摘要:

JULY, 1912. Vol. XXXVII., No. 436. THE CONSTITUENTS OF OIL OF SAVIN. BY J. WATSON AGNEW F.I.C., AND ROBIN B. CROAD. (Read at the Neeting, May 1, 1912.) SEVERAL samples of oil of savin have been analysed with the object of obtaining pure sabinene, and the following paper is an account of the method used to obtain the terpene, with a description of the various fractions obtained from a, pure specimen of oil of savin.” The oil was first of all hydrolysed by boiling under a reflux condenser with This oil was obtained from Schimmel, who guaranteed i t to be a genuine sample of oil of savin.The sample contained very little pinene, but other samples which we examined from other sources had evidently been mixed with oil of turpentine, as the amount of pinene was very high, while the sabinene was correspondingly low.296 AGNEW AND CROAD: I.11. 111. DESCRIPTION OF FRACTIONS OBTAINED. I. a,. I n most of the samples examined this fraction was large in comparison to I. b, though in one case the amount of I. b was very large, whilst I. a was an exceedingly small fraction. This fraction was undoubtedly pinene, since on oxidation with mercuric acetate solution, a mixture of sobrerol and 8-hydroxycarvotanacetone was obtained.The presence of these two oxidation products of pinene was confirmed by the formation from the original sobrerol (m.-pt. 131" C.), of sobrerol dibromide (m.-pt. 131"-132" C.), and pinol dibromide (m.-pt. 94" C.). The sobrerol dibromide was analysed with the following result : Br calculated for sobrerol dibromide = 48.48 per cent.The semicarbaaone of the hydroxyketone was also prepared, and was found to melt a t 175" C. This agrees with what already has been published (Henderson and Agnew, J. Chenz. SOC., 1908, 95, 289), and the yields from pure pinene and from this fraction are comparable. I. b. As already stated, this fraction was only obtained in large quantity in the case of one sample, and consisted of the terpene sabinene.That this fraction is sabinene was shown by shaking a small quantity with dilute sulphuric acid for about two weeks, when a terpin (m.-pt. 137" C.) and a terpineol (b.-pt. 209-212' C.) were isolated from the solution (Wallach, Ber., 1907, 40, 585). As these were obtained pure it is practically certain that no pinene was present, or crystals of a terpin hydrate (m.-pt. 120" C.) would have separated out.This was further confirmed by preparing the nitrosochloride according to the method used for pinene nitrosochloride (Wallach, Annalen, 1889, 253, 250), the only resulting product being a sticky, green oil, with no trace of the solid pinene nitrosochloride. The formation of this green Br found ... ... ... =48.27 ,,THE CONSTITUENTS OF OIL OE' SAVIN 297 oil is in accordance with the observations of some other workers.The constants of the pure sabinene were as follows : b.-pt. 162" to 166" (chiefly 164" C.) ; sp. gr. 20" C. = It will be noticed that the oil was laevo-rotatory, which is contrary to the published results of other workers, who have only noted the dextro form. Semmler (Bey., 1900, 33, 1464) records a rotation +63", and Wallach (Ber., 1907, 40, 587) a rotation of + 67.5" [.ID = 80.17.The sp. gr. is also somewhat higher than the figures usually given (Wallach = ,8420, and Semmler = ,840). These two fractions, I. a and I. b, can be tested by adding 2 to 3 C.C. to a saturated solution of mercuric acetate in a Nessler tube. In the case of sabinene, oxidation commences at once, and there is a large precipitate of mercurous acetate at the end of fifteen minutes.I n the case of pinene there is no oxidation until at least one hour has elapsed, 11. a. On careful refractionation this portion splits up into two fractions with the same boiling-points and properties as I. b and 11. b. 11. b. This fraction, according to Fromm (Bey., 1898, 31, 2025), consists of terpinene, and this was confirmed by the ready formation of the nitrosite (m.-pt.155' to 157' C.) in good quantity (Wallach, Annalert, 1887, 239, 36). 11. c. This fraction was redistilled, and the lower and higher fractions were added to 11. b and 111. a respectively. 111. a. This fraction consisted of the alcohol sabinol, the constants of which were found to be as follows : b.-pt.208" to 209" C. ; sp. gr. 15 " C. 0.9391 ; [a] D 15. c. = +17*04. The rotation of this sabinol is much higher than any we have observed in published results. 111. b. The residue from this fractionation consists chiefly of unhydrolysed esters. The solution left in the flask after the original steam distillation contained the potassium salts of the acids, originally present in the esters.This solution was extracted with ether to remove resin and then evaporated down to dryness. The purified potassium salts thus obtained were acidified with dilute sulphuric acid and extracted with ether. The residue, after evaporating off the ether, was found to be a mixture of formic and acetic acids, with a small quantity of another acid, which melted at 85" C.This acid is saturated and is colourless when first isolated, but turns brown in the air. The presence of formic and acetic acids in oil of savin has been already noted, and the quantity of this third acid was too small to permit of our fully identifying it. The following is a table showing the percentage yields : 0.8468 ; [U]D 150 C. = - 42.5. 1. Resin from steam distillation ...1.. . . . 31.0 2. First runnings 150" to 160" C. ... ... ... 1.7 3. Sabinene 162 O to 166" C. ... ..- ... ... 16.0 4. Terpinene fraction 175 " to 185 " C. ... ... 5.3 5. Sabinol 208 " to 209" C. ... ... ... ... 17.0 6. Residue 210" C. upwards ... ... ... ... 16.0 7. Acids-calculated from amount of sabinol ... 7.0 The percentage of resin is high owing to the difficulty of entirely freeing from According to Semmler (Eer., 1900, 33, 1463), a yield of 30 per cent.of water.298 RICHMOND : aabinene was obtained by fractionating the crude oil. Altogether we have examined about 15 lbs. of oil of savin in different samples, and the above results are those of the best sample, which gives 16 per cent. I n some cases the amount of sabinene was exceedingly low, and the amount of pinene correspondingly high.I n conclusion we desire to express our thanks to Professor G. G. Henderson for the interest he has shown in this work and for many valuable suggestions. DEPARTMENT OF CHEMISTRY, ROYAL TECHNICAL COLLEGE, GLASGOTV. DISCUSSIOK. Mr. H. E. BURGESS said that he had examined a large number of samples of savin oil, and had never found any fraction that was not dextro-rotatory. I t would seem that the sample worked upon by the authors must have been either inactive or laevo-rotatory, and therefore, as far as his experience went, abnormal. Nr. RAYMOND Ross suggested that the authors might with advantage add to their communication the refractive indices of the various fractions. For the determination of the optical activity a considerable quantity of material was required, and the refractive index-which, as well as the boiling-point, could be determined with a few drops-would be more useful in actual practice, where the quantity of material available was often very small.

ISSN:0003-2654    

DOI:10.1039/AN912370295b

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

298 RICHMOND : THE COMPOSITION OF MILK. BY H. DROOP RICHMOND, F.I.C. (Read at the Meeting, June 5, 1912.) THE present communication deals with the results obtained during 1911 in the Aylesbury Dairy Company’s Laboratory. In Table I. the mean composition of 19,997 samples of milk as received from the farms is given. This series is selected, as it contains the largest number of samples, and is therefore the most nearly representative; the morning and evening milks are averaged separately.So far as the mean composition is concerned, it is con- firmed by four other series, consisting of 11,269, 1,472, 2,908, and 1,836 samples respectively. The average percentage of fat (3.71) is slightly below that found last year., and this was principally due to a falling off in the last months of the year.As is almost universally found, the lowest percentages of fat occurred in May and June and the highest in October and November. The evening milk is practically always richer than the morning milk, but the average difference found (0.30 per cent.) is slightly less than usual, and the slightly smaller amount of fat found in 1911 is due to that in the evening milk being less.THE COMPOSITION OF MILK 299 TABLE I.Average Composition of Milk during 1911. Morning Milk. Evening Milk. Mean. - Solids not- Fat. Solids- not- Fat. Month. Total Solids. - Fat. Total Solids. Fat. Solids- not- Fat. Total Solids. Sp. Gr. Sp. Gr. Sp. Gr. Fat. % 12.64 12-55 12-41 12.31 12'12 12.09 12.17 12.13 12.35 12.52 12.65 12.54 12.37 % 3.68 3-57 3.49 3-48 3-26 3.24 3 -44 3.54 3-69 3-76 3'83 3-72 3-56 - - % 8.96 8.98 8-92 8-83 8-86 8.85 8-73 3-59 8.66 8-76 8-52 8-82 - S -81 - % 12.86 12.79 12.66 i2.59 12-51 12.42 12.35 12.42 12-68 12.82 12.85 12.69 12-64 % 3-91 3-83 3.76 3.77 3.68 3-64 3'74 3.90 4.07 4-05 3.88 3'86 4 -07 % 8-95 8-96 8.90 8-82 8.83 8-78 8-61 8.52 8-61 8.75 8.80 8-81 8 -78 % 12-75 12-67 12-53 12.45 12.32 12.26 12'26 12'27 12.51 12-67 12.75 12-61 12.51 % 3.80 3.70 3 '62 3.62 3.4i 3-44 3'59 3-72 3.88 3-91 3.94 3-50 - 3-71 - % 8.95 8.97 8.91 8.83 8-85 9-82 8.67 8.55 E.63 8.76 8-81 8'81 January ... February , .March ... April ... ... May ... .., June ... ... July ... ... August ... September . . . October ... Kovembcr . . . December 1.0323 1 -0325 1-0324 1.0321 1.0323 1-0323 1.0316 1-0309 1.0311 1.0315 1.0316 1.0318 1.0319 1.0321 1-0322 1 -0321 1.0318 1.0319 1 '031 6 1.0309 1 *0304 1.0306 1.0312 1.0314 1.0315 1 -0322 1 *0324 1.0322 1'0319 1.0321 1 -0320 1.0313 1.0306 1 so309 1.0313 1.0315 1.0317 Average ...1.0315 1.0317 8.80 In continuation of the tables given in former years, I give the percentages of the morning milks falling below 3 per cent. in April, May, and June.TABLE IT. Month. 2.9 to 3.0. 2'8 t o 2.9. 2.7 t o 2.8. Below 2.7. April ... ... 0-8 0.2 0.2 - May ... ... 4.0 2.1 0.5 0-2 June ... ... 5.5 0.5 0.5 0-2 I n the evening and morning milks during the other months of the year samples containing less than 3 per cent. of fat were practically absent. The year 1911 was remarkable for the prolonged drought during the summer months, and not only was the quantity of milk influenced by the deficient herbage, but also the quality.I t is usual to find that the solids-not-fat are lower in July, August, and September than during the other months, but during 1911 a greater deficiency than usual was observed. The table below shows the percentages of the milks falling between the per- centages of solids-not-fat given for these three months : TABLE 111.Month. 8.4 t o 8.5. 8.3 t o 8'4. 8'2 to 8.3. Below 8-2. Total. July ... ... 6.5 1.1 0.2 0.1 7 *9 August ... 19.9 6-5 0.4 0.2 27.0 September ... 10.4 2-6 0.1 0.1 13.2 During the other months of the year very few samples fell below 8.5 per cent. In order to see to what constituent of the solids-not-fat the deficiency was due, of solids-not-fat.300 RICHMOND : the following table has been prepared.This gives the mean percentages of solids- not-fat, the mean percentage of proteins determined from the aldehyde figure, the percentage of ash determined directly, and the percentage of milk-sugar by difference. Although the number of protein and ash determinations is very much smaller than that of the solids-not-fat, the average figure is probably sufficiently close to the true value to render a comparison possible.TABLE I V . Month. January ... February . .. March ... April ... May ... June ... July ... August ... September October . . . November December Solids-not-Fat. Milk-Sugar. ... 8.95 4.62 ... 8.97 4-70 ... 8-91 4.72 ... 8.83 4-66 ... 8.85 4-64 ... 8.88 4-68 ... 8.67 4.69 ... 8.55 4.59 ... 8.63 4.63 ...8-76 4.63 ... 8-81 4-63 ... 8-81 4-56 Proteins. 3.57 3.52 3.45 3.42 3-47 3.42 3.23 3 a25 3.26 3.38 3.42 3.50 Ash. 0.76 0.75 0.74 0-75 0.74 0.74 0.75 0.71 0.74 0.75 0.76 0.75 I t is seen from the above figures that the deficiency in solids-not-fat during July, August, and September is due principally to a deficiency in proteins, and this is shown in the accompanying curve. *9 - ‘8 - -7 - ‘6 - *5 - *4 - ‘3 ‘2 -1 - - - - Jan.Fcb. Mar. Apr. Jun. Jul. \ / -- Bug. In conclusion, I wish to express my indebtedness to Mr. H. C . Huish, to whom the bulk of the above figures are due.THE COMPOSITION OF MILK 301 DISCUSSION. Mr. R. Ross asked whether Mr. Richmond found the proportions of 13 : 9 : 2 for milk sugar, proteins, and ash respectively, still to hold good for normal milk.In the case of several recent samples taken under the Sale of Food and Drugs Act, he (Mr. Ross) had found deficiency in non-fatty solids to be due to deficiency in milk sugar, and he had accordingly reported the samples to be not adulterated, but abnormal. He should like to know what were the intervals between the times of milking. Dr. VOELCKER expressed some surprise that, in an exceptionally dry year like 1911, the quality of the milk was lower, and not higher, than in the previous year.He referred incidentally to the unreliability of the results shown by cows when milked in the showyard for purposes of competition, instancing a recent case, which had been commented upon in the Press, in which a Jersey cow, under such conditions, had yielded milk containing only 2-75 per cent.of fat. From subsequent inquiries it appeared that the cow in question was of an unusually nervous temperament, and that the poorness of her milk on that particular occasion was due entirely to nervous disturbance caused by the strange conditions. He instanced this as showing how much better it was to rely upon such statistics as Mr.Richmond had put forward, than on ‘( showyard ” results. Mr. C. REVIS said that the results of his own analyses during 1911 were similar to those obtained by Mr. Richmond, but he was not quite satisfied that an average of the results o€ such analyses exactly represented the state of the case. Some three or four years ago he had abandoned the calculation of such averages, and, instead, had adopted the plan of analysing samples drawn at intervals as the milk was being measured out from the mixing vessel, throngh which would pass some 4,000 gallons twice a day.I n this way one eliminated such errors as would be incidental to calculations based on separate samples from about 250 different farmers which this represented. During the two months in question, the non-fatty solids in this quantity of milk were below 8-45 in eleven cases, being in one case as low as 8-34.He had never before met with such low figures in mixed milk, and he thought that Nr. Richmond had not laid sufficient stress on the profound effect of last year’s drought. The effect of the drought was felt for some months, and the slightly lower average percentage of fat found in 1911 was no doubt attributable to the almost entire failure of proper feeding-stuffs towards the end of the year.Mr. A. E. PARKES asked whether Mr. Richmond considered it to be possible, by determining the percentages of milk sugar and proteins, to ascertain whether a sample had been artificially prepared with milk powder, or was a mixture of fresh rnilk and this product.During last year’s drought t\l considerable quantity of milk had been made up in this way, and he believed that in some districts the practice was still going on. Mr, L. M. NASH said that, in a large butter factory, it was found that the quantity of milk required for the making of a given quantity of butter was almost exactly the same in 1911 as in 1910, while in a casein factory it was found that the percentage of casein obtained from the milk during 1911 was lower than usual.302 RICHMOND: THE COMPOSITION OF MILK Mr.J. EVANS asked whether any of Mr. Richmond’s samples came from the North of England. Mr. J. CONNAH said that he had been under the impression that the contracts under which farmers supplied the large dairy companies included a stipulation.that the milk should not be below a certain minimum standard of composition, any milk below that standard being rejected. He should like to hear whether Mr. Richmond’s averages included such rejected samples or not. Mr. RICHMOND, in reply, said that the proportions of 13 : 9 : 2 for milk sugar, proteins, and ash (which were originally laid down by Dr. Vieth) still held good. This was, indeed, according to his experience, t’he closest approximation to the average that could be obtained in round figures, and he was still strongly of opinion that any wide departure from the proportions of 13 : 9 : 2 indicated that the milk was abnormal.As to the times of milking, these varied considerably in different districts, and were, practically speaking, determined by the train service.On going into this question some little time ago, he had found that on the average there was an interval of 13.2 hours from the evening milking to the morning milking, and of 10.8 hours from the morning milking to the evening milking. He did not quite understand why Dr. Voelcker expected the quality of the milk to be higher in a dry season, unless it was because of the smaller yield.When the quantity was checked by such a cause as a fall in temperature, the resulting decrease in the total metabolic change would not be accompanied by a corresponding decrease in the fat metabolism, and consequently the proportion of fat in the milk would be greater; but when the decrease in quantity was due to a decrease in the total amount of actual nourishment, one would expect a falling off in quality as well.He entirely agreed with Dr. Voelcker that results obtained at shows could not be regarded as representing the normal composition of milk. It was a very good plan to take average samples from large quantities of milk. He had followed it himself, and his experience had been similar to that of Mr. Revis, though the quantities sampled were not so large as in Mr.Revis’s case. The question raised by Mr. Parkes was a very difficult one, more especially when the sample consisted only partially of milk made up with milk powder. At present he did not see how it was to be solved. The most northerly district represented among the samples was Cheshire. With regard to Mr. Connah’s remarks, the practice was to name in the contract a certain standard of composition, to which the farmer was expected to conform as nearly as possible. As, however, the farmer had no real control over the percentages of fat and of non-fatty solids yielded by the cows, milk falling below the contract standard would not necessarily be rejected, unless the deficiency was very serious, and even then the milk that was rejected would be used for making cream, and the samples would be included in the average unless there was evidence of adulteration. As far as the non-fatty solids were concerned, very low percentages would of course be rejected, but not percentages between, say, 8.0 and 8-5, unless further examination indicated the presence of added water. Low percentages of fat would not lead to rejection unless there was some evidence-such, for example, as the arrival of the churn unsealed, with a deficiency in the quantity of milk-to show that cream had been removed.

ISSN:0003-2654    

DOI:10.1039/AN9123700298

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

NITRIC AND NITROUS ACIDS IN ACETIC ACID SOLUTION 303 THE DETERMINATION OF NITRIC AND NITROUS ACIDS IN ACETIC ACETIC ACID SOLUTION. ACID SOLUTION. THE STABILITY OF NITRIC ACID IN BY KENNEDY J. P. ORTON, M.A., PH.D., F.I.C., AND WILLIAM HERBERT GRAY. ALTHOUGH numerous papers on the determination of nitric and nitrous acids and their salts have been published, the determination of these acids in acetic acid solution has not been investigated.The inquiry arose from the need of knowing, for the purpose of experiments on the nitration of aromatic compounds, whether nitric acid was reduced by acetic acid. For these experiments very dilute solutions-not greater than 1 per cent.-of nitric acid were required. This fact was the objection to the use of the Kjeldahl-Gunning-Jodlbauer mehhod, which would be applicable to more concentrated solutions.For example, it was used with success by Pictet arid Khotinsky (Ber., 1910, 40, 1163) in the analysis of acetyl nitrate. The method here described is based on the fact that all the nitric acid in acetic acid solution is retained as potassium nitrate if the solution is evaporated to dryness on the water-bath with a slight excess of potassium carbonate ; any nitrous acid is destroyed under this treatment. The potassium nitrate, which is mixed with some acetate, is determined by the Lunge process.The nitrous acid can be best deter- mined by Raschig’s permanganate method (Ber., 1905, 35, 3911). Nitric acid is remarkably stable in acetic acid solution, and can be kept of constant concentration for many weeks. If nitrous acid (oxides of nitrogen) is present, the major part is gradually oxidised to nitric acid, the solution becofning nearly colourless.Solutions in 50 per cent. acetic acid showed similar behaviour. Reduction of the nitric acid does not occur even after prolonged exposure to diffused light, but any colour due to oxides of nitrogen originally present gradually fades, the concentration of the nitric acid somewhat increasing.This remarkable behaviour will be €urther investigated. DETERMINATION OF NITROUS ACID IN ACETIC ACID SOLUTION, The problem resolved itself into ascertaining which of these could be used in a medium containing about 10 per cent. acetic acid, as that was practically the maximum dilution attainable in any but the permanganate method on diluting the original glacial acetic acid medium.Further, the method should be accurate in the presence of the relatively very large excess of nitric acid. Corn- pared with aqueous solutions of nitrite, solutions in dilute acetic acid (5 to 40 per cent.) showed paler tints. The discrepancy is progressively greater as the proportion of acetic acid is increased.I t should be noted that the mere addition of acetic acid after diazotisation does not in itself affect the tint. ( b ) The.Dunstan-Dymond method. In the presence of small quantities of acetic acid (5 to 10 per cent.) this method gives high results. Moreover, in the very dilute solutions which we required, the manipulative difficulties are excessive. All the well-known methods of analysis were tested.(a) The tintometric method with mphenylenediamine failed completely.304 ORTON AND GRAY: (c) The method devised by Maderna and Coffetti (Gnxetta, 1907, 37, 595), which is based on the reduction in a Lunge nitrometer of nitrous acid to nitric oxide by potassium ferrocyanide and citric or acetic acid-an environmeut in which nitric acid is stable-was found to give excellent results in the analysis of fuming nitric acid, which was neutralised before introduction into the nitrometer, with slight excess of sodium hydroxide.The solubility of the nitric oxide in the more concentrated acetic acids, which were unavoidable in this method, rendered i t inaccurate. (d) In Raschig’s method we found a perfectly satisfactory means of estimating minute quantities of nitrous acid in acetic acid solution. The following procedure was finally adopted : A given volume of the acetic acid solution, 10 to 30 c.c., was added drop by drop, over a period of four minutes, to a mixture of about 20 C.C.of & permanganate, 5.5 C.C. of 10 per cent. sulphuric acid and 320 C.C. of water. The permanganate should be about double that required for the oxidation of the nitrous acid; the sulphuric acid is nearly the minimum quantity required for this dilution ; the nitrous acid, when added to the mixture, should not be below a dilution of 1 in 20,000. The mixture is allowed to stand for fifteen minutes, and then excess (about 8 to 9 C.C.of a 2.5 per cent. solution) of potassium iodide introduced, and the iodine titrated with of thiosulphate.The time of addition of the acetic acid solution could be considerably shortened without materially affecting the accuracy, but the fifteen minutes’ standing is a minimum. The following numbers illustrate the results of determinations of nitrous acid in fuming nitric acids : Percentage of Acetic Acid in C.C. of $j KMnO, used in 5 ... ... 8.38 ... ...1-97 5 ... ... 8-48 ... ... 1-99 10 ... ... 8.44 ... ... 1.98 10 ... .. , 8-50 ... ... 1.99 Grms. of HNOz in 100 C.C. the Permanganate Mixture. oxidising Nitrous Acid. of fuming Nitric Acid. THE DETERMINATION OF NITRIC ACID IN ACETIC ACID SOLUTION. The procedure we adopted is as follows : To an aliquot part of the acetic acid solution, which is placed in a glass dish, covered by a clock-glass, a slight excess (5 to 25 per cent.) of potassium carbonate solution is cautiously added.The liquid is then evaporated on the water-bath until no odour of acetic acid remains, the clock- glass being left on the dish. The slightlyrmoist solid is then transferred by a spatula to the cup of a Lunge nitrometer. The spatula is then washed with 0.3 C.C. of water into the cup, and the liquid drawn into the tube.Five C.C. of pure concentrated sulphuric acid (96.6 per cent,) are poured into the glass dish, when the all but negligible residue is dissolved, and then introduced into the nitrometer. It was found by trial that 4-5 C.C. of the 5 C.C. of the sulphuric acid used reached the nitrometer tube. This proportion of water and acid gave a concentration of 93.2 per cent.in the nitrometer. I1 I shaking, etc., we followed the directions which Marqueyrol and Florentin ANALYST, 1911, 36, 243) recommend in their recent critical study of the Lunge method, It was found that, after two of the shakings described by these authors,NITRIC AND NITROUS ACIDS I N ACETIC ACID SOLUTION 305 occupying one minute each, the maximum volume of gas was obtained.In calcu- lating the results, the nitric oxide absorbed by the sulphuric acid, as given by Lunge, was allowed for, namely, 0.15 C.C. for 5 C.C. of sulphuric acid. This method was tested by blank experiments (a) with potassium nitrate, (b) with mixtures of potassium nitrate and nitrite. (a) On evaporating pure potassium nitrate with acetic acid on the water-bath, no nitric acid was lost, since no acetic acid was recognisable in the residue by any of the usual qualitative tests.The following numbers illustrate the results : C.C. of Acetic Acid. KNO,< used. C.C. of NO. KNO, found. Percentage Error. 5 0.1188 25.81 0*1180 0.7 5 0.1192 25.94 0.1181 0.95 5 0*1185 25.84 0.1175 0-80 ( b ) Mixtures of potassium nitrate and nitrite were evaporated with glacial acetic Quantitative acid.The residue gave no trace of the reactions of nitrous acid. determinations of the nitrate showed that no nitrite had been oxidised to nitrate. Potassium Nitrite as a C.C. of Acetic Acid. percentage of Nitrate. KNO, used. KNO, found. Percentage Error. 5 2.5 0.1160 0.1147 1.1 5 2.5 0.1160 0.1156 0.36 5 9.48 0.1160 0.1147 1.1 A comparison of determinations of the concentrations of a fuming nitric acid by direct titration, and by this method, shows that, with these quantities, there is a constant error, probably manipulative, of about 0.7 per cent.; the addition of this loss would not be unjustifiable. THE STABILITY OF NITRIC AND NITROUS ACIDS IN ACETIC ACID SOLUTION. For testing the stability of nitric and nitrous acids in acetic acid solution, we used the purest glacial acetic acid, which is not attacked by chlorine in the dark (Orton, Edwards and King, J.Chem. Soc., 1911, 99, 1178). At first the solutions were carefully preserved in the dark, but, as we found later, exposure to diffused light has no perceptible influence. When nitrous acid is present, the original colour of the solution fades quickly to a scarcely perceptible tint.As the nitrous acid disappears, the nitric acid increases somewhat in quantity. No reduction of the nitric acid was observed in any of the solutions which were prepared. The following numbers will illustrate the evidence we obtained : 1. Glacial Acetic Acid Solutions.-(a) The solution was made up to contain 7.03 grms. HNO, and 0.102 grm.HNO, per 100 C.C. : Concentrations of nitric acid, varying from 1 to 7 per cent., were used. Time after making up. 2 hours 6 9 , 25 ?, 4 days 5 ,, 7 hours 7 ,, 1 hour 29 9, Grms. of HNOz Grms. of HNO, per 100 C.C. per 100 C.C. / Y 0.084 - - 0.069 - - 0.048 - - 0-021 - - (i.) 7.198 (ii.) 7.172 0.0123 (i.) 7.170 (ii.) 7.172 0.0026 (i.) 7.247 (ii.) 7.247 -306 ABSTRACTS OF CHEMICAL PAPERS ( b ) The solution was made up to contain 1.0164 grms.HNO, per 100 C.C. : Time after Grms. of HNO, Grms. of HNO, per 100 C.C. making up. / L \ per 100 C.C. 7 days - (j.) 1.037 (ii.) 1.042 3. Fzfty per Cent. Aqueous Acetic Acid-The solution was made up to contain 3-51 grms. HNO, and 0.0557 grm. HNO, per 100 C.C. : Time after Grms. of HNO, making up. per 100 C.C. 2. -. Grms. of HNO, per 100 C.C. - - 2 hours 0.044 45 3 ) 0.015 96 > 9 - (i.) 3.562 (ii.) 3.565 - - 3. Glacial Acetic Acid Solutions exposed to Light.-The solution was made up t o contain 2-13 grms. HNO, and 0.03 grm. HNO, per 100 C.C. : Time of exposwe Grms. of HNO, Grms. of HNO, per 100 C.C. to light. per 100 C.C. 7- 10 hours 0.009 (i.) 2.136 (ii.) 2.128 - (i.) 2.167 (ii.) 2.172 20 9 ) 64 9 ) per 100 C.C. : 0.009 - - The solution was made up to contain 7.02 grms. HNO, and 0.100 grm. HNO, Time of exposure Grms. of HNOg Grms of HNO, per 100 C.C. to light. per 100 C.C. F % 32 hours 0.052 (i.) 7.11 (ii.) 7.15 UXIVERSITY COLLEGE OF NOXTH WALES, BANGOX.

ISSN:0003-2654    

DOI:10.1039/AN9123700303

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

306 ABSTRACTS OF CHEMICAL PAPERS ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. ANALYSIS OF FOOD AND DRUGS. Determination of Iron in (Pharmaceutical) Scale Preparations. W. R. Pratt. (Phtwrn. J., 1912, $8, 641-642.)-For the analysis of ferri citrus cum quinina et strychnia and other scale preparations of ferric salts, the author prefers the method of the U.S. Pharmacopoeia to that of the British.If alkaloids be present they are separated, the residual liquids evaporated until free from ammonia and then diluted. The ferric solution is placed in a stoppered bottle together with hydrochloric acid and potassium iodide, heated in a water-bath, and the iodine liberated is titrated with thiosulphate. The author has investigated the limits of variation of the amount of acid, the time of reaction, and the temperature.He found that the quantity of hydrochloric acid must be at least twice the theoretical quantity, and may be increased to ten times the theoretical quantity without error. If a sufficient quantity of acid be used, the reaction is complete in ten minutes at 40" C., but no appreciable error is introduced by increasing the time to thirty minutes. The most suitable range of temperatures appears to be from 20" to 60" C., but at lower temper- atures a longer bime is required for the completion of the reaction. J.F. B.FOOD AND DRUGS ANALYSIS 307 Method of Preparing Lecithin Emulsions and the Subsequent Estimation of their Strength. J. C. Schippers. (Biochern. Zeitsch., 1912, 40, 189-192.)-The emulsion may be prepared by dissolving a weighed quantity of lecithin in the least possible amount of toluene, and then mixing the solution with a sufficient volume of 0.9 per cent.sodium chloride solution to give the required concentration. After the mixture has been shaken thoroughly, a current of hydrogen is passed through it until a11 the toluene has been removed, the emulsion being then submitted to centri- fugal action, and filtered through cotton-wool.The following method may be employed for checking the strength of the emulsion thus prepared; the method is based on the estimation of the aniount of oxygen required to oxidise the lecithin. Ten C.C. of the emulsion are heated to 90" C. for six hours in a stoppered flask with 10 C.O. of a solution consisting of potassium bichromate, 5 grms., 38 per cent.hydro- chloric acid, 300 c.c., and water, 700 C.C. After cooling, 10 C.C. of a 5 per cent. potassium iodide solution are added, the mixture is allowed to stand for at least two hours, 30 C.C. of water are then added, and the solution is titrated with & thiosulphate solubion. A similar titration is made, using 10 C.C. of the sodium chloride employed in making the emulsion, and the difference in the quautity of thiosulphate used in the two titrations is a measure of the lecithin present.Experi- ments carried out by the author show that 1 C.C. of gS thiosulphate solution is equivalent to 1.12 mgrm. of lecithin. w. P. s. Freezing-Point of Milk. J. B. Henderson. ( A m Assoc. Adv. Sci., 1912, 13.) -Since the reading of a paper before the Australian Association for the Advance- ment of Science at its meeting in Brisbane (1909), the determination of the freeziog-point of all doubtful samples of milk has been continued in the Government Chemical Laboratory, Brisbane.The added water indicated by the freezing-point is on the average well above that calculated from the 8-5 per cent. solids-not-fat standard, and still further emphasises the fact that the 8.5 per cent.solids-not-fat legal minimum standard is by no means too high. During the year 1909 every milk eample containing less than 8.5 per cent. of solids-not-fat was found by the determination of the freezing-point to have been watered, and last year the same result was obtained, except in the two following cases :- Total solids ...... ... ... Fat ... ... ... ... .... Solids-not-fat ... ... ... ... Ash ... ... ... ... ... Nitrogen ... ... ... ... Freexing-poin t *.I ... ... (a) August 19, 1910 (4 cows). 11.62 per cent. 4-00 ,, 7-62 ,, 0.64 ,, 0.487 ,, - 0*565"C. ( h ) September 16, 1910 (1 COWS). 11% per cent. 3.3 9 , 8-3 9 , 0.68 ,, 0.474 ,, -0.55 c.308 ABSTRACTS OF CHEMICAL PAPERS But for the determination of the freezing-point there is little doubt that both of these samples would have been adjudged watered, As it was, the freezing-point showed them to be genuine, and the dairymen were warned to raise the quality of the milk to at least the legal minimum by better attention to their herds.The determination of the freezing-point is useful in distinguishing between naturally poor milks and watered milks, and the author hopes that its use will soon lead to the prosecution of those who add water to a naturally rich milk, but do not add sufficient water to bring the milk below the legal minimum standards.The average composition of the milk of one herd in Brisbane, the result being the mean of 104 samples, is-Fat 4.5 per cent. and solids-not-fat 9.2 per cent.Such a milk could have 7.5 per cent. of water added, and yet pass the ordinary 3 per cent. fat and 8.5 per cent. solids-not-fat standard. The determination of the freezing-point would, of course, at once show the addition of water. Estimation of Iron in Milk. F. E. Nottbohm and W. Weisswange. (Zeztsch. Untersuch. Nahr. Genussm., 1912, 23, 514-523.)-The small quantities of iron which occur in milk cannot be estimated satisfactorily by means of gravimetric or volumetric methods, and experiments carried out by the author show that the colorimetric method with thiocyanate yields incorrect results owing to the interfering influence of the phosphates and other constituents of the milk ash.I t is therefore recommended that the iron be separated by means of ‘‘ cupferron ” (cf.ANALYST 1910, 35, 327; 1911, 36, 175), and then estimated colorimetrically with thiocyanate. One hundred C.C. of the milk are evaporated, ignited, and the white ash evaporated twice to dryness with hydrochloric acid free from iron. The residue is then dissolved in about 40 C.C. of 4 hydrochloric acid, the solution is transferred to a flask, and oxidised with nitric acid. After cooling, the solution is rinsed into a, separating funnel, 2 C.C.of a 5 per cent, ‘‘ cupferron ” solution are added, and, after the lapse of fifteen minutes the mixture is shaken with 25 C.C. of chloroform. The chloroform layer is now separated, evaporated to dryness, and the residue ignited; the iron oxide in this ash is dissolved in hydrochloric acid, the solution is oxidised with nitric acid, then evaporated twice with hydrochloric acid, and the iron estimated colori- metrically as thiocyanate.Experimental proof is given that the method is trust- worthy. w. P. s. Estimation of Morphine in Opiates. E. Anneler. (Arch. Pharm., 1912, 250, 186-198.)-Details are given of a critical study of the different methods of estimating morphine in opiates, and especially in “ Panopon Roche,” a preparation containing hydrochlorides of all the opium alkaloids in a very pure form, It was found that the method of the b.-pt.and its modification in the French Codex was the most generally suitable, but that the results were invariably too low. The error was constant, however, and a correction could be made by adding 30 mgrms.per 50 C.C. of the mother liquor to the amount of morphine found. Of the shaking-out methods the following was the most satisfactory, the average error in the case of “ panopon” being 1.5 per cent. too high: From 0.8 to 1.0 grm. of the sample is dissolved in 30 C.C. of water, and shaken with a concentrated solution of 1 grm. ofFOOD AND DRUGS ANALYSIS 309 sodium bicarbonate in a little water, which effects the separation of some of the morphine and the bulk of the other alkaloids.The latter are then removed by shaking the liquid with 10 C.C. of chloroform previously saturated with pure morphine (100 C.C. dissolve 0.051 grm. of morphine at 15" C.). After separation of the liquids, the chloroform is drawn off through a small filter, and the residual liquid extracted twice more with 10 C.C.of the saturated chloroform. The filter is then washed with 60 C.C. of a mixture in equal parts of isobutyl alcohol, and chloroform, and the washings transferred to the separating funnel, which is then shaken for about ten minutes and allowed to stand. The layer of isobutyl alcohol, and chloroform (which need not be absolutely clear) is withdrawn, and the extraction of the residue repeated first with 20 C.C.and then with 10 C.C. of the mixed solvents. The extracts are filtered into another separating funnel, where they are shaken with 20 C.C. of Tn hydro chloric acid, and subsequently washed with three successive portions of 10 C.C. of water, after which the filtered acid extract and washings are covered with 30 to 40 C.C.of ether, and the excess of hydrochloric acid titrated, with iodeosin as indicator. C. A. M. Estimation of Essential Oil in Mustard. D. Raquet. (Ann. Chim. anal., 1912, 17, 174-178.)-The usual practice of mixing the mustard with water and allowing it to stand for some time before the essential oil is separated by distillation does not always yield concordant results ; in some cases the preliminary digestion requires to be prolonged for an hour or more in order that the whole of the essential oil may be liberated, whilst in others the time required is much shorter.Further, the essential oil is decomposed by micro-organisms, and if the digestion be carried on for too long a time the results obtained will be too low. If, however, dilute alcohol be used in place of water, the digestion may be allowed to proceed for even twenty- four hours without loss of essential oil.Having regard to these conditims, the following method is recommended for the estimation of the oil : Five grms. of the mustard flour are mixed in a 250 C.C. flask with 100 C.C. of water and 20 C.C. of 90 per cent. alcohol ; the flask is now closed and set aside for six hours, or heated to a temperature of 35' C .for one hour. The contents are then distilled, and 50 C.C. of the distillate are collected in a 100 C.C. flask in which 10 C.C. of ammonia have been placed previously ; 20 C.C. of & silver nitrate solution are now added, the distillation is continued until the 100 C.C. flask is filled nearly to mark, and after the flask has been closed with a stopper carrying a long glass tube, the contents are heated to 8 5 O C. for one hour.When cold, the mixture is diluted to 100 c.c., filtered, and the excess of silver is titrated in 50 C.C. of the filtrate by means of TT thiocyanate solution after the additionof nitric acid, Thenumber of C.C. of TT silver nitrate used is multiplied by 0.198 to obtain the weight of allyl thiocarbimide in 100 grms.of the mustard. The following percentage quantities of mustard oil (as allyl thiocarbimide) were found in samples of black mustard of different origin : English, 1.39 ; Greek, 1.20 ; French, 1.08 ; Sicilian, 0.99 ; Italian, 0.99 ; Bombay, 0.81. w. P. s. Detection of Adulterants in Saffron. E. Nockmann. (Zeitsch. Unterswh. Nahr. Genussm., 1912, 23, 453-456.) - The presence of added mineral matter in31 0 ABSTRACTS OF CHEMICAL PAPERS saffron can usually be detected by estimating the amount of ash in the sample, the presence of borax, potassium nitrate, etc., being also ascertained by means of the usual characteristic reactions for these substances.Ammonium salts can also be detected without difficulty in the saffron itself, but the detection of added sugars and glycerol is not such a simple matter, and the author records the results of his experiments with regard to this problem.The following results of analyses of seven samples of saffron of authenticated purity are given : Saffron, select ... ,, superior ... ,, Sierra ... ,, Maneanares ,, commercial 9 , 2 ) 9 , 9 ) In the Original Substance.Water. Per Cent. 8.42 8.63 9.E3 8-68 13-54 13-49 11-51 Ash. Per Cent. 5.01 5-62 5.84 6.83 6.05 5.81 6.11 Aqueous Extract . Per Cent, 73.97 71.62 70.87 70.13 7 6.01 74.72 70.83 I n thc Dry Substance. Reducing Substances, calculated its Invert Sugar. Before Iiivcrsion. Per Cent. 23.54 23.60 23.45 22-57 23.56 24-35 22.56 After Inver- sioii by Official Method. Per Cent.24-05 24-27 24.35 23.35 24.44 24.92 24.03 After Four Hours' Inversion. Per Cent. 39.17 39.12 38.40 38.11 39.75 39.65 38.84 The inversion process consisted in adding 4 C.C. of hydrochloric acid of sp. gr. 1.19 to 50 C.C. of the aqueous extract, and heating the mixture in a boiling water-bath for four hours, the maximum reduction being obtained after this length of time. The results obtained by the official method of inversion are also given.I t will be seen that the presence of added sugar would be indicated plainly by the values for the invert sugar before and after inversion. Glycerol cannot be detected by oxidising the aqueous extract with permanganate and identifying the oxalic acid formed, as genuine saffron yields considerable quantities of oxalic acid when treated in this manner.Attempts to separate added glycerol from saffron by means of the method used in the estimation of glycerol in wine (evaporation with calcium hydroxide and extraction with a mixture of alcohol and ether) did not yield satis- factory results, as saffron itself gave 3 to 4 per cent. of extract which would be counted as glycerol. If, however, the glycerol residue be transferred to a flask, mixed with solid boric acid, distilled until carbonisation is attained, the distillate being collected in water, this distillate may be tested in the following manner : To 5 C.C.of the distillate are added 1 C.C. of albumin solution (1 C.C. of egg-albumin diluted with 7 C.C. of water and filtered through linen), and 18 c.c, of hydrochloric acid containing nitrous acid (0.1 C.C.of 3.6 per cent. potassium nitrite solution to 200 C.C. of hydrochloric acid of sp. gr. 1*18), and the mixture heated in a water-bath to 50" C. The distillate froin a sample containing added glycerol yields a greenBOOD AND DRUGS ANALYSIS 31 1 coloration, whilst that from genuine saflron gives a faint red-blue tint. The spectruni of the distillate is also characteristic.When added glycerol is present in the sample, a dark absorption band is seen in the red portion of the spectrum, whilst the distillate from genuine saffron does not exhibit any absorption spectrum. w. P. s. Estimation of Nicotine in Tobacco. E. F. Harrison and P. A. W. Self. (Pharm. J., 1912, 88, 718-719.)-1n the method recommended, the tobacco is treated with slaked lime and distilled in a current of steam until all the nicotine has passed over into the distillate, as shown by a few drops giving no cloudiness when treated with acid and an excess of iodine.The distillate is received in a measured quantity of standard acid, and at the end of the distillation the distillate is titrated with standard alkali, using litmus as indicator.A further quantity of 10 C.C. of p acid is then added to the neutral solution, the latter is evaporated to a volume of 50 c.c., the nicotine is next precipitated by the addition of an excess of iodine, and the ammonia is estimated by distillation. The whole of the volatile alkali is calculated as nicotine in the first instance, and ten times as much iodine as would be required to combine with that amount is dissolved in potassium iodide solution and added to the 50 C.C.of evaporated distillate ; after diluting to 100 C.C. the mixture is filtered, 75 C.C. of the filtrate are treated with thiosulphate to destroy the excess of iodine, and then distilled in the presence of a large excess of sodiuin hydroxide. The quantity of nicotine present is then calculated.It is convenient to work on a weight of tobacco which will yield about 0.5 grm. of nicotine. The authors have proved that nicotine may be separated completely from ammonia by the above-mentioned method, and state that the process as a whole yields accurate results. w. P. s. Detection of Other Hydrocarbons in Turpentine. Utz. (Farbenxeit., 1912, 17, 1208-1209 ; through Chem.ZentraZbZ., 1912, I., 1641.)-Mennechet (BUZZ. Commer., 1911, No. 9) has proposed a test which consists in shaking 5 C.C. of the turpentine with a small quantity of magenta and 2 drops of nitric acid ; at the end of five minutes the mixture remains bright red in the absence of added hydrocarbons, but should 5 per cent. of the latter be present the colour of the mixture is reddish-brown, and light brown or colourless with upwards of 25 per cent.of hydrocarbon. The author has examined this test and finds that, whilst turpentine and its various substitutes and adulterants by themselves give quite characteristic colorations, it is not possible to detect less than 30 per cent. of the substitutes when added to turpentine. The reaction may be used as a rough test, but the colour changes in the case of mixtures are so indefinite that the test cannot be relied on to give useful information as to the presence of adulterants in turpentine.w. P. s. Critical Remarks on the Direct Estimation of the Total Solids of Wine. (Zeitsch. anal. Chenz., 1912, 51, 429-466.)-For reasons which are given below, the authors consider that the direct method of estimating the total solids of wine (evaporation and drying in the water- oven) should be abandoned, and that the total solids should be calculated from the C.von der Heide and E. Schwenk.312 ABSTRACTS OF CHEMICAL PAPERS sp. gr. of the de-alcoholised wine. The accuracy of this sp. gr. may be checked by determining the sp. gr. of the wine and of the alcoholic distillate from the same, Tabarie’s formula being used to calculate the sp.gr. of the alcohol-free liquid. The experiments carried out by the authors show that, during the evaporation of the wine and the subsequent drying of the residue, the following changes in the con- stituents may, and do, take place: (1) Acetic acid and its homologues are not present in the residue ; (2) lactic acid is volatilised to a varying extent ; (3) tartaric acid is converted partially into m. tartaric acid; (4) succinic acid remains unaltered ; (5) malic acid is decomposed partially; (6) the non-volatile acids form esters with the glycerol; (7) there is only a slight loss of glycerol; (8) the sugars are decom- posed to a very considerable extent. As a result of these changes, the sp. gr. of the aqueous solution of the total solids is less than that of the de-alcoholised wine. The alterations which occur in the proportions of the constituents as a wine ages influence the changes which take place when the wine is evaporated. For instance, the total solids (as estimated directly) of a new wine, which contains much malic acid, but no lactic acid, cannot be compared with the total solids of the same wine after this has been kept for a length of time sufficient for the malic acid to have been converted into lactic acid. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9123700306

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

312 ABSTRACTS OF CHEMICAL PAPERS BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Estimation of the Amino-Acids in Plants by Means of the Formaldehyde Method. (Bull. Sci. Pharmacol., 1912, 18, 702-711; through Chem. Zentralbl., 1912, I., 1640.)-Amino-acids may be titrated in the aqueous extracts of plants by means of the formaldehyde titration method, after the extracts have been treated with barium chloride to remove phosphates, and decolorised by means of quinine silicotungstate. As ammonia is estimated at the same time, this must be estimated separately in another portion of the extract., and an allowance made for its quantity. The details of the process are : One hundred C.C.of the extract are treated with 10 C.C. of hydrochloric acid, 10 C.C. of a 10 per cent. silicotungstic acid solution, and 10 C.C.of a 3.1 per cent. quinine hydrochloride solution, shaken, submitted to centrifugal action, and filtered. The filtrate is shaken with animal charcoal, again filtered, and 78 C.C. of the filtrate are treated with I grm. of barium chloride, then rendered alkaline with potassium hydroxide solution, diluted to 100 C.C. , and filtered, Twenty-five C.C.of this filtrate (equivalent to 15 C.C. of the original extract) are acidified with & hydrochloric acid, 1 drop of a saturated p-nitrophenol solution is added, and the solution exactly neutralised with & potassium hydroxide solution. Fifteen C.C. of neutral formaldehyde solution are now added, and the amino-acids are titrated with & potassium hydroxide solution, using phenolphthaleln as indicator.Let N denote the number of C.C. required for the titration; the ammonia is then estimated by distilling a further quantity of 50 C.C. of the extract in the presence of magnesia ; the quantity of ammonia is expressed in C.C. of & acid-let it be n- then the amount of amino-acid in 100 C.C. of the extract expressed in terms of (2N-n) The results obtained are correct 3 nitrogen, is found by formula: within 3 per cent., except in the case of tyrosine and histidine, when the error may 0.Bailly.BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 313 amount to 10 per cent. The following quantities of amino-acids (expressed as nitrogen per 100 grms. of the dry substance) were fomd in various plants : Turnip leaves, 0.507 ; tobacco flowers, 0.272 ; cabbage leaves, 0.886 ; lucerne, 0.350 ; carrot tops, 0,280 ; birch leaves, 0.144 ; tobacco leaves, 0420. w.P. s. Detection and Estimation of Small Quantities of Copper in Plants. E. Guerithault. (BUZZ. Xci. Pharmacol., 1912, 18, 633-639 ; through Chem. Zcntralbl., 1912, I., 1639.)-The method employed by the author consisted in dissolving the ash of the plants in hydrochloric acid, separating the silica, pre- cipitating the copper as sulphide, and converting the latter into oxide by ignition ; the oxide is then dissolved in nitric acid, and estimated electrolytically and colorimetrically.Peas, beans, maize, rye, wheat, oats, barley, linseed, radish seeds, cress seeds, gentim root, juniper twigs, and verbena wood, were examined, and found to contain from 0.0046 to 0.0171 part of copper per 1,000 parts of dry substance.w. P, s. Photographic Estimation of the Intensity Distribution in Blood Spectra. W. Heubner and H. Rosenberg. (Biochem. Zeitsch., 1912, 38, 345-384.)-A photographic method is described for estimating the relative intensity of the absorption of light in the absorption bands of blood spectra, the method depending on the niicrophotometric measurement of the light which is transmitted by the negative on which the absorption spectrum has been photographed.Under definite conditions, the extinction of light by the precipitated silver is a measure of the light absorbed by the blood colouring matters. Blood from rabbits, sheep, and pigs, was examined, and showed no difference in the intensity distribution.w. P. s. Rate of Evolution of Hydrocyanic Acid from Linseed under Digestive Conditions. S. H. Collins. (Univ. Durham Phil. SOC. Proc., 1912, 4, 99-106.)- The author has digested linseed at temperatures approaching those of animal life, and has removed hydrocyanic acid by a stream of inert gas (hydrogen, air, etc.). The inert gaH, passing at a regular rate obtained by means of a gas-governor (ANALYST, p.330), bubbles through a vessel immersed in a thermostat (Zoc. cit.), the vessel containing the linseed to be tested and 50 C.C. of water. The vapours are caught in an absorbing vessel containing 5 C.C. of zC sodium hydroxide. A clock and meter are attached to the apparatus immediately before the issuing of the gas, and thus the rate of flow, the time, and the temperature are controlled.Generally, 10 litres of gas per hour at 45" C. were the conditions employed. From time to time the sodium hydroxide in the absorbing vessel is removed by a tap, and fresh quantities of alkali are added through an attached tap-funnel, so that several fractions of 5 C.C. of the hydrocyanic acid-containing solution are obtained. To each of these is added 1 drop of a solution of ferrous sulphate (12 per cent.), the liquids shaken up and allowed to stand for an hour, when 1 drop of diluted sulphuric acid (1 : 2) is added, and, after shaking, the liquids allowed to stand at least thirty-six hours.The colours are matched after three, four, and five days with standards, made from potassium cyanide solution of known strength, prepared with iron and314 ABSTRACTS OF CHEMICAL PAPERS Linseed (Calcutta). Sample 1.Sample 2. HCN mgrm. HCN nigrm. acid similarly. Standards of prussian blue keep well (twelve months), 0.01 mgrm. to 0.30 mgrm. HCN being useful quantities to prepare. The mean reading of the separate days is taken as correct. The amount of hydrocyanio acid yielded by linseed, and the rate of its yield, depend upon the amount of cyanogenetic glucoside and enzyme, on the temperature, degree of acidity of the liquid present, and on the presence or absence of a number of other substances.I n normal health the acidity of the stomach is too high to allow of evolution of hydrocyanic acid, but under abnormal conditions-for example, in the case of a linseed rich in cyanogenetic glucosides fed to a beast suffering from indigestion such that the food was not rendered acid-hydrocyanic acid poisoning may set in.Acids of && strength prevent the action of the enzyme, and hydro- chloric acid of r&a retards the evolution of hydrocyanic acid. Probably all acids prevent this action. The following are some of the results obtained by the above method : Linseed Cake.Minutes. HCN mgrm. Minutes. 23 59 125 314 366 26 61 122 195 305 0-000 0.057 0-210 0.393 0.446 (= 100 ?&) Linseed (Calcutta) and 50 C.C. of ~~a N HCL. Min 11 t es , HCN mgrm. 24 0.000 59 0.024 130 0.104 225 0.191 325 0.272 (= 71.6 %) 0-103 0.243 0.333 0.370 0-374 (= 98.5 %) Linseed (Calcutta) and 50 C.C. .& Lactic Acid. Minutes. HCN mgrm. 23 0~000 51 o*ooo 125 0.028 216 0.055 300 0.086 (22% %) 0.100 0.243 0.336 0.372 0.382 (= 100.5 %) A.R. T. Quantitative Estimation of I-P-Hydroxybutyric Acid in Urine and Blood. B. 0. Pribram. (Zeits. exper. Path. u. Ther., 1912, 10, 279-283 ; Chem. Zentralbl., 1912, I., 1509.)-The method is based on the fact that the crotonic acid produced by the distillation of P-hydroxybutyric acid in sulphuric acid solution combines quanti-BACTERIOLOGICAL, PHYSIOLOGICAL, ETC.315 tatively with two atoms of bromine. The conversion of the P-hydroxybutyric acid into the volatile crotonic acid is best effected by means of sulphuric acid of 58 to 60 per cent, by weight. An excess of standardised bromine water is added to the distillate and titrated back with thiosulphate. In the estimation of P-hydroxy- butyric acid in diabetic urine, the method is complicated owing to the presence of phenols and sugar. The difficulty is surmounted by saturating the urine with ammonium sulphate, acidifying with sulphuric acid, and extracting with ether.The estimation is made on the ethereal extract. Blood is defibrinated before the estima- tion by a preliminary treatment witb six times its quantity of alcohol.J. F. B. Use of Mice and Birds for Detecting Carbon Monoxide after Mine Fires and Explosions. (Technical Paper II., Bureau of Mines, Washing- ton, 1912.)-The formation of a cap on the safety-lamp flame is not satisfactory as a means of detecting carbon monoxide. Blood solution and cuprous chloride solution show its presence with considerable sensitiveness, but the best method is the use of mice or birds. When exposed to an atmosphere of carbon monoxide, canaries show signs of poisoning sooner than mice, and the symptoms are more easily observed.The author remained for twenty minutes in an atmosphere containing 0.25 per cent. of carbon monoxide, without experiencing more than a slight headache, though later he became ill for several hours; canaries in the same atmosphere showed distress in one minute and fell from their perches in five.A party exploring a mine in which an explosion had taken place, carried with them a canary, which collapsed on reaching a spot at which there was 0.2 to 0.3 per cent, of carbon monoxide; the G. A. Burrell. party retreated without distress. 0. E. M. Modification of Wohlgemuth’s Method for the Quantitative Investigation of the Pancreas Function.P. B. Hawk. (Arch. hzternal Med., 1911, 8,552-556, through Chem. ZeiztralbZ., 1912, I., 1477.)-Wohlgemuth (Bed. Klin. Wochensch., 1910, 47, 92) described a method for the quantitative estimation of fEecal-amylase. According to this method, a weighed quantity of faeces is extracted with rt 1 per cent. sodium chloride solution, the extract is centrifuged, and the amylolytic power of regularly decreasing quantities of this extract is determined at 3 8 O C. by the hydroIysis of 5 C.C.of a 1 per cent. solution of soluble starch. After twenty-four hours’ action, iodine solution is added, and the degree of digestion is estimated colorirnetrically. The author’s experiments have shown that this method gives Satisfactory results in the case of faeces having a reaction within the normal limits, but in the case of strongly acid feces false results may be obtained, owing to the extreme sensitiveness of the amylase towards acids. In order to avoid this source of error, the author recommends, for the extraction of the faeces, a solution of 0.1 mol.of sodium dihy- drogen phosphrtta and 0-2 mol.of disodium hydrogen phosphate in 1 litre of 1 per cent. sodium chloride solution. J. F. B. Separation of Peroxydase from Catalase. A. Kasanki. (Biochem. Zeitsch., 1912, 39, 64-72.)-The method described is based upon the fact that catalase is precipitated when treated with pyrogallol, whilst peroxydase remains in solution.316 ABSTRACTS OF CHEMICAL PAPERS On adding pyrogallol to the clear filtered juice obtained from hemp seedlings in quantity sufficient to make the concentration of the precipitant between 4 and 5 per cent., a precipitate is formed which is free from peroxydase; the latter, however, passes into the filtrate when the mixture is filtered.If the pyrogallol be added in suEcient quantity, the catalase is rendered inactive, and cannot be detected in either the precipitate or the filtrate.The method may be employed for preparing catalase- free peroxydase froin different sources. w. P. s. Experiments with the Castor-Bean Lipase. K. G. Falk and J. M. Nelson. (J. Amer. Chent. Soc., 1912, 34, 735-745.)-A comparative study was made of the hydrolysis of methyl acetate, ethyl butyrate, and olive oil, caused by the castor-bean lipase.No appreciable influence on the subsequent hydrolysis was found when small amounts of alkali were added at the beginning of the action on methyl acetate, but with ethyl butyrate the action was diiferent, depending on the amounts of alkali added. Corrections were introduced in every case for the acid formed from ester solvent and lipase solvent.When the solvents used were ether saturated with water, and acetone containing a small amount of water, methyl acetate was hydrolysed to a considerable extent with lipase, both at the ordinary and at more elevated tempera- tures. Small amounts of an active constituent wereextracted from the lipase preparation by water and by ethyl acetate, By the electrolysis in water of the lipase preparation a substance was produced in the anode solution, probably by oxidation, showing marked hydrolytic action.In all cases the amount of ester hydrolysed was measured by titrating with a Tc aqueous solution of sodium hydroxide, using phenolphthalein as indicator. A large number of experiments are described with details as to temperature, time of action, solvent used, and titration figures.The lipase preparation used was prepared by grinding the castor-beans roughly, extracting 8 number of times with carbon tetrachloride or chloroform, and then grinding to a fine powder and passing through a hundred-mesh sieve and thus separating the majority of the shells. The fine powder was then exhaustively extracted with ether, leaving a light grey preparation containing 9 per cent.of ash, which, when mixed with water, had always a slightly acid reaction, increasing slowly on standing. H. F. E. H. Biochemical Method for the Estimation of Small Quantities of Salicylic Acid in Presence of Excess of p-Hydroxybenzoic Acid. J. Boeseken and H. Waterman. K. Akad. van Wetensch., Amsterdam, 1912, 20, 548-552; through Chern., Zentralbl., 1912, I., 1503-1504.)-p-Hydroxybenzoic acid is capable of being utilised by Penicillium glaucum as a source of carbon nutrition, whereas salicylic acid exerts a retarding influence on the growth of this organism.For the estimation of small quantities of salicylic acid in the presence of p-hydroxybenzoic acid, the following process may be adopted: 3 grms. of p-hydroxybenzoic acid, 0.5 grm.of dipotassium hydrogen phosphate, 0.5 grm. of ammonium chloride, and 0.2 grm. of magnesium sulphate, are dissolved in 1 litre of water, and several Erlenmeyer flasks are charged with equal quantities of the solution ; increasing quantities of salicylic acid are added to the series of flasks, the contents are sterilised, and each flask isBACTERIOLOGICAL, PHYSIOLOGICAL, ETC.317 infected with a culture of Peszicillium. A 0-3 per cent. solution of the acid mixture to be analysed is treated in the same manner, and the development of mould-fungus growth which takes place in the latter is compared with that in the flasks contaiuing the standard mixtures. J. F. B. Refractometer Value of the Serum of Cow’s and Goat’s Milk. K. Alpers. (Zeitsch.Untersuch. Nahr. Genussm., 1912, 23, 497-513.)-The author considers that the refractorneter value of the calcium chloride serum of milk, as determioed by the process described by Ackermann (ANALYST, 1907, 32, 117) is of value as a criterion in the detection of added water in milk. For the milk of separate healthy cows the value lies between 35.8 and 41.3 at 17.5” C., the average value for 126 samples of milk examined being 39.11. The daily variation observed did not exceed 1.4. Goat’s milk showed values of from 34.7 to 40.3, with an average of 38.0, a value slightly lower than that given by cow’s milk. w. P. s. Value of Direct Enumeration of Bacteria in Water by Means of the Ultra-Microseope. Aumann. (Zentralbl. Bakt.-u.-Parasitenk., 1912, II., 624-635 ; through Chem. Zesztralbl., 1912, I., 1594.)-The ordinary method of counting bacteria in the glass apparatus of Thomas and Zeiss is regarded as unsuitable, owing to the difficulty of completely sterilising the glass, though this objection does not apply to apparatus of quartz. The use of the latter is as a rule only practicable with water containing many bacteria, as, for example, in detecting large leakages in filtration. For the general examination of water the counting method with the ultra-microscope does not afford any certain conclusion 8s to the number of micro-organisms present, much less as to the suitability of the water for drinking purposes. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9123700312

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 317 ORGANIC ANALYSIS. Methods of Analysing Coal and Coke. F. M. Stanton and A. C. Fieldner. (U. S. Dept. of Interior, Bureau of Mines, Technical Paper, 8, pp. 19.)-This publi- cation describes in detail the methods of analysis in use in the laboratories of the Bureau of Mines, and is published in consequence of the numerous requests addressed to the Bureau for information as to its methods.The methods are substantially those recommended by the American Chemical Society, but a few modifications have been introduced, and somewhat elaborate apparatus is figured. The practice in the Bureau laboratories is to dry the whole 3-pound samples received by them to constant weight at 30°-350 C., and an oven specially designed for this service is figured.After quartering down to about 400 grms., the sample is then reduced to 60 mesh in a ball mill. Moisture is determined in the usual way by drying for one hour at 105' C., and a glycerol oven of quite novel form, which is said to insure great uniformity of temperature, is illustrated. The greatest deviation from the methods of the American Chemical Society is in the use of a sheet-iron chimney to protect the crucible from draughts during the determination of volatile matter.The publi- cation also includes descriptions of apparatus for the ultimate analysis of coal, and directions for the use of the bomb calorimeter and for the determination of true as well as apparent specific gravity. G. C. J.318 ABSTRACTS OF CHEMICAL PAPERS Volatile Acidity of Gum Tragacanth compared with that of Indian Gum.W. 0. Emery. (J. Ind. and Eng. Chem., 1912, 4, 374-376.)-The author has investigated the question of the detection of Indian gum in admixture with trage- canth by a method based on the estimation of the volatile acid produced on hydrolysis with acids. Indian gum is derived from the Sterculia urens or the Cochlospermum gossypium, the specimens examined belonging to the former species.The quantita- tive estimation of the volatile acidity is carried out in the following manner : One grm. of the whole or powdered gum is treated in a 700 C.C. round-bottomed flask, provided with a long neck, for several hours in the cold with 100 C.C. of water and 5 C.C. of syrupy phosphoric acid until the gum is completely swollen.The mixture is then boiled gently for two hours under a reflex condenser, whereby a clear colourless solution is obtained, a very small amount of cellulosic residue remaining. The hydrolysed product is next distilled slowly in a vigorous current o? steam until the distillate amounts to 600 C.C. and the acid residue to about 20 c.c., care being taken not to scorch the organic matter in the flask.The spraying of phosphoric acid may be prevented by fitting a spray-trap to the still-head. The distillate is titrated with Tc potassium hydroxide in presence of 10 drops of phenolphthalein solution, finally boiling the liquid under titration until a faint pink colour persists. The result is controlled by a blank distillation with the omission of the gum.The volatile acidity is expressed in terms of C.C. of & alkali per 1 grm. of gum. A number of authentic samples of gum tragacanth showed, for lumps, 3.2 to 4.2 c.c., mean 3.6 c.c.; for powder, 3.5 to 4.1 c.c., mean 3.7 c.c., equivalent to 2.2 per cent. of acetic acid from the original gum. As regards Indian gum, it has previously been shown by Robinson that the gum of Cochzlospernzum gossypium yields on hydrolysis 14.4 per cent.of acetic acid. The author has treated several samples of the gum of Xterculia wens, and found-for lumps, 25.9 to 28.3 c.c., mean 26.7 c.c., equivalent to 15.9 per cent. of acetic acid; for powder, 25-4 to 27.7 c.c., mean 26.5 c.c., equivalent to 15.89 per cent. of acetic acid. It is noted that, whereas gum tragacanth yields practically a colour- less solution after hydrolysis, the gum of Sterculia wens yields a rose-pink solution on boiling with phosphoric acid.It is concluded that the volatile acidity values are sufficiently constant to afford a good means of detecting and estimating admixtures. J. F. B. Investigations on Mercury Fulminate. R. Philip. (Zeitsch. ges. Schiess. u.. Sprengstofwesen, 1912, 7, 109, 156, 180, 198, 221.)-The Brownsdon method for the estimation of fulminate ( J .SOC. Chem. Ind., 1884, 3,17 ; 1905,24,382) consists in determining, without delay, the alkalinity produced by excess of sodium thiosulphate on the fulminate, using methyl orange. This was modified to eliminate the error due to the reduction of the alkalinity on standing, by using a large excess of thiosulphate, and working always under standard conditions.A method in which the excess of thiosulphate is titrated back with iodine was also evolved, and finally, a combination was found to give good results. Three grms. of pure potassium iodide (the use of which reduces the loss of alkalinity) are dissolved in 50 C.C. & thiosulphate solution, 0.3 grm. of fulminate is washed in and dissolved by agitation with a rotary motion, and the solution titrated first with methyl orange and pi acid, then with starchORGANIC ANALYSIS 319 and fc iodine (1 C.C.acid = 0*0071 grm. mercury fulminate ; 1 C.C. Tc iodine = 0.0142 grm. mercury fulminate). I n most cases the results were consistent, and the two titrations agreed satisfactorily, the iodimetric ones being somewhat the higher ; but with certain fulminates purified by crystallisation from potassium cyanide, the alkalimetric titration apparently showed 1.2 per cent.more mercury fulminate than the iodimetric. This is attributed to the possible presence of a product of the partial decomposition of the fulminate by the solvent. It was found that brown fulminate is not necessarily less pure than white.0. E. M. Analysis of Indigos containing Starch. G. H. Frank and A. G. Perkin. (J. SOC. Chem. Ind., 1912, 31, 372-373.)-1t has been shown by Thomson (ANALYST, 1911, 36, 290) that the sulphonation methods of Rawson or Bloxam do not give accurate results in the analysis of indigo containing starch. The author's experi- ments upon mixtures of pure indigotin and starch confirm Thornson's conclusions, and show that the low figures obtained are probably due to the destruction of indigotin through a reducing action of the products of hydrolysis of the starch during the sulphonation.This process is counterbalanced more or less by an oxidising process, when fuming sulphuric acid is used for the sulphonation, as in Bloxam's process ; and this would explain the concordance of the results obtained by Bergtheil and Briggs ( J .Soc. Chem. Ind., 1906, 25, 733) with mixtures of indigotin and starch. Further experiments have shown that pure indigotin is not altered when digested with dilute hydrochloric acid in the presence of starch, and that there is no reason against the method of extracting the starch from a mixture by treatment with boiling dilute hydrochloric acid, and estimating the indigotin in the residue by the tetrasulphonate process.Only by boiling the mixture for a long time with the potassium acetate were the results too low with Bloxam's process; but this is unnecessary, and a temperature of about 90' C. is quite sufficient for obtaining a clear solution. C. A. M. Occurrence of Methylcyclopentenolon in Pyroligneous Acid. J.Meyer- feld. (Chem. Zeit., 1912, 36, 549-552.)-A hitherto unknown unsaturated ketonic alcohol of the pentamethylene series, methylcyclopentenolon, C,H,O,, has been isolated by the author from pyroligneous acid. I n the pure condition it melted at 106" C., and sublimed with slight decomposition at 210' C. I t had a characteristic odour and a sweet pungent taste.I t could readily be obtained in crystalline needles from hot water, alcohol, acetone carbon tetrachloride, etc. In aqueous solution it gave a deep violet stable coloration with ferric chloride. I t reduced ammoniacal silver nitrate on gently heating, and Fehling's solution on boiling, and with phenyl- hydrazine yielded an osazone, C,,H,,N,, which cry stallised from alcohol in yellow needles, melting at about 140" C.I t yielded salts with metals, and from these the ketonic alcohol could be regenerated by treatment with a mineral acid, C. A. M. New Reaction for Organic Bases. Charitschkoff. (Chem. Zeit., 1912,36, 581.)-A solution of the so-called inactive naphthenic acid in hydrocarbons or in320 ABSTRACTS OF CHEXICAL PAPERS ether does not react with copper sulphate by itself; but as soon as a trace of aniline, pyridine, quinoline, piperidine, coniine, codeine, nicotine, quinine, or other base that is soluble in ether is added, the reaction takes place with the formation of copper naphthenate.On this reaction is based a sensitive test €or the detection of the above-named basic compounds, a solution of the inactive naphthenic acid in ether or petroleum spirit, with the addition of 3 per cent.of copper sulphate solution being used a8 the reagent. On shaking the mixture the liquid remains colourless until a, trace of a base is added. It is suggested that the test may be of value for the detection of alkaloids and ptomaines in physiological investigations, Caffeine and diphenylamine do not give the reaction.Oleic acid may take the place of inactive naphthenic acid in the test. I n the case of crystalline bases and alkaloids which are only sparingly soluble in ether or petroleum-spirit, free acid or amyl alcohol may be used for the extraction. C. A. M. Use of Phenolphthalein as an Indicator. J. W. MeBain. ( J . Chem. Soc., 1912, 101, 814-820.)-Stress is laid upon the great influence of extraneous carbon ,dioxide upon the results of a titration, and it is shown that in the presence of that gas i n solution about ten minutes are required for the final end-point of the reaction to be reached. I n the absence of carbonate, however, or if much carbonate is present, as in the case of a normal bicarbonate solution, the end-point occurs practically instantaneously and is permanent.The effect of carbon dioxide (carbonates) upon the sensitiveness of the end-point was estimated by titrating solutions of potassium hydroxide freed from carbon dioxide and carbonate, with and without the addition of known quantities of carbonate. It was found that with the greatest care the amount of alkali needed to change the colour was about fifty times greater than the 0.0043 C.C.of ;v alkali anticipated. The changes of colour in these experiments were compared with those of a colour scale ranging from No. 1 to 200, the first solution matching in colour that of a solution of 0*50 grm. of cobalt nitrate and 0.62 grm. of copper sulphate per litre, and the others containing two, three, four, etc., times these amounts.For comparing the colours above No. 10, a Donnan’s colorimeter *was used, and the colour of a solution nearly saturated with sodium phosphates and coloured with phenolphthalein was standardised against the cobalt and copper solu- tions. The difference between each member of the standard series was intended to correspond to the change in colour produced by the addition of one drop of & acid or alkali. McCoy (Amer.Chem. J., 1903, 29, 437) gives the alkalinity of Tv sodium hydrogen carbonate as 2-9 x 10-6N - OH‘, which would correspond to about No. 70 in the phenolphthalein standard. Hence, the amount of alkali required to produce the colour change in a titration, considered in conjunction with McCoy’s value, affords a sensitive means of estimating the amount of carbonate in a given solution.Estimations made with the different strengths of phenolphthalein solution showed that a pale colour, corresponding to about No. 3 in the standard scale, was the most sensitive for the end-point, and was also closer to the point of theoretical neutrality. It is advisable always to use about 20 drops of a 1 per cent. alcoholic solution of the phenolphthalein per 100 C.C.; since when carbonate is present the depth of colour is approximately proportional to the amount of phenolphthalein added up to theINORGANIC ANALYSIS 321 saturation point (50 to 60 drops). The error caused by adding only 1 drop instead of 20 drops of the indicator to 100 C.C. of distilled water corresponded to 0.08 C.O. of & potassium hydroxide solution.The phenolphthalein solution had been freed from carbon dioxide, neutralised with alkali, and was protected by a guard-tube of potassium hydroxide. With regard to the degree of accuracy possible in ordinary titrations, 0.01 per cent. was found to be the limit of agreement in duplicate estima- tions when large quantities of acid and alkali were used, and all precautions were taken in the ordinary atmosphere.As a precaution it is suggested that the water in the titration flask should be coloured to a pale tint similar to that to be attained at the end-point, before adding the acid, and that care should be taken not to breathe in the direction of the flask. Under these conditions the results of two estimations should agree within 0.1 per cent. C. A. M. Simultaneous Effect of Alcohol and a Neutral Salt on the Sensitiveness of Phenolphthalein. E. Lenk and G. Mondsehein. (Chem. Zeit., 1912, 36, 534.)-The effect of varying amounts of water on the system-ammonium chloride, water, phenolphthalein-and of water and alcohol on the system-ammonium chloride-water-alcohol-phenolphthalein was investigated. Alcohol displaces the end-point very much more than does water. For example, 10 C.C. of 2 N ammonium chloride solution, neutral to litmus, required 2-4 C.C. & potassium hydroxide solution to give a coloration with phenolphthaleln; the addition of 20 C.C. of neutral water increased this to 3.8 c.c., while 20 C.C. of alcohol raised it to 38.0 C.C. This is not an ionisation phenomenon, but is due to constitutional alterations in the indicator. 0. E. M.

ISSN:0003-2654    

DOI:10.1039/AN9123700317

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

INORGANIC ANALYSIS 321 INORGANIC ANALYSIS. Use of Arsenious Acid in Volumetric Analysis. 11. Estimation of Mercury. F. Litterscheid. (Chem. Zeit., 1912,36, 601.)-The solution of mercuric salt? which should not contain less than 0.1 grm. nor much more than 0.4 grm. of mercury, and which should have a volume of about 50 c.c., is mixed with 50 C.C. of A- arsenious acid solution and 5 grm. sodium bicarbonate in a 200 C.C.flask, and the mixture is heated on the water-bath until the precipitate acquires the dark grey tint of finely-divided metallic mercury. If the flask be shaken from time to time, the reaction is complete in half an hour. The contents of the flask are then diluted somewhat, cooled, and finally made up to 200 C.C. Since the mercury is very finely divided, the mixture is filtered through a double hard filter, or a teaspoonful of precipitated chalk is mixed with the contents of the flask before filtering through an ordinary paper.The first runnings are rejected, and the subsequent ones returned to the filter until 100 C.C. of clear filtrate has been collected. This is then diluted to about 500 c.c., and, after addition of a further 5 grms. of sodium bicarbonate, the excess of arsenious acid is determined by means of Tn iodine solution.If the original solution contained ammonium salts, the filtrate from the reduced mercury is first acidified with sulphuric acid and then saturated with sodium bicarbonate (10 grms.). G. C . J.322 ABSTRACTS OF CHEMICAL PAPERS System of Qualitative Analysis for the Common Elements.Part V. Acidic Constituents. A. A. Noyes. ( J . Amer. Chem. SOC., 1912, 34, 609-643.)- This paper forms a continuation to those previously published by the author under the same main title ( J . Amer. Chem. SOC., 1927, 29, 137 ; 1908, 30, 481 ; 1909, 31, 611). In the aggregate, these papers cover more than 200 pages, and constitute in effect a textbook of qualitative analysis, largely based on the author’s original investigations, but necessarily embodying so much that is common knowledge that no ordinary abstract of them is possible.The scope of the present paper is indicated in its sub-title, and the system of analysis is based on the volatilisation of most acids by boiling with phosphoric acid, collecting the distillate in two portions, the first of which contains the readily volatile, slightly ionised acids, the second the less volatile, largely-ionised acids.In the search for individual acids, the attempt has been made to select or devise tests of known and roughly equal sensitiveness, and preference has been given to those methods which enable the experienced analyst to form an approximate estimate of the quantities present.G. C. J. Study of Cobaltinitrites and their Application to Analytical Chemistry. L. L. Burgess and 0. Kamm. (J. Amer. Chem. SOC., 1912, 34, 65%659.)-The sensitiveness of the cobaltinitrite test for potassium may be greatly increased by having silver nitrate present, the double cobaltinitrites of potassium and silver- Ag,KCo(NO,), and AgK,Co(NO,),-being much less soluble than potassium cobalti- nitrite or sodium di-potassium cobaltinitrite, one or other of which, according to the amount of reagent used, constitutes the precipitate of the ordinary test.For example, when 1 drop of a freshly prepared 25 per cent. solution of sodium cobaltinitrite is added to a solution containing less t h m 100 parts per million of potassium, no perceptible precipitate is formed.If the test is repeated in presence of i& silver nitrate, a copious yellow precipitate is formed immediately. In presence of i& silver nitrate, solutions containing only 2 parts of potassium per million give an almost immediate precipitate, which persists for half an hour, and a solution containing only 0-5 part per million gives a distinct precipitate within fifteen seconds, the precipitate persisting for about five minutes.In applying this test, it is essential that the solution be neutral, or only slightly acidified with acetic acid. Halogens are conveniently removed by addition of silver nitrate and filtering, such an excess of silver being used as will make the filtrate an approximately & solution of silver nitrate.I n the usual scheme of analysis, the test may be applied after removal of the heavy metals. The filtrate from the latter is acidified with an excess of nitric acid, evaporated to dryness and ammonium salts volatilised, since ammonium silver cobaltinitrite is so insoluble that the test here described would serve for the detection of ammonia in concentrations of 5 parts per million in absence of potassium.Rubi- dium, caeeium, and thallium, form double cobaltinitrites with silver which are even less soluble than the corresponding potassium salt. No other metal is likely to interfere, for, though barium forms sparingly soluble cobaltinitrites, it will not interfere, unless the concentration of barium exceeds & strength. G. C. J.INORGANIC ANALYSIS 323 Separation of Iron from Titanium.F. Bourion. (Coniptes rend., 1912, 154, 1229-1232.)-The substitution of sulphur monochloride for chlorine in the process where iron is separated from titanium by volatilisation in a current of chbrine and hydrogen chloride simplifies the apparatus necessary for this separation, and permits of its being accomplished at a lower temperature. To prevent volatilisa- tion of titanium, it is necessary to keep the concentration of sulphur monochloride low, but this is readily accomplished as follows : The sulphur monochloride (2 c.c.) is contained in a flask of 160 to 170 C.C.content, surrounded by melting ice, and the stream of dry hydrogen chloride is introduced into the flask by a tube which comes within 4 to 10 mm. of the surface of the liquid, the mixed gases then passing to the combustion tube in which the mixed oxides of titanium and iron are contained in a porcelain boat.At its forward end the combustion tube is connected to a Will and Varentrapp apparatus, charged with water. The reaction commences at %XIo c-, and until a temperature of 400" C. is reached the gas stream may be as rapid 8s seventy-five bubbles per minute, but should then be reduced to half this rate, whilst the temperature is raised to 700" to 750" C., at which the reaction is complete in from two and a half to four hours with 0.3 to 0-5 grm.substance. After allowing the tube to cool, the hydrogen chloride in it is expelled by means of a current of dry air. Under the conditions described, no trace of iron will be left in the boat, nor can titanium be detected, even by the peroxide test, either in the contents of the receiver or in the washings of the combustion tube.I n these washings and the contents of the receiver the iron is precipitated by means of ammonia after oxidation of any ferrous iron by means of nitric acid. Occasionally magnetic oxide of iron may be formed in the forward part of the tube, as the result of the action of the steam of reaction on ferrous chloride, and the analyst must bear this in mind and fake appropriate steps for bringing this iron into solution.G. C. J. Estimation of Radium in Minerals and Rocks. E. Ebler. (Che?iz. Zeit., 1912, 36, 604.)-The method depends on the determination of the quantity of emanation given off in some definite interval of time by a known weight of the mineral.The weighed substance is placed in a platinum boat, either alone or mixed with some suitable flux, such as potassium carbonate, borax, or alkali phosphates (Cf. Joly, Phil. Mag., 1911 [vi], 22, 134 ; Eve and McIntosh, Traizs. Boy. SOC. Canada, 1910 [iii], 4, IIT., 67), and is heated to free it completely from emanation.The boat is then placed in a quartz combustion tube, which lies in an electric furnace, and which is connected by ground connections and taps to a mercury pump. After an interval of time, which may vary from two days to a month, according to the amount of radium present, the gaseous contents of the tube are transferred by means of the pump to a small gasholder, the contents of the boat being strongly heated towards the close of the operation. The air and emanation are then transferred to an evacuated ionisation chamber, and the radium emanation measured in the usual manner by determination of the saturation current.The absolute weight of radium is arrived at by means of a control experiment on a weighed quantity of some substance of known radium content.For use as a standard, radium barium oxalate of approximatelv 10 per cent. radium content serves well,324 ABSTRACTS OF CHEMICAL PAPERS and its real radium content may be estimated with an accuracy of 0-5 per cent. by determining its mean molecular weight, for which purpose a small quantity is weighed on a micro-balance, converted into oxide, and reweighed. The use as standards of mixtures of radium and barium salts of organic acids of higher molecular weight than oxalic acid would increase the accuracy of the method, and experiments with this object in view are in progress, The method, as described, permits of the estimation of radium in minerals with an accuracy of about 0.5 per cent.G. C. J. Spectroscopic Process for the Estimation of Small Quantities of Rubidium in Presence of much Potassium.E. Wilke-Dorfurt. (Zeitsch. amrg. Chem., 1912, 75, 132-140.)-The process consists in dissolving the substance (potassium salts) in water, feeding atomised spray from this solution to a special burner, photographing a portion of the spectrum and comparing the photograph SO obtained with a series of standards prepared under nearly identical conditions. The illustration shows the atomiser and burner.The glass burner tube B is of 9 mm. internal diameter and extends for 7 cm. above the point D, where a capillary, 3 cm. long and 0.8 mm. in internal diameter, is fused into it. Opposite the capillary jet are two openings for the supply of air to the burner through the atomising device A. To the top of the glass burner tube, a porcelain tube of the same internal diameter and 5 cm.long is attached by means of rubber tubing. Rubber tube is also used for G making the joints at G and E, where the burner tube enters and leaves the bulb- shaped extension of the vessel A . The vessel A is constructed from tubing of 2.8 cm. internal diameter, the height of the anode chamber being 8 cm., and the length of the knee-shaped portion, the lower part of which accommodates the cathode, 12 cm.The bulb through which the burner tube passes is of 3.5 cm. diameter, and the distance between G and IZ 5.5 cm. E is a cork sufficiently nicked to allow a free supply of air to the burner. The cathode wire passes between the cork and the glass wall of the tube, but the anode is suspended within a short length of glass tubing, which serves to allow the escape of electrolytic oxygen and traces ofINORGANIC ANALYSIS 325 chlorine.The colouring of the flame is effected, on the Beckmann-Riesenfeld principle, by electrolytic atomising of the solution, of which 40 C.C. is placed in the vessel A* The solution should be a 10 per cent. solution of the mixed salt, as a high concentration of potassium insures the current being conducted by the potassium chloride, and avoids any possibility of rubidium becoming transformed into hydroxide or perchlorate.The electrodes are of 0.8 mm. platinum wire and a current of 2.5 amperes at 4.5 volts gives a suitable evolution of gas. For photographic work, the most suitable portion of the spectrum to select is that between 396 pp and 435 pp, that is to say the blue, not the red, which serves best for work with the naked eye.The spectroscope used by the author has a prism, the dispersion of which between c and h amounts to 4-25 O ; the opening of the collimator and of the camera is 19 mm. As the inner cone of the Bunsen flame gives lines in the blue, the inner cone of the flame is kept as small and sharply defined as possible.Obviously, in attempting to make a process such as this quantitative, every precaution must be taken to work under constant conditions. Among important conditions, easily controlled, are gas pressure, region of flame observed, time of exposure, and manner of development of the plates. Uniformity in manufacture and age of the plates is insured by buying direct from the makers.The author uses Agfa “extra rapid” plates, and gives a half-hour exposure. This length of exposure tends to eliminate errors due to small periodical changes in some of the conditions which are difficult to suppress, but which neutralise each other during a prolonged exposure. Too long an exposure, however, leads to the appearance of a continuous spectrum, due to dust particles, which reach the flame, in spite of all precautions.The author describes the development of his plates, but any process, provided it be a rigidly uniform one, may be used. For concentrations of rubidium relative to potassium of from 0.05 to 10 per cent., the method is accurate to within about 10 per cent. It was designed to estimate only the order of magnitude of the rubidium percentage in new potash workings, but has proved more accurate than this, as stated.G. C. J. Estimation of Sulphides in Lime Liquors. J. R. Blockley and P. V. Mehd. (J. Xoc. Chem. Ind., 1912, 31, 369-372.)-Estimation of the sulphides in lime liquors for leather by titration with zinc sulphate gives abnormal results owing to the precipitation of zinc as hydroxide, and this is also the case when the zinc sulphate solution is prepared as suggested by Procter (“ Leather Industries Laboratory Book,” pp.55, 87), by adding ammonia to the solution until the precipitate just redissolves. If, however, an excess of ammonium chloride is added to the zinc sulphate solution (50 grms. per litre of FG solution), or if the ammonium chloride is added to the liquor to be titrated with Procter’s solution, the precipitation of zinc hydroxide is prevented, whilst only zinc sulphide is precipated, and a sharp end-point of the reaction is indicated with lead acetate or sodium nitroprusside (preferably the latter) as an outside indicator. It is usual to take the alkalinity of a, lime liquor as an index of its freshness, and to discard the liquor when the increase in alkalinity due to amino- compounds from the hides has reached a certain limit. I n the presence of sodium sulphide, however, this direct measurement of alkalinity is not applicable ; nor does the alkalinity of a sulphide lime liquor correspond to the separate alkalinities due to326 ABSTRACTS OF CHEMICAL PAPERS the sulphide and to the lime, a liquor containing sulphide showing less lime than pure lime liquor, owing to the sulphide precipitating calcium hydroxide. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9123700321

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

326 ABSTRACTS OF CHEMICAL PAPERS APPARATUS ETC. Modification of the Landsberger Boiling-Point Apparatus. J. H. Paterson. (Proc. Phil. SOC. Univ. Durham, 1912 4 142-144.)-The author has simplified the apparatus of Landsberger (Ber. 1898 31 458). The boiling-flask C is partly filled with the pure solvent and a few pieces of unglazed porcelain added to prevent bumping. The solvent is boiled with the tap E (of large bore) open until the whole of the inner tube A is raised to the temperature of the boiling solvent as shown by the condensation of the vapour from the condenser. The tap E is closed when the vapour ascends by the side tube and the measuring vessel A begins to fill with the liquid. When the thermometer registers a constant boiling-point the burner below is removed and the tap E opened.The liquid collected above this tap flows back into the flask causes a temporary cooling of its contents and sucks the solvent in A back into the flask. A weighed quantity of the substance to be examined is next introduced into A and the tap closed to such an extent that some vapour passes up through it and warms the outer jacket, while the rest passes by the side tube. When sufficient liquid has collected in A and a definite temperature is noted the tap E is opened and simultaneously the tap I? is opened to prevent the liquid being sucked back. The volume of liquid and the temperature are then noted the tap again partly closed and the experiment repeated at various dilutions. The apparatus gives good results. The thermometer has a range of 50" C.and is graduated in twentieths of a degree. The glass tap is greased with glycerol or vaseline according as benzene or alcohol is used as the solvent. A. R. T. Adiabatic Device for Bomb Calorimeter. J. A. Fries. (J. Amer. Chem. Soc. 1912,34 643-652.)-Adiabatic calorimeters have been described before (ANALYST, 1910,35 283) but the present device is applicable to existing calorimeters of the more usual patterns. 4 to 5 mm. air space from a double-walled cylindrical copper jacket B which has an air space of 4 mm. between its walls and bottoms and is constructed of polished sheet copper of 0.25 mm. gauge. This copper jacket is in effect the bulb of an air-thermometer and is connected by a small brass tube as shown to a water-gauge which is shown-broken off-making an angle of 14' with the horizon a capacious bulb being interposed between the gauge and the copper vessel to prevent water being The calorimeter A is enclosed within and separated all round b APPARATUS ETC.327 sucked over into the latter should the temperature be unduly depressed. The fact that the air thermometer is sensitive to changes of barometric pressure is but rarely important having regard to the short time required for a determination. The jacket is heated by means of an electric current passing through a German silver wire about 3.5 metres long and 0.8 mm. in diameter with a total resistance of about 6 ohms. This wire is strung through brass eyelets screwed directly into the inner insulating fibre jacket of the Atwater-Berthelot calorimeter used by the author.The eyelets are so arranged that there is one coil of wire near the bottom a little distance from the sides the rest of the wire going up and down along the sides making eight loops spaced evenly and coming to within 30 mm. of the top of the inner fibre jacket The two ends are fastened to insulated copper wire and brought through the side of the fibre jackets. The manner of wiring described was adopted to avoid induction The distance between heating wire and fibre vessel is about 6 mm leaving 15 to 20 mm. between wire and calorimeter. On a 110 volt circuit, the current obtained through five 130 Watt lamps in parallel serves well. Since the air thermometer is affected by changes of pressureas well as changes of temperature its scale must be a movable one.This scale is graduated by placing a good mercury thermometer in the copper jacket allowing the conditions to become constant taking readings then switching on the current for a short period and again taking readings when the conditions are constant and so on correcting for barometric changes if necessary. The scale of the air thermometer should be in O - l O . With the author's instrument adiabatic conditions are sufficiently realised if the heating device be put in operation when the charge is ignited and the current switched off after forty seconds supposing that is that the charge is likely to generate some 4,500 calories. Whether another instrument would need a longer or shorter heating or one or two additional short contacts after the first can soon be determined.The author also finds that he gets the most exact results when his jacket temperature is maintained about 0.1 to 0.16" C. higher than that of the calorimeter the explanation of this being probably the constant radiation from the water surface and top of the calorimeter. The advantages of the apparatus are those common to adiabati 328 ABSTRACTS OF CHEMICAL PAPERS calorimeters generally-namely obviation of tedious computation with some increase of accuracy. The following test numbers are given with some details of the experi-ments Heat of combustion of benzoic acid 6323 6315 6316,6323 the best attested value known to the author being 63210. G. C. J. New Densivolumeter for Deter-mination of Density of Solids. J. Escard. (Comptes rend.1912 154,1242-1244.) - The illustration is nearly self-explanatory. Before use the graduated tube (on the left) is raised and the other tube lowered and the apparatus charged with water though B. By moving one of the tubes slightlyup or down the water level in t is made to coincide with the zero of the scale which is in C.C. A friction runner on m is then moved until it marks the level of the meniscus in the right-hand tube which is then lowered until the bulb A is partly empty. The stopper a is removed, the weighed substance introduced and the stopper reinserted. The levels of the tubes are readjusted until the meniscus in the right-hand tube again coincides with the position of the friction runner and the volume of the solid introduced is read off direct on the graduated tube.G. C. J. Apparatus for Determination of Vapour Pressure Isothermals of Silicic Acid Gels. R. Zsigmondy W. Bach-mann and E. F. Stevenson. (Zeitsch. anorg. Chem. 1912 75 189-197.)-The apparatus illustrated in the paper con-sists of (1) a small glass vessel for holding the gel provided with a glass stopper which is removed for the introduction of the gel and which by a half-turn serves to make or break connection with the rest of the apparatus from which it is detachable by a ground-glass joint; (2) a more capacious vessel for holding any liquid with the vapour pressure of which it is desired to bring the gel into equilibrium this vessel being connected to a manometer and also provided with a tap to disconnect its con-tents from the rest of the system; and (3) a T-tube connecting (I) and (2) the third limb of the T connecting through a tap to a mercury pump.For use with hydrogels the taps and ground joints are greased for the upper part of their groun APPARATUS ETC. 329 surface with Bamsay grease jY; but for use with alcohol or benzene grease is not permissible for the ground joint of the weighed vessel containing the gel and mercury-cupping must be resorted to. As an example of the manner in which the apparatus is used the following particulars relating to a series of experiments with a, hydrogel of silicic acid are given. This gel was cut into pieces not larger than 4 mm. cube and dried over concentrated sulphuric acid in an ordinary desiccator. The glass vesseI for the reception of the gel was then weighed full of air after removing every particle of grease from the stopper; the stopper was then greased and the apparatus again weighed exhausted and weighed a third time.About 0-7 grm. of the gel was next transferred to the vessel and the latter connected by its ground joint to the rest of the apparatus the larger vessel with manometer attachment, being charged with concentrated sulphuric acid. With the weighed vessel cut off by its tap from the rest of the apparatus the rest of the apparatus was exhausted, connected momentarily with the weighed vessel and the cycle repeated until OD opening the tap of the weighed vessel the manometer remained stationary. The vessel containing the gel was then weighed daily always closing its tap before disconnecting from the rest of the apparatus and removing grease from its ground connection before weighing until the difference between two successive weighings was less than 0-5 mgrm.Dry air was then admitted to the vessel and another weighing made. The concentrated acid in the vessel with manometer attachment was then replaced by acid of weaker strength the system freed from air by the pump, and daily weighings again made this series of operations being repeated with weaker and weaker acid and finally with water. A reverse series with increasing concen-tration of acid was also made and the results plotted on a system of rectangular co-ordinates in which the ordinates are proportional to the vapour pressures and the abscissae to the water content of the gels in molecules of water per molecule of silica.The method though tedious is much less so than that of Van Bemmelen (Zeitsch. anorg. Chem. 1897 13 239) and unlike his method can be applied to alcohol and benzene gels as well as to hydrogels. For use with benzene sulphuric acid is replaced by mixtures of benzene with paraffin oil whilst a mixture of glycerol and alcohol is used in experiments with alcohol gels. G . C . J. Colorimeter for Rapid Work with Widely Varying Standards. C. H, White. (J. Arner. Chem. Soc. 1912 34 659-662.)-The colorimeter is of the type in which the thickness of the sections observed is the variable. It consists essentially of two wedge-shaped hollow glass prisms of exactly equal dimensions and open at the large end for the introduction of the solutions to be tested.The wedges are held in a vertical position side by side in a camera and may be raised or lowered by rack and pinion actuated by thumbscrews. The pinions are screened from view on the side towards the operator except for a narrow horizontal slit across the middle of the camera through which the solutions are observed when a test is being made. The carriers are graduated to correspond to the length of the wedges the zero of the scale being opposite the index when the sharp edge of the wedge is opposite the narrow opening in the screen through which the colour is observed. The screens are adjustable so that the opening may be varied to suit the operator. The ground glas 330 ABSTEACTS OF CHEMICAL PAPERS shutter at the forward end of the camera for diffusing the light is hinged in the manner of a door to facilitate the transfer of the wedges to and from the camera.To carry out a determination with this instrument equal quantities of the standard and of the material to be tested are diluted to equal volumes and convenient amounts of the solutions are transferred to the wedges. The wedge containing the solution of unknown strength is set at the graduation representing the percentage-or some multiple of it-of the colouring matter in the standard. The wedge containing the standard is then adjusted until the two fields seen through the camera appear identical. The percentage of colouring matter in the unknown is then indicated by the reading of the scale on the carrier containing the standard. If the depths of colour first compared are too great or too small for the most accurate comparison, the result may be checked without changing the solutions by setting the wedge con-taining the unknown at some new point 011 the scale and again adjusting the other wedge until equality is reached.In the author's hands the maximum error of a single observation is 0.6 per cent. The apparatus which is illustrated in the paper, is made by Eimer and Amend of New York. G. C. J. Combined Governor Collins. (Proc. Phil. SOC. n C and Gauge for Regulating Flow of Gas. S. H. Univ. Durham 1912 4 llO-l13.)-The figure shows the governor and gauge for maintaining a flow of gas : A is a glass tap with pointer and scale ; b c and rn are rubber connections; d is a piece of glass rod drawn out to a long fine point ; e is a piece of glass Sprengel tube blown with a bulb and then ground down; F is a float containing mercury and having ' a flat glass platform cemented on; K is a piece of wide glass tube and J is a glass cylinder.The gas enters at ?z and leaves at x. When working the gas depresses the water to i but instead of entering here, it passes by d into the chamber containing the valve. The rate at which the gas passes through this valve depends upon the position of F which is kept hover-ing about a position determined by the level h accord-ing to the size of the instrument. The level of water g is dependent on the amount of water placed in the jar and may be adjusted at the commencement. The height gh is thus fixed; the height gi shows the pressures of the incoming gas hi the surplus pressure being got rid of by the valve.As the difference of pressure on the two sides of the tap is kept constant and the tap is fixed by experiment both pressure and resistance are constant and the current also in the absence of variation of specific gravity of the gas. The instrument in trial has shown an average flow of 10.05 k 0-22 litres of gas per hour when 10 litres were required. A. R. T APPARATUS ETC. 331 Constan t-Pressure Hydrogen Generator. S. H. Collins. ( P ~ o c . Phil. SOC. Uniw. Durham 1912 4 107-109.)-The author claims that the apparatus delivers pure hydrogen at a steady rate. The figure shows a Winchester quart bottle A containing diluted sulphuric acid (1 8 by volume) and supplied with a stopcock C.The wooden block B and the air-tube in A provide coarse and fine adjust-ment respectively for pressure of gas. The wide tube d is roughly graduated in c.c. the level of the sprinkler f being zero. The large bottle K serves to hold the waste acid and in conjunction with the -inverted cylindrical jar J acts as a gas-holder. The trough P receives the waste acid and is emptied occasionally. The jar J contains about 7 kgrms. of zinc in lumps (not granulated) resting on a ball of copper wire. Between the mouth of J and the bottom of K are two pieces of wide rubber tube to prevent breakage. The acid tube has a rubber connection at t and the gas delivery tube similarly one at w and these should be narrower than the tubes used as a cushion for J to prevent their being closed by the weight of zinc.Three corks are placed in the mouth of K to fix J firmly. The hydrogen is freed from sulphuretted hydrogen and other impurities by passing it through a tube containing ( ( mercury lime,” prepared by mixing 3 parts of mercuric chloride and 1 part of lime making into a paste with water drying the mixture and breaking it into convenient sized lumps ready for use. and then black by absorption of the impurities. hl is only about three-quarters of df. This purifier gradually becomes yellow A. R. T. Analysis of Organic Substances by an Electrical Method. E. E. Reid. (Amer. Chem. J. 1912 47 416-419.)-The following method is recommended for the simultaneous estimation of carbon hydrogen and sulphur. A combustion-tube of transparent quartz 600 mm.long by 17 or 18 mm. internal diameter is Used though one of hard glass may serve. In the end A is inserted a two-holed rubber-stopper, through one hole of which passea a small quartz tube 300 mm. long by 4 mm. externaldiameter ( A to 0). At 25 mm. from the end this tube is bent to an angle of 4 5 O the bent end projecting from the stopper. To the outer end of this is fastened a T-tube into the other side of which is fused 8 platinum wire. This wire must b 332 ABSTRACTS OF CHEMICAL PAPERS large enough to carry a current of 3 amperes without heating. The wire passes through the T-tube and small quartz tube and connects at the end of the latter with one end of two metres of fine platinum wire ( ‘ I No. 30”) used as the heating coil; this is wound into a spiral about 12 mm.in diameter and is supported on the small quartz tube. When hot this has a resistance of 24 ohms and is used on a IlO-volt circuit in series with an external resistance of 18 ohms taking 2.6 amperes of current. This wire is coiled tightly round the small quartz tube for a distance of about 125 mm; from the stopper and its end is joined to a rather stout platinum wire passing through the stopper. These close coils are so placed as to keep the lead peroxide in the boat just below them nearly but not quite up to its decompo-sition point. A piece of platinum foil 100 by 25 mm. has welded across it 1 mm. from the end a piece of platinum wire Tho other end is notched and turned up and the foil bent to form a semicircular trough to fit inside the combustion tube.At E just beyond the end of the small quartz tube is placed a plug of quartz wool 75 mm. long (asbestos will not answer as it absorbs oxides of sulphur). Over this portion of the combustion tube is suspended a shield of thick asbestos board and under it is placed a strong burner with a (4 wing” top. The plug of quartz wool at G contains a loop of platinum wire to withdraw it when the boat is to be inserted. The portion of the tube containing the heating coil is provided with a close-fitting cover of asbestos board having a narrow slit through which the coil may be observed. A blank experiment to deter-mine its loss in weight when reduced to the monoxide is made by heating a weighed quantity of the peroxide in the platinum boat in the combustion tube using two burners under the tube and one from above.The peroxide is heated till it is at a red heat (3 mins.) when the source of heat is removed and the boat cooled quickly. The resulting pure yellow monoxide is weighed and the loss of weight calculated per grm. of peroxide. For an estimation 1 to 2 grms. of the peroxide in the boat, spread out evenly are placed in the combustion-tube the quartz plug at E heated very hot and the platinum coil brought to a bright red heat before inserting the boat containing the substance to be burned. Next the burner under the plug G is lighted, and a slow current of oxygen is admitted through the small quartz tube care being taken that an excess of oxygen is present in the gases issuing at A. A third burner heats the boat at F to cause slow volatilisation of the substance and the vapours are passed through the quartz plug at E by means of a slow current of air or nitrogen admitted at B.The most refractory substances are completely burned at the high temperatures possible in the quartz tube admitting oxygen at B if necessary. 0.2 grms. of substance is burnt in about one hour and even if complete combustion of the carbon is not assured the sulphur is usually satisfactorily burned and absorbed When the combustion is complete the platinum boat containing the peroxide is heated to reduce it as already described. Using the results of the blank, the loss in weight on reduction is calculated. The weight of the boat and its contents is diminished by this amount and the remainder subtracted from the final weight, gives the weight of sulphur trioxide absorbed during the combustion.Lead peroxide is used as the oxidising material. A. R. T APPARATUS ETC. 333 New Method for Quantitative Analysis of Solutions by Precise Thermometry. T. W. Richards and J. W. Shipley. ( J . Amer. Chem. sot. 1912, 34 599-603.)-The method depends upon noting the precise temperature at which the solution attains exactly the same density as a given previously calibrated float, and its application is of course limited to cases where not more than one substance, in addition to the solvent is present When as is usual the solution is denser than the solvent the more concentrated the solution the higher is the temperature necessary to reach floating equilibrium ; hence each concentration corresponds to a definite temperature and after a few points on the almost linear curve connecting the two variables have been determined by means of known solutions all the inter-vening ones are determinable by simply reading the thermometer at the points d ~ e r e floating equilibrium is attained.When the solution is less dense than the solvent, it must be cooled instead of warmed to attain floating equilibrium as the concentra-tion increases. The exact density of none of the solutions need be known since the method depends only on differences of density. A mercury thermometer used for this purpose is best calibrated with great care ; but if the bore is very uniform and the graduation is perfectly spaced the degrees need not correspond to any recognised scale.Good results may be got with any good Beckmann thermometer. Platinum resistance thermometers may be used by those familiar with very exact electrical measurements and in this case ohms or multi-volts may be plotted directly against concentrations without translation into Centigrade degrees. A thermostat capable of being adjusted to any needed tempera-ture and of being kept there within 0.005" C. is required in order that the greatest accuracy may be attained. The solution to be investigated is placed in a litre Erlenmeyer flask immersed in the thermostat and the float within the flask is viewed by reflection in a small inclined mirror kept beneath the water of the bath. The glass float should be small (5 c.c.) and cigar-shaped and if permanency in calibration is desired should have been made several months before use.A recently-made float may be used but will require calibration every few days. For wide ranges of concentration several floats will be necessary. Because the co-efficient of expansion of the float enters into the effect the results obtained with floats made of different materials are not directly comparable. Probably Jena thermometer glass (59111) is the best material available. The exact density of the float is of no consequence all that is necessary is that it shall float at room temperature in the lightest solution for which it is to be used and sink when the temperature is raised a few degrees. A float of slightly too low density is easily adjusted by attaching to it a few points of glass. The sensitiveness of such floats is very great and the temperature at which they sink or rise can be determined within 0*001" C. As an example of the order of magnitude of the temperature differences corresponding to differences of concentration which the method is designed to measure the following may be given A particular float just sank in alcohol of 98-99 per cent. strength at 15.391' C. On adding water so that the percentage of water in the alcohol was increased from 1-01 per cent. to 3-44 per cent. the temperature of floating equilibrium was 24.093 and intermediate experiments showed that the increase of temperature of floating equilibrium was very nearly a linear function of the concentration of water. I t is obvious that thi 334 REPORT float affords a means of determining the percentage strength of strong alcohol with a degree of accuracy which is limited rather by errors inherent in the methods avail-able for determining the strength of the 98.99 per cent. spirit used as the basis of calibration than by the experimental errors of the method now described. G. C. J

ISSN:0003-2654    

DOI:10.1039/AN9123700326

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

334 REPORT REPORT. The Softening, Purification, and Sterilisation of Water Supplies. A. C. Houston. (Metropolitan Water Board. Eighth Report on Research Work.) -The report deals with a novel method of using lime primarily as a bactericidal agent, and only secondarily and incidentally for softening purposes. This would make possible the safe and speedy utilisation of flood-water, and the absolute elimination, so far as the portion of water treated with an excess of lime is concerned, of any danger from such epidemic water-borne diseases as typhoid fever and cholera.As an illustration of the method, it is assumed that it is required to deal with 10,000 gallons of the Thames supply, to remove at least 15 parts of total hardness, and to render the water innocuous. Fifteen pounds of quicklime, costing l i d ., would be added to 7,500 gallons of raw, unstored Thames water. This would kill within twenty-four hours the B. colz, and inferentially, but certainly, the microbes also of epidemic water-borne disease-e.g., the typhoid bacillus. The water would also be improved considerably as judged by physical and chemical standards. The excess of lime (about 0-007 per cent.) would then have to be neutralised with 2,500 gallons of adequately stored water, which, according to all the author’s experiments, would not contain any of the microbes of epidemic water-borne disease.Thus 75 per cent. of the water would be sterilised chemically, and the remaining 25 per cent. by storage, The mixture would have lost about 15 parts of its total hardness, and would contain no undesirable excess of free lime, besides being perfectly innocuous. Rapid filtration alone would then be required to remove the precipitate of inert carbonate of lime, and to bring the water up to a reasonable standard of chemical purity, As an alternative, the case of a well water is considered, having over 15 parts of temporary hardness, which is considered to be dangerous. Seventy-five per cent.of the whole would be lime-sterilised, and the remaining 25 per cent. sterilised by ozone or heat, or by active chlorine, and the two portions mixed together to produce a softened and bacteriologically safe drinking-water. As only 25 per cent. of the total would require the more expensive treatment, the cost is proportionately reduced, and the faint taste in the 25 per cent.portion would be diluted to such an extent as to be negligible. Experiments are cited showing that the bactericidal dose of lime with hard waters is about 1 to 5,000, falling in the case of very soft waters to about 1 to 50,000. The experiments were made with ‘( uncultivated ” B. coli-the state in which they would be ingested by the consumer, The B.coli in London crude sewage were killed by 1 part of quicklime (about 75 per cent. CaO) in 2,000 parts of sewage. The disadvantages and the advantages (of theREVIEWS 335 excess lime method) are set out, and among the former, assuming the method to be grafted on to an existing water-purification plant, is the fact that the mere cost of lime to reduce the hardness, even by 10 parts, would be about double the cost of the existing process of sand-filtration.The capital expenditure on the machinery and softening tanks would be very large, and the periodical removal and disposal of sludge would entail great expense, and might even be impracticable. Softening proposals (apart from the novel application of utilising the lime as a germicidal agent) would seem to run counter to the authoritative “findings” of the (‘ Richmond,” ‘‘ Balfour,” and ‘‘ Llandaff ” Commissions, and of the Arbitration Court.As against all these, the .method can be applied to 75 per cent. or any smaller proportion of the total supply, and is specially suitable for flood-waters, because the water is then usually less hard, and the treatment has a clarifying and purifying action, apart from its bactericidal effect.The cost of lime treatment is not wholly unremunerative, and it is even claimed by some that a substantial gain on balance is obtained, due to saving in soap and fuel consumption. Of first-rate importance is the capacity of the method quickly (five to twenty-four hours) to render an initially foul water absolutely safe bacteriologically ; it also virtually increases the yield of the sources of supply by rendering them always fit for abstraction.The method is perfectly innocuous, since no substance is left in the water which was not there initially in greater amount. The construction of new storage reservoirs could be postponed, as the lime-treated water is brought into a parallel bacteriological condition with the adequately stored water. This would mean, in effect (on the 75 per cent. basis), prolonging the period of storage from 30 to about 120 days, since 25 per cent. of the water from the storage reservoirs could be mixed with 75 per cent. of raw water after lime-sterilisation. H. F. E. H. +%s+fitfi&*

ISSN:0003-2654    

DOI:10.1039/AN9123700334

出版商:RSC    

年代:1912

数据来源: RSC

摘要:

REVIEWS 335 REVIEWS, METHODS OF AIR ANALYSIS. By J. S. HALDANE, M.D., F.R.S. Pp. x + 130. Most of those who are actively engaged in air analysis are more or less familiar with the work of Dr. Haldane in this direction, and to these it is enough to say that this little book contains illustrations and detailed instructions for the use of all those pieces of apparatus which we owe to the author-illustrations and instructions which until now were hard to come by, as they were scattered among a number of journals not usually to be found on the analyst’s shelves and among Bluebooks.To those whose general knowledge of the subject was acquired a few years ago, and who have not given close attention to more recent periodical literature, it may be said, without exaggeration, that the work of Haldane has revolutionised methods of air analysis-at any rate of methods designed to estimate three or a less number of constituents in a gas mixture.Haldane’s original apparatus was described as long ago as 1898, but since that date various modifications of it have been devised for special purposes, and perhaps the best known is his apparatus for the gasometric London : Charles Griffin and Co.1912. Price 5s. net.336 REVIEWS estimation of carbon dioxide in the air of ordinary rooms, and this apparatus serves as well as any to illustrate the principles common to all. For the gasometric estimation of the small proportion of carbon dioxide usually found in ordinary rooms and factories, a portion at least of the measuring burette must be of very narrow diameter, and a feature of all apparatus of the Haldane type is a burette with a bulb of relatively large dimensions, and a narrow, graduated stem.The relation between the volume of the graduated stem and the bulb differs according to the purposes the apparatus is intended to fulfil; but for the determina- tion of carbon dioxido in air the stem makes up only one-hundredth of the volume of the whole burette, and is divided into 100 divisions.Since the scale is sufficiently open to allow fractions of a scale division to be estimated with an error not exceeding 0.1, very close reading is possible ; but it is obvious that such close reading would be futile unless there existed means for correcting for variations-even very small variations-of temperature and pressure between two readings.An essential feature of the Haldane apparatus is that it provides such a means of compensating for variations of pressure or temperature. The means adopted is a control-tube, of the same size and shape as the burette, placed alongside the latter in a water jacket, the burette and control-tube being connected by independent connections to separate limbs of what is in effect a differential pressure gauge, charged with a, solution of caustic potash. Dr.Haldane, in his book, acknowledges the use of a control-tube by Williamson and Russell, and the use of the same principle by Pettersson; but the application of the principle in a simple and practical form is due to Dr. Haldane alone, as is constantly recognised by designers of new forms of gas apparatus when, to shorten their descriptions, they say their apparatus embodies the Haldane principle.Since the appearance of the publications in which Dr. Haldane’s various pieces of apparatus were first described, many minor improvements have been introduced, and some of these were described in a paper by Butterfield (ANALYST, 1909,34, 257) -a paper which had a special value at the time because of the inaccessibility to many of Haldane’s original papers.All these minor improvements are referred to in the present book, which will therefore be welcomed even by those familiar with the original papers. In addition to gasometric methods, the book includes a description of the Haldane and Pembrey method for the gravimetric determination of moisture and carbon dioxide-a method which, by simple means, enormously increased the speed and accuracy of such determinations-and modern methods for the recognition and determination of small proportions of carbon monoxide in air are also dealt with at length.I n this connection, again, the work of Haldane (and Douglas) has at once simplified and increased the accuracy of the blood test, the use of the spectroscope being dispensed with and the delicacy of the test increased about fivefold, This book, which, in addition to its other merits, is well illustrated and excep- tionally free from misprints, must find a place in the library of every chemist who is at all interested in the subject with which it deals, and those chemists who are not interested in the analysis of simple gas mixtures must be few.G. CECIL JONES.REVIEWS 337 AN INTRODUCTION TO QUANTITATIVE ANALYSIS. By S. J. &I. AULD, D.Sc. (Lond.), Ph.D., F.I.C. London: Methuen and Co., Ltd. 1912. Pp. x + 215. Price 5s. net. This is one of Methuen’s Textbooks of Science series, and aims at providing “ an introductory course in quantitative analysis, suitable for college and university students, without entering too deeply into the details of special technical analysis,” and in this object it succeeds.That it does so to an appreciably greater extent than many of the existing similar handbooks is open to doubt. Little can be said in favour of the practice of multiplying elementary textbooks, which do not efficiently replace good laboratory teaching, which do not particularly encourage independent ingenuity on the part of the student, or which fail to emphasise the scientific foundations of analytical chemistry.The author has traversed practically the whole range of ordinary analysis, and has been in this respect too ambitious; for instance, the accounts of water and gas analysis are inevitably scrappy.No doubt the actual manipulative detail of water analysis may be properly described in seventeen pages, and it may be argued that the really important thing, which is the interpretation of the results, can be taught by experience alone. This branch of analysis is surely better left to the special technical treatise. As to the methods and exercises properly included in a college course, the selection in the present volume is satisfactory.It is to be regretted that the use of standard thiocyanate is omitted, and that no reference is made to the volumetric estimation of mixed alkali, hydroxide, and carbonate, but, on the other hand, m e is pleased to see borax brought into line with other weak alkalis. The book is reasonably free of errors and misprints, but grave exception will be taken to the explanation of bichromate oxidation by the scheme- Cr,O,---tCr,O, + 30, on p.58. In the estimation of sulphur by means of sodium peroxide, the possible injury to a platinum vessel should be indicated, and in the determination of the equivalent of magnesium by heating in air, mention ought to have been made of the formation of magnesium nitride, a point that often puzzles a thoughtful student.The weighing of a precipitate on a “tarred” filter-paper (p. 125) points to a somewhat hasty revision. Apart from these criticisms, which after all might be directed against most elementary books, this volume has the merit of brevity, and will no doubt be of use to the students for whom it is intended. G. DRUCE LANDER. SULPEURIC ACID AND ALKALI.By G. LUNGE. Vol. iii. : Ammonia Soda, Various Processes of Alkali Making and the Chlorine Industry. London : Gurney and Jackson. 1911. Price 30s. net. The analyst who may have to refer to the third volume of Dr. Lunge’s great work on alkali industries in search of detailed information respecting special analytical methods will be disappointed. For these another volume by the same author must be consulted; but the present volume contains a number of tables of specific gravities and strength of solutions, as well as sufficient analytical information338 REVIEWS for carrying out the various operations in a factory.Many tables of statistics are given which might have been useful had they been brought up to date. The produc- tion of ammonia soda, for instance, is only given to 1895, and can only possess historical interest sixteen years later.There are numerous indications throughout the book that it has neither been carefully revised nor brought up to date since the issue of the second edition in 1896. As the author remarks, even the description of many antiquated or impracticable processes may be of occasional use to the professional reader ; but still those who refer to a work by a technical expert expect up-to-date information as to the actual working of factories and a little more guidance than a mere enumeration of processes because they have been patented.The reader who is not already an expert will have difficulty in ascertaining what the best practice is at the present time in factories producing the materials referred to in the work.For instance, Schlcesing’s ammonia soda process of 1889 is called new, and the same term is applied to a patent taken out in 1893 and long since expired. The bulk of the volume might, with advantage to the reader, be reduced by at least one-third, and it is to be hoped that in any future edition the editing will be more carefully done and the matter brought up-to-date.Errors are very numerous, and in some cases misleading. We are told, for instance, that the American short ton is 1,000 pounds, and in a description of apparatus on p. 121, a drum is substituted for a chain. The 184 illustrations are clear and well executed, but many of them are mainly of antiquarian interest to the chemical technologist of to-day.Even the reprint of a German title contains two errors in one line. WALTER F. REID. NITROCELLULOSE INDUSTRY. By E. C. WORDEN. 2 vols. London : Constable and It is impossible, in the course of a short review, to do anything approaching justice to the results of the author’s industry. The text runs to over 1,000 pages, the references total nearly 18,000, some 500 different journals have been consulted, and the patent specification references are international, and are inclusive of Japan and Mexico.The reviewer has been particularly struck with the reliable and up-to-date nature of the information in those sections of the book which deal with gun-cotton and propellants. The analyst will find many subjects very fully dealt with. Fuse1 oil and amyl acetate are treated at considerable length from the manufacturing point of view, and the analysis of amyl acetate, crude fuse1 oil, and purified amyl alcohol are dealt with very adequately.The section on camphor, artificial camphor and camphor substitutes, is a very important one. Very full details are given of the methods adopted for the analysis of lacquers, celluloid, photographic films, and pharmaceutical collodion. The article on artificial filaments is especially worthy of note, as it deals with the subject; in a most interesting manner. Thirty pages are devoted to the United States regulations for denatured alcohol. The book, as a whole, claims the highest commendations, and it can certainly be consulted with very great profit by everyone who has to deal with nitrocellulose, either in its wide ramifications in the arts, or in its use in explosives. Go., Ltd. 1911. London. Price 42s. net. The compilation of this book has been a work of very great magnitude. GEORGE W. MACDONALD.

ISSN:0003-2654    

DOI:10.1039/AN9123700335

出版商:RSC    

年代:1912

数据来源: RSC