摘要:

OCTOBER, 1913. Vol. XXXVIII., No. 451. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE ESTIMATION OF IRON IN SYR. FERRI PHOSPH. CO. AND OTHER PHARMACEUTICAL PREPARATIONS. BY NORMAN EVERS, B.Sc., F.I.C. Syr. Ferri Phosph. Co.-The estimation of iron in chemical foods is attended by many difficulties. The ordinary precipitation or titration cannot be carried out in the presence of the sugar and cochineal; and, further, the removal of the organic matter by ignition or oxidation is tedious, and it is not always easy to dissolve the residue obtained.A process has been recently put forward by Salamon and Seaber (Chemist and Druggist, 1913, 83, 2) for the estimation of total iron in syr. ferri phosph. co. depending on precipitation with ammonia, washing out the sugar, dissolving the precipitate in dilute acid, reducing, and titrating with permanganate.In my experience it was not possible to remove the sugar in one precipitation, even by prolonged washing with boiling water. High results were therefore obtained. Recently, having had to estimate the iron in this preparation, I used the following method, depending on oxidation of the iron with nitric acid, and direct colorimetric estimation as thiocyanate.This procedure has the advantage of being rapidly and easily carried out, and is sufficiently accurate for ordinary purposes. Moreover, the iron present in the ferrous condition can also be determined. Estimation of Total Iron.-Ten C.C. of the syrup are pipetted into a, flask, diluted with 50 C.C. of water, 5 C.C.of strong nitric acid added, and boiled for about a, minute to convert the iron into the ferric condition. The IiqGid is then cooled and made up to 100 c.c., 5 C.C. diluted to 100 c.c., and 5 C.C. of the diluted solution measured into a 100 C.C. Nessler cylinder, and diluted to the SO C.C. mark with water. Five C.C. dilute hydrochloric acid (1 in 3) and 10 C.C.of 5 per cent. potassium thiocyanate solution are then added. The colour is compared with that formed under the same conditions by a standard solution of ferric chloride (1 C.C. = 0.00002 Fe), as in the process of Nesslerising. In the final comparison the thiocyanate should be added to the iron, not vice versa. In about ten minutes the colour begins to fade slightly; comparisons should therefore be made within that time.Using the above quantities, 1 C.C. standard iron solution = 0.08 per cent, iron in the syrup. As the addition of 0.1 C.C. standard iron produces a distinct change in448 EVERS: ESTIMATION OF IRON I N SYR. FERRI PHOSPH. GO. the depth of colour, the process is accurate to 0.008 per cent. of iron, which is sufficient for ordinary purposes.The process has been tested, using known quantities of ferrous iron, with the same proportions of sugar and cochineal as are present in the syrup. I n each case the results obtained were within the limits of error of the process : Grm. / h 1 Iron taken ... ... 0.0389 0*0220 0.0193 ,, found ... ... 0.0388 0.0216 0.0194 Estimation of Ferric Iron.-Ten C.C. of the syrup are diluted to 100 C.C.with air- free water, 10 C.C. again diluted to 100 C.C. with air-free water, and 20 C.C. taken in a Nessler cylinder. The slight tinge of cochineal which still remains is matched with standard ferric chloride and thiocyanate, as it is of the same tint. Another 20 C.C. of the diluted solution is then taken, diluted to 50 C.C. with air-free water, 5 C.C.dilute hydrochloric acid and 10 C.C. thiocyanate added, and the colour matched as before, The number of C.C. of standard iron solution used to match the cochineal is subtracted from the final amount used. One C.C. standard iron solution = 0.01 per cent. ferric iron in the syrup. In order to prove that no oxidation occurred on dilution, a similar quantity of ferrous iron was diluted under similar conditions.A mere trace of colour was obtained. RESULTS. Sample. A B C D E F G H Total Iron per Cent. 0-424 0.412 0.408 0.408 0.408 0.344 0.300 0-248 Ferric Iron per Cent. 0.024 0.016 0.013 0-018 0.034 0.020 0.016 0.005 Ferrous Iron per Cent. 0.400 0.396 0-395 0.390 0.374 0.324 0-284 0.243 Sample A was carefully prepared by myself in accordance with the directions of the B.P.Codex. The other samples were from various commercial sources. Sample E had been kept for about a month, and had deposited somewhat, whence the high percentage of ferric iron. After standing a fortnight, the percentage of ferric iron in A had increased to 0-031 per cent. The method has also been applied to the following preparations : Syr. Ferri Phosph. d Quirtin. et Strychnirt.(Easton’s Syrup).-Five C.C. are taken and treated as above. One C.C. standard iron solution = 0.16 per cent. Fe. A syrup prepared containing 0.80 per cent. Fe gave 0.80 per cent, by this method. Other syrups gave the following results : A. B. Total iron ... ... 0.80 0-75 Ferric iron ... ... 0.02 0.02 Ferrous iron ... ... 0.78 0.73AND OTHER PHARMACEUTICAL PREPARATIONS 449 Lip.Ferri Hypophosph. Fort.-The estimation of iron in this preparation is somewhat troublesome on account of the fact that, inorder to precipitate the iron as hydroxide, it is necessary to use strong potash, which is difficult to remove by washing. I t is necessary to dissolve the precipitate in acid after ignition, and reprecipitate with ammonia. The colorimetric process described above was used, leaving out the oxidation with nitric acid, diluting 1,000 times instead of 200, and taking 5 C.C.for comparison. One C.C. standard iron solution = 0.4 per cent. Fe. Owing to the larger amount of iron present, the error in this case is greater; but where time is important, and only approximate results are required, the process is useful. The following are the results : Iron per Cent.A. 2. Gravimetric . . . ... 1.92 1.57 Colorimetric . . . ... 1.96 1-60 Syr. Ferri Hypophosph.-In this case the colorimetric method is of great value, 8s the presence of the sugar interferes with the gravimetric estimation Ten C.C. of the syrup are diluted 200 times, and 5 C.C. taken for comparison. Two syrups prepared from the above solutions of ferric hypophosphite gave the following results : Iron per Cent.A. B. F \ Theory ... ... ... 0.384 0.314 Found ... ... ... 0-376 0.312 Nist. Fevri (70.-Ten C.C. are diluted to 50 C.C. with water, boiled for one minute with 5 C.C. nitric acid, cooled, diluted to 100 c.c., 10 C.C. of this diluted to 100 c.c., and 5 C.C. taken for comparison. One C.C. standard iron solution = 0.04 per cent. Fe. A prepared sample, containing 0.114 per cent. Fe, gave 0.116 per cent. Fe by this method. These are all the cases in which the method has been tried, but obviously there are others to which it would be equally applicable. I t appears to be especially useful where the amount of iron is less than 1 per cent., and the organic matter present is such as to prevent the usual estimation by titration or precipitation.

ISSN:0003-2654    

DOI:10.1039/AN9133800447

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

450 ELSDON AND SUTCLIEFE : NITRATES AND NITRITES IN MILK. BY G. D. ELSDON, B.Sc., A.I.C., AND JOHN A. L. SUTCLIFPE, A.I.C. A PORTION of the matter contained in the present communication has received lately a considerable amount of attention. Our results, however, are in some respects contrary to those obtained by other workers, and we therefore publish them, thinking that they may be of general interest.We suggest also a new method for the deter- mination of nitrates in milk when present in any considerable quantity, and which is applicable in the presence of nitrites. As milk serum muet be used in the processes for the estimation of nitrates in milk, we here describe the method of preparation we have adopted. Preparation of Milk Serum-We find that the best results are obtained by the method suggested by Tillmans and Sutthoff (Zeitsch.Untersuch. Nahr. Genussm., 1910, 20, 49; ANALYST, 1910, 35, 434), a slight modification being made for the sake of convenience and rapidity. The reagent consists of a 2.5 per cent. solution of mercuric chloride in 1 per cent. w/v hydrochloric acid, and we proceed as follows : Twenty-five C.C. of milk are mixed with 25 C.C.of the reagent, and after well mixing, the whole is poured on to an 11 cm. filter-paper and 25 C.C. of filtrate collected. The rate of iiltration may be hastened very considerably by warming the milk before adding the reagent, but in this case the filtrate obtained is not quite so clear. We prefer to work in the cold. The Detection of Nitrates in Xilk.-Since milk is normally free from nitrates, their presence affords strong presumptive evidence of the addition of water, and therefore several methods have been suggested for their detection. The method that seems to have been most favoured is that which depends upon the blue coloration produced by a solution of diphenylamine sulphate in concentrated sulphuric acid.We have found this test to be both delicate and easy of application, and we therefore recom- mend it for the detection of nitrates ; but as the reaction is also given by nitrites, it cannot be used in the presence of the latter.The solution before being examined for nitrates should always be tested for the presence of nitrites by the Griess-Ilosvay method. If nitrites are found, a special method has to be followed in order to test for nitrates, For this purpose we use the brucine-sulphuric acid reagent, which is described later.We would here draw attention to the erroneous conclusions of P. Soltsien (Pharm. Zeit., 1906, 51, 765 ; ANALYST, 1906, 31, 374) concerning the diphenylamine test. H e states that nitrous acid not only fails to give the reaction, but actually hinders it, when nitrous and nitric acids are present together.We have found that this is not the case, as nitrous acid not only does give the reaction, but gives a deeper colour in equivalent strengths than does nitric acid, and in a shorter time. The Diphenylamine Test for Nitrates.-The test is carried out in the following manner, which is a slight modification of the method suggested by Tillmans (Zeitsch.Unterszbch. Mahr. Genussm., 1910, 20, 676 ; ANALYST, 1911, 36, 67) : The reagent is prepared by adding 50 C.C. of water to 0.085 grm. of diphenylamine sulphate containedNITRATES AND NITRITES IN MILK 45 1 in a large flask, and gradually adding 450 C.C. of strong sulphuric acid. I n performing the test 1 C.C. of the serum of the suspected milk is placed in a test-tube (4 by 0.5 in.), 4 C.C.of the reagent are added, and the whole thoroughly mixed and cooled. The presence of traces of nitrates causes the production of a blue colour. The Brucine-Sulphuric Acid Method.-In the presence of nitrites this reagent (see below) gives an immediate red coloration, which gradually fades to pale straw tint in three to six hours if nitrates be absent.In the presence of nitrate8 and nitrites, however, although the first immediate deep red colour will fade, a reddish coloration will persist for several weeks, To detect nitrates, therefore, in the presence of nitrites it is necessary to compare a solution known to be free from nitrates with the one in question by the method given below under the ‘( Determination of Nitrates.” The Presence of Nitrates in Milk.-Potassium nitrate has been used as a pre- servative, and also to remove the turnip-like taste, Samples of milk recently examined in this laboratory were found to contain potassium nitrate, the vendor stating in court that it had been added for this latter purpose.I t is wise, therefore, to examine for nitrates as a routine test, and this is carried out con- jointly with the estimation of fat by the Gerber method.When milk containing either nitrates or nitrites is shaken up with 90 per cent. sulphuric acid, a vivid brown colour is produced-golden-brown in the case of nitrites, somewhat darker in the presence of nitrates. This colour is very easily seen on shaking the milk in the Gerber tube with milks containing as little as 5 parts per 106.When such a colour is noticed, the milk should be further tested. The Determination of Nitrates in Milk.-Tillmans (bc. cit.) recommends his diphenylamine method described above; but we have found that, although this gives good comparative results with such quantities of nitrate as are found in watered milks (1 per IOS), the method is too delicate, however, for concentrations of nitrate, about 2 per lo6.As larger quantities than this have occurred in practice when potassium nitrate has been added to milk, a method was required for estimating them in such concentrations. Sulphuric Acid Method.-Five C.C. of milk are placed in a stoppered cylinder, and 5 C.C. of sulphuric acid (sp. gr, 1.770) are added. The cylinder is then shaken, and the colour produced compared with that given with milks containing known quantities of nitrate treated in a similar manner.This method gives good results in the absence of nitrites ; but as nitrates and nitrites are sometimes found together in milk, the following test, which is applicable in the presence of nitrites, is of more general application : Brucine-Sulphuric Acid Method.-The reagent is prepared by dissolving 0.2 grm.of pure brucine in 75 C.C. of sulphuric acid (sp. gr. 1-82>, and adding this to 25 C.C. of water. In the absence of nitrites, 5 C.C. of the serum (q.v.) are placed in a test-tube, and 10 C.C. of the reagent are added. The contents are well mixed, poured into a Nessler cylinder and allowed to stand for half an hour. The colour is then compared with standards prepared in the same manner.In the presence of nitrites the colour is produced immediately on the addition of the reagent, and then quickly commences to fade owing to the bleaching action of452 ELSDON AND SUTCLIFFE : 3rd Day. 8 2 the nitrites. Such action is apparent even after standing all night, although the total effect is not great. We have found, however, that the bleaching effect due to the presence of nitrites upon the colour produced by nitrates is practically indepen- dent of the amount of nitrite present-at least, in quantities between 2 and 40 per 100,000.I n such cases of a mixture of nitrate and nitrite the procedure is as follows : Five C.C. of the serum are placed in a test-tube, and 10 C.C. of the reagent are added.At the same time standards are prepared containing suitable quantities of nitrate, and each containing about 10 per 100,000 of sodium nitrite. The contents of the tubes are poured into Nessler cylinders, and matched any time after three hours. Reduction of Nitrates to Nitrites in Milk on Keeping.-A short time ago some samples of milk were examined in this laboratory, which, after standing, gave a faint nitrite reaction with the Griess-Ilosvay reagent, about 3 parts per lo6 of sodium nitrite being found. The following day, repeating the determination, 10 parts per lo6 were present. We eventually found this phenomenon to be due to the presence of nitrate in the milk, this nitrate being decomposed with the formation of nitrite.On going into the matter further, we found that if potassium nitrate be added to milk, after two days nitrite can be detected in the milk, and the quantity becomes appreciable after another day.In order to follow the course of this decom- position, two milks were prepared containing respectively 100 and 20 parts per lo6 of potassium nitrate. These were tested for the presence of nitrite on five successive days, with the following results : 4th Day.25 4 Parts per lo6 of Nitrite found. 1 1st Day. I 2nd Day. Milk containing 100 per Milk containing 20 per 106 KNO,. lo6 KNO,. 5th Day. 12 0 It will be seen from these results that the proportion of nitrite formed increases to a maximum, and then decreases. The above figures were obtained starting with fresh milk, but similar figures were given by sour milk.The Detection and Estimation of Nitrites in Milk.-The question of nitrites in milk came into prominence Rome little time ago in connection with a proprietary milk preservative called ‘( Mystin,” upon which a report was issued by G. W. Monier- Williams (Food Reports, Local Government Board, No. 17 ; QNALYST, 1912, 37,155) ; G. A. Stokes ({bid., 1912, 37, 178). I n both these papers it is stated that sodium nitrite interferes with the Hehner test for formaldehyde when present in the proportions found when using ‘‘ Mystin.” We have been unable to confirm these statements.With a Hehner solution, prepared by mixing 1,000 C.C. concentrated sulphuric acid and 25 C.C. of a 5.5 per cent. solutionNITRATES AND NITRITES IN MILK 453 of ferric chloride, we obtained a distiact purple ring after four hours with a milk con- taining 1 part per 300,000 of formaldehyde and 1 part per 9,000 of sodium nitrite, which is the strength recommended if using '( Mystin " as a preservative.The colour produced was certainly not as bright as in the absence of the nitrite, but it was unmistakable. We have repeated this on several occasions, and always with the same result.G. A. Stokes (Zoc. cit.) suggests that the presence of the formaldehyde will be detected whilst performing the Gerber test, but this we are unable to do if nitrite be present. We find, however, that the presence of a nitrite is shown by the golden- brown colour produced on shaking the tube, the colour produced being somewhat brighter than that produced in the corresponding manner from a nitrate.This colour is unmistakable. Estimation of Nitrites.-There are two methods in general use for the estimation of nitrites in small quantities-the metaphenylene-diamine and the Griess-Ilosvay methods. Of these the latter is by far the more delicate, and the colour produced is easier to match. The reagent is made up as follows : 0.1 grm.of a-naphthylamine is dissolved in 20 C.C. of glacial acetic acid, and mixed with 0.5 grm. of sulphanilic acid dissolved in 150 C.C. of warm 6 per cent, acetic acid, the whole being diluted to 300 C.C. with more 6 per cent, acid ; 150 C.C. of 60 per cent. acetic acid are added to this. In carrying out the test, 5 C.C. of the milk are placed in a test-tube (4 by 0.5 in.), and 3 C.C.of the reagent are added, Milks containing known quantities of nitrite are treated in the same way. The colour produced is matched with the standards after about one hour. The reaction with sulphuric acid can also be made use of as a quantitative test. The procedure is identical to that given above for the estimation of nitrates. The Detecbion and Estimation of Formaldehyde in the Presence of Oxidising Agents.- We have stated that nitrites only interfere slightly with the Hehner test for formaldehyde, and that it is possible to detect quantities greater than I in 500,000 even in the presence of quantities of nitrite, such as 1 in 5,000.Potassium nitrate seems to have no effect whatever on the Hehner test as carried out by US, and the same is true of potassium chlorate.In this respect our experience differs from that of Stokes and Monier-Williams (Zoc. cit.). For the estimation of formalde- hyde in milk under ordinary circumstances we have found the Shrewsbury and Knapp method to be by far the most delicate and the most accurate of the methods yet euggested, but it breaks down in the presence of nitrite. A modification of this test, suggested by Monier-Williams (Zoc.cit.), in which the nitrite is destroyed by urea previous to the colorimetric estimation, has been found by ue to work well, and to give results very near the truth. The presence of potassium nitrate does not affect the ordinary Shrewsbury and Knapp test. The Preservative Action of Potassium Nitrate and Potassium Nitrite.-In the discussion following the paper by Stokes (Zoc.cit.) surprise was expressed that formal- dehyde of a concentration of 1 in 300,000 was sufficient to preserve milk for three days, this opinion being based upon the statement by Stokes that " ' Mystin ' added to milk in the proportion of 3 C.C. per litre was found to be a fair preservative; thus, after three days, the acidity developed was only equivalent to 0.24 per cent.of lactic454 NITRATES AND NITRITES IN MILK Control. Date. acid, whereas the same milk unpreserved showed an acidity equivalent to 0.69 per cent. of lactic acid.” We have experimented with formaldehyde and *( Mystin ” as preservatives in these dilutions, and have found that practically the whole of the preservative action of ‘( Mystin ” is due to the sodium nitrite which it contains.In the following tables some of our results are given; the acidities are expressed as C.C. of Tc alkali, using 10 C.C. of milk. The figures given are acidities so expressed : With CH 0 With NaN02 With CH20 1 in lo5 1 in 105: 10 in 106. and NaNOz 10 in lo6. I Date. Control, “ Mystin ” aa recommended, NaNOz 10 in 100,000. I I I I May 4, 1912 ... May 6, 1912 ... 1.8 5.2 1.8 3.9 1-8 3.2 1.8 3.2 May 9, 1912 ... May 10,1912 ... May 11,1912 ... 1.9 4.2 7.8 1-9 2.3 3 -3 1.9 2.3 3.3 Potassium nitrate has sometimes been used as a milk preservative, but itsuse has not become general on account of its inefficiency. We have done some work showing that it has, however, a slight preservative action. Thus a milk containing 10 parts of potassium nitrate per 100,000 in four days developed an acidity of 5.5, the same sample of milk to which 2 in 100,000 had been added showed an acidity of 5.9, whilst the untreated milk in the Bame time developed an acidity of 6.2. I n conclusion, we would express our indebtedness to Mr. J. F. Liverseege for his valuable criticism and advice. CITY OF BIRMINGHAM, ANALYTICAL DEPARTMENT.

ISSN:0003-2654    

DOI:10.1039/AN9133800450

出版商:RSC    

年代:1913

数据来源: RSC

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454 NITRATES AND NITRITES IN MILK NOTE ON COFFEE AND CHICORY. BY T. R. HODGSON, M.A., F.I.C. A SHORT time ago a vendor in the Midlands was summoned for selling a mixture of coffee and chicory not of the nature, substance and quality demanded ; the Analyst’s certificate stating that the sample “ contained 10.1 per cent. of water,” and in the Observations that the sample contained “4.1 per cent.excess of water. A weI1- roasted sample should not contain more than 6 per cent.” With a, view of testing this statement, a number of samples were purchased in the ordinary course of busi- ness in various parts of the country, and the percentage of moisture determined.HODGSON: NOTE ON COFFEE AND CHICORY 455 Coffee 100 per cent. .... ... ... > 9 9 9 9 , $ 9 9 , ...... ... $ 9 9, 9 9 1 9 9 9 2 9 9 ) 7 9 9 9 9 , ... ... ... 9 . . ... 0 . . ... ... ... ... ... ... Percentage of Moisture. ... 2.0 6 . . 4.9 ... 5.3 ... 5.4 ... 5.6 ... 6.0 ... 6.3 ... 2.6 ... 3.0 ... 3.5 ... 4.0 ... 4-2 ... 4.6 ... 5.0 ?? 50 9 9 Y, 50 7, . a - ... 9.7 44 9, 9, 56 9 , ’ . * ... 11.0 Cii’cory 100 ,, ... ... ... ... 10.8 ,, 99 9 , ... ... ... ... 11.3 Owing to the very large variation in the amount of moisture present, I thought it would be advisable to see whether a sample would absorb moisture on being kept under conditions similar to those under which it is usually kept in retail shops ; one sample of pure coffee and one of pure chicory and one of a mixture of coffee and chicory were therefore placed in a drawer, such as is usually seen in small retail shops, and the moisture was determined at intervals.(( Pure Chicory.” Original sample ... ... ... 11.3 After 3 davs in the drawer ... ... 14.4 Percentage of Moisture. ( ( Pure Coffee.” After 3 davs in the drawer ... ... 7.8 Original sample ... ... ... 2.0 .I 9 7 Y 9 ,, 9 9 9 , I , ... ... 9.5 9 ) 7 9 9 97 14 9 , ... ... 9.7 ... ... 9.7 ,, 21 9 9 t L Cofee 66 per Cent., Chicory 34 per Cent.” Original sample ... ... ... 3.5 After 3 days in the drawer ... ... 9.7 9 9 9 , ... ... 11.2 I , 7 9 9 9 , 14 9 , 9 , , I ... ... 11.3 ?, 21 9 ) 8 9 9 , ... ... 11.5 I t is obvious that coffee and chicory when kept absorb moisture somewhat rapidly, and therefore the standard of 6 per cent. of moisture which it was proposed to set up cannot stand.

ISSN:0003-2654    

DOI:10.1039/AN9133800454

出版商:RSC    

年代:1913

数据来源: RSC

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456 ABSTRACTS OF CHEMICAL PAPERS Alcohol ... ... ... Extract ... ... ... Original gravity ... ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. 8 20 0 19 0 6 7 1 20 0 14 30 0 40 5 FOOD AND DRUGS ANALYSIS. Use of the Immersion Refraetometer in Examining American Beers made from Malt and Unmalted Cereals. R. Sehwartz. (J. Ind. and Eng. Chem., 1913,6,66O.)-Danzer (Zeitsch. ges. Bruuw., 1910,33,32) has published a series of tables (based on the alcohol and extract tables of K.Windisch) from which the alcohol and extract of any beer can be calculated from the same determinations 8s those necessary when using Ackermann’s tables (ibid., 1905, 28, 33). As there was some doubt whether Danzer’s tables could be employed in the case of beers contain- ing 60 to 70 per cent. of malt and 30 to 40 per cent.of adjuncts such as unmalted cereals, the author has examined with the aid of these tables and the refractometer forty-seven samples of beer, some of them being malt and hop beers only, some top fermentation beers, and the rest typical American substitute beers. The original gravity of the same beers by the official distillation and pycnometer method was done by another worker, and serves as the standard.Differences in r+aths per Cent. Plus. Minus. I - - -\ 1 Average. 1 Highest. I Lowest. Highest. 1 Lowest. For calculating the original gravity, the formula G= 1-93 A + E was used, and the results recorded to the nearest 0-05 per cent. The conclusion is reached that the agreement between the results of the two methods is as good for American beers as it is for European all-malt beers, and that the refractometer method may safely be used for brewery control and for all ordinary work, with the possible exception of legal and disputed cases.(Cf. ANALYST, 1908, 33, 320.) H. F. E. H. Determination of Small Amounts of Caffeine : A Comparison of Methods. B. L. Murray. (J. Ind. and Eng. Chem., 1913, 5, 668.)-Two methods are com- pared-that of Garter (ANALYST, 1908, 33, 124) and that of Lendrich and Nottbohm (ANALYST, 1909, 34, 214).The former gives results from 50 to 100 per cent. higher than the latter, especially when the total amount of caffeine present in the sample is 0.5 per cent. or less. The advantage of purifying the crude caffeine with per- manganate as advised by Lendrich and Nottbohm is confirmed by experiments, andFOOD AND DRUGS ANALYSIS 457 in all cases the caffeine percentages recorded were calculated from the nitrogen present, and not by weighing the caffeine itself.Duplicate analyses by different analysts using the Lendrich and Nottbohm method agree well. The author gives no indication as to which method he considers gives results nearest to the truth.H. F. E. H. Reactions of Digitoxine. C. Reichard. (Pharm. Zentralhalle, 1913, 54, 687-693 ; through Chem. Zentralbl., 1913, II., 719.)-Pure digitoxine crystallises in long needles, grouped in star formations. I t is insoluble in water, but dissolves in chloroform and alcohol, and acetic acid, and is unattacked by cold sulphuric acid. Nitric acid (25 per cent.) produces no coloration, but potassium hydroxide gives a faint yellowish-red colour.The reactions of digitoxine with chromic acid or molybdic acid are very characteristic. When a trace of the alkaloid is rubbed with ammonium molybdate or potassium bichromate and water, the mixture allowed to evaporate, the residue moistened with acetic acid and again evaporated, and then treated with strong sulphuric acid, colourless solutions are obtained, and these on heating give pronounced colorations.The molybdate mixture gives a sky-blue colour and the chromium mixture a green colour, both of which disappear when the liquid cools, but reappear on heating. If a mixture of sodium metavanadate with solid digitoxine and water be dried, and the residue moistened with strong sulphuric acid, there is produced after a few hours a nearly colourless solution, which becomes deep yellow when gently warmed, and colourless again on cooling.Potassium ferrocyanide, applied in the same manner as described for molybdic acid, gives a deep blue coloration, changing to blackish-blue, whilst potassium ferricyanide gives a sky-blue coloration. Sodium nitroprusside, however, has no action upon digitoxine.Sodium tungstate gives an amorphous white precipitate, partially soluble in dilute sulphuric acid. Copper sulphate also yields an amorphous precipitate, which is darkened by sulphuric acid. Mercuric chloride, added to an acetic acid solution of digitoxine, on evaporation a residue is left which yields a blue solution when warmed with sulphuric acid, whilst mercuric nitrate gives a yellow liquid under the mme conditions. Bromine-water has no action ; hydrochloric acid gives a green coloration on warming, and ferric salts a deep red-brown colour.The greenish-yellow colour given by cobalt nitrate when evaporated at a gentle heat with digitoxine and acetic acid is characteristic. C. A. M. Estimation of Nitrobenzene in Earthnut Oil.H. J. Lucas. (J. Ind. and Eng. Chem., 1913, 5, 576-577.)-The author has found the following process to afford a satisfactory means of estimating nitrobenzene in earthnut oil, oil thus flavoured being largely consumed by the poorer classes in Porto Rico. The process consists, essentially, in reducing the nitrobenzene to aniline by means of zinc and hydrochloric acid, extracting the aniline, and weighing it as aniline hydrochloride ; about 95 per cent.of the nitrobenzene present is recovered. The oil is shaken with zinc dust and hydrochloric acid for fifteen minutes, and then with a mixture of ether and water. After several shakings with this mixture, the separated aqueous layers are filtered, mixed with sodium hydroxide solution, and extracted with ether.The458 ABSTRACTS OF CHEMICAL PAPERS ethereal extracts are now shaken with hydrochloric acid, and the acid extractions are evaporated in a tared platinum basin. The evaporation is stopped before com- plete dryness is reached, and the moist residue is dried over soda-lime for from sixteen to thirty-five hours. The dry residue of aniline hydrochloride is then weighed and afterwards ignited, any residue of inorganic salts thus obtained being deducted from the first weight. w.P. s. Viscosity of Butter Fat and its Substitutes. G. F. White and R. H. Twining. (J. Ind. and Eng. Chem., 1913,5,568-573.)-1t is suggested that determina- tions of the viscosity of butter fats may afford a means of detecting the presence of margarine. Margarine fats are always more viscous than butter fat, except when the former contains a large proportion of oils.Results of numerous determinations of the viscosities of butter fats, margarines, and mixtures of the same are recorded, the apparatus employed for the determinations being a modification of that described previously by one of the authors (ANALYST, 1912, 37, 143). w. P. s. Differentiation .of Animal and Vegetable Fats.J. Mareusson and H. Schilling. (Chern. Zeit., 1913, 37, 1001-1002.)-The method described is a, com- bination of Bomer's phytosteryl acetate test with Windaus' digitonine precipitation of cholesterol or phytosterol (ANALYST, 1910, 35,256). No preliminary saponification is required, the fat being merely shaken with a dilute alcoholic solution of digitonine : Fifty grms.of the sample are shaken for fifteen minutes with 20 C.C. of a, hot 1 per cent. solution of digitonine in 96 per cent. alcohol, and allowed to stand for several hours. The oil is drawn off as completely as possible, and the separated digitonides in the upper alcoholic layer are shaken with 50 to 100 C.C. of ether, then filtered, and washed with ether until free from oil.They are next heated for thirty minutes in a test-tube with 1.5 C.C. of acetic anhydride, and the acetates which separate upon cooling are recrystallised and examined in the usual way. The method gives good results in the separation of the alcohols from blown and oxidised oils, and the presence of paraffin wax or mineral oils does not interfere with the test. By means of this method a small quantity of cholesterol was isolated from sperm oil.The acetates from a mixture of 90 per cent. of sperm oil and 10 per cent. of rape oil melted after two recrystallisations at 116" to 117" C., whilst when 5 per cent, of rape oil was present the melting-point of the acetates was 114O to 116' C. C. A. &I. Fatty Acids of Kaya Oil. S. Ueno. (Chem. Rev. Fett Ind., 1913, 20, 208- 209.)-The fatty acids of the oil examined by the author had a mean molecular weight of 286.2, and an iodine value of 139.9. Examined by the usual methods, they were found to consist of about 9 per cent.of palmitic and stearic acids, 19 per cent. of oleic acid, and 72 per cent. of a linolic acid which yielded a sativic acid melting at 151" to 152' C. (instead of the usual m.-pt.174' C.). C. A. M. Detection of Paraffins in Lanolin. G. Tellera. (Boll. Chim. Farm., 1913, 52, 1-4 ; through Chem. Zeiztralbl., 1913, II., 818.)--The following test is proposed for the detection of vaseline in lanolin : One grm. of the sample is dissolved in ether,FOOD AND DRUGS ANALYSIS 459 and the stearin which separates on cooling the mixture is removed by filtration.Five C.C. of absolute alcohol are then added to the filtrate. When the lanolin con- tains from 3 to 4 per cent. of vaseline, a flocculent precipitate is obtained immediately, whilst when only 1 per cent. of vaseline is present the precipitate appears after the lapse of .about thirty minutes. Crude lanolin gives a slight turbidity on the addition of the alcohol, but purified lanolin gives a clear solution.w. P. s. Constituents of Hops. F. B. Power, F. Tutin, and H. Rogerson. ( J . Chem. Sac., 1913, 103, 1267-1292.)-Fresh air-dried Kentish hops (1911) contain- ing 10.5 per cent. of moisture were used for this investigation, and indications were obtained of the presence of a very small amount of an alkaloid. The tannin as estimated by Chapman’s cinchonine method (ANALYST, 1908,33, 95, and 1909, 34, 372) was 2.40 per cent.Twenty-five kgrms. of the hops were completely extracted with hot alcohol, and the extract distilled in a current of steam to remove the essential oil. From the portion of the extract soluble in water were isolated small amounts of choline and Z-asparagine. The aqueous liquid also contained in addition to tannin a quantity of potassium nitrate, and a sugar yielding d-phenylglucosazone as well as an amorphous bitter-tasting substance.The portion of the alcoholic extract insoluble in water consisted of a dark green oily resin, equivalent to 14 per cent. by weight of the hops, and from this were isolated ceryl alcohol, hentriacontane (C31H64), a phytosterol, a phytosterol glucoside, a mixture of volatile fatty acids (formic, acetic, butyric, etc.), 6-isopropylacrylic acid, saturated and unsaturated non- volatile acids (palmitic, stearic, cerotic, and an isomeride of arachidic acid) ; chry- tinic acid, binolic acid, a new crystalline phenolic substance, humulol, having a pale fawn colour and a bitter taste, which on hydrolysis with caustic potash yielded, amongst other products, an acid (C1,Hl,O,, m.-pt.210°), and p-hydroxybenzaldehyde ; a new crystalline phenolic substance, xanthohumol (C1,H140,, m.-pt. 172O), which is tasteless and has an orange-yellow colour. The presence of a yellow colouring matter resembling quercitrin or of a wax consisting of myricyl palmitate was not confirmed. The bitterness of hops is not due to any single substance, such as ‘6 hop-bitter acid ” or ‘‘ lupulic acid,” but is to be attributed to a number of products mostly amorphous.The differentiation of the resinous material as a-, p-, and y-resins is misleading, since it is much mGre complex than would be indicated by the methods used for their separation. As the resinous material contains a large proportion of the ordinary fatty acids and their esters, such methods for the valua- tion of hops as are based on the titration of extracts obtained by means of light petroleum, etc., are of very doubtful utility.H. F. E. H. Nitrogenous Constituents of Hops. A. C. Chapman. (Chem. Sac. Pm., 1913, 29, 182-184.)-The material employed was either hops extracted in the laboratory or hop-extract prepared on the commercial scale.Four different methods of preparing and separating the hop constituents were employed. By the first method the concentrated aqueous extract was precipitated with basic lead acetate, and the filtrate, after removing the excess of lead, was precipitated with phospho- tungstic acid. Histidine, betaine, and choline were thus isolated, and, from the460 AESTRACTS OF CHEMICAL PAPERS phosphotungstic filtrate, asparagine.In the second method the hops were mixed with lime, boiled with water, and the mixture evaporated, dried, and extracted with alcohol, the extract freed from alcohol being then precipitated with phosphotungstic acid. The solution of the bases so obtained, on precipitation with an ammoniacal solution of silver chloride, yielded a,denine and hypoxanthine.I n the filtrate from the purine precipitate betaine and choline were again obtained. In the third method the hops were extracted with ammoniacal amyl alcohol, which was then treated with dilute hydrochloric acid. On treatment with phosphotungstic acid, adenine, betaine, choline, and a trace of some alkaloid, were obtained. Further experiments were carried out upon a concentrated aqueous extract of hops, which was treated with a mixture of alcohol and acetic acid, filtered, and the filtrate freed from alcohol, the residue being extracted with water.Amino-acids, (?) polypeptides and potassium nitrate were among the substances so obtained. H, F. E. H. Extension of Vieth's Table for Correeting the Specific Gravities of Milk. C, H.Wright. (J. Soc. Chem Ind., 1913,32, 777-7'78.)--For the convenience of workers in tropical climates, the author has extended Vieth's correction table so that it may be used in the case of specific gravities determined at temperatures between 24" and 31' C. The table is used in the same way as Vieth's; if, for example, the sp. gr. of a milk is 1.028 at 28O C., its sp. gr. at 15.6" (60' F.) is 1.0311.Degrees of Lactometer. 20 ... ... 21 ... ... 22 ... ... 23 ... ... 24 ... ... 25 ... ... 26 ... ... 27 ... ... 28 :.. ... 29 ... ... 30 ... ... 31 ... ... 32 ... ... 24. 21.7 23.7 23.7 24.7 25-7 26.8 27.8 28.9 30.0 31-0 32.1 33.1 34.3 25. 21.9 23.0 23.9 24-9 26.0 27.0 28.1 29.2 30-2 31.3 32.4 33.4 34.6 Temperature in Degrees Centigrade. 26. 22.1 23*2 24.2 25.2 26.2 27.3 28.4 29.4 30.5 31.6 32.7 33.7 34.9 27.22.4 23.4 24.4 25.4 26.5 27.5 28.6 29-7 30.8 31.9 33.0 34.0 35.2 28. 22.6 23.7 24.7 25.7 26.8 27.8 28.9 30.0 31.1 32 -2 33.3 34.4 35.6 29. 22.8 24.0 25-0 26.0 27-0 28.1 29.2 30.3 31.4 32.5 33.6 34.7 35.9 30. 23.1 24.2 25.2 2 6-2 27.3 28.3 29.5 30.5 31.7 32.8 33.9 35.0 36.2 31. ~ 23.3 24.5 25-5 26.5 27.6 28.6 29.8 30.8 32 -0 33.1 34.2 35.4 36.6 w.P. s. Morres's " Alizarol " Test for Milk. A. Devarda and A, Weieh. (Arch. Chem. u. Mikroskopie, 1913, 1-6 ; through Chem. Zentralbl., 1913, II., 718.)-The acidity of milk may be estimated with sufficient accuracy for practical purposes by the colour obtained in the alizarol test (ANALYST, 1912, 37, 26), but not when the acidity is pronounced or aJkaline decomposition products have been produced.FOOD AND DRUGS ANALYSIS 461 When the coagulation caused by the alixarol test does not correspond to the acidity, abnormal composition, or decomposition of the milk due to coagulating and pep- tonising bacteria,, is indicated. C.A. M. Determination of Sodium Borate in Soap. P. Poetschke. (J. Ind. and Eng. Chem., 1913, 5, 645.)-The usual method of extracting soap with absolute alcohol, and estimating the borax in the insoluble residue by titration, is inaccurate, owing to the solubility of borax in alcohol, an error of about 20 per cent.being thus introduced. Attempts to determine the borax by ignition of the soap with alkali carbonates and titration in presence of glycerol failed owing to the presence of silica. The following method, adapted from Wherry and Chapin (ANALYST, 1909,34, 34) was employed successfully : Ten grms.of the soap (or 5 grms. if more than 5 per cent. of borax is present) are weighed into a platinum dish, and 2.15 grms. of fusion mixture, consisting of 200 grms. of sodium carbonate and 15 grms. of silica in fine powder, are added, together with 15 C.C. of alcohol. The whole is evaporated to dryness on the water-bath, and then ignited and fused, after which the mass is boiled out with water, transferred to a 250 C.C. round-bottomed flask, and acidified with 20 C.C. of dilute (1 : 1) hydrochloric acid. The solution is heated nearly to boiling, and then a slight excess of precipitated calcium carbonate is edded, after which the whole is boiled for ten minutes under a reflux condenser. The insoluble matter is filtered off and washed, and the filtrate returned to the flask with a small quantity of calcium carbonate, and again boiled under the reflux condenser, then cooled, and titrated in presence of 50 C.C. of neutral glycerol with & sodium hydroxide, using phenolphthalein as indicator. Figures are given showing that known amounts of borax added to borax-free Castile soap can be accurately detsrmined. Many ‘‘ borax soaps ” are free from any borax, others contain from 1 to 10 per cent. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9133800456

出版商:RSC    

年代:1913

数据来源: RSC

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FOOD AND DRUGS ANALYSIS 461 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Estimation of Chlorine in Blood. H. Rog6e and C. Fritsch. (Biochem. Zeitsch., 1913, 54, 53-59.)-The method differs from that of K. 0. Larsson (ANALYST, 1913, 270) in that the proteins are removed by iron according to Michaelis and Rona, and a correction is applied for the chlorine contained in the iron solution. The blood (10 c.c.) is weighed into a 250 C.C.flask, diluted with 150 C.C. water, 50 C.C. Ziiqzcor ferh oxydati dialysiti added, and, after adding 5 C.C. of a 20 per cent. magnesium sulphate solution, the liquid is made up to the mark with water and shaken vigorously for some seconds. After allowing to settle and filtering, the chlorine in the filtrate is estimated according to Mohr’s method.A blank experiment without blood is carried out in order to apply the necessary correction. The method can be suitably modified for micro-es tim ations. E. W. Disinfectant Value of Mercuric Hydroxyeyanide. H. Kuhl. (Arch. Pharm., 1913,251,340-349.)-When added in very dilute solution 1 : 200,000 to culture media, mercuric hydroxycyanide stimulated the growth of bacteria, but in stronger462 ABSTRACTS OF CHEMICAL PAPERS concentrations inhibited and destroyed bacterial growth.For example, 1 mgrm. of the hydroxycyanide added to 25 C.C. of raw milk had a strong restrictive effect upon the growth of bacteria, 3 mgrms. destroyed streptococci after three days, whilst 5 mgrms. killed all micro-organisms, The same results were also obtained with mercuric cyanide containing only 33 per cent, of hydroxycyanide.In the author’s opinion, although the OH ions play a considerable part in the disinfecting process, the relationship between the cell protoplasm and the poison is of much more impor- tance. The fact that in certain experiments in which common salt was also used there was a more pronounced germicidal effect, is attributed not to the direct action of the sodium chloride, but to its promoting the absorption of the poison by the protoplasm. C.A. M. Physiological Standardisation of Digitalis Preparations. R. Heinz. (Merck’s Jahresber., 1913, 26, 1-20 ; through Chem. Zentralbl., 1913, II., 621.)-The method depends upon an estimation of the minimum dose required to arrest the heart’s action in twelve hours when subcutaneously injected into a frog, the results being compared with those obtained with a standard preparation of strophanthine of known physiological action.Taking the value of the strophanthine as 1,000, the following results were obtained : Digitoxine, 200 ; digitaline, 100 ; and powdered digitalis leaves, 0.5. Comparative experiments have also been made upon rabbits, cats, and mice.C. A. M. Biochemical Examination of Soil. J. Stocklasa. (Chem. Zeit., 1913,37, 1005.)-Reference is made to the author’s method of measuring the respiration intensity of the bacteria in soil, and of the measurement of the quantity of nitrogen consumed by soil bacteria. When oxygen is excluded, decomposition of nitrogenous organic substances takes place, with putrefactive changes.These decompositions, and also the oxidation changes produced by aerobic bacteria, may be estimated by biochemical methods. Estimations of the oapacity of the soil for decomposing cellulose, of the catalase in the soil, and of the biological absorption, ought also to be made. C. A. M. Significance of the Estimation of the Reaction and Basicity of Soil. H. R. Christensen.(Chem. Zeit., 1913, 37, 1005.)-Estimation of the reaction of the soil affords an index, not only of the need of lime, but also of other substances required by plant life. It may also show whether the soil can offer resistance to certain plant diseases. The biological method will indicate, not only the lack of lime, but also whether an addition of other nutrient substances is required.Results so far obtained tend to show that the introduction of nitrogen in the form of nitrates gives better results than when the nitrogen is added to the soil in the form of cyanamido or ammonium sulphate. As regards potassium fertilisers, it appears that the injurious effects sometimes observed when chlorides are present in the potassium salts are less pronounced when the soil is acid than when it is alkaline.C. A. &l.BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 463 Sources of Error in the Estimation of Sugar in the Blood of Frog and Tortoise. E. J. Lesser. (Biochem. Zeitsch., 1913,54, 252-256.)-The filtrate obtaiced after removing proteins by means of colloidal iron from the blood of frogs or tortoises, contains substances which dissolve cuprous oxide, and therefore interfere with sugar estimation.They can be removed, however, by precipitation with mercuric nitrate, and the filtrate, after being freed from mercury with sulphuretted hydrogen, is treated with sodium acetate, and after concentration on the water-bath can be used for the sugar estimation. E. W. Estimation of Small Amounts of Glucose in Urine. E. Hirschberg.(Zeitsch. Physiol. Chem., 1913, 86, 484-494.)-Bertrand’s method, modified as suggested by Oppler (ANALYST, 1912, 37, 140), by adding alcohol in order to lower the boiling-point, yields reliable results for glucose contents ranging from 0.50 to 0.90 per cent. For smaller glucose contents up to 0.10 per cent. the method is not so reliable, but frequently gives good results. The separation of cuprous oxide is incomplete in too dilute solutions.Bang% method (ANALYST, 1910, 35, 70) gives results which are consistently high, and is useless for sugar contents of less than 0.40 per cent. E. W. Detection of Urobilin. T. Hausmann. (Zcitsclz. exper. Path. Ther., 1913, 13,373-399 ; through Chem. Zentralbl., 1913, II., 819.)-The method depends on the fact that the urobilinogen of urine is oxidised by copper sulphate to urobilin, which may be extracted with chloroform. Twenty C.C.of the urine are mixed with 2 C.C. of a 10 per cent. copper sulphate solution, and the mixture is shaken with 2 C.C. of chloroform. The chloroform layer is coloured pink, orange, or red ; in the case of very acid urines the colour obtained is yellow. If, in place of copper sulphate, the urine is treated with a concentrated solution of either ferrous sulphate, zinc acetate, zinc sulphate, or potassium ferricyanide, the chloroform layer remains colourless, whilst lead acetate, mercuric chloride, and phosphotungstic acid yield precipitates with the urine, and only a small proportion of the urobilin is extracted by the chloroform.Previous treatment of the urine with formaldehyde or dimethylamino- benzaldehyde hinders the oxidation of the urobilinogen. The chloroform extract contains the actual urobilin and not its copper compound; the urobilin may be extracted from its chloroform solution by shaking the latter with sodium hydroxide solution ; the alkaline solution exhibits the characteristic properties of a urobilin solution (absorption bands, fluorescence with alcoholic zinc acetate, etc.).For the estimation of the urobilin, the urine is treated with copper sulphate and extracted many times with chloroform ; the chloroform extracts are evaporated to dryness, the dry residue is dissolved in & sodium hydroxide solution, and the excess of the latter is titrated with Tn hydrochloric acid; the dif‘ference between the quantities of alkali and acid used is multiplied by 0.0062 to give urobilin. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9133800461

出版商:RSC    

年代:1913

数据来源: RSC

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464 ABSTRACTS OF CHEMICAL PAPERS ORGANIC ANALYSIS. Estimation of Petroleum Spirit in Turpentine. C. Bakker. (Chem. Weekblad, 1913,10, 420; through Chem. Zentralbl., 1913, II., 179.)-To 10 to 25 C.C. of the turpentine is added, with cooling, three times its volume of strong sulphuric acid; the liquid is allowed to stand for twenty-four hours, and the proportion not attacked by the acid determined. This is then allowed to drop into three times its volume of fuming nitric acid, with cooling, and the unattacked layer is pipetted off, washed with water until neutra1, distilled with steam, and the volume of petroleum spirit passing over read off.0. E. 1%. Estimation of Brisance and of Velocity of Detonation. H. Kast. (Zeit. Schiess- u. Sprengstofwesen, 1913, 8,65,88, 133, 155, 172.)-The hrisance of an explosive may be expressed approximately as B=:d, or B= ETd, in which E is &he V quantity of energy set free in time t, d is the gravimetric density of the explosive, and represents the energy concentration, Y the velocity of detonation, and I the length of explosive over which the measurement is made.The direct determination of brisance is not possible; the lead block gives figures which are merely comparative.The velocity of detonation has been measured in various ways ; the Siemens spark chronograph is the most accurate (cf. Kast, 4 ‘ Anleitung,” p. 1025), and was used in this investigation; its chief sources of error are considered. The velocity of detona- tion increases as the diameter, strength of enclosure, and density of the explosive are increased.The strength of enclosure has no material influence, however, except. at low densities of loading. With nitro-compounds, such as trinitrotoluene, picric acid, etc., the limiting diameter was 10 mm., no increase beyond this, up to 300 mm., which was the largest diameter tried, causing a higher rate of detonation ; the statement that the propagation of a detonative wave takes place only in narrow tubes is not supported.With ammonium nitrate explosive of low density the velocity increased up to a, limiting diameter of 40 to 50 mm. The observation of Dautriche, that there is a limiting density beyond which the velocity falls off, was not confirmed in the case of nitro-compounds, no such limit being reached with the densities employed;.but with a mixture such as monachit the limit was found to be 1.2, beyond which the velocity fell off. The tendency to incomplete detonation, shown by a diminishing velocity in successive portions of the length tested, and most marked with plastic explosives, is due to an insufficiently powerful detonator. On the other hand, cases occur in which the velocity rises, as the detonative wave advances, to the normal rate.In the use of explosives, if their full energy is to be developed, the density and means of ignition must be such that the normal rate of detonation is reached; this is ascertained by a determination of the velocity of detonation. This. principle may also be applied to the testing of explosives, such as dynamite and cheddite, which on storage become more difficult to detonate, and hence lose power unless larger detonators are used.The influence of chemical composition, which with nitro-compounds is much less important than the density, and of other factors, is considered. 0. E. &l.ORGANIC ANALYSIS 465 I Simple Method for the Determination of Carbon in Organic Materials. E. B. Hart and K.J. Woo. (J. Amer. Chem. Soc., 1913,35, 1056.)-The principle of the method is the fusion of the material with sodium peroxide in an ordinary crucible, whereby all of the carbon is converted into sodium carbonate. This is distilled with 25 per cent. sulphuric acid, the escaping carbonic acid being collected in caustic soda and titrated by the double titration method, using phenolphthalein and methyl orange as indicators.The method gives accurate results and is specially suitable for routine carbon determinations in soils, and also where it is desired to follow this element in certain phases of animal nutrition, as in urine analysis. Materials low in carbon content prove most satisfactory. About 6 grms. of the per- oxide and from 0.1 to 2 grms. of the material are ignited in an enclosed crucible of porcelain, nickel or iron, which must be of smooth interior surface.For soils 1 to 2 grms. are employed unless peaty, when as little as 0.1 to 0.2 grm. is taken. The burner should be withdrawn at the first signs of action, or the reaction may proceed with too great violence. The whole determination can be completed in three- quarters of an hour.H. F. E. H. No. 1. Studies on Caoutchouc Resins. M. Klassert. (Zeitsch. angew. Chem., 1913, 26, 471-472.)-The resins obtained in the purification of caoutchouc are now prepared on the commercial scale. The following samples have been examined by the author- No. 1 : The crude resin, yellowish, opaque, with conchoidal fracture, and an odour of caoutchouc even in the cold. No.2 : The same, dried and fused, yellowish-brown, transparent, with a fracture like colophony, becoming strongly electrified when powdered, odourless in the cold, but developing an odour when rubbed or heated. No. 3 : The same as No. 2, powdered, a yellowish powder. No. 4 : The crude resin specially purified, a nearly white powder, practically odourless in the cold. No. 5 : A greenish-brown, pasty mass, with microscopic crystals, apparently containing chlorophyll, and probably isolated by means of volatile solvents.For the sake of cornparison some results, published by Vstubel and Diller (Gummi Zeit., 1912, 1587), are also given in the table : No. 2. " I I 0.2 2.5 92"-98" 36.3 85.9 1.2 84.7 Moisture ... ... ... Ash ... ... ... Hub1 iodine value ... Saponification value .. . Acid value ... ... Ester value (by difference) Melting-point "C. ... 112'-118 34.2 90.5 1.3 89-2 No. 3, 0-3 1-1 110"-118" 36.0 86.8 1.3 85.5 No. 4. Vaubel and Diller. Fluid Resin. No. 5. 25.10 0.8 I 14'-119' 28-3 62.3 0.9 61.4 - 0.5-2.1 20-41 19-24 3 -2-1 3 -6 90"-125 ' - 8.4 0-3 82-3, 67.1 77.5 23.8 53.7 - The melting-points were extremely deficient in sharpness, and the samples were In the case of No.5, the iodine value decreased not really liquid until above 130" C. considerably after heating the sample at 110' C. to expel volatile matters.466 ABSTRACTS OF CHEMICAL PAPERS The solid resins are soluble in most organic solvents when heated, but separate for the most part on cooling, the acid constituents, however, being more soluble than the rest.Mixtures of equal parts of resin and oils, including paraffin oil, give plastic pastes, which are less (( greasy " than pastes similarly prepared with colophony. Solutions of the resin in chlorinated hydrocarbon solvents show no separation of the constituents, and such solutions are suitable for lacquers. A number of products, possibly of technical interest, are obtained by destructive distillation of the resin : Total distillate, 85 per cent.; pitchy residue, 8 per cent. J. F. B. Estimation of Cholesterol Bodies in Presence of Each Other. J. Lif- schutz. (Biochem. Zeitsch., 1913, 54, 212-236.)-The spectral intensities of the acetic anhydride sulphuric acid reaction for cholesterol bodies, and the acetic acid- sulphuric acid reaction for oxycholesterol, were found to be proportional to the amounts of these substances in the respective reaction mixtures.The spectral phenomena of the acetic anhydride sulphuric acid reaction of such cholesterol bodies as give this reaction were found to be fundamentally identical. The method is based upon these two facts. The total cholesterol bodies are determined spectro- metrically by means of the acetic anhydride sulphuric acid reaction carried out in chloroform solution and the oxycholesterol determined by the acetic acid sulphuric acid reaction as described (ANALYST, 1913, 209). I t has been found that the acetic anhydride sulphuric acid reaction in presence of chloroform indicates the total choles- terol, whilst, in the absence of chloroform, free cholesterol, but not that in the form of fatty ester, is indicated. E.W. Detection of Formaldehyde with p-Nitrophenylhydrazine. E. Zerner. (Movzatsh. f i r Chem., 1913, 34, 957-961.)-1n studying Bamberger's reaction for the detection of small quantities of formaldehyde by means of p-nitrophenylhydrazine, the author obtained a sparingly soluble body other than the normal hydrazone described by Bamberger, end melting at a higher temperature.The new body need not interfere with the performance of the test in the ordinary way, since it is formed only when a considerable excess of formaldehyde is present. Under normal conditions, with excess of p-nitrophenylhydrazine, Bamberger's hydra- zone, melting at 181' C. after crystallisation from benzene, is obtained. For the preparation of the new body, 1 grm.of p-nitrophenylhydrazine hydrochloride is dissolved in 10 C.C. of boiling water, the solution is filtered, and, while at a tempera- ture of about 65' C., is poured quickly into 5 C.C. of cold 40 per cent. formaldehyde solution. A precipitate of small yellow crystals is formed, which, after separation, washing, and recrystallisation from benzene, melt somewhat indefinitely between 222' and 225' C.Analysis of the product indicates a formula of C,,HI1N,O,, which would correspond with a condensation product formed from 2 molecules of formal- dehydenitrophenylhydrazone with the loss of 1 molecule of ammonia. Such a body might have the constitution of a 1, 4-bisnitrophenyl-1, 2, 4dihydrotriazo1, and the substance obtained does not show the coloration with alcoholic potassium hydroxide characteristic of the imino-group in ordinary nitrophenylhydrazones.J. F. B.ORGANIC ANALYSIS 467 Colour Reaction for Gallic Acid and Tannin. 0. Schewket. (Biochem. xeitsch., 1913, 52, 271-275).-A solution of gallic or tannic acid is trea.ted with an excess of a 1 per cent. solution of iodine in potassium iodide, shaken, and tap-water or a very weak solution of a salt with alkaline reaction added, when a reddish-violet coloration is produced.Weak organic acids and hydriodic acid do not interfere, but even dilute mineral acids prevent the reaction. Concentrated alkaline hydroxides and carbonates disturb the reaction and give a dirty brown coloration. The reaction can be employed to distinguish gallic and gallo-tannic acids from tannins which are free from gallic acid, E.W. Estimation of Free Sulphur in Leather. Jalade. (Ann. Faksi$c., 1913,6, 435-446.)-When hides are treated with sulphur in the tanning process, the resulting leather frequently contains a quantity of free sulphur ; as a rule, carefully manufac- tured leather does not contain more free sulphur than corresponds with 0.36 per cent.of SO,, and any leather which contains more than this quantity (calculated on the dry material) is considered to be of unsatisfactory quality, as the sulphur oxidises gradually to sulphuric acid, and the strength of the leather is thus destroyed. The quantity of free sulphur is calculated from the difference between the quantity of sulphate in the ash of the leather and the amount of sulphate found in the ash after the leather has been treated with potassium carbonate (Balland and Maljean's method).I n order to obtain concordant results, it is essential that a sufficient quantity of potassium carbonate be used, and that the leather be in a suitable state of division. The following procedure is recommended : The leather is cut up into thin shavings by means of a plane (Stanley's No.ZZO), and 5 grms. of the dried shavings are mixed in a crucible with 40 C.C. of a 1 per cent. potassium carbonate solution; the mixture is evaporated on a water-bath, dried for a short time at 110" C., and then ignited for about thirty minutes in a muffle-furnace. The crucible should be placed near the mouth of the muffle.When cold, the contents of the crucible are moistened with hydrochloric acid, evaporated to separate the silica, and the sulphate is then estimated in the usual way by precipitation with barium chloride. w. P. s. Source of Error in the Kjeldahl-Gunning Method. E. Carpiaux. (Ann. Chirn. anal., 1913, 18, 315-316.)-The fact that loss of ammonia takes place in this method when the composition of the acid digestion mixture approximates to that of potassium hydrogen sulphate, as mentioned by Self (ANALYST, 1912, 37, 203), is fully confirmed by a series of experiments carried out by the author. To avoid such loss of ammonia, it is recommended that only moderate quantities of potassium sulphate should be employed, and that the heating should not be unduly prolonged after the digestion is completed, w.P. s. Kapok Seeds and Kapok Oil. H. Sprinkmeyer and A. Diedrichs. (Zeitsch. Untersuch, Nahr. Genussm., 1913, 26, 86-101.)-Kapok seeds are obtained from Eriodendron anfractuosum, a plant growing in almost all tropical countries. The plant resembles the cotton-plant in that the seeds are embedded in a mass of468 ABSTRACTS OF CHEMICAL PAPERS f i b m ~ s material which may be used for textile purposes, The seeds obtained from &m~bax malabaricum, are also known as kapok seeds, and in commerce little, if any, distinction is made between the two kinds of seeds.About 18 per cent. of Oil is obtained from the seeds by hot pressing, the actual oil content of the seeds varying from 19 to 26 per cent. The expressed oil varies in colour from yellow to dark brown, and sometimes deposits a mass of solid glycerides.The following results were obtained on the examination of expressed oils obtained from kapok seeds from Java, German East Africa, Ceylon, and Ecuador: Sp. gr. at 15" C., 0.9235 to 0.9326; refractometer reading at 40" C., 51.7 to 59.7 ; iodine value, 85.2 to 93.5 ; acid value, 18.5 fo 210.2 (corresponding with from 5-22 to 59.3 per cent.of free oleic acid); saponification value, 189.2 to 194.5. The fatty acids separated from the oils had : Iodine value, 88.7 to 98.9 ; mean molecular weight, 277.6 to 982.1 ; m.@. 32.2" to 34.2" c.; solidifying-point, 26.9" to 3 1 * 8 O . The expressed oil from the seeds of & w h z malabarkurn gave the following results : Sp.gr. at 15" C,, 0.9300 ; refracto- meter reading at 40° C., 57.0; iodine value, 78.6; acid value, 3.0 (equivalent t o 0.85 per cent. of oleic acid) ; saponification valu'e, 194.3. Kapok oil yields a more intense coloration with Halphen's reagent than does cottonseed oil ; but Milliau's test (ANALYST, 1905, 30, 98) serves to distinguish these two oils from one another. (See also ANALYST, 1903, 28, 40, 320).w. P. s. Drying Rates of Raw Paint Oils. L. V. Redman, A. J. Weith, and F. P. Broek. (J. Ind. and Eng. Chem., 1913,5,630-636.)-The object of this research was to compare the relative drying qualities of a series of raw oils without the use of dryers. The method adopted was the weighing a t daily intervals of a series of films spread on glass plates which were exposed to a brisk current of air and but poorly illuminated by diffused day- light.Elaborate precautions were taken to eecure uniform conditions and, an abundant supply of dust-free air. The apparatus employed is figured in detail in the paper. The air passed over the films with a speed of about ten miles per hour, and in each second about four times as much oxygen passed through the apparatus as was actually absorbed by the oil films in twenty days.Chinese wood oil attained its maximum weight on the ninth day, whereas linseed oil under the same conditions reached its slightly greater maximum two days earlier. The Chinese wood oil set sooner and gave the harder film, but this had a frosted appearance. Soya oil reached its maximum weight on the sixth day and yielded a transparent film, but one much less tough than that given by linseed oil.The maximum increase in weight was under 8 per cent., against the 12 per cent. of linseed oil and 10.5 per cent. of Chinese wood oil. Fish oils of several kinds were experimented with, and showed very rapid absorption of oxygen, the maximum increase-about 13 per cent.- being reached in less than four days, but in no case was a solid film obtained in twenty days.G. C. J. Further work with standard dryers is in progress. Examination of Steam Turbine Oils. F. Sehwarz and J. Marcusson. (Chem. Rev. Fett Ind., 1913, 20, 215-220.)-The following modifipation of Kissling's method of estimating the tar-forming capacity of oils is recommended : Fifty grms,ORGANIC ANALYSIS 469 of the sample are heated for fifty hours in an Erlenmeyer flask (lower diameter 7.5 cm., height 12.5 em.) in a large oven, the temperature of which is kept constant at 120" C.The oil is then mixed with 50 C.C. of 50 per cent. (by weight) alcohol and 50 C.C. of 4 per cent. sodium hydroxide solution, and heated for fifteen minutes at about 80" C. beneath a reflux condenser, after which it is vigorously shaken for five minutes and allowed to stand overnight in a separating funnel.The alkaline layer is then drawn off as completely as possible, and extracted with 30 C.C. of petroleum spirit to remove any oil. I t is next acidified with hydrochloric acid, and shaken with three successive portions of 50 C.C. each of benzene, the united benzene extracts washed with water and evaporated, and the residue of tar dried for ten minutes at 150" C., and weighed and calculated upon 50 C.C.(not 50 grms.) of the oil. A further point to be observed in the selection of turbine oils is that they should not readily emulsify with water, since in the presence of water and metal the resinification capacity is increased. From the examination of a, large number of samples the authors conclude that the most suitable oils for turbines are those with a viscosity of 9" to 14" Engler at 20" C.; sp. gr. of 0.870 to 0.905 at 15" C. ; and a tar-forming value not exceeding 0.2. The oils should be pure mineral oils free from acid and soaps, and should not contain more than 0.01 per cent. of ash. The resinification of mineral oils appears to be due to the presence of resinous viscous substances of high sp. gr.and optical refraction. As a rule they contain sulphur and oxygen, and are apparently derived from unsaturated terpenes. C. A. M. Fractionation of California Petroleum by Diffusion through Fuller's Earth. J. E. Gilpin and P. Schneeberger. (Amer. Chern. J., 1913, 50, 59.)- The investigation of the effect produced on petroleums by diffusion through fuller's earth was extended to a very heavy petroleum from California.It was found that for petroleums of sp. gr. 0.912 at 20" C. there was no fractionation unless the oil was heated to 75' C. ; from petroleums containing sulphur compounds light fractions were separated, containing less sulphur than the original oil. Nitrogen compounds were removed by upward diffusion of an oil.Mixtures of benzene and paraflin oil gave fractions dependent upon the proportion of benzene and paraffin in the mixture. Petroleum rich in benzene and olefine hydrocarbons gave fractions in which the proportions of benzene and olefines increased with the density of the fractions. The explanation is put forward that the fuller's earth acts as a dialysing septum on the petroleum, which is an emulsoid; the paraffin oils have free passage, while the bituminous material is adsorbed and coagulated by the extensive surface of tho fuller's earth, and carries with it the sulphur and nitrogen compounds, and the benzene and olefine hydrocarbons.0. E. M. Estimation of Rosin in Blown Oils. W. Fahrion. (Chtern. Rev. Fett Ind., 1913, 20, 150-152, 177-l79.)-Twitchell's method of estimating rosin (ANALYST, 1891, 16,169) gives incorrect results when applied to blown oils, owing to the hydroxy acids being incompletely esterified.The error thus produced is reduced, but not eliminated, by making the estimation by the author's modified method (ANALYST, 1911, 36, 557). In examining blown oils, 5 grms. of the sample (from which any metals have been470 ABSTRACTS OF CHEMICAL PAPERS previously removed) are dissolved in 50 C.C.of petroleum spirit, and the solution mixed with 20 C.C. of 96 per cent. alcohol, and neutralised with alkali solution, with phenolphthalein as indicator. I t is then brought to an alcoholic strength of about 60 per cent., shaken, and left overnight. The soap solution is diluted to a t least 200 c.c., acidified with hydrochloric acid, and twice shaken out with petroleum spirit. The extracts are united and esterified with absolute alcohol and hydrochloric acid, and the rosin estimated as described (ANALYST, 1911,36,557), the last traces of soap being removed by washing the solution of the esters with 10 C.C.of 60 per cent. alcohol.Esterification of the fatty acids insoluble in petroleum spirit is more difficult in the case of oxidised than of unoxidised oils. Thus, a blown linseed oil containing no rosin yielded by this method 0.86 per cent. of a substance which was apparentlyrosin. On the other hand, certain neutral bodies and hydroxy-abietic acids which are present in colophony escape estimation by this method.The amount of these subs’tances ranges from about 10 to 25 per cent., with an average of about 14 to 15 per cent. The results of the estimation are also influenced to some extent by the relative proportions of the fatty and rosin acids. The following corrections were found applicable in the case of the samples examined by the author : Amounts below 1 per cent. were ignored, whilst those between 1 and 4per cent.were regarded as rosin, without making any addition. When above 4 per cent., the results were multiplied by 1.17, an empirical factor corresponding to the average loss of hydroxy-abietic acids and neutral substances in the colophony. These washings are added to the solution of the rosin soap. C. A. M. New Colour Reactions of Di- and Tri-Phenols.0. Schewket. (Biochem. Zeitsch., 1913, 54, 282-285.)-A solution of catechol (0.01 grm.) in 1 C.C. water is treated with 3 to 5 drops of a 1 per cent. solution of iodine in potassium iodide, diluted somewhat with water, and a few drops of 5 per cent. sodium hydroxide solution added, when a beautiful green coloration immediately forms. On standing or boiling, the colour changes to a dirty brown, but after cooling or vigorous shaking, Or 011 adding a few drops of hydrogen peroxide, the green colour reappears.This reaction distinguishes catechol from resorcin and hydroquinone. Pyrogallol similarly treated yields an evanescent bluish-violet to reddish-violet coloration. A solution of pyrogallol in 30 to 50 per cent. alcohol after adding a few drops of sodium or potassium hydroxide gradually yields a violet coloration, very similar to permanganate. This test distinguishes pyrogallol from phloroglucin.On adding a, solution of iodine in potassium iodide drop by drop to a solution of phloroglucin (0.01 grm.) in 5 C.C. hot water the colour of the iodine disappears. On adding a few drops of caustic soda to this solution a light brown coloiir appears, which on boiling turns into a light reddish-violet (distinction from pyrogallol). On adding a few drops of caustic soda to 8 solution of phloroglucin (0.01 grm.) in 5 C.C.boiling water and shaking, a bluish- violet coloration appears. This reaction, which depends upon oxidation by atmo- spheric oxygen, succeeds better on adding a few drops of hydrogen peroxide. The coloration produced lasts for days ; on acidifying, the colour changes, first into light red and then into light yellow.On making alkaline, the bluish-violet colour reappears. This reaction is sensitive and characteristic of phloroglucin, and distinguishes it from pyrogallol. E. W.ORGAKIC ANALYSIS 471 Direetions for Testing Pyridine Bases. (Ctzem. Zeit., 1913, 37, 1035.)- The following directions have been formulated by the German Customs' Board for the examination of pyridine bases : CoZour.-The colour should not be darker than that of a freshly prepared solution containing 2 C.C.of TG iodine in 1 litre of water. The colours are to be compared in 170 mm ,4 _.___-_-------. - - - - - _ _ - _ _ - - - _ _ _ _ _ .,, tubes 150 mm. long and 15 mm. wide, closed at the ends with glass plates and screw-caps, : having a hole 12 mm.in diameter. I I Reactioiz with Cadmium Chloride.-Ten b C.C. of the pyridine bases are dissolved in 1 litre of water, and 10 C.C. of this solution are shaken with 5 C.C. of a solution of 5 grms. of anhydrous fused cadmium chloride in 100 C.C. of water. A copious separation of crystals should appear in ten minutes.The precipitate, colIected on a filter of 9 cm. diameter, weighing 0.45 to 0.55 grm., drained, and dried on filter-paper for one hour at 50" to '10' C. without washing, should weigh not less than 25 mgrms. Reaction with Nessler's Reagent.-Ten C.C. of the same pyridine solution with 5 C.C. of Nessler's reagent should give a white precipitate. Boiling-Point.-One hundred C.C.of the pyridine bases are measured into a short- necked flask of 180 to 200 C.C. capacity ; the flask is placed on an asbestos plate with a circular hole, and a distillation-head, with a bulb of the dimensions shown in the figure, is fitted and connected with a Liebig's condenser having a water-column of at least 40 cm. At the other end an adaptor conducts the distillate into a narrow measuring cylinder of 100 C.C.The bulb of the thermometer must reach to the centre of the bulb in the head of the flask, and the column of mercury must be surrounded by the vapour. Distillation is conducted at the rate of 5 C.C. per minute. When the thermometer indicates 140" C., the flame is extinguished, and the volume of distillate is read when the liquid ceases to drop.The temperature is then raised to 160" C., and the same operation repeated. At least 50 C.C. should distil at temperatures up to 140" C., and 90 C.C. up to 160° C., the distillate being measured at 15" C. Solubility in Water.- Fifty C.C. of the sample of pyridine bases, when mixed with 100 C.C. of water, should give a clear or faintly opalescent mixture without separation of layers, which, after five minutes and before ten minutes have elapsed since mixing, should be sufficiently transparent in the 150 mm.tube to allow printed characters to be read when the tube is held over them in a vertical position at such a distance that the printing is illuminated. Moisture.-Twenty C.C. of pyridine bases and 20 C.C. of caustic soda lye, sp. gr. 1.40, are measured by a pipette into a stoppered cylinder, graduated in + c.c., and shaken. After settling, the upper layer should measure at least 18.5 C.C.at 15" C. Titration.-Ten C.C. of pyridine bases are placed in a 100 C.C. flask containing 50 to 75 C.C. of water. The mixture is made up to the mark and shaken. Ten C.C. are then titrated with sulphuric acid, using congo paper as indicator, until a drop shows a distinctly blue edge, which then disappears.acid should be required. Not less than 9.5 C.C. of J. F. B.47 2 ABSTRACTS OF CHEMICAL PAPERS Estimation of Starch in Commereial Products. J. Pieraerts. (Bull. de I'Assoc. des Chim. de S~LCT. et Dist., 1913, 30,628 ; through Chem. Zentralbl., 1913, II., 176-177.)-The estimation of starch by converting it into soluble starch and examin- ing the solution in the polarimeter is discussed by the author in the light of his own experiments.Potato starch containing 98.86 per cent. of starch, reckoned on the dry substance, was used, 5 grms. of it being well mixed in a 200 or 250 C.C. measuring- flask with 100 C.C. of the reagent under investigation, and heated in an autoclave for a period not exceeding two hours at 3 atmospheres.After cooling, the liquid was clarified with alumina, made up to the mark, and examined in the polarimeter. The reagents used were : (1) 2.5 per cent. solutions of citric, acetic, succinic, and mono- and trichloro-acetic acids ; (2) cold saturated solution of picric acid; (3) 5 per cent. solutions of citric and trichloroacetic acid ; (4) salicylic acid, solid, in quantities of 25 per cent.of the solution ; ( 5 ) asaprol citrate (7.5 grms. asaprol dissolved in 600 to 700 C.C. 25 per cent. citric acid, cleared with a small quantity of animal charcoal, made up to 1 litre with 25 per cent. citric acid, and filtered). The samples of starch were dried in a vacuum at a temperature gradually rising to 120" C. Methods of rendering the starch soluble by means of alkalis, mineral acids, or high pressure, were not considered.The experiments showed that the hydrolysis proceeds differ- ently, as shown by the iodine test, according to the acid employed. Trichloro- acetic acid in particular is different from the rest, causing the formation, from the beginning, of I-dextrosan, while the other acids give amylodextrin, and to some extent erythrodextrin. The action of acetic, salicylic, and picric acids is not satisfactory, but very accurate starch determinations can be carried out with 2.5 per cent.solutions of citric acid, monochloroacetic acid, or succinic acid, or with asaprol citrate and 5 per cent. citric acid. Substances poor in starch are best treated with 2.5 per cent. citric, succinic, or monochloroacetic acid in an autoclave with the valve open for one hour. The results with tricholoro-acetic acid were all much too low. The asaprol did not equal citric acid in hydrolysing effect; it indeed appeared to delay the further hydrolysis of the amylodextrin. In two hours at 3 atmospheres, 2.5 and 5 per cent. citric acid, 5 per cent. trichloroacetic acid and asaprol citrate effect complete conversion to dextrose, without the formation of considerable quantities of humus-bodies. 0. E. M. Action of Tartaric Acid on Tin in the Presence of Oxygen. A. C. Chapman. ( J . Chem. Soc., 1913, 103, 775-781.)-Rods of pure tin were exposed for long periods of time to the action of 5 and 10 per cent. solutions of tartaric acid by suspending them in bottles nearly full of the acid, and closed with corks through which passed the tin rods in such a, manner as to allow of the very slow access of atmospheric oxygen to the liquid. If the fitting of the corks was such as to prevent this, no action occurred, but in the other cases crystals of stannous tartrate were deposited. The stannous tartrate so formed undergoes slow dissociation, and the resulting stannous hydroxide slowly oxidises, forming a coloured compound which is probably hydrated sesquioxide of tin. Orange-coloured colloidal solutions containing as much as 6 per cent. of tin were obtained. H. F. E. H.

ISSN:0003-2654    

DOI:10.1039/AN9133800464

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

INORGANIC ANALYSIS 473 INORGANIC ANALYSIS. Colour Reactions of Alkaline Ealoths with Oxygallol Derivatives. 0. Schewket. (Biochem. Zeitsch., 1913, 54, 285-291.) - Numerous colour and precipitation reactions are given for solutions of calcium, barium, and strontium salts with alkaline solutions of tannic, gallic, and pyrogallic acids in the presence and absence of alcohol. These reactions are recommended for the detection of the alkaline earths in presence of each other.For the detection of calcium in the presence of strontium and barium, 10 C.C. of a 2 per cent. solution of the earths are treated with a small quantity of pyrogallol and a few drops of caustic soda added, when an intense violet coloration indicates calcium. The alkaline earth solution (10 c.c.) is treated with 5 C.C.alcohol and 10 drops of 1 per cent. gallic acid, and a few drops caustic alkali added; a rose-red precipitate and slow formation of blue colour indicate calcium. In the absence of calcium, strontium can be detectd in presence of barium by extracting the mixed sulphates with water and treating the filtrate with trtnnic acid and caustic alkali. The formation of an evanescent meadow- green colour indicates strontium.E. W. Quantitative Separation of Chromium and Aluminium : Analysis of Chromite. F. Bourion and A. Deshayes. (Compt. rend., 1913, 157, 287-289.) -A method was recently described (ANALYST, 1913, 387) for the quantitative separa- tion of the oxides of chromium and iron by conversion into chlorides by the action of a mixture of chlorine and sulphur chloride, the chromium chloride being insoluble.The same process has now been applied for the separation of chromium and aluminium oxides, the reaction in this case being complicated by the circumstances that the aluminium oxide is not so easily chlorinated as ferric oxide, and that aluminium chloride forms a double compound with sulphur chloride. When the aluminium oxide amounts to 50 per cent.or more of the mixture, the loss on heat- ing is very considerable ; nevertheless, satisfactory results may be obtained by adding to the oxides a certain amount (e.g., 30 per cent.) of ammonium sulphate. With mixtures containing less than 50 per cent. of chromium oxide, there is always a slight residue unattacked ; the whole of the chromium chloride is volatilised.Mixtures containing more than 60 per cent. of chromium oxide behave like the mix- tures of chromium and ferric oxides. Thedouble chloride of aluminium and sulphur dissolves in water with evolution of much heat, but without appreciable formation of sulphur. The method has been applied to the analysis of the mineral chromite, which is mainly ferrous chromite, accompanied by oxides of aluminium and magne- sium, and a little calcium and silica.For the satisfactory chlorination of the mineral, it must first be broken down by heating, preferably with mercuric sulphate, the temperature being gradually raised to redness. The material so prepared is chlorinated in the manner described, the conversion being complete in about five hours ; the silica is not completely attacked.The constituents are thus separated into three groups ; the non-volatile residue contains unattacked silica, magnesium and calcium chlorides ; the volatilised chromium chloride is insoluble in water,474 ABSTRACTS OF CHEMICAL PAPERS and is collected in a Gooch crucible ; the volrttilised ferric and aluminium chlorides arereadily soluble in water.Each of the constituents is then estimated by ordinary methods, but a quantitative estimation of the silica in this manner is not possible. J. F. B. New Separation of Chromium and Manganese. W. Cornelius. (Pharm. Zeit., 1913, 58, 427 ; through Chem. Zentralbl., 1913, II., 175.)-The fusion is carried out in the usual manner, and the fused mass, containing potassium permanganate and dichromate, is dissolved in a large quantity of water, and heated on the water- bath with sodium nitrite solution until the separation of hydrated manganese peroxide is complete.The chromium remains in solution, being partly or wholly converted into chromate. The precipitate is washed on a filter with hot water, ignited strongly, and weighed as manganous manganic oxide. The chromate in the filtrate is con- verted into chromium chloride, with sodium nitrite and hydrochloric acid, precipitated with ammonia, and weighed as chromic oxide.Specimen analyses show the utility of the method. 0. E. M. Separation of Chromium and Manganese. W. Dederichs. (Pharm. Zeit., 1913, 58, 446 ; through Chem. Zentralbl., 1913, II., 175.)- The following method is said to be superior to the method of Cornelius (see preceding abstract) in simplicity and rapidity.The melt of manganate and chromate is converted, by evaporating it to dryness with concentrated sulphuric acid, into the mixed sulphates, which are then converted into sodium manganate and chromate by fusion with sodium hydroxide and a small quantity of sodium peroxide. The fused mass is dissolved in hot water, and sodium peroxide added until the solution is yellow ; the hydrated manganese dioxide is then filtered off.The chromium is estimated in the filtrate, after acidifying it with hydrochloric acid, by titration with potassium iodide starch and thiosulphate, or, after neutralising it with nitric acid, by precipitating with mercurous nitrate, igniting, and weighing as chromic oxide.0. E. M. Copper in Distilled Water. E. Abel. (Zeitsch. f. Elektrochem., 1913,19,477- 480 ; through Chem. Zentralbl., 1913, II., 479-480.)-The reaction between hydrogen peroxide and sodium thiosulphate is bimolecular. If, however, the water has been distilled from a copper vessel, the catalytic action of the copper in the water upon the reaction is so pronounced that it is possible to estimate the proportion of copper by the velocity of the reaction.Other metals, such as iron, chromium, and manganese, have no appreciable influence upon the reaction. C. A. M. Analysis of Ferrotitanium. A. R. Scott. (Chem. News, 1913,108, 52-53.)- The following scheme of analysis is recommended both on the ground of simplicity, and because it effects a very sharp separation of titanium and aluminium, The finely divided alloy (0.25 grm.) is fused with 10 grms. potassium bisulphate until gritty particles can no longer be felt.The cooled melt is extracted with water in a porcelain basin, 10 C.C. of sulphuric acid being added, and the whole kept hot for half an hour. The insoluble matter is then filtered off, washed, ignited in a platinumINORGANIC ANALYSIS 475 crucible, and fused once more with a little bisulphate.The melt is extracted as before, and the silica (contaminated always by a little ferric oxide and titanium dioxide) is filtered off, washed, ignited, and weighed. The residue is treated with hydrofluoric acid and reweighed to determine the silica, and the small residue of non-volatile matter is dissolved in hydrochloric acid and the iron precipitated by means of ammonia.The difference between the weight of non-volatile matter remaining after treatment with hydrofluoric acid and the weight of ferric oxide found gives the weight of titanium dioxide precipitated with the silica. The combined filtrates from the bisulphate fusions are treated with ammonia until a slight permanent precipitate results.This is redissolved by the least possible addition of hydrochloric acid, and then a solution containing about 15 grms. sodium thiosulphate is added. The mixture is boiled for fifteen minutes, and then filtered through a pulp filter. The precipitate is washed with water acidified with acetic acid, and is finally ignited and weighed as titanium dioxide.The filtrate is con- centrated considerably, diluted with 200 C.C. hot water, and this alternate concentra- tion and dilution repeated until a clear solution results. Bromine water is added, and any titanium dioxide which may have passed through the pulp filter is filtered off, washed, ignited, and weighed. The filtrate is heated to boiling, iron and aluminium are precipitated by means of ammonia, and the mixed hydroxides are filtered off, washed, ignited, and weighed as oxides.The ferric oxide is then determined by solution of the mixed oxides in hydrochloric acid, reduction by means of stannous chloride and titration with dichromate, alumina being calculated by difference. I n the filtrate from the hydroxides of iron and aluminium, manganese is precipitated by means of bromine, and weighed as Mn,O,.G. C. J. Estimation or" Fluorine in Zinc Ores. L. Schneider. (Oesterr. Zeits. Berg.- u. Hiittenwesen, 1913, 61, 365-367 ; through Chem. Zentralbl., 1913, II., 615.) -Estimation of fluorine in zinc ores by distillation with concentrated sulphuric acid in the presence of quartz, and collection of the silicon hydroxide which separates in water, gives inaccurate results.The bulk of the fluorine is liberated as silicohydro- fluoric acid, but a portion escapes with the sulphur dioxide as hydrofluoric acid. I t is therefore necessary to precipitate the fluorine as calcium fluoride after removal of the sulphur dioxide. Ten grms. of the finely powdered ore are mixed with 5 grms. of quartz-powder, and heated on an oil-bath at 160" to 170" C.with about 100 C.C. of strong sulphuric acid, whilst a current of dry air is meanwhile drawn through the apparatus. The gases are passed through a U-tube filled with fragments of quartz into a receiver containing 100 C.C. of water. After the distillation, the water in the receiver is mixed with potassium nitrate and evaporated to dryness, the residue taken up with water, and 25 C.C.of ammonia solution added. The precipitate is separated and ignited in a platinum basin, the residue (CaFz+ SiO,+CaO) treated with acetic acid, evaporated to dryness, and ignited, and the calcium fluoride and silica weighed. The silica is then expelled by means of hydrofluoric acid. The weights of calcium fluoride and silica should stand in the empirical ratio of 1 : 3.4.C. A. M.476 ABSTRACTS OF CHEMICAL PAPERS Detection of Gold and Platinum. G. Malatesta and E. D. Nola. (Boll. Chim. Farm., 1913, 52, 461-463 ; through Chem. Zentralbl., 1913, II., 716-717.)- The method devised by Pertusi and Gastaldi for the detection of hydrocyanic acid (by means of copper acetate and benzidine acetate) may be adapted to the detection of gold and platinum.The reagent consists of a solution of 1 grm. of benzidine in 10 C.C. of acetic acid and 50 C.C. of water. With solutions of gold salts it gives a deep blue coloration, which gradually changes to violet. In the presence of free acetic acid the coloration is preen., but is changed to blue on the addition of an excess of benzidine. Very dilute platinum solutions yield with the reagent a blue flocculent precipitate, which may possibly be utilised for the estimation of the metal.Heat promotes the separation of the precipitate and makes it darker. Dilute solutions of ferric salts give with benzidine acetate a blue coloration, which is only stable in the presence of excess of benzidine. Free mineral acids do not affect the gold reaction, but retard the precipitation of platinum in the cold.Before applying the test for gold or platinum, iron salts should be removed by means of dilute hydrochloric or nitric acid. The reaction is capable of detecting 0.0000035 grm. of gold and 0*0000125 grm. of platinum. C. A. M. Colour Reaction of Hypochlorites with Methylaniline and Ethylaniline. P. N. Leech. (J. dmer. Chem. Xoc., 1913, 35,1042.)-Hofmann (Ber., 1874, 7, 526 ; and Ann., 1851, 77, 130) stated that no colour reaction was given upon the addition of bleaching-powder solution to methyl- or ethylaniline.Pure methylaniline specially prepared by two separate methods was diluted to make a i+-rr mol. aqueous solution. The intensity of the blue colour which is produced and its time of appearance vary with the concentration.For 1 C.C. of the solution made alkaline with 3 drops to 0.5 c.c, of 6 N sodium hydroxide solution, and treated with 0.5 C.C. to 2 C.C. of half-saturated calcium ovychloride solution, the colour begins to appear in about twelve seconds, and reaches a maximum intensity of navy blue in about thirty five seconds. After about one minute the colour begins to fade slowly, leaving a yellow solution and a white precipitate of calcium carbonate.As little as 1 mgrm. in 8 C.C. can thus be detected. An excess of alkali, and especially of bleaching- powder solution, is to be avoided. An analogous colour reaction occurs with pure ethylaniline, except that the blue colour goes through green and dark brownish hues before finally leaving a yellow solution.The time required to produce the colour and its persistence are two to three times longer than with methylaniline. H. F. E. H. Solubility of Lead Sulphide and Lead Chromate. G. v. Hevesy and F. Paneth. (Zeitsch. anorg. Chew., 1913, 82, 323-328.)-The authors have made use of the fact that radium D is inseparable from lead to determine the solubility of lead chromate and lead sulphide.A solution was made containing 10-6 grru. of radium D and 10 mgrms. of lead chloride. This solution was treated with excess of potassium chromate, and the resulting precipitate filtered off and washed. A solution of the chromate, saturated at 25' C., was then prepared, filtered from undissolved chromate, and a measured portion was evaporated to dryness, and theINORGANIC ANALYSIS 477 radio-activity (p) of the residue measured as soon as equilibrium between radium D and E was established.From this result and the known radio-activity and per- centage of lead in the solution which was used to prepare the chromate the solubility of lead chromate at 25' C. was calculated to 1-2 x 10-5 grm. per litre. I n a similar manner lead sulphide was shown to be soluble to the extent of 3 x grm.per litre at 25" C. in pure water, the solubility in water saturated with hydrogen sulphide being just half as much. G. C. J. Colorimetric Estimation of Small Quantities of Manganese in Water. E. Sehowalter. (Zeitsch. Untersuch. Nahr. Genzissm., 1913, 26, 104-108.) - An investigation of the method proposed by Haas (ANALYST, 1913, 225) showed that chlorides are not eliminated from the water by heating with sulphuric acid and persulphate. As it is essential that all hydrochloric acid be removed before the manganese is estimated, the author adopts the method given below.The removal of chlorides by the addition of silver nitrate is objectionable owing to the turbidity produced. A t the same time, the presence of a small quantity of silver nitrate renders possible the estimation of manganese in waters containing less than 2 mgrms.of the metal per litre. The reaction is dependent on the concentration of the acid and the quantity of silver nitrate, and in the presence of the latter the full intensity of the permanganate coloration is attained. One hundred C.C. of the water are acidified with 10 C.C. of nitric acid and evaporated to dryness; the residue is treated with 10 C.C.of nitric acid, again evaporated to dryness, and then dissolved in 5 C.C. of nitric acid and 10 C.C. of water. The solution is filtered, the insoluble portion is washed, and the filtrate (measuring not more than 35 c.c.) is heated to boiling after the addition of 5 C.C. of nitric acid and 1 grm. of ammonium persulphate.Ten drops of a 5 per cent. silver nitrate solution are now added and the mixture again boiled, the boiling being maintained for 1.5 minutes after the first appearance of the pink coloration. The intensity of the coloration obtained is then compared with that of standard permanganate solutions. The presence of iron salts in moderate quantity, and of organic reducing substances, does not interfere with the estimation.w. P. s. Estimation of Mercury in the Air of Rooms, ete., where the Metal is Used. A. Blomquist. (J. Pharm. Chim., 1913, 7, 8-15, 71-75, 112-118, 166-172.)- The author has estimated the quantity of mercury present in the atmosphere of rooms in laboratories, hospitals, and works, where considerable quantities of the metal or its salts are employed.It was found that mercury vapour was almost invariably present in such places, the quantity varying from a mere trace to about 1 mgrm. per 4,000 litres of air. Mercury was also detected in the dust collected from the rooms, and was present in the urine of persons working therein. The method employed for the estimation of the mercury consisted in liberating chlorine in the room, and then aspirating 4,000 litres of the air through a series of absorption vessels containing a dilute hydrochloric acid solution of stannous chloride and potassium hydroxide solution respectively. The contents of the vessels were then mixed and treated with hydrochloric acid and potassium chlorate.The mercury in478 ABSTRACTS OF CHEMICAL PAPERS the solution was then precipitated (amalgamated) by the addition of zinc dust, redissolved, and collected on a gilded asbestos filter as described by Farup (ANALYST, 1913, 111).I n the case of minute quantities of mercury, it was found to be preferable to collect the mercury from its solution on a small piece of brass-foil. The latter was then heated in a tube, and the mercury collected in a capillary portion of the latter.The small sublimates thus obtained were compared with capillary tubes containing known quantities of sublimed mercury. w. P. s. Sensitive Reaction of Molbydenum. A. Komarowsky. (Chem. Zeit., 1913, 37, 957.)-In Melikoff's test for molybdenum the solution is evaporated to dryness on the water-bath, and the cold residue treated with a drop of strong ammonia and a drop of hydrogen peroxide.In the presence of molybdenum, a cherry-red to rose- yellow coloration, due to the formation of ammonium permolybdate, is obtained. The test is capable of detecting 0.006 mgrm. of molybdenum. Ammonium permolybdate is decomposed by gentle heat, and the original substance reproduced. C. A. M. Determination of Phosphorus in Steels containing Vanadium. J.R. Cain and F. H. Tucker. (J. Ind. and Eng. Chem., 1913,5, 647-650.)-When vanadic acid is present, even in small quantity, the precipitation of phosphorus as phospho- molybdate is incomplete, and the precipitate is contaminated by vanadium compounds. The following method, which depends on reducing vanadium compounds to the quadrivalent condition and preventing their reoxidation until the precipitation of the phosphorus is complete, is adapted to any steel containing vanadium, provided no other element which ordinarily complicates the determination of phosphorus is present.If tungsten, titanium, arsenic, tin, etc., are present, their disturbing influence is eliminated by the usual methods for steel containing no vanadium. Neither nickel, copper, chromium, molybdenum, nor aluminium, interfere.The steel (1 to 2 grms.) is dissolved in 100 C.C. of dilute nitric acid (sp. gr. 1-135), the solution is oxidised while hot by a slight excess of permanganate, manganese dioxide or excess of permanganate is reduced by means of sulphurous acid, and the solution is cooled and partially neutralised by addition of 40 C.C. of dilute ammonia (sp.gr. 0.96). The solution is cooled again to 15" to 20" C., and 5 C.C. of a saturated solution of ferrous sulphate and a few drops of sulphurous acid solution are added to complete the reduction of the vanadium. Molybdic reagent (40 c.c.) is added, and the mixture shaken vigorously for ten minutes, after which the precipitate is filtered off, washed until free from acid, and titrated by the alkelimetric method.The use of a second reducing agent (ferrous sulpbate) can be avoided, and the complete reduction of the vanadium effected by means of sulphurous acid ; but it is essential to keep the temperature low, and reduction is then so slow that the method is not recommended. On the other hand, although ferrous sulphate alone would reduce excess of permanganate as well as the vanadium, it is found that, unless sulphurous acid is simultaneously present, the reduced solution suffers reoxidation before the precipitation of the phosphorus can be effected.It is probable that the nitric oxide formed by the action of the ferrous salt on the nitric acid acts as aINORGANIC ANALYSIS 479 carrier of atmospheric oxygen to the vanadyl compound.Whatever the nature of the action, the test numbers show that it is completely held in check by the presence of a trace of sulphite. G. C . J. Action of Persulphate on Iodate, and Estimation of Periodate in Presence of Persulphate. E. Muller and W. Jacob. (Zeitsch. anorg. Chew., 1913, 82, 308-314.)--Xn absence of iodate, a mixture of periodate and persulphate may be analysed as follows : To a measured volume of the solution is added so much caustic alkali that the mixture is approximately alkaline. Potassium iodide is added, the mixture boiled for two minutes, cooled, acidified with dilute sulphuric acid, and the liberated iodine is titrated with & thiosulphate.This measures the sum of the available oxygen of the persulphate and periodate.Another portion is made alkaline with caustic alkali, and reduced by boiling for an hour with zinc under a reflux air-condenser. The iodide in the resulting solution of iodide and sulphate is then determined by pouring off from the zinc, cooling, acidifying with dilute sulphuric acid, treating with excess of iodate, and titrating with & arsenious solution after addition of a considerable excess of sodium bicarbonate.Five-sixths of the iodine found is the measure of the periodate originally present, and the oxygen equivalent of this periodate subtracted from the total available oxygen due to periodate and persulphate gives the measure of the persulphate. The authors' work was undertaken for the purpose of studying the reaction between persulphate and iodate, one of the products of which is periodate.They have been unable to devise an exact method for the estimation of periodate in presence of persulphate and iodate, but the following method gives results which are -t.5 per cent. The solution is made with caustic alkali, an egcess of potassium iodide is added, and the mixture left for twenty-four hours at room temperature. Under these conditions persulphate alone is reduced quantitatively to sulphate with production of iodate, whereas periodate alone is unacted on by iodide in caustic alkaline solution.The error of the method is due to the fact that in presence of persulphate an uncertain proportion of the periodate reacts with iodide to form iodate. After standing twenty-four hours as described, the solution is mixed with a measured and more than sufficient quantity of arsenious solution, then with a large excess of sodium bicarbonate, heated for five minutes to 50" C., cooled, and the excess of arsenious solution titrated with FG iodine. to G.C . J. Separation of Tin from Tungsten Electrolytically. W. D. Treadwell. (Zeitsch. Electrochem., 1913, 19, 381-384 ; through Chem. Zentralbl., 1913, II., 85.)- The chief difficulty in working out a satisfactory method for the electrolytic separa- tion of tin and tungsten has been to find an alkaline electrolyte, from which the tin could be deposited rapidly and in adherent form whilst the tungsten remained in solution as tungstate.A warm solution of sodium sulphide has been found the most satisfactory electrolyte, and the best results are obtained by working at a temperature of 50" to 60* C., and a P.D.of 1.7 to 2.3 volts. The method is not available n presence of molybdenum. G. C. J.480 ABSTRACTS OF CHEMICAL PAPERS Estimation of Sulphur in Pyrites and Other Sul- phides. M. Dittrich. (Zeitsch. anorg. Chem., 1913, 83, 27-32.)-The method described consists in conibustion of the sulphide in a current of oxygen, absorption of the sulphur trioxide and oxidation of sulphur dioxide by means of bromine- water and bromine, and precipitation of the sulphuric acid by means of barium chloride in the usual manner.The combustion is carried out in a specially-constructed silica combustion-tube, 30 cm. long and 12 mm. in internal diameter. The back end is ground to receive the enlarged end of a silica tube of small bore which connects to a sulphuric acid wash-bottle, and thence to the supply of oxygen.The forward end of the combustion-tube is drawn out and ground to fit into the enlarged end of a silica bend, which, except at the enlargement, is 5 mm. in internal diameter. The absorption apparatus g is of such design that, if 2 C.C. of bromine be introduced into the large bulb together with the bromine-water, every bubble of gas will come in contact with bromine in the horizontal tube 2, whereas very little bromine vapour will go forward. The Peligot tube h is also charged with bromine-water, the Volhard bubbler i with caustic soda solution, and k with water.The substance to be burned is weighed out into a porcelain boat, which is pushed up to the front of the combustion-tube, and the current of oxygen is so adjusted that two or three bubbles pass per second.The forward part of the boat is then heated with the full flame of a Bunsen burner until combustion commences, when the heat is moderated and the rest of the boat and of the combustion-tube are heated up to prevent condensation of sulphur trioxide.When combustion slackens, the heat is increased, and finally a Tech burner is used. Finally the flame is carried to the forward ground joint, and beyond it to the bend of the tube f. The contents of g and h are now transferred to a beaker, together with the washings off, boiled to expel bromine, neutralised with ammonia, acidified with 1 C.C. of hydrochloric acid, and heated to boiling.Boiling solution of barium chloride is then added, and the analysis completed in the usual manner. The soda solution in i and the residue in the boat should be tested for the presence of sulphate. In the case of pyrites, none will be found, according to the author’s experience. With blende, on the other hand, 1 to 2 per cent. of the sulphur will remain in the boat unless the sample he very finely divided and spread in a very thin layer in the boat.A 5-inch boat is necessary to give sufficient distribution to 0-7 grm. of blende. G. C. J.INORGANIC ANALYSIS 481 Application of Tantalum Electrodes to Electro-Analytical Estimation Of Copper and Zinc. G. Wegelin. (Chem. Zeit., 1913, 37, 989.)-Brunck (Chem. Zeit., 1912, 36, 1233) anh others have recommended the use of tantalum electrodes for the estimation of copper, of zinc from alkaline zincate solution, and for other purposes.The resistance of tantalum towards chemical reagents, including concen- trated nitric acid and mixtures of dichromate with sulphuric acid, is high, and its low cost compared with platinum would justify its use, even at some loss of speed or increased complexity of technique.So far as the estimation of zinc is concerned, however, the author has been unable to obtain adherent d.posits. No modification of the character of the electrolyte or other conditions of experiment gave rise to results even approximately quantitative. The existence of a superficial layer of oxide, such as forms on aluminium, is held to be the probable explanation of these results.Copper can be deposited quantitatively from sulphuric acid solution, using the current for a single accumulator. Deposition is complete in nineteen hours, but not in fifteen hours, when 0.2 grm. of copper is present in 100 C.C. The relative slow- ness of the deposition itr the only disadvantage of the method, and in some circum- stances this disadvantage may be negligible. Attempts to increase the speed of deposition by resort to higher temperatures led to the formation of deposits which were insufficiently adherent. Before use, the electrodes are treated with a mixture of dichromate and sulphuric acid, any copper from a previous estimation being first dissolved in nitric acid.G. C. J. Estimation of Thiosulphate in Presence of Sulphites.A. A. Besson. (Chem. Zed., 1913, 37, 926.)-In a mixture containing sodium sulphite, bisulphite, and thiosulphate, the sulphite and bisulphite are estimated by the method of Bosshard and Grob (ANALYST, 1913, 297), the sulphite by titration with standard acid and methyl orange, and the total bisulphite by titration of the same solution with standard alkali and phenolphthaleh, the true amount of bisulphite being calculated from these results.To determine the thiosulphate, another portion of the solution is heated with 25 C.C. of & alkali and 20 C.C. hydrogen-peroxide solu- tion (5 C.C. of Merck’s perhydrol diluted to 100 c.c.) for ten minutes on the water- bath or wire gauze, and, after cooling, the excess of alkali is determined with methyl orange and acid.The quantity of alkali absorbed by the bisulphite is known and is deducted. One C.C. of & alkali corresponds to 0-01241 grm. Na,S,O,, 5H,O. Separation of Tungsten from Thorium, Lanthanum, Cerium, Erbium, Didymium, and Silica. M. Wunder and A. Schapira. (Ann. Chim. anal., 1913,18, 257.)-The methods were tried on the oxides mixed in known proportions. The quantities recovered showed satisfactory agreement with those taken.Separation of Tungsten and Thorium Oxides.-The oxides are heated to constant weight and fused for an hour with fifteen times their weight of sodium carbonate ; the melt is boiled for twenty minutes with water and more sodium carbonate, and filtered. The residue, thorium dioxide, is ignited ; the tungstic trioxide is precipitated from the neutralised filtrate with mercurous nitrate solution containing a slight excess of nitric acid.The thorium dioxide residue is insoluble in 5 per cent. hot hydrochloric acid. 0. E. M.482 ABSTRACTS OF CHEMICAL PAPERS Separation of Tungsten and Lanthanum Oxides.-The method is identical with the above. The residue of lanthanum oxide is completely soluble in hot 5 per cent. hydrochloric acid, Separation of Tungsten and Cerium Oxides.-The mixture of oxides is volatile, consequently, in testing the validity of the method it was necessary to ignite them separately to constant weight before mixing them. The separation is identical with the above. Separation of Tungsten and Erbium Oxides.-The filtration of the dissolved melt must take place in the cold. The residue of erbium oxide is dissolved in 5 per cent. hydrochloric acid and reprecipitated with ammonia. Separation of Tungsten and Didymium Oxides. - I n testing the method, the oxides required treating separately to constant weight. The separation is identical with that for tungsten and erbium. Separation of Tungstic Trioxide, Alumina, and Silica.--In presence of a large excess of ammonium nitrate the tungsten is not precipitated by mercurous nitrate, and the silica, in presence of tungstic trioxide, is only incompletely precipitated by the ammonium nitrate. The separation is therefore effected as follows: The alumina and part of the silica are Precipitated with ammonium nitrate, and the pre- cipitate ignited and weighed, treated with hydrofluoric acid and a few drops of sulphuric acid, ignited, and weighed as alumina, the difference giving the silica pre- cipitated with it. The tungsten is precipitated as mercurous tungstate from the filtrate with mercurous nitrate, and treated with hydrofluoric acid and sulphuric acid, the tungstic trioxide and silica precipitated with it being thus obtained. Finally, the rest of the silica is determined by the usual methods in the filtrate from the mer- curous tungs tate precipitate. 0. E. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800473

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

482 ABSTRACTS OF CHEMICAL PAPERS APPARATUS, ETC. Ebullioscope of High Accuracy. A. Contassot. (Ann. Chim. anal., 1913, 18, 273.)-The apparatus is designed for the determination of the alcohol-content of wines and other liquids. Previously it has been necessary to determine separately the boiling-point of the water and of the sample, the two operations requiring twenty to twenty-five minutes ; an estimation can now be carried out in five to six minutes.The sample is taken as it stands, or diluted, according to its alcohol content. The alcohol in distillery residues and in vinegar in process of manufacture may be deter- mined by means of the apparatus. I t is obtainable from A. Manoncourt, 76, Boule- vard St. Germain, Paris. 0. E. M. Apparatus for Gas Analysis Laboratories at Coal Mines, G.A. Burrell and F. M. Seibert. (27.5'. Bureau of Nines, Technical Paper 14, pp. 24.)-An apparatus for the exact determination of carbon dioxide and methane, another for for the exact determination of methane alone, portable modifications of each, and a modified Orsat apparatus for complete approximate analysis of mine air are illus- trated and described.No new principle is involved in any of them, but advantage has been taken of the work of Haldane and others to devise appliances exactly suited to the requirements of some mine laboratories. The pieces of apparatus describedAPPARATUS, ETC. 483 appear to be identical with some of those in an earlier paper (ANALYST, 1912, 37, ZSS), but whereas the journal in which that paper appeared is not everywhere avail- able, the present publication may be obtained free by applying to the Director, Bureau of Mines, Washington, D.C.G. C. J. Melting-Point Apparatus for High Temperatures. E. Schwinger. (Monatsh. fur Chem., 1913, 34, 977-979.)-0n the upper end of a Bunsen burner, B, is fixed an incandescent gas- burner, A , as shown in the illustration-if necessary, the tube of the burner being wrapped round with asbestos-paper.On the incandescent burner is fixed the ordinary chimney C, of Jena glass provided for that type of burner. This cylinder serves as an air-bath which is very easily regulated, and in which the melting-point apparatus is heated. This consists of the fairly thick-walled test-tube, E, 18 to 20 cm. long, held by a clamp at its upper end.The tube forms a bath, charged for high temperatures with an equimolecular mixture of sodium and potassium nitrates, or for lower temperatures with sulphuric acid. With such a form of bath there is plenty of room for ex- pansion, so that it is not necessary to pour away the salt mixture when the operation is finished. With a short thermometer the mercury column may be completely surrounded by the fused salt, and the corrected melting-point directly obtained.The thermometer is fixed in the tube by a split cork. The chief advantage of this apparatus is its convenient and rapid manipu- lation, so that the temperature of the bath immediately responds to any adjustment of the flame, the heating being performed by the upward current of air. The regulation is facilitated by attaching a pointer to the tap of the burner and a fixed scale.This mode of heating may be applied for other purposes-e.g., maintaining liquids at gentle ebullition for long periods-and temperatures up to 550" C. are readily obtained. J. I?. B. Preparation of Sections of Crystalline Substances. E. Korreng. (Zentralbl. Bin. u. Geol., 1913, 408-412 ; through Chem.Zentralbl., 1913, TI., 614.)-Thin sectionclr of fused salts, etc., for crystallographic examination are prepared by rubbing one surface upon emery-paper of different grades and polishing it upon smooth glass, a drop of castor-oil being added in the case of hygroscopic substances. The polished surface is attached to the object-glass with Canada balsam, and the other surface rubbed down with emery-paper until sufficiently transparent, after which the preparation is mounted in Canada balsam.Very hygroscopic substances may be melted between two cover- glasses, which are afterwards mounted in Canada balsam. C. A. M. I i484 ABSTRACTS OF CHEMICAL PAPERS Simple Modification of Skita's Hydrogenising Apparatus. H. H. Franek. (Chem. Zeit., 1913, 37, 958.)-The measuring cylinder A of this apparatus is 75 to 100 cm. long, and has a capacity of about a litre.The upper end is c l o d by a 5 km t" rubber cork (wired down), through which passes a tube, b, which can be connected with the hydrogen cylinder or the shaking vessel ; whilst the rubber cork in the lower end has two out- lets : one of these, d, is attached to the water- tap, and the other, a, with a mercury regulator, B.In using the apparatus, all air is first expelled from A by means of water from d. The tube b is next connected with the hydrogen cylinder, the tube d disconnected from the water-tap, and the gas introduced into A until nearly the whole of the water has been driven out. The tube d is then again connected with the water-supply, and hydrogen passed into the cylinder until the first bubbles of water rise through the mercury in B-i.e., until the pres- sure equals 1 atmosphere.The tap a is now closed, the tube b connected with the shaking vessel, containing the unsaturated substance, the tap a opened again, and water introduced through d until bubbles again appear above the mercury. In this way the absorption is com- pensated and constant pressure maintained.As the water rises in A during the absorption the mercury regulator is raised, or an empirical correction may be applied. The hydrogen value of unsaturated bodies is measured by the volume of gas absorbed. C. A. M. New Designs for Speeifie Heat Apparatus. A. R. Johnson and B. W. Hammer. (J. Amer. Ohem. Soc., 1913, 35, 945-948.)-Two pieces of apparatus are described and illustrated, having for their object the rapid yet accurate determination of the specific heat of liquids.Both depend on electrical heating, and one is intended for use where electrical energy at constant voltage is available, whereas the other is independent of the voltage. In the apparatus for constant voltage, the calorimeter vessel is a thin copper or glass cylinder of 500 C.C.capacity, which is supported on cork points in a, Dewar vessel some 12 cm. in diameter and 15 cm. deep. The Dewar vessel rests on a wooden support and has a hollow wooden cover, which is adapted to be raised and which carries a thermometer and an 8 c.p. lamp which dip into the calorimeter vessel when the cover is in place. The lamp has agitating vanes attached to it, and is adapted to be rotated.The liquid to be tested is placed in the calorimeter, the temperature noted, the current switched on, and readings of the temperature taken every minute for five minutes. A second experiment with an equal weight of water is then made. The correction to be applied for radiation is determined in the usualAPPARATUS, ETC.455 way. An alternative method for determining specific heats with this apparatus consists in noting the time required to raise a definite weight of the liquid through a definite temperature interval, and comparing this with the time required to raise an equal weight of water through the same interval. In the second apparatus the calorimeter vessel is a copper or glass cylinder 6.25 cm.in diameter and 8.75 cm. high, and it is supported on cork points in a cylindrical space hollowed in a block of cork about 12 cm. cube. Surmounting this hollowed block is a heavy asbestos cover in three pieces, the middle piece being adapted to slide, and above the asbestos cover is another large block of cork with a cylindrical hole about 5 cm. in diameter bored through it.I n the cylindrical space thus formed and resting on the asbestos slide is the heater, consisting of a copper vessel 4.7 cm. in diameter and 8.1 cm. high, containing 100 C.C. of water and, immersed in it, a small incandescent lamp. The heater has a tight-fitting cover, and the leads from the lamp pass through a glass tube which serves as a handle by means of which the whole heating appliance can be raised or lowered.The heater as well as the calorimeter is supplied with a thermometer. In use, 100 grms. of the sample is placed in the calorimeter, and the heater (out- side the instrument) is raised to a temperature about 25" C. higher than initial temperature of the sample, and is then placed in its chamber in the upper cork block. When radiation becomes regular, the calori- meter thermometer is read, and when the heater has cooled to some chosen temperature it is dropped into the calorimeter vessel.The liquids in both vessels are agitated by means of vanes attached to the thermo- meters, and the maximum calorimeter temperature is noted. A similar experiment is then made with water. Corrections for radiation and for the water equivalent of the calorimeter must, of course, be applied.I n a series of determinations of the specific heat of aniline, made with the apparatus first described, no result differed by more than 0.2 per cent. from the mean. G. C. J. Combination Specific Gravity Bottle and Dila- tometer. C.A. Browne. (J. Amer. Chem. SOC., 1913, 35, 955-958.)-The accompanying block makes clear the principle of the instrument, which holds about 30 C.C.W-hen used to determine specific gravities it is used like an ordinary pycnometer. By raising or lowering the temperature after the vessel is filled, the coefficients of expansion or contraction may be calculated. The author has found the apparatus convenient for measuring the contraction which sugar solutions undergo during hydrolysis or inversion, and, from the fact that 100 C.C.0 B-486 ABSTRACTS OF CHEMICAL PAPERS of 1 per cent. cane-sugar solution undergo a contraction, during inversion, of 0.02 c.c., the approximate percentage of cane-sugar present in a solution may be measured after the addition of invertase or acid. The contraction which sugar solutions and water undergo when mixed may be easily demonstrated by placing a few C.C.of strong sugar solution in the instrument, filling carefully with water to some mark on the capillary, and then mixing by reversing the whole. H. F. E. H. Simple Apparatus for Ultrafiltration. R. Zsigmondy. (Zeitsch. angew. Chem., 1913, 26, 447-448.)-1n conjunction with others, the author has-previously ~12+---- - - - - _ jl& _ _ - - _ _ _ -1 described (ANALYST, 1912, 37, 223) an apparatus which serves well, but has the dis- advantage that the collodion films are liable to get torn at the edges.The apparatus now figured is in three pieces, of which the funnel tube A and the ring B are of glass, the perforated plate S of hard rubber. The whole apparatus was at first con- structed of hard rubber, but the partial substitution of glass reduces the cost of construction. The flanges of all three parts are ground to fit, and are held together by clamps when the filter has been prepared. To do this, B is removed, a filter- paper is fitted over s, in- cluding the flange, and on this is superimposed a collodion film. B is then set in place, and the whole screwed together. The collodion films are prepared by diluting 4 parts of commercial collodion (6 per cent.) with 2 parts ether and 5 parts alcohol, pouring on to a polished glass plate, and stripping in the manner previously described. By the aid of a pump 100 C.C. of water may be sucked through a 9 cm. filter in five minutes, and 100 C.C. of water separated from 0.1 grm. of colloidal ferric hydroxide in twenty minutes. I * -- - - - - - - - - - - - j o o - - - - - - _ _ _ - - _ _ _ - , G. C. J.

ISSN:0003-2654    

DOI:10.1039/AN9133800482

出版商:RSC    

年代:1913

数据来源: RSC

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REPORT 487 REPORT. Metropolitan Water Board : Seventh Annual Report, March 31, 1913. A. C. Houston.-The author considers that the means now adopted for the purifica- tion of the Metropolitan water-supply are such as to render the water reasonably, if not absolutely, safe for drinking purposes. The average quality of the water supplied during the year, together with that of the Rivers Thames and Lea, was as follows : Parts per 100,000.Ammoniacal nitrogen . . . Albuminoid ,, ... ... Oxidised 9 , ... Chlorine ... ... ... Oxygen absorption, 80’ F. ... Total hardness . . . ... ... Permanent hardness . . . ... Turbidity . . . ... ... Colour : mm. brown in 2 feet ... ... Bacteria per C.C. gelatine ... 3 ) ,, agar ... ... I 9 ,, B. coli ... Thames Water. Filtered. + 0-0051 0.0146 0.26 1.56 0.2097 4.96 2.57 65 22.3 6550 428 15 0-0004 0.0063 0.24 1.53 0.0924 21.16 5.58 nil 18 14.5 1.9 2 to 3 per 1, Lea Water.Raw. Filtered. 0.0088 0.0135 0-30 2-0 0,190 25-12 5.99 3.12 67 11,772 484 0.0003 0.0053 0.26 1.96 0-0753 23.37 6.36 nil 16 30.5 5.2 Owing to the excessive development of Tabellaria in the Staines reservoirs, the filtered water from these reservoirs had often a most unpleasant ( ( geranium ” taste and smell.Although this was innocuous, the water was at times almost undrinkable. The author concludes with a, review of the sources of the London water-supply, in which he states that the river waters are undoubtedly unsatisfactory in quality, and the judicious selection of water is becoming increasingly difficult, as the con- sumption increases whilst the volume of the rivers remains constant.The levelling effect of storage, however, renders the possibility of any sudden dangerous pollution a matter of less grave concern than would otherwise be the case. But if, owing to any accidental circumstance, a considerable amount of infective material should gain access to the water directly feeding the filters, the result would be likely to be disastrous. In this connection, too much reliance must not be placed on the work of water examination. For technical and other reasons, the most perfect and costly system of water examination that could be devised might fail altogether to detect an accidental contamination.” J. H. J.

ISSN:0003-2654    

DOI:10.1039/AN9133800487

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

488 REVIEWS REVIEWS. AN INTRODUCTION TO THE STUDY OF FUEL. By F. J. BRISLEE, D.Sc. London: This is the first of a series of volumes on I ‘ Outlines of Industrial Chemistry,’ under the editorship of G. D. Bengough, and has for a subtitle ‘ I A Textbook for those entering the Engineering and Technical Industries.” The series is intended, in the word8 of the editor, to provide a link between the elementary chemistry taught in schools and colleges which provide instruction up to, say, the matriculation standard of a modern University, and the larger textbooks dealing with the details of the several industries.The subject of fuel is of importance in a wide range of industries, and there is no doubt that the editor has made a wide choice of subjects for the opening volume, more especially as there was no modern work on the subject covering the same ground. The arrangement of the book is good, the exposition of the subject being clear and lucid, proving the author’s experience as a teacher ; but as a whole the book is disappointing.One of the most usual complaints of the manufacturer employing a man straight from the University is that he is apt to waste time in working out his results to five places of decimals when his fundamental measurements are not reliable to three.A striking example of this is given in chapter viii., where the heats of formation of two coals are worked out. Analyses of two coals are given, from which the heats of combustion are calculated as 6301.68 and 6183.65 respectively ; the measured heats of combustion are taken as 7433.00 and 6013.00 calories ; and the differences of these are quoted as the heats of formation.Incidentally it may be noted that the analyses of the coals, although apparently complete, including carbon, hydrogen, oxygen, nitrogen, moisture, sulphur, and ash, add up to 98-65 per cent. and 100.52 per cent., and are probably liable to sampling errors of at least 0.5 per cent.And yet we have a thermal measurement given to six significant figures. This example is quoted from Juptner, but there are plenty of other examples else- where. Thus, 11,934 B.T.U. per pound is given as a figure obtainable with the W. Thomson calorimeter. In chapter ii., again, on the weight and volume of air required for combustion, starting with the round number of 21 per cent.of oxygen in air by volume and a fuel analysis of three significant figures, we find the weight and volume of the products of combustion given as 12,8565 grms. and 9410.2 Iitres. On p. 221 there is another example, in which the weight of the products of com- bustion of a coke is given as 11,1934 grms., or, including excess air, 22,511-8 grms. Returning to the narrower standpoint of analysis, with which this journal is more specially concerned, very little stress is laid on the importance of sampling, nor is there any intimation of the magnitude of the errors likely to arise from this source.The methods given for the determination of moisture and volatile matter in coal would lead to figures differing considerably from those obtained by methods currently used.Pn flue gas analysis the Winkler burette is described as a Hempel; both the methods given for the estimation of carbon monoxide in flue gas are unreliable, the accurate iodine pentoxide method not being mentioned. The Stead gas sampler is figured, but the instructions for its use are quite inaccurate, the author not having, apparently, grasped the reasons for its design.No carbon dioxide recorder Constable and Co., Ltd. Pp. xxii + 269. Price 8s. 6d. net.REVIEWS 489 is figured, for lack of space, but eleven pages are devoted to a full mathematical treatment of producer gas and water gas reactions. This chapter concludes with the remark : ‘‘ From a technical standpoint, however, these calculations are at present of little value, as equilibrium is certainly not reached in the production of either water gas or producer gas.” The reviewer agrees with this conclusion, and thinks this chapter might be omitted with advantage, I n chapter iv. descriptions and working directions are given for the Lewis Thompson, W.Thomson, Rosenhain, F. Fischer, Berthelot-Mahler, and Parr coal calorimeters, also for the Junker and Boys gas calorimeters.The descriptions are clear and the instructions sufficiently detailed for use by a student. There is no attempt, however, at a critical examination of the various types, and the student would naturally, but erroneously, assume that all were of equal accuracy. I t is difficult to fathom the reason which has led the author to classify the Lewis Thompson instrument as belonging to the type in which the combustion takes place at atmospheric pressure, whilst the Parr (sodium peroxide) calorimeter is classified under the type in which combustion is carried out at pressures greater than atmospheric.There is no discussion of the use of the “ gross ” and “ net ” calorific values; the latter is defined incidentally as obtainable ‘( by subtracting the latent heat of vaporisation of water, 10,800 cals.per molecule, from the value obtained experiment ally.” The chapter on natural solid fuel contains some curious statements. Anthracitic coals and anthracites are described under the main heading of ‘‘ Bituminous Coals.” The calorific values of the coals given on pp. 132 to 135 are impossible, and in no way correspond with the compositions given.I t is diEcult to understand how any- one who has had anything to do with the handling of fuel could give 16,560 to 17,280 B.T.U. per pound as a typical value for short-flame caking coals. These figures are repeated in the table on p. 135. The figures in the adjacent column, on the other hand, headed Water evaporated per Cent.” (probably a misprint for ‘‘ Pound ”-“ Water evaporated per Pound ”) are much too low, and do not correspond to the average boiler efficiency.In this chapter also it is stated that ‘‘ anthracite coal is used for firing the boilers of steamships, especially warships.” The book does not appear likely to be of service to the class of students mentioned in the preface. G. NEVILL HUNTLY. METHODS IX CHEMICAL ANALYSIS ORIGINATED OR DEVELOPED IN THE KENT CHEMICAL LABORATORY OF YALE UNIVERSITY.New York : John Wiley and Sons ; London : Chapman and Hall, Ltd. 1912. Price 17s. net. As stated in the preface, the object of this volume is to present concisely the principal results reached by workers in the Kent Chemical Laboratory in the investi- gation and development of methods in (inorganic) chemical analysis.Consequently one finds here described apparatus and processes with many of which one has become familiar through the original papers or abstracts published in the ANALYST during the past twenty years or more. As representing the work of a laboratory presided over by a master in the science of analytical chemistry, it is valuable to have these results collected in a single volume, and every practising analyst will find it worth while to place the volume upon his shelves. I t is full of original ideas in Compiled by F.D. GOOCH.490 REVIEWS apparatus and methods, the descriptions are models of clearness, and the illustra- tiom are beautiful examples of the book-illustrator’s art. It is unfortunate that, in order to obtain a surface suitable for their reproduction, it should have been neces- sary to load the paper with mineral matter to such an extent as to make the volume inconveniently heavy, but this is a fault by no means limited to the volume under notice.References are given to the originals of all the papers, there is a good index of authors, and a fair one of subject-matter. In the first line of the table on p.242 there appears to be one of the very few errors noticed by the reviewer-the CaF, present was presumably nil. On p. 203 ‘I dessicator ’’ is spelt with two s’s and one c ; on p. 227 one s and two c’s are correctly used. “ Etherial ” is printed for ‘‘ ethereal ” on p. 492, and throughout the book ‘‘ cm3” is used for “c.c.,” which, although sanc- tioned, seems cumbersome.These are details. The bock is an excellent supplement to the ordinary analytical treatises, and covers a wide range of elements. L. ARCHBUTT. FOOD INRPECTION AND ANALYSIS. Andrew L. Winton. and Hall. 1913. Price 61 11s. 6d. By ALBERT E. LEACH. Revised and enlarged by New York : John Wiley and Sons ; London : Chapman The recent death of the author of this work is doubtless responsible for the statement on the title-page that the revision of this third edition has been undertaken by Dr.A. L. Winton. I n his prefatory remarks the reviser points out that new matter equivalent to about eighty pages has been added, and that much antiquated matter has been replaced by new. When a reviewer has dealt with an early edition of a certain work, it is only natural that when criticising a succeeding edition he should first turn to those portions on which he had previously felt himself compelled to pass more or less adverse criticism.In the present instance this proceeding has been productive of disappointment, for very few of the errors of omission or commission to which attention was called in the previous review appear to have been rectified. I n dealing with the detection and estimation of arsenic, no reference is made to the work of the Joint Committee of the Society of Chemical Industry and the Society of Public Analysts, and the author seems to have been unaware that it was the labours of that body which first rendered possible the accurate determination of minute traces of arsenic in food-stuffs.Analysts are instructed in carrying out the “Marsh test ” to add “20 to 30 grms.of arsenic-free stick zinc and a perforated ‘platimm’ disk to form an electric couple.” The author appears to have overlooked all the work that has been done on the insensitiveness of zinc, and if American analysts generally are accustomed to follow the procedure recommended in this work, it would be a matter for some surprise if they were to find more than “insignificant traces ” of arsenic in the food-stuffs which they are accustomed to examine.The quite unnecessary destruction of organic matter in the case of beer and certain other liquids is recommended, and the operator (working on 100 C.C. of beer) is told that the “arsenic mirror may be weighed in the usual manner if of sufficient size.” The extreme insensitiveness of the test as carried out under the conditions mentioned in the text is exemplified by the fact that one of the mirrors intended for comparisonREVIEWS 491 purposes is made with as much as +G mgrm.of arsenious oxide (p. 76), and it is directed that the test should run for from two to three hours. I n good practice and with a sensitive apparatus no mirror corresponding with more than i+G mgrm.can safely be used. Reference is made to the cases of arsenical poisoning by contaminated beer which occurred in this country in 1900, but the possibility of heavy traces of arsenic being introduced through the medium of carelessly dried malt has been quite overlooked. The above will serve to show how inadequate has been the treatment of this particular subject, and it is to be hoped that before another edition appears the reviser will take steps to familiarise himself with the work which has been done in this country on the estimation of traces of arsenic and on the bearing of the question of electrical supertension on the sensitiveness of the test.While speaking of beer, the reviewer cannot refrain from calling attention to the somewhat extraordinary statement that the lack of gas caused by the absence of proper cask fermentation is “ sometimes made up by the addition of sodium bicarbonate.” I n the section dealing with metallic impurities in tinned food, no mention is made of the influence of air (oxygen) in the tins, as affecting the solution of the metal, although attention is directed to a number of much less important factors, Not yet does the valuable report on this subject of the Local Government Board published in 1908 appear to have found its way into the Chicago Food and Drug Inspection Laboratory, and not yet does Schryver’s colorimetric method receive any mention.“ Malt Extract ” would appear, in the author’s view, to be a designation restricted to a material prepared according to certain directions contained in the United States Pharmacopceia, 1880.We are told that it “ has a residue of at least 70 per cent.,” and consists “chiefly of maltose, and contains about 2 per cent. of diastase” (the italics are the reviewer’s). I n a work devoted to analytical chemistry we are actually supplied with three analyses of pure malt extract, in not one of which is any dextrose shown. In the section on butter analysis, the author, when discussing the Reichert- Meissl number, repeats the statement of the earlier edition that “the result is conclusive, excepting in those rare instances when the admixture of foreign fat is so small as to cause the Reichert number to approximate that of pure butter.” No mention is made here (and very little elsewhere) of the effect of the presence of cocoanut oil, and no more unsuitable word than ‘‘ conclusive ” could have been used in the above connection.The chapter on sugars and saccharine products is on the whole good, but it is worthy of remark that no reference is made in the text to any of the work of Horace Brown and others in this country, and we are informed that “maltose is of little importance from the standpoint of the food analyst excepting as an ingredient of commercial glucose, and as being the sugar produced by the action of ptyaline .. on the starch of food in the ordinary process of digestion.” Having regard to the quite correct statement on p. 356 that the sugars of a, considerable number of infants’ and invalids’ foods consist largely of maltose, this needs some modification.I t is not correct, moreover, to say that few complete analyses of infants’ foods have been made, and much more complete series than that given have been published.492 REVIEWS In the section dealing with the estimation of chicory in coffee, the average specific gravities of coffee and chicory infusions are given to five decimal places, but no warning is conveyed to the analyst as to the extent to which the percentage of extract in chicory may vary, depending on the degree of roasting and other factors.Under the heading ‘‘ Vegetable and Fruit Products,” ketchup occupies an amount of space which would appear to be out of all proportion to its importance. In connection with the examination of this condi’ment, in a paragraph headed ‘ 4 Estimation of Yeasts and Spores ” the following remarks occur : (( These are counted togethar because of the difficulty in differentiation without making cultures, which is impossible with a sterilised product.” The analyst is then instructed to shake a certain quantity of the material with some water, to examine in a Thoma-Zeiss cell with a magnification of 180, and to “count the number of yeasts and spores in one-half of the ruled squares, which gives the number present in gc of a cubic millimeter of the original material.” The first sentence is unintelligible.If the yeast cells were dead, they would necessarily have undergone disintegration, and it is doubtful if they could be identified with a magnification of 180 diameters; whereas if they were living, there should be no difficulty in making cultures, assuming such a proceeding to be desirable.The further statement in reference to yeast cells and mould spores, “the number in home-made and best factory-made ketchups is practically none ; the allowed limit is 25,” is not devoid of humour. Apart from the transatlantic phonetic spelling, to which we are now becoming accustomed, and which has in some instances (e.g., levulose) sacrificed all considerations of derivation to what is regarded as practical utility, there are a good many misprints and occasional inelegancies of diction, Thus we are told that port wine on aging “looses considerable of its astringency,” and quite a number of proper names are misspelt, notwithstanding that attention was called to these in the review of the preceding edition.Bourguelot still appears for Bourquelot, Sangle-Ferriere for SanglB-FerriBre, Bechi for Becchi, Villivecchia for Villavecchia, Blythien for Beythien, Klocker for Klocker, and Plummer for Plimrner. Some of the photomicrographic illustrations at the end of the book are good, but others are so indistinct as to have little or no practical value. The book is much too good to become solely a textbook for the American analyst and food inspector, and is well qualified to take an international position as a work of reference on the analysis of food-stuffs. One of its main drawbacks, however, and one which must limit materially its sphere of usefulness, is the apparent impression of both author and reviser (notwithstanding numerous bibliographical references to foreign journals) that food chemistry is an almost exclusively American branch of science. I t would not be good taste on the part of the reviewer to point out how far that is from being the case, but he may perhaps be permitted to express the hope that when future editions are in course of preparation, Dr. Winton or some other reviser may see his way to study a little more closely the literature of other countries, and to free himself rather more from the bondage of United States Departmental Reports and Official Bulletins. In this way only can this work take the full position to which its many merits entitle it. The above criticisms are made in no ungenerous or carping spirit. A. CHASTON CHAPMAN.

ISSN:0003-2654    

DOI:10.1039/AN9133800488

出版商:RSC    

年代:1913

数据来源: RSC