles.We were aware that attention had been directed to the fact that it was necessary to calibrate the bottles before use, but we could not find a ready method for effecting this. As the 80 divisions on the neck of the bottle represent collectively a volume of only 1.2 c.c., the calibration is attended with difficulties which are not met with in many other cases. We first attempted to calibrctte the bottles by running in water from a fine burette, but this method was found to be useless, as an error of =t 0-05 C.C. per 10 divisions corresponded to 0.3 per cent. of fat, and in practice an error of this magnitude was unavoidable, chiefly owing to the tendency of the water to adhere to the sides of the neck of the bottle.I n later experiments proof-spirit was used, and the liquid weighed instead of being measured. In each case the bottle was filled up to the lowest division (number 80) with the spirit, and weighed carefully. More spirit was then run in from a small pipette until the liquid stood at the 70th division, when the bottle and its contents were again weighed, and this procedure was repeated at each 10 divisions until the liquid had reached the zero-mark of the bottle. This method appears to provide a ready and fairly rapid method of checking the accuracy of the graduations. I t overcomes completely the difficulty due to adhesion of the liquid to the neck, without the inconvenience and necessity of whirling, with consequent liability to change of temperature and correction for expansion.If a balance turning to haIf a milligramme be used and the calibration conducted expeditiously, the loss of alcohol by evaporation is insignificant, and the use of mercury, with its objections, is avoided, the slightly greater accuracy obtained by the use of the latter being little or no advantage compared with the greater tediousness of the method. If the tem- perature of the balance-room is constant, no correction need be applied, as only the relative volumes of the graduations are required. The following are some of the figures obtained : Weight of spirit in grammes : 80 to 70 divisions ... 70 to 60 ,, ... 60 to30 ,, ... 50 to 40 ,, ...40 to 30 ,, ... 30 to 20 ,, ... 20 to 10 ,, ... 10 to 0 ,, Total weight of alcohol grammes) ... ... 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . ... -114 -117 el44 -141 a156 ~155 -134 -150 ... -095 ~150 -145 -149 ,145 ~150 -145 ,129 ... -107 -102 el58 -142 -142 el50 -151 -161 ... -141 -119 ~ 1 4 3 ,131 *I50 -151 -145 *I45 .. . ,145 -149 el50 *134 -150 0134 .144 ,157 ... *148 -153 ,143 *150 -150 -166 -160 -157 ... -151 -147 el53 -142 -150 *151 -150 ,148 ... el42 *157 -150 -158 ,150 -146 ~156 -150 ... 1.042 1.099 1-186 lb147 1.193 1.203 1.185 1.197 (in -------- These figures show how very imperfectly the bottles are graduated by the manu- facturers, and how necessary it is to check each bottle before use if the Leffmand- Beam process is to be relied on. Thus, if No. 6 bottle were used, and the reading taken between divisions 80 and 50, the amount of fat shown would be 2.7 per cent.,THE ANALYST.5 instead of the 3 per cent. aotualIy present in the milk. I n the case of bottle No. 1, if the reading were taken between the 50th and 80th divisions, a milk containing 2.3 per cent. of fat would show 3 per cent. Bottles Nos. 3 and 5, on the other hand, are much more evenly graduated than any of the others in this series, and these two bottles have been found in praotice to give fairly good results. Another set of bottles, calibrated in the same manner as the first set, showed that the scale in each was very uniformly graduated, but all the divisions were slightly too large. Hence the percentage of fat indicated was rather less than the true amount present, but the error was not sufficiently great to prevent the bottles being used.DISCUSSIOK. Mi*. A. W. STOKES' agreed with the authors that the best liquid to use was alcohol, which possessed, among other advantages, that of being able to pass easily down a very narrow tube. He thought, however, that in filling the bottles with a pipette an error might arise through drops of liquid clinging to the sides of the tube, unless care was taken to get rid of such drops by rotating the bottle after the liquid had been added. Mr. RICHMOND thought that alcohol was not a, desirable fluid to use on account of its sensibility to changes of temperature. No provision segmed to have been made by the authors for obtaining a constant temperature. He thought it ought to be constant to a tenth of a degree, as otherwise the expansion or contraction of the alcohol would give rise to a distinct error. He had himself obtained excellent results with water.As far as he could remember, the bottle No. 3 was exactly correct, according to a specification which he had drawn up for Messrs. Baird and Tatlock, and to which all bottles supplied by that firm were made. He had found that a, satisfactory method of calibrating these bottles was by means of a finely divided rule. He had not himself used the Leffmsnn-Beam process at all for about two years, but had previously used about two or three hundred of the bottles, and had always found them to be excellently graduated. He could not say whether they had fallen off in character ; but from the results shown in the paper this would seem to be the case. Mr.HEHNER said that faulty graduation was not found merely in Leffmann- Beam bottles, but in almost every other kind of measuring instrument. He had lately checked the graduation of a number of burettes, and had found that out of a dozen, only three came up to the requirements of an ordinarily careful analyst, the other nine being from 1 to 1.7 per cent. out. Too much trust had been put in the makers of scientific instruments in this matter, and he certainly thought that every burette and pipette should be checked before being used, as had been suggested by Mr. Richmond years before. The PRESIDENT said that he had no experience of Leffmann-Beam bottles, but he had used a set of Gerber bottles for a long time, and had never met with any discrepancies such as would indicate inaccurate graduation. Occasionally the results did not agree very closely, but this had generally been due to imperfect whirling before the use of the apparatus had been thoroughly mastered. It was very whole-6 THE ANALYST. some indeed for papers of this kind to be brought before the Society. Most analysts had had experiences similar to those which Mr. Hehner had mentioned, and had grown cautious in accepting the graduation of the instrument makers. It was not merely in instruments for the measurement of capacity that errors were found. They were very common indeed in hydrometers, even of a fairly expensive kind, and even in thermometers, which were so very easily tested.

ISSN:0003-2654    

DOI:10.1039/AN8982300003

出版商:RSC    

年代:1898

数据来源: RSC

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6 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOU R N ALS. FOODS AND DRUGS ANALYSIS. The Determinatios. of Fat in Watered Milk, Human Milk, Eumanized Milk, and Condensed Milk. (Jour. Pharm. Chinz., 1897, vi., 485-489,)- I n the author’s opinion, the most exact method of determining fat in milk is to precipitate the fat, together with the casein, by means of a dilute acid, and to extract the precipitate with ether But in the case of the milks cited above, coagulation is incomplete and clear filtration not possible, The author accounts for this by the fact that normd C ~ W ’ S milk contains a large amount of soluble calcium salts (from 6 to 7.5 grammes per litre), chiefly phosphates, which largely assist the coagulation ; whereas human milk onlycontains from 1.5 to 2.8 grammes per litre.In. the case oi humanized milk the &use is the same, as the phosphates are precipitated by the sterilization, and only partially redissolve on cooling. Similarly, condensed milk, when diluted, according to the directions, with four or five parts of water, contains only 3.5 to 4 grammes of mineral matter per litre. Experiments showed that the added sugar played no part in the imperfect coagulation, which was entirely due to the small proportion of salts. On these facts the author has based the following process, which he has found rapid and exact, and applicable in every case. It consists in precipitating the casein and fat with a solution prepared by mixing about 70 grammes of freshly precipitated calcium phosphate with 12 C.C. of glacial acetic acid and about 250 C.C.of water, and making the solution up to 2 litres. I n the determination 90 C.C. of this solution are mixed with 10 C.C. of the milk, the precipitate filtered off, dried, and extracted with ether in a Soxhlet apparatus. If required, the lactose may be determined in the filtrate in the usual way, after adding a few drops of potash to facilitate the precipi- tation of the cuprous oxide. In the case of condensed milk, 10 grammes are diluteitr,with warm water, the mixture cooled, made up to 100 c.c., and 10 C.C. taken for the estimation. C. A. M. J. Froidevaux. Action of Micro-organiams of Milk on Indigo-Carmine. I,. Vaudin. (Ama. cle Chinz. Aqzalyt., 701. ii., pp. 441-445.)-From a series of experiments made on the decolorization of indigo-carmine by milk, the author agrees with Duclaux inTHE ANALYST.7 attributing this reaction to the influence of microbes, and not to the action of albuminoids. He suggests that the addition of alkalies and antiseptics to milk should be prohibited, and that the decoIorization test should be applied to all milk offered for sale, the minimum permissible standard of time ensuing before decoloriza- tion occurs being fixed at twelve hours at temperatures below 15" C., eight hours at 15" to 20" C., or four hours above 20" C. c. s. Estimation of Volatile Fatty Acids in Butter. E. Wrampelmeyer. (Laizdw. Versuchsst., 1897, xlix., 215 ; through Chent. Zeit. Nep., 1897, 269.)-In carrying out the Leffmann-Beam process (c$ ANALYST, xxi., 259), the author dissolves the butter soaps in 250 C.C.of well-boiled hot distilled water, adds one drop of indicator and 50 C.C. of sulphuric acid (strength not stated). The whole is then distilled in a, current of superheated steam, which is introduced into the flask through a tube reaching below the level of the liquid; and the vapours are made to pass through a condenser at least 0.5 matre long. The steam i s obtained from distilled water free from GO,, and is superheated by means of a flat flame burner during its passage along a copper tube 30 cm. long and 1.4 cm. in difimeter. By working in this manner, the amount of decinormal alkali required by 5grammes of the butter- fat is increased some 5 or 6 c.c., and as the figures yielded by pure margarine remain the same as in Wollny's proceBs, the delicacy of the test is thus raised 15 or 20 per cent.F. H. L. ___ ~~ - On the Compulsory Addition of Sesame-Oil to Margarine. von Baumer. (Zeit. auyew. Chem., 1897, 749-751.)-By an imperial statute of July 4, 1897, it waB made obligatory on all margarine manufacturers in Germany to add at least 10 per cent. of sesame-oil to their products, so that any subsequent admixture of the margarine with butter might be readily detected by Baudouin's reaction. I n the author's ophion, such an addition is absolutely useless, for, apart from the fact that the margarine and butter industries are frequently carried on by the same individuals, and that the greater part of the admixture of margarine with butter takes place in large factories, where obviously margarine containing sesame- oil would not be used for the purpose, it is pointed out that Baudouin's test cannot always be regarded as conclusive.Thus it was shown by Spampani and Daddi (Stm. Sper. Agric. Ital., 1896, xxix.) that the fat from the milk of goats whose fodder had contained sesame-oil gave Baudouin's reaction. Of various vegetable coloring matters examined by the author, only one- t urmeric-gave the same colour as sesame-oil with hydrochloric acid and furfurd. But although turmeric gave the pink colour with hydrochloric acid alone, it was not possible to subsequently test for sesame-oil by adding furfural. (Of. ANALYST, this uol., p. 235.) In the case of yellow and orange coal-tar colours, the following gave a pink coloration with hydrochloric acid alone : (1) Ponceau.(2) Orange II., &naphthol orange, tropaeolin 000 No. 2. (3) Acid yellow G, the sdium salt of amido-azo- benzene sulphonic acid. (4) Dimethyl aniline orange, the sodium salt of dimekhyl-8 TEE ANALYST. amido-azo-benzene-mono-sulphonic acid. (5) Methanil yellow S, the sodium salt of a disulphonic acid of phenyl-amido-azobenzene. In the case of the two first, it is suggested that the colour might have been due to impurities, Butter-fat colored with any of these gave exactly the same colora- tion with hydrochloric acid alone as that shown by sesame-oil with hydrochloric acid and furfural; and although the author has no knowledge that these are employed to colour butter, there is nothing to exclude their use, whilst it is possible that other coloring matters may behave in a similar manner.C. A. M. Estimation of Glycerol in Wines. F. Bordas and 8. de Raczkowslri (Ann. de Chim. AnaZyt., vol. ii, [20], pp. 381-383.)-The first step is to separate the glycerol by distillation in a current of steam. This is effected by heating 25 C.C. of the wine- previcrusly neutralized by potassium hydroxide-in a short-necked 300 C.C. fla& immersed in brine-bath, the temperature of which is gradually raised to 110" C. The removal of the alcohol and more volatile substances is facilitated by connecting the apparatus with an exhaust ; and as soon as these are all distilled, a current of steam is passed through the liquid in the flask (still kept at 110" C.) during three hours, when the glycerol distils over. At the close of the operation the action of the exhaust is continued until the delivery-tube is thoroughly cooled down.The distillrtte containing the glycerol is then made up to 200 C.C. for titration. When the wine is poor in glycerol, 50 C.C. should be taken for the experiment, in which caw $he stesm is passed for an extra half-hour. A condenser at the rear of the receivers prevents any increase of pressure in the distilling flask. The glycerol is estimated colofimetrically : four test-tubes are taken, into each of theaa 5 C.C. of the before-mentioned solution are placed along .with exactly 2-5 C.C. of pure concentrated sulphuric acid, and 0.5, I, 1.5, and 2 C.C. of a solution of potassium bichromate (24 grammes per litre) added to them respectively. .The contents of one of the tubes will, after boiling, exhibit a yellowish-green tinge, and this one is selected as the basis for a second series of tests wherein the quantities of bichromate added are graduated by one-tenth of 1 C.C.above and below the quantity employed for the tube in question. &urn this series is selected the tube immediately preceding that one in which the Iiquid is of a slightly yellowish-green tint; and sinae 1 C.C. of the bichromate ,equals 0.0025 of glycerol,,the volume of bichrom& employed, multiplied by five, gives the quantity. of glycerol per litre of wine. In (case of doubt between two tubes, the mean is taken, bbt such instances are hardly likely to occur. Ln very sweet wines the complete extraction of the glycerol is prevented by the apposition of the syrupy residue to the penetration of the steam.c. s. On the Microscopical Examination of Food Substances. A. Hebebrand (Foorsch. Ber., 1897, iv., 306, 307.)-The author has found a preliminary treatment of the substance (suspended in an alkaline solution) with chlorine to give the most satiisfwtoty results, both a8 regards the dearness of the structure and the quantita- tive eSfimrttioa of foreign substances. I n his experience, the reagents usually employed, such as aqua regia and caustic soda, act too energetically in many instances,THE ANALYST. 9 Ip. gr. a t 25" C. and.cause the proporhion of foreign substance to be different from what it was in the original sample. Or if, on the otiher hand, weaker reagents are used, the structure does not appear with suffiaient clearness.A small quantity of the finely-powdered substance is mixed with 10 to 15 C.C. of a solution of 7 grammes of dry sbdium carbonate in 100 c.c., and chlorine passed in for a fewaminUtes (from two to ten, according to the nature of the substance), care being taken that the reaotion remains alkaline. The liquid is then diluted with water, and the bleached material separated, washed twice with water, and examined. This method is claimed to give especially good results with starches, and in some cases has enabled the authoz to make a carrect quantitative determination of rye meal in the presence of wheat meal owing to the former being attacked by the chlorine much more rapidly than the latter. The results, however, cannot always be relied upon. C.A. M. (Amer. JozLr. Pharnz., 1897, lxix., 577-579.)-The different products described in the U .S. Pharmacopceis as balsam copaiba, oil of copaiba, mass copaiba, and resin copaiba, are derived from shrubs and trees of the genus Copaiba, all of which. with the exceptiorr of two African species, are natives of tropical America. According to J. C. Umney, the sub&apces obtained from the latter differ very much from the more common American pud,ucts. The author has examined a large number of commercial samples, with the object of obtaining data as to their composition. I n every case his modification of the &a,cial acetic acid test ( A m e ~ . JOUY. Pharm., lxvii., 394) was found reliable for the detection of Gurjun bdsam. The samples in the subjoined table marked ' copaiba' are Fpid to be representative of the commercial article.Of the Para, samples, ~ 1 1 are good with the exception of that with a specific gravity of 0.9874 at 15" C., which in the author's opinion is not a normal Para copaiba, but a more concentrated oleo- resin. The solidifiable copaiba may also be taken to fairly represent those found in Copalba Balsam and Gurjun Balsam. L. F. Kebler. Per cent. of Oil distilled from Metallic Bath. commerce. 0.9800 at 15" C., which solidified well : The author has never met with a sample with a 0.9506 0.9372 0.9467 0.9381 0.9200 0.9583 0.9818 0.9116 0.9101 1.000 Source. 53 56 76 62 90 88 54 92 90 23 Carthagena . . . South America . . . Central America Collected in 1.846 South America ... ' I ? ) 7 7 9 , , I ,, 7 7 I , > > 7 7 Commerce ..... ,) 7 7 0.9516 0-9722 0,9476 Xnd of Balsam - 54 66 Copaiba 9 ) 7 , 9 , Para t , 8 , ,, SolidIkable Gurjun 2 , 9 , Sp. gr. at 15" C. 0.9560 0.9416 0.9526 0.9410 0.9254 0.9661 0.9874 0.9176 0.9146 0.9926 0.9576 0.9796 0.9531 Uoiling- point of such Oil c.. 250-265 253-268 250--274 253-270 258-270 254-268 253-265 256-268 254-264 260-269 - 245-263 240-260 specific gravity below SP. PT. of such Oil at 15" C. 0.9207 0.9174 0.9231 0.9116 0.9100 0.9346 0.9150 0.9283 - - - 0 *9202 0.9146 Sp. gr. of Steam- distilled Oil a t 15' C. 0.8997 0.9014 0.9132 0.9036 0.9079 0.9093 0.9019 0.9951 0.8936 0-9201 0.9200 0.9192 0.9930 Yp. gr. of Btesrri- distilled Oil at 25" c. 0.8981 0.9000 0.9067 0.8978 0.9066 0.9037 0.9100 0.9043 0.8904 0-9172 0.9146 0.9141 0.917610 THE ANALYST.The demand for solidifiable copaiba, mass copaiba, and resin copaiba, is very limited, and the article most in use is a copaiba containing 40 to 60 per cent. of oil. I n the U.S. Pharmacopaia only the solidifiable balsam copaiba (properly an oleo- resin of copaiba) is recognised, and the author considers that the official require- ments for it are inadequate. Thus he states that the residue is not necessarily brittle in the absence of any fixed oil, that the range of specific gravity is too low, and that a better limit would be 0.9800-1-0173. The test for Gurjun balsam, by heating the substance to 130" C., is said to be erroneous, for none of the samples examined congealed at that temperature, but only became slightly more viscous.He considers that more stringent tests are required for resin copaiba, since a t present almost any resin will answer the requirements. C . A. M. Detection of Turmeric in Powdered Rhubarb. A. Jaworowsky. (Phrm. Zeits. Russl., 1897, xxxvi., 543 ; through Chem. Zeit. Rqj., 1897, 281.)-One gramme of the sample is shaken for some minutes with 10 C.C. of chloroform, the liquid filtered, diluted with fifteen times its volume of petroleum spirit, and divided into two portions. One is shaken with 2 or 3 C.C. of sulphuric acid and the other with 1 or 1.5 C.C. of a saturated solution of borax. If the rhubarb is pure, the chloroform has a straw-pllow colour, which disappears on dilution. On addition of sulphuric acid, the acid becomes bpown, and the rest of the liquid remains colorless.The borax causes no change. I n presence of turmeric, the chloroform is yellowish- brown, and exhibits a green fluorescence. Petroleum spirit yields a flocculent yellow precipitate, but neither the colour nor the fluorescence of the chloroform is affected by it. The sulphuric acid itself is colored a magenta red, which quickly alters to a red and then yellow-brown; the other liquid turns violet. The borax solution becomes violet, but the spirituous layer is unchanged in its appearance. F. H. L. The Important Constituents of Taraxacum Root. L. E. Sayre. (Arne?.. Jour. Pharm., 1897, lxix., 543-546.)-The most important constituents identified by the author in taraxacum root are : (1) a resin, soluble in chloroform and ether, and insoluble in alcohol ; (2) a resin soluble in alcohol ; (8) taraxacerhz, a white, wax-like substance ; (4) a bitter principle, taraxacin, which in concentrated solution is pre- cipitated by many alkaloidal reagents. Attempts to isolate the bitter principle in crystalline form all proved unsuccessful, for it was found impossible to obtain crystals free from oleo-resinous drops, though acetone appeared to be the most promising solvent. Taraxacerin, the wax-like body referred to above, separates from alcoholic solution in cauliflower-like forms. It melts at about 450 C., and has an empirical formula corresponding to C,H,,O, or a multiple of this. The amount of ash in one sample of the root dried at 100" C., was 11.13 per cent. with the following composition :THE ANALYST. :I. 1 Silica, ... ... ... ... Alumina, ... ... ... ... Ferric oxide ... ... ... Calcium oxide ... ... ... Potassium oxide ... ... ... Magnesium oxide ... ... Sulphuric acid (SO,) ... ... Phosphorus pentoxide ... ... Carbon dioxide ... ... ... Chlorine ... ... ... ... ... ... ... ... ... ... ... ... ... ... 7 . . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... Per cent. 43.27 18.07 0-80 5.75 6 *60 13.83 4.22 trace 6 53 1.20 100.27 C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8982300006

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年代:1898

数据来源: RSC

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THE ANALYST. ORGANIC ANALYSIS. Examination of Wax. G. Buchner. (Zeit. fiir oflea. Chemie, iii., 570.)- In the Chem. Revue iiber die Fett z6nd Harzindustrie, 1897, p. 261, K. Dietricb pub- lished some results obtained on examining bees-wax by Hiibl's method and by Henriques' cold saponification method, leading to the conclusion that the constants obtained by Hiibl's method are not always to be depended upon. The author bas examined two samples of bees-wax, of unquestionable pu&y, by both methods, (a) by dissolving in 25 C.C. of warm petroleum benzine in the ordinary way, whereby some loss of benzine by evaporation is sustained, and ( b ) by dissolving under special precautions, to avoid such loss. The following results were obtained : HURL'S METHOD. I. 11. - - (a) ( h ) fa) @) Acid number ...... ... 18.37 18-50 17-23 17.76 Ether number.. . ... .. 75.98 75.81 75.98 74-60 Saponification number ... 94-35 94.31 93.21 92.36 Ratio ... ... ... ... 4.15 4-10 4-41 4-20 HENRIQUES' COLD SAPONIFICATION METHOD. Petroleum bemine boiling at 100" to 150" C. I. 11. & & ( a ) ( b ) ( a ) ( b ) Acid number ... ... ... 19.48 19.48 19.11 19.11 Ether number ... ... ... 72.81 72-81 72.81 72.81 Saponification number ... 92-29 92.29 91.92 91.92 Ratio ... ... ... ... 3.74 3.74 3.90 3-90 Petroleum benzine boiling at 50" to 80" C. I. 11. & 7- ( a ) ( b ) ( a ) ( b ) 17.64 19-11 Acid number ... ... ... 18-39 19.48 Ether number . . . . . . ... 53-60 71-09 54.53 68.16 Saponification number ... 72.99 90-57 72.27 87.27 Ratio ... ... ... ... 2.91 3-65 3.09 3.5612 THE ANALYST.The lower the boiling-point of the benzine, the more dificult is it to effect the solution of the wax, and the more incomplete is the saponification. For cold saponification, petroleum benzine boiling at 100" to 150" C. is indispensable; but the results obtained are very exact, surpassing those yielded by Hubl's method. Hiibl's method has, however, the advantage of rapidity of execution. H. H. B. S. Examination of Rose-Oil, F. Dietze. (Reprint from Sudd. Apoth. Zeit., 1897, No. 89 ; through Chenz. Xeit. Bep., 1897, 288.) -The author states that geranium-oil can be detected in rose-oil by determination of the saponification number, and he has obtained the following values for this constant in different specimens of the two substances : Rose-oil from Germany, 8.6 ; Bclgaria, 9.2; Turkey, 8.9 ; geranium-oil from France, 59.1 ; Africa, 53.1 ; Spain, 75.3 ; India, 32.5.He also suggests the annexed specification : Genuine rose-oil should have a specific gravity not exceeding 0.870 at 15" ; its solidifying point should not be lower than 15" or 20"; its saponification number not higher thari 9.5 or 10; and its rotatory power in a 100 rnm. tube at 20" C. not more than -1" 30. F. H. L. Properties of Some Essential Oils. Reports of Schimmel and Co. and H. Haensel. (Deutsche Chem. Zeit., 1897, xii., 385.)-01~ OF BAu.-When freed from terpenes this oil separates into two immiscible layers; the upper one is yellow and has a sp. gr. of 0.9533 ; the lower is a brown commercial product, sp. gr. 1,0358; and the terpenes themselves have a spI gr.of 0.8146 (all at 18" C.). OIL OF ANIsEEn-This is liable to be adulterated with oil of fennel and stearoptene. OIL OF CANANGA is largely sophisticated with cocoa-butter, which raises the saponification number; but as other esters (Ylang-ylang oil), boiling at a lower temperature, are apt to be present, this test alone is not satisfactory. Its behaviour with alcohol and in a freezing mixture are, however, characteristic : Solubility in. Rehavioui in Sp. gr. Rot. Power. Sap. No. Vols. of 95 per Freezing cent. Spirit. Mixture. Pure Cananga, crude 0.916 - 21" 27' 17.8 0.5 to 2. Liquid. l i k e d wiih cocoa-fat 0-919 - 17" 1' 83.7 Se;.' of oil. Bilomes buttery. Ditto and rectified ... 0.908 - 21" 50' 14-4 0.5 to 2. Liquid.(1) From Malabar.-Sp. gr., 0.943 ; rot. power, + 34" 52' at 19" ; sol. in 4 parts of 70 per cent. alcohol ; sap. no., 137 (.? 13.7). Contains acetic acid, cineol, and dextro-terpineol. (2) From Siam.-Sp gr., 0.905 ; r. p., +38" 4' at 42" ; sol. in 1-2 parts of 80 per cent. alcohol ; sap. no., 18.8 ; after acetylation, 77.2 ( = 22.5 per cent. of borneol). Contains + borneol and camphor. (3) From Cameroons. -Sp. gr., 0.907 ; r. p., - 20" 34' ; sol. in 7-8 parts of 80 per cent. alcohol. Contains cineole. (4) Oil of Gyains of Paradise.-Sp. gr., 0.894; r. p., -3" 58' ; sol. in 10.11 parts of 90 per cent. spirit. OIL OF CEDAR-WOOD.-Cedrene, the hydrocarbon of this oil, after distillation over sodium, boils at 131"-132" at 10 mm. pressure ; its r. p. is - 47" 54! ; and it is a refined 0.915 -20" 48' 16.0 OIL OF CARDAMOMS.TEE ANALYST.13 sesquiterpene. With chromic and glacial acetic acids it yields a ketone (cedrone), boiling at 147" to 151' (7.5 mm.). ItB oxime boils at 175" to 180" (8 mm.), and forms an acetate boiling at 185" to 190" (9 mm.). By reduction with sodium in ethereal solution the ketone gives liquid isocedrol (b.p., 148" to 151" at 7 mm.), the benzoic ester of which boils at 221" ta 223" C. at 6 mm. OIL OF CITRON.-For this and the two next oils, the 'Italian Government has specified the following (far too severe) requirements : Sp. gr. at 15", 0-857 to 0.862 ; r. p. at QO", between +57" and +67" in a 100 mm. tube. When 50 C.C. are frac- tionated, the first 5 C.C. distiIled must have an opticity not exceeding 5" less than the original oil.(According to SoEdiani and Bert&, when half the oil is dietilled the distillate should have a r. p. higher than that of the residue, and also than that df the sample.) OIL OF ORANGE.-S~, gr., 0,847 to 0.853 at 15" ; r. p., +96" to 98" at 20". OIL OF BERGAMOT.-^^. gr., between 0.882 and 0.886 at 15" ; r. p., between + 8" and + 20" at 30" ; the ester content, determined on 2 or 4 grammes of the oil with normal potash in a flask fitted with inverted condenser, not below 30 per cent. ; 5 grammes evaporated on the water-bath not to leave more than 6 per cent. of residue ; must be soluble in 0.5 vol. of 90 v/v* alcohol, and remain clear on further dilution. AMBIREAN FIR-OIL (Pinus syZvestris).-Sp. gr., 0.884 ; r. p., - 24" 8' at 18" ; sol.in 8 or more parts of 90 per cent. spirit with slight turbidity; sap. no., 34.8 (the ester is probably bornylic acetate ; if so, it equals 12.1 per cent.). The English oil is also laevorotatory, while the German and Swedish specimens are dextro- rotatory. Con- tains 38 per cent. of laevorotatory bornylic acetate, also lzvorotatory pinene, and % sol. in 1 or more parts of 90 per cent. alcohol. SPRUCE-OIL (Picea niqra or aZba L.).-Sp. gr., 0.913; r. p., -23" 50 at 81"; sol. in 0-5 vol. of 90 per cent. alcohol, and yields with 5 vols. a strongly opalescent liquid. It also contains ltlevorotatory bornylic acetate and laevorotatory pinene, and cannot be distinguished either by odour or otherwise from the previous oil. GUAIACUM-OIL in its normal state melts at 45" or 50" ; but for the preparation of essences a more fluid sort is preferred, which remains liquid at summer temperatures.The crystalline alcohol, guaiacal, is odourless. The oil forms a favourite perfume, and is used in soap. OIL OF &fYRRH.-Bisabol myrrh, coming from the interior of Somaliland, has been investigated by Tucholka. On shaking out the alcoholic resin solution with petroleum spitit, evaporating the solvent and distilling the residue with steam, a pale-yellow limpid oil was obtained, having a characteristic odour, the yield being 7.8 per cent. Dried over calcium chloride, its sp. gr. at 24" was 0.8836 ; it boiled between 220" and 270" ; and its optical values were : nu22.30 = 1.4874, and [ a ] D240 = - 14" 2 0 (100 mm. tube). By the action of HCl gas on its ethereal solution, 65 per cent.of a hydrochloride WEMLOCK-OIL (Abies Canademis).-Sp. gr., 0.911 ; 'r. p., - 25" 22' at 16". * Per cent. by volume (cf. ANALYST, xxii , 89).14 THE ANALYST. was produced, which, after repeated crystallizations from alcohol and ether, melted at 79.3". Sodium acetate and glacial acetic acid split this up into a hydrocarbon with sp. gr., 0.8914 at 17"; b. p., 259" to 260.5"; and refractive index, 1.4608. I t appears to be a new terpene, and has been named bisabolene. OIL OF PETIT-GRAIN.-Passy has lately found that this oil contains considerable quantities of geraniol, partly free and partly as the acetic ester ; these seem to exert much iduence on its odour. OIL OF PEPPERMINT.-TO estimate the menthol, 5 grsmmes are heated under an inverted condenser with (exactly) 5 C.C.of acetic anhydride for half an hour, and, after cooling, the excess is titrated with normal soda, the strength of the anhydride being determined in the meantime in a similar manner. The volume of alkali neutralized x 0.156 gives the menthol. OIL OF ROSEMARY has been proved to contain pinene. Ih should answer to the following requirements : sp. gr., above 0.9 ; r. p., + ; sol. in 0.5 vol. of 90 per cent., and also in 10 vols. of 80 per cent. alcohol ; on distillation, the first 10 per cent. must have a + r. p. OIL OF SANDAL-WOOD should be examined by acetylation, determination of sp. gr., r. p., and sol. iQ 70 per cent. spirit. OIL OF VETIVER (Cuscus) differs largely in its constaBts. When pure it has sp. gr.11019 to 1.027 at 15"; r. p., +25" or 26"; sap. no., 70 to 80; SOL in 80 per cent. alcohol 1.5 to 2 vols. OIL OF XANTHoRRHau.-On distilling the resin from the Australian yellow grass tree," 0.37 per cent. of yellow oil smelling like storax is obtained. Sp. gr., 0.937 ; r. p., - 3" 14' ; acid no., 4.9 ; sap. no., 74.3 ; ester no., 69.4. The free acid is cinnamic, and melts at 133". On saponification, 20 per cent. of the same substance may be recovered. OIL OF MARVEL OF PERU (Tanacetunz balsanzitu L.).-Prepared from the flowers ; yield, 0.064 per cent. ; odour like tansy ; sp. gr., 0.943 ; r. p., -53" 48' at 16" ; sap. no., 21. Insol. in SO per cent., but sol. in 1 or 2 vols. of 90 per cent. alcohol, further additions causing turbidity and separation of white flocks. Distils between 207" and 283".. Colour reactions are useless. HeZiotropk-A product having this name has been put on the market by a Swiss firm. It consists of heliotropin, 90 per cent. ; vanillin, 10 per cent. ; solution of ionone, 0.5 per cent. ; and a trace of rose-oil. Ionone.-A crystalline preparation called '' ionone " has been met with, composed of one of the artificial musks, which had been given a violet-like odour by being crystallized from ionone. It contained nitrogen in the form of a nitro compound, exploded on heating with sodium, while its odour changed from that of violets to that of musk on boilisg with water, Concrete Violet.-This is an American product belonging to the class of fixed scented oils. It consists of a mixture of fat, oil of iris (sweet flag) and artificial musk.If the molten substance is shaken with 80 per cent. alcohol, the fat filterad off, and the solution treated with parabromphenylhydrazine, a yellow precipitate is produced, which The latter crystallizes out of its solution in petroleum ether.THE ANALYST. 15 crystallizes in transparent scales from hot spirit (m. p., 156"). The odour is there- fore due to irone, and noti ionone. Myristic acid is much used as the fat or solid matter in these fixed scented oils; and the following figures give approximately the amount of it contained in different varieties : Jasmine, 50 per cent. ; elder flowers, 49 per cent. ; acacia, 69 per cent. ; fixed rose-oil, 73.8 per cent. ; reseda (mignonette), 85 per cent. ; violet flowers, 86 per cent.[NOTE BY ~STRACTOR.-T~~S article also contains a number of further details respecting these oils, etc. ; but they do not appear to possess any analytical interest.] F. H. L. Application of lklaurnen6'a Method to the Examination of Essential Oils. M. Duyk. (Rev. dc Chim. AnaZyt. AppZ., vol. v., pp. 442-445.)-1n order to prevent the violence of the reaction which ensues, in applying this test to essential oils, it was found necessary to dilute the oil with an inert substance, and for this purpose com- mercial, colorless, liquid paraffin was employed. To apply the test, 4 C.C. of the liquid paraffin and 1 C.C. of essential oil are mixed by shaking in a 15 C.C. dask fitted with a thermometer, the bulb of which is immersed in the liquid. Two C.C. of pure monohydric sulphuric acid are then carefully pipetted down the side of the flask, and, after the thermometer has been read, are shaken up with the other contents, the resulting increase of temperature being read off as soon as the maximum is obtained.The difference gives the increase occurring under the conditions of the experiment. The subjoined figures were obtained by the foregoing method, the initial temperature being 120' C., and the weight of the flask 30 grammes : TERPENE HYDROCARBONS. Cymene, C10H14, from turpentine essence, 4" C. Pinene, ClOHl6, from turpentine essence, 36" C. Limonene, Cl0El6, from citron essence, 26" C. Carvene (Limonene), from caraway essence, 26" C. Thymene, CIOHIG, from thyme essence, 13" C. Cedrene, C15H24, from cedar essence, 15" C. OXYGENATED COMPOUNDS.Anisol, from anise essence, 22" C. Thymol, from thyme essence, 7" C. Safrol, from sassafras essence, 33" C. Carvacrol, from thyme essence, 4.5" C. Apiol camphor, from parsley essence, 32" C. Eugenol, from clove essence, 27" C. Geraniol, from geranium essence, 31.5" C. Menthol, from mint essence, 9" C. Linalool, from linaloe essence, 38" C. Eucalyptol, from eucalyptus essence, 22" C. Terpind, from turpentine essence, 26" C. Santalol, from santol essence, 33" C.16 THE ANALYST. Citral, from lemon-grass essence, 40" C. Anisic aldehyde, 14" C. Benzaldehyde, from bitter almond essence, 90 C. Menthone, 11" C. Citronellol, from citronella essence, 33" C. Carvof, from caraway essence, 30" C. ESSENTIAL OILS. That prepared by the author gave 30" C. Santal-Enst Ij2diun ; Sarnples from different makers ranged between 22.5" C.West Indian: 12", and 31" C, 16", 18" C., according to the maker. Cedar : different makes, l@ to 18" C. Copaiva : 24" C. Gurjum : 21" C. Mint : Mitcham, 16" C. ; Saxon, 13" C. ; Crkpue Japanese, 20" C. Lavender : French, 37", 36", 34" C. ; English,.33" C. Spike lavender : 29.5" to 30" C. Rose : Pure Turkish, 34.5" C. Geranium : Turkish, 24" C. ; freed from hydrocarbons, 25" C. Citron : 25" to 26.5' C. ; freed from hydrocarbons, 29" C. Portugal orange : 37" C. ; Neroli, 36.5" C. ; Petitgrain, 33.5" C. Red thyme : 23.5" C. Clove : 28O.C. Bitter almonds : 9.5" C. Canella : Ceylon, 20" C. ; China, 14" C. Caraway : French, 28" C. ; German, 30" C. ; Cumin, 17" C. Green anise : 17" C. Aniseed (badiane) : 21' C.Rectified thyme : 22.5" C. Eucalyptus : 24" .C. Fennel : 19.5" C. c. s. Preparation of Su.gar Liquors for Polarimetry. J. Diamant. (Chenz. Zeit., 1897, xxi., 981.)-The author recommends the use of zinc-dust to remove the excess of lead from sugar solutions which have been decolorized by meanq of lead acetate. The precipitates settle quickly, the liquids are much clearer than before treatment with zinc, and the salts of the latter metal are without influence on the readings of the polarime t er. F. H. L. Use of Alcohol for the Reduction of Cuprous Oxide in Sugar Determina- tions. (Zeit. fiir. oflent. Clzemie, iii., 573.)-The cnprous oxide ob- tained in gravimetric sugar-determinations by Fehling's solution is reduced by means of alcohol, and the copper weighed in tho metallic state.The procedure is as follows: The copper precipitate is filtered off and ignited in a platinum crucible. The crucible is then covered with a lid, having a hole in the centre and 1 C.C. of methyl alcohol added, a drop at a time, through the hole, the crucible being mean- while maintained at a red-heat. The lamp is now turned out, and 1 C.C. of methyl alcohol run in at one time. The drops of alcohol at first added assume the spheroidal state, and consequently evaporate but slowly, so that the vapour has time to exercise its reducing action upon the oxide. The 1 C.C. added after the lamp has been turned out prevents, by its evaporation, the entry of air into the crucible, and thus protects the copper, while hot, from oxidation. The vapour of the alcohol is finally ignited, G.Bruhns.THE ANALYST. 17 and when it has burnt out, the crucible lid is removed and the crucible exposed to the air until no further odour of alcohol or formaldehyde is given off. I t is allowed to remain five minutes in the balance-case, and is then weighed. The weight is quite constant, but, for the sake of control, the crucible can be heated again for a short time and re-weighed. Ethyl alcohol of 99 per cent. can be substituted for methyl alcohol; but in this case a little carbon separates, which discolors the copper, though scarcely any increase in weight is perceptible. H. H. B. S. Reactions of the Glucotannins of the Cinnamic Acid Serbs. 'H. Khnz- Krause. (Chem. Zeit., 1897, xxi. , 941.) - These bodies exhibit several reactions common to the whole group, among which the following are the most important.Dissolved in alcohol and treated with metallic sodium, they give a yellow precipitate, which is easily soluble in water. They evolve hydro- cyanic acid with Liebermann's reagent in the cold. They yield glucosazones on the addition of phenylhydrazine. The best-khown member of the series is caffetannic acid (glucosyldihydroxy- cinnamic acid), which is identical with matetannic acid. This substance readily absorbs water, alcohol, and ammonia. It combines with orthophenylenediamine , and its osazone melts at 180" C. With uranium acetate it yields a reddish-brown precipitate, but no carbon dioxide is given off when the products of the reaction are insolated. By itself, and in presence of acids, caffetannic acid is quite permanent ; even on warm- ing alone or with dilute acids it is not easily attacked; but on heating with strong hydrochloric acid it is converted into an amorphous, humus-like body. Bromine water splits up the molecule into a soluble sugar and a brown insoluble substance containing the halogen.The reaction, however, does not proceed smoothly, SO that it is impossible to estimate caffetannic acid by determination of the sugar with Fehling's solution. Nevertheless, the decomposition praves that these glucotannins are true glucosides, a point about which there has previously been some uncertainty. They form yellow lead-salts. With chloral hydrate it forms a yellow, rather unstable compound. F. H. L. Volumetric Estimation of' Uric acid. J. W. Tunnicliffe and 0. Rosen- heim. (Ceiztralbl. Physiol., 1897, xi., 434 ; through Chew,. Zed. Rep., 1897, 280.)- This process depends on the fact that piperidine combines with uric acid in mole- cular proportions (4.25 grammes of base equal 8-4 grammes of acid) to form a soluble salt. A & solution of the former is prepared by dissolving about 4.2 grainmes of piperidine in 1 litre of water, standardizing it on hydrochloric acid of equivalent strength, phenolphthaleh being used as indicator, The sample of uric acid is suspended in water, heated nearly to the boiling-point, and the reagent run i n ; neutrality being shown either 'by the liquid becoming clear or by the use'of phenol- phthalein ae before. Although the solubility of the urate at 15" is 5.3 per cent., it is better to employ hot solutions ; and there is no danger of losing any piperidine by volatilization, as the reaction is instantaneous. The method is particularly adapted for the examination of urine ; and the uric acid is best obtained in a form suitable18 THE ANALYST. for titration by Eopkin’s process. This eonsists in separating the acid as its acid ammonium salt, and then decomposing the latter with HCL The crystals must, of course, be washed on a filter till free from hydrochloric acid; but 15 or 20 C.C. of water are usually sufficient for the purpose. The paper is then perforated, and the uric acid is rinsed into a flask with 20 or 30 C.C. of hot water. F. H. L.

ISSN:0003-2654    

DOI:10.1039/AN8982300011

出版商:RSC    

年代:1898

数据来源: RSC

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18 THE ANALYST. INORGANIC ANALYSIS. The Determination of Lead in Lead Ores. R. K. Meade. (Jow. Amer. Chcm. SOC., 1897, xix., 374-377.)-The following is recommended as a simple and rapid method for the determination of lead in galena and lead ores in general in the absence of barium, strontium, and calcium, and of metals oxidized to insoluble com- pounds by nitric acid : One gramme of the ore, or more if poor, is heated in a covered platinum dish on a sand-bath with 40 to 50 C.C. of a mixture of one part of sulphtiric acid (specific gravity b.84) and three parts of nitric acid (specific gravity 1-42) until the action has apparently ceased. 10 to 15 C.C. of hydrofluoric acid are then added, and the solution evaporated until fumes of sulphuric acid begin to come off. The dish is cooled, and aft& dilution of the liquid to about 100 c.c., the insoluble matter is filtered off, washed first with a 2 per cent.solution of sulphric acid and then with alcohol, dried, ignited apart from the filter-paper, and weighed as lead sulphate. Experiments with a solution of lead nitrate proved that no lead was lost by volatilization as fluoride, although the results were slightly lower on evaporating 25 C.C. of the solution with sulphuric and hydrofluoric acids fhan with sulphuric acid alone, the averages of six determinations being 0.4280 gramme and 0.4297 gramme respectively. 25 C.C. of the solution, to which 0.2 gramme of silica, had been added, when evaporated with the two acids, gave 0.4285 gramme of lead sulphate. The analysis of different lead ores by the method given by Fresenius (Qua&.Anal., 213), and by this method, after calcium, barium, and strontium had been proved to be absent, gave the following results : Fresenius. New Method. Per cent. lead. Per cent. lead. Galenite ... ... ... ... ... 77.34 ... 77-46 Cerussite ... ... ... ..f ... 76.46 ... 76-53 Barium and strontium are rarely found associated with lead, and calcium, when present as calcite, may be removed by treating the ore with hydrochloric acid and filtering. The residue containing the lead is then treated with sulphuric, nitric, and hydrofluoric acids, as described above. Pyromorphite ... ... ... ... 75.26 ... 75.35 C. A. M. Note on the Analysis of Bronze and Braas. F. Fatet. (Am. de Clzinz. Analyt., vol. ii. [ZO], pp. 383-385.)-Having found that the titration of zinc in an ammoniacal solution containing copper cannot be accurately performed by meau s of sodium sulphide after the copper has been decolorized by potassium cyanide, and also that the presence c~f zinc falsifies the titration of the copper by the last-named reagent, the author examined the method proposed by F.Jean for estimating theseTHE ANALYST. 19 metals in impure galena-viz., titration of the two metals by sodium sulphide in an ammoniacal solution, then acidifying with hydrochloric acid, to redissolve the zinc, and, after boiling ;he filtered liquid and adding ammonia, titrating the latter metal with the same reagent, the copper being estimated from the difference between the two tests. He finds that this method affords an accurate and speedy means for the analysis of bronze and brass.To check the end point of the precipitation of the sulphides, he recoinniends the test proposed by Mohr-ie., the brown arc formed at the point of contact between a drop of an alkaline solution of lead and a drop of the test liquid placed on filter-paper. c. s. Estimation of Iron with Permanganate in Presence of Hydrochloric Acid. M. HaufFe. (Chenz. Zeit., 1897, xxi., 894.)-The author employs the following combination of well-known methods : Reageuts mcessary. - (1) Permanganate solution containing 3 grammes per litre, standardized on p r e iron under the conditions as detailed below ; (2) 100 grammes of crystallized manganese sulphate, dissolved in 1,300 C.C. of water and 200 C.C. of pure concentrated sulphuric acid; (3) a cold-saturated solution of mercuric chloride ; (4) a dilute solution of stannous chloride.Process.-A suficient quantity of the material under examination to serve for several titrations is dissolved in a moderate excess of warm HC1, and, if organic matter is present, the liquid is treated three times with some strong permanganate, and boiled till free from chlorine, any oxide of manganese thrown out being taken up in F+ few drops of acid. When cold, it is diluted to a definite volume, and an aliquot portion (50 to 200 c.c.) is heated to boiling in a beaker capable of holding 2 litres. Stannous chloride is then run in from a burette till, after all the iron is reduced to the ferrous state, enough of the reagent still remains unoxidized to give a slight precipitate when 100 C.C.of the mercuric chloride solution are next added (cf. the somewhat similar, process, ANALYST, xxii, 299). If the excess of stannous chloride is too large, the precipitate of mercurous chloride becomes so bulky as to hide the pink colour in the final titration, but if the mercuric chloride does not produce any precipitate, too little tin has been employed. Finally, 60 to 100 C.C. of the manganese aulphate are intraduced, the liquid cooled as rapidly as possible, 1 litre of water added, and the whole titrated with the permanganate. When only trifling amounts of iron have to be determined, a blank experiment should be carried out on 10 C.C. of the stannous chloride, 10 C.C. of HCl, and 50 C.C. of water, warmed together, and treated with HgCl,, etc., as above, in order to make proper allowance for the few drops of permanganate required to yield a visible pink in such a large mass of fluid (1-5 litres).Iron orea should be dried at 105"C., and 5 grammes dissolved, first by boiling with HC1 (specific gravity 1-19), and then by fusion with alkali carbonates in the ordinary manner; and if the proportion of silica is not so high as to cause the liquids to boil badly, it need not be removed. The volumes employed should be adjusted to allow either 0.5 or 1.0 gramme of the mineral to be titrated according to its richness in iron. In the case of phosphates, 25 grammes should be dissolved in 50 or 60 C.C. of strong acid, and 5 grammes taken for each analysis ; but the amount of manganese20 THE ANALYST.sulphate should be increased to 100 or 150 c.c., so that there moly be no odour of chlorine perceptible during the addition of the permaneate. F. H, L. Estimation of Alumina and Iron m Phosphates. F. Jean. (Ann. de Chinz. Analyt., vol. ii. [20], p. 403.)-The solution of the phosphate is made up to 100 c.c., and, after the phosphoric acid has been thrown down by the ordinary citro-magnesia, method, 50 C.C. of the clear liquid are pipetted into a bulb flask, and there concen- trated to 8 or 10 C.C. This quantity is boiled with 25 C.C. of 66 per cent. sulphuric acid and 5 C.C. of fuming nitric acid until colorless, the elimination of the organic matter being accelerated by the addition, at intervals, of a few crystals of sodium nitrate or a little nitric acid.When cooled, the liquid is diluted and treated with alcohol to precipitate calcium sulphate. After filtration the alcohol is boiled off; and, after the addition of a few crystals of potassium chlorafe, the iron and alumina are thrown down by ammonia. When manganese is present, the precipitate is fused in a platinum crucible with an alkali carbonate and potassium nitrate, the mass being taken up with water and the residue (iron oxide) weighed. Manganese is determined by titration, and the alumina estimated by difference. c. s. The Behaviour of Thoria with Oxalic Acid and Ammonium Oxalate, and the Estimation of Thoria. (Zeit. anal. Chem., 1897, xxxvi., 213-219.) -In a former communication (Chem. Zeit., lxiii., 612 ; ANALYST, xsi., 274-277) the author stated that the thoria recovered after the ammonium acetate treatment, when redissolved, could no longer be completely precipitated by adding ammonium oxalate, boiling, and allowing the liquid to cool.This he now finds to be due to the fact that thorium oxalate in nearly neutral solution is soluble in large excess of ammonium oxalate, a statement which confirms the results of other observers. When there is not an excess of ammonium oxalate, no precipitation occurs in a boiling nearly neutral mineral acid solution of thoria, but on cooling the thorium oxalate comes down in crystalline form. Ammonium acetate only increases the solvent action of the liquid. By adding oxrtlic acid, or by making the solution strongly acid with hydro- chloric acid, the thorium is precipitated quantitatively even when there is a large excess of ammonium oxalate.The composition of the precipitate varies considerably, according to the method by which it is obt&ned. Thus, on adding oxalic acid to a solution of thoria before boiling, a precipitate of the normal oxalate is formed on cooling; but if the solution be boiled before the oxalic acid is added, the precipitate coneists of a mixture of thorium oxide and oxalate, the oxide being sometimes partially precipitatad before the oxalic acid is added. On precipitating thorium by ammonium oxalate (not in excess) from a nearly neutral solution, the normal oxalate is not obtained, nor is it when the thorium is precipitated by ammonium oxalate from a solution made strongly acid with hydro- chloric acid.From these experiments it follows that a complete separation of thoria and C. G l a e r .THE ANALYST. 21 zirconia by means of ammonium oxalate is only possible when care is taken to avoid a greater excess of ammonium oxalate than is required for the solution of the zirconium oxalate, but when cerium is also present, it is very difficult to avoid an excess on account of the insolubility of cerium oxalate. The author finds further that in separating cerium and thorium oxalates by me8rns of ammonium acetate, a large excess of the latter must be avoided, since cerium bxalatd ia slightly soluble in ammonium acetate. Only a few C.C. of the reagent are required to dissolve out the whole of the thorium from the mixed oxalates. As it was possible that these facts might make an alteration necessary in the scheme of analysis given in the previous paper, a sample of monazite Rand was anttlysed by that method, but it was found that, notwithstanding its solubility in excess of ammonium oxalate, the whole df the thoria had separated out completely.I t is, however, advisable to examine the filtrate from the mixed oxalates of thorium and cerium, by adding aminonis in excess, filtering, dissolving the precipitate fn hydrochloric acid in excess, adding oxalic acid, and leaving the liquid in a warm place. When a determination of cerium is not required, the solution of the earths in dulphuric acid can be treated a6 once with an excess bf hydrochloric &cia and oxalic acid, and the precipitated thorium and cerium oxalates separated in the usual way by means of ammonium acetate.The following remarks refer to the table of the more iniportant reactions of the fare earths in the former paper : 1. The statiment that thoria and ceria are precipitated by ammonium carbonate as well as by ammonia (Graham-Otto, part 2, 902-904) is incorrect. 2. Ammonium oxalate precipitates thoria in cold, but not in boiling, solution. An excem of hydrochloric acid precipitates the oxalate quantitatively on cooling. 3. The statement that thorium oxalate kept in solution by means of ammonium acetate and ammonium oxalate is partially precipitated by hydrochloric acid should h a d : that in the presence of a sufficient excess of hydrochloric acid the precipitation is complete. 4. Mention should be made of the solubility of zirconium oxalate in hydrochloric acid.5. Cerium oxalate is slightly soluble in ammonium acetate. C. A. M. Analysis of Sodium Bicarbonate. G. Lunge. (Zed. angezil. Clzenz., 1897, 169-171).-This method, which was devised by Sundstrom, depends on the fact that a solution of sodium bicarbonate, when treated with sodium hydrate, is converted into carbonate. The end of the reaction is indicated by the excess of sodium hydrate giving a brown colour with silver nitrate solution, used as an outside indicator. From the result thus obtained, together with that of the total acidity determined by titration with normal acid, the composition of the sample can be calculated. The solution of sodium hydrate is prepred by dissolving commercially pure cauetid soda, in water till the specific gravity reaches 1.16, precipitating with barium chloride, adding barium hydrate to saturation and diluting the solutiOn to normal strength.22 TBE ANALYST.The use of ordinary normal sodium hydrate did not give satisfactory results, and, as the author points out, the barium hydrate in Sundstrom's solution at once detects the presence of any carbonate. C. A. If. Analysis of Commercial Liquid Ammonia. A Lange and J. Hertz. (Zed. angezo. Chm., 1897, 224-228.)-The authors find that the residue left on the evaporation of German liquid ammonia consists chiefly of water, pyridine bases, acetonitrile, ethyl alcohol, and a little machine oil ; with ammonium carbonate, benzene, and naphthalene as occasional impurities. For the valuation of liquid ammonia in practice, it is sufficient to determine the amount of residue without taking into account its composition.This is done by placing the bottle in a horizontal position, and screwing on to the valves an open steel tube. By opening the valve, from 20 to 50 grammes are allowed to flow into a previously-weighed Erlenmeyer flask, and rapidly weighed after the insertion of the stopper. This has two openings, through one of which passes a glass tube (a), bent at right angles, whilst the other communicates with a potash tube ( b ) . The glass tube is kept closed, so that the evaporating ammonia must pass through the potash tube. The evaporation, which is complete in from two to three hours, may be assisted by an occasional shake. The residue which it still contains is warmed to (at most) 40" C., and a current, of dried air passed into the flask through the glass tube (a) Both tubes are then closed, the apparatus again weighed, and the amount of residue calculated.I t was proved by experiments that the different samples taken were homo- geneous in character, and that none of the impurities referred to were lost during the evaporation of the ammonia. Thus, on taking samples of 33 grammes each from the same bottle in onequarter, in one, and in five minutes, the amount of residue obtained was 0.9, 0.9, and 1.0 per cent. respectively. The apparatus used by the authors for the volumetric determination of the residue consists of a glass tube of from 30 to 40 mm. internal diameter, which is fused at the bottom to a narrow tube of about 5 mm.diameter, this part holding at least 1.1 C.C. The larger part of the tube contains about 100 c.c., and has a mark at 49 C.C. corresponding to 33.3 grarnmes of ammonia. The lower narrow portion of 1.1 C.C. is graduated into fifteen parts, so that each corresponds to 0-2 per cent. The tube is filled to the mark with ammonia, a grooved cork inserted, and the liquid allowed to evaporate spontaneously. This takes about three hours, but the operation may be completed in half an hour by placing the tube in water. The presence of much water in the residue is a source of error, since the latter may then retain about 25 per cent. of ammonia, but with the average constituents of the residue the error is trifling. C. A. &I. Separation of Bromine from a Mixture of Soluble Bromides and Chlorides.Baubigny and Rivals. (Comptes Rendus, October 11, 1897, p. 527 ; through Ann. de Chim. Analyt., vol. ii. [22], p. 425).-The mixture is treated with copper sulphate and potassium permanganate, a current of air being passed through the liquid to remove ITHE ANALYST. 23 the bromine, which is absorbed by a 3 to 4 per cent. solution of soda contained in a tube fitted with glass balls, which are kept apart by constrictions in the tube. The mixed salts and the copper sulphate are placed in a, long-necked flask con- taining water, and after solution has been effected by the aid of heat and the liquid has cooled down, the permanganate is added, the flask is connected with the air- supply and the absorption-tube, and is heated on the water-bath.To prevent loss by evaporation, the air is saturated with moisture by being passed through water in a flask on the same water-bath. When all the bromine is driven over, the cold alkaline liquid in the condenser- tube is decanted and treated with a little gaseous sulphur dioxide, followed by a 10 per cent. solution of silver nitrate aud a fairly large amount of nitric acid. In the acid liquid the sulphurous acid reduces any oxygenated bromine products present, and if heat be then agplied, the nitric acid oxidizes the residual sulphur dioxide and the silver sulphite formed, leaving only silver bromide behind as the insoluble residue. The silver nitrate should be added along with, and not after, the nitric acid, to prevent loss of bromine.c. s. The Detection of Traces of Bromine by means of Fluorescein. €3 Baubigny. (Compt. Rend., 1897, cxxv., 654-657.)-The method here described is based on the fact that bromine converts fluorescein into its tetra-bromo derivative, eosin. Test-paper is prepared by steeping paper in a solution of pure fluorescein (40 to 50 per cent.) in acetic acid and allowing it to dry. When moistened and brought into contact with bromine, such paper assumes a rose coloration. To detect bromides (in the absence of chlorides) the bromine is liberated by warming the solution with copper sulphate 16 grammes, and potassium permanganate 0.7 gramme, in I00 c.c., and passing a slow current of air through the flask while the test-paper is applied to the delivery tube. The formation of eosin on the paper after a few minutes shows the presence of bromine.The test is not suitable for the detection of bromine in the presence of free chlorine, especially if the latter be present in large excess, since chlorine gives a white derivative with fluoresoein which masks the effect of the bromine. I n such cases the free halogens may be converted into chloride and bromide, and then tested by treating the solution with copper sulphate and permanganate without warming and passing air through the flask. When chlorine is present alone, the paper remains unchanged after ten minutes ; but if as little as 0.001 gramme of bromide be present with 5 to 10 grammes of a chloride, rose-coloured streaks appear within four or five minutes. The presence of an iodide does not interfere with the test if it is first transformed into ihdate by warming the solution with a little permanganate, for iodine is not then liberated on the subsequent addition of the copper sulphate.The author is still studying the method of pro- ceeding in the case of insoluble bromides. The test-paper is said to keep as well as turmeric-paper . C . ,4. M. On the Estimation of Sulphuric Acid as Ammonium Sulphate. F. Marboutin and A. Pecoul. (BdZ. SOC. Chzm., 1897, xvii., 880,88l.)-Weinig described a method24 TEE ANALYST. for determining sulphuric acid in dilute solutious by adding an excess of ammonia, evaporating and drying the ammonium sulphate at 115". Shiver (Chem. SOC., 1895, 351) found that the results thus obtained were too low, and recommended the addition to the residue of a little strong ammonia, evaporation on the water-bath and drying at 140" C.The authors tested this modification on $& solutions, but their results were still too low. I n order to determine under what conditions this source of error might be 'avoided, they evaporated 100 c. c. of the solution (yielding theoreticaly 343.6 milli- grammes of ammonium sulphate) with an excess of ammonia at 65", and brought the residue gradually up to 120", with the following results : MiIligran-mex. At 65" after forty-eight hours (the time required for evaporation) 343.5 The residue heated at 70" for twenty hours ... ... ... 343.5 75" ,, ... ... ... 343.7 80" 9 1 ... _.. ... 343.6 85" ,, ... ... ... 344.2 90" 9 , . . . ... 345.4 95" 9 , ... ... ...346.2 100" ,, ... . . ... 345.2 110" ,, ... ... ... 344.8 120" ,, ... ... 343.3 9 , 2 , ? t ,' 9 ) ,, ,, 9 , 7 7 ,, 1 ) 9 , 9 , 9 , 9 , 1 , 9 , 7 9 ,, ,? 9 , 7 , ,, 9 9 The authors attribute the increase of weight which takes place at 85" to the liberation of free sulphuric acid which absorbs moisture from the atmosphere. C. A. M. Note on the Separation of Silicic and Tungstic Acids. J. S. de Benneville. (JOZW. Amer. Chem. SOC., 1897, xix., 377-379.)-A common method of determining silicon in tungsten steel and ferro-tungsten is to dissolve the tungstic oxide on the filter by means of hot d h t e ammonia, and so obtain the silica at once for determina- tion. I t has been pointed out by various cheniists that precipitated eilicic acid, and even amorphous silica, are perceptibly soluble in hot ammonia, and the author finds that this is also the case with cold ammonia.He therefore advocates the method, recommended by Arnold, of weighing the total oxides and volatilizing the silica with hydroffuoric acid, with the addition of a few drops of sulphuric acid, as the most satisfactory. ,4 sample of wolframite, containing 65.5 per cent. of tungsten trioxide, and by the volatilization method 5.61 per cent. of silica, gave, on dissolving the tungeten oxide from the silica by ammonia : (1) InsolubIe silica, 3.84 per cent., and soluble silica, 1.64 per cent. ; and (2) insoluble silica, 3-22 per cent., and soluble silica, 2.20 per cent. The silica was mainly derived from intermixed mica. C. A. M. The Determination of Silica in Blast Furnace Slag.G. E. Meeker. (Jour. Anzey. Chem. Soc., 1897, six., 370-374.)-For the method here described there is claimed (1) greater accuracy than in the usual methods on account of more complete dehydration of silicic acid and thorough decomposition of the slag, and (2) greater rapidity and ease of execution. Half a gramine of the finely-powdered slag is mixed in a basin with about 3 C.C.T,HE ANALYST. 25 of water, and then stirred up with 10 C.C. of concentrated hydrochloric acid, till the slag has dissolved as mmpletely as possible. 40 C.C. of sulphuric acid (1 : 4) are then poured into the basin covered with an inverted funnel, and the liquid boiled until fumes of sulphur trioxide appear, After cooling, 10 C.C. of hydrochloric acid are added, the liquid diluted and boiled for one minute, the basin being covered with a watch- glass.The residue is then filtered off, washed five times with hot hydrochloric acid (specific gravity 1.10) and five times with hot water, ignited, and weighed. The silica is remarkably pure. I n '' chilled " slags the impurities amount to from 0.05 to 0.20 per cent. This method has been compared with a method consisting of two evaporations to dryness with hydrochloric acid, the heat being regulated so as not to exceed 120" C., and finally purifying the silica with hydrofluoric acid, and has, as a rule, given results in close agreement, though somewhat lower (about 0.1 per cent.), owing to the more complete dehydration of the silicic acid. The only exceptions to such agreement were in cases such as sIags associated with spinel, in which the treat- ment with hydrofluoric and sulphuric acids changed the impurities (e.g., alkalies) in the spinel into other compounds, which would influence the final result.The percentage of silica obtained by the ordinary method and by this method in a slag containing spinel residue were : Ordinary Method. New Method. Silica and impurities ... ... ... 35.42 ... 31.20 Impurities determined by treatment with hydrofluoric and sulphuric acids ... 5.88 ... 0.20 29.54 31-00 . Attempts to readily determine alumina and lime in the filtrate from the silica all failed, the results being iiiuch too low. C. A. M. On the Estimation of Phosphoric Acid as Phosphomolybdic Anhydride. H. Pellet. (Rev. Chiiib. Aizalyt. AppZ., vol.v. [20], p. 405.)-The double precipita- tion indicated by Woy (ANALYST, xxii., 250) for obtaining a pure precipitate of ammonium phosphomolybdate is considered unnecessary. I t is found that when a suEciency of ammonium nitrate is used, the molybdic acid is not precipitated, and the dried precipitate of ammonium phosphomolybdate corresponds to 3-75 gramnies of phosphoric acid or to 3.95 of phosphomolybdic acid. The estimation can therefore be accelerated by substituting ignition for desicca- tion, provided the heat is applied slowly and the heating is not continued too long, otherwise the results may be too low. c. s. Valuation of Calcium Carbide by Measurement of the Acetylene it evolves. F. Fuchs and F. Schiff. (Chem. Zeit., 1897, xxi., 875.)-When olive-oil is Ethaken for half an hour with acetylene, it dissolves 48 per cent.by volume of the gas; but if a layer of the oil previously saturated and 15 mm. thick is floated on the surface of water contained in the holder of the apparatus described below, the further loss26 THE ANALYST. of acety€ene in the time taken by each experiment does not exceed 1.5 or 2.0 per cent. The generatcir, as seen in the accompanying cut, consists of a three-necked Woulffe’s bottle (W), carrying a thermometer, a stoppered funnel, and a leading tube for the gas, the bottom of the vessel being covered with asbestos to avoid danger of breakage by the heat produced during the decomposition of the carbide. The gas- holder (G) is a glass bottle 50 cm. high and 25 cm. in diameter, having a capacity of 15 litres, and filled with water bearing the film of oil alreaiky referred to.The inlet tube is cut off just below the cork, so that the gas does not e w e in contact with the water itself. The outlet for the displaced liquid is a tube passing through the same Cork, reaching to the bottom of the vessel, bent twice at right angles, and having both ! legs of equal length. At its external ex- tremity it is connected by means of a short piece of rubber tube provided with a screw clip to another length of glass tube, passing to the bottom of a second vessel ( M ) the same size and shape as G, which at the beginning of the test contains exactly 1 litre of water, and Stands at a lower level. By this arrangement, when the tube between G and M is full of water, it acts as a syphon, so that the gas in G and also in the generator is under diminished pressure, and there is no danger that the water in the funnel of the latter will be blown out when the cock is opened.About 30 grammes of carbide are taken for analysis, and 200 C.C. of water are used to decompose it, the rate of admission through the funnel being regulated with the stop-cock. Although the introduction of the water alters the capacity of the apparatus, if the generator is well shaken after the production of gas has ceased no error will arise, because water dissolves exactly its own volume of acetylene. In about an hour and a half the temperature of the generator will have fallen t o its original point. The generator W is well shaken, the clamp at c is then closed, M and the glass tube s removed, and 7’ is brought below the surface of a known quantity of water contained in a tall beaker.The clamp is again opened, and as the liquid runs back into G, a measured amount of water is poured into the beaker till the level is the same in both vessels, when G and the generator are evidently once more under ordinary atmospheric pressure. The volume of water which has been drawn back into G out of the beaker, deducted from that which has passed from G into M during the decomposition of the carbide, thus gives the volume of acetylene generated; and this is corrected for temperature, pressure, and vapour tension of water in the usual way. TWO samples of Neuhausen carbide gave as the mean of five tests each 286% and 297.6 litres per kilogramnie (4.59 and 4.88 cubic feet per lb.).4 & .1 i F. H. L.‘THE ANALYST. 27 The Analysis of Commercial Calcium Carbide and Acetylene. G. Lunge and E. Cedercreutz. (Zeit. angezo. Chsm., 1897, 651-655.) -The gas produced on adding water to commercial calcium carbide is never pure acetylene, but contains impurities up to 4 per cent., including sulphuretted hydrogen, phosphuretted hydrogen, ammonia, carbonic oxide, hydrogen, nitrogen and oxygen. Of these the most important are the two first. In good calcium carbide the amount of calcium phosphide and calcium sulphide is very trifling; but the authors have met with a, sample containing so much of the former that the gas liberated ignited spon- taneousI y. I n the analysis a, sample of from 50 to 100 grammes, as representative of the bulk as possible, is decomposed with water, and the gas conducted into a laboratory gasometer holding not less than 40 litres, and the water in which is saturated with acetylene.Here it is measured and reduced to standard temperature and pressure. Theoretically, 100 grammes of pure calcium carbide yield 40.625 grammes of acetylene (= 34.877 litres), and commercial carbide ought to produce not less than 300 litres of gas per kilo, For the determination of the phosphuretted hydrogen the ordinary method of oxidation with bromine water is not applicable, on account of the strong action of bromine on acetylene, and the authors therefore employ a solution of sodium hypo- chlorite as the oxidizing agent. From 50 to 70 grammes of the carbide in lumps are decomposed by water, which is allowed to fall drop by drop from a stoppered funnel passing through the cork of the flask.The outlet tube of the flask is connected with a tube composed of a series of bulbs, in which are placed 75 C.C. of a 2 to 3 per cent. solution of sodium hypochlorite. After the whole of the carbide has been decom- posed, which takes from three to four hours, the flask is filled to the neck with water, a little air drawn through the apparatus, the contents of the bulb-tube emptied into a beaker, and the phosphoric acid determined by precipitation with magnesia mixture. The sulphur, which has been simultaneously oxidized, can be determined in the filtrate from the ammonium magnesium phosphate precipitate by acidifying with hydrochloric acid and precipitating with barium chloride.C. A. M. The Commercial Analysis of Sulphur Chloride. G. A. Le Roy. (Rev. de Chinz. Indust., 1897, viii., 294, 295.)-The chief industrial uses of sulphur chloride are in the vulcanizing of rubber, the preparation of artificial indiarubber, and the treat- ment of minerals containing gold. I t contains normally 47 per cent. of sulphur and 53 per cent. of chlorine, but in many industrial samples the proportions are very different from this. Thus, in several the author found as much as 10 per cent. of uncombined sulphur in solution, whilst in others there was a large excess of free chlorine. In Rose's method of analysis the sulphur is estimated by oxidation with fuming nitric acid and precipitation as sulphate, and the chlorine determined by difference. I n place of this, the author describes the following volumetric method : From 10 to 12 grammes of the sample (roughly measured) are placed in a graduated flask28 THE ANALYST.containing a known weight of crystallizable benzene; the flask and its contents are weighed after the addition, and the difference gives the amount of sulphur chloride taken. The liquid is made up to the mark with benzene, and an aliquot portion used in the determination. The fraction taken is shaken with a known volume of standard soda, containing 19-37 grawmes Na,O per litre (1 C.C. = O n 0 1 gramme sulphur), which decomposes it into the sulphide, sulphite, hyposulphite, sulphate and chloride of sodium, with the liberation of some sulphur in the free state.The flask is then warmed on a sand- bath, which causes the benzene to evaporate and the sulphur to dissolve in the soda. When the sulphur has completely dissolved, an excess of hydrogen peroxide is added. The latter must be neutral and free from substances which can be precipitated by silver nitrate. On warming the liquid, the various compounds of sodium and sulphur are converted into sulphate. The excess of hydrogen peroxide is removed by boiling, or, if necessary, by the addition of several drops of permanganate solution, and after cooling the excess of soda is titrated with normal nitric or sulphuric acid. The quantity of soda left free, plus the soda in combination with the chlorine subsequently determined, deducted from the total amount of soda taken, gives the number of C.C. equivalent to the soda converted into sulphate. From this the amount of sulphur is obtained by multiplying by 0.01. I n the liquid thus neutralized, the chlorine is determined by titration with a silver solution by Mohr or Volhard’s method. C. A. &I. Use of Caustic Alkalies in a Powdered Condition. A. Seyda. (,-Yeit. fiir Gfent. Chemic, iii., 438.)-Powdered caustic alkali is recommended for use in the preparation of alcoholic saponifying solutions, etc. The quantity required is weighed approximately in the form of stick caustic, and is then finely powdered and dried in an exsiccator over sulphuric acid. Alkali in this powdered condition dissolves almost immediately in alcohol. The author uses powdered sodium hydrate prepared in this way in his method of testing organic preparations for iodine (ANALYST, vol. xxii., p. 325), and suggests its use for many other purposes where fusion with soda is required. H. H. B. S. APPARATUS A Combustion Boat with Partitions. E. Nurmann. (Zeit. anal. Chem., 9897, xxxvi., 380-381.)-1n the ordinary boat the melted substance collects in the cooler end where the entire mass is suddenly decomposed when the decomposition lternperature is reached. This is obviated by the use of a partitioned boat, in which only a small portion of the substance is decomposed at a time. The boats are made of porcelain, with ten divisions, and may be obtained in two sizes (70 mm. by 10 mm. and 100 mm. by 13 mm.) from Lenoir and Forster, Chem. Phys. Institut. Vienna. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8982300018

出版商:RSC    

年代:1898

数据来源: RSC