摘要:

JULY, 1906. Vol. XXXI., No. 364. THE ANALYST. A NEW METHOD OF ESTIMATING MOISTURE, WITH SPECIAL APPLICATION TO MOISTURE IN CORDITE AND OTHER SUBSTANCES CONTAINING VOLATILE MATTERS OTHER THAN WATER. BY P. V. DUPRE. (Read at the Meeting, A p d 4, 1906.) IN a paper on ammonium oxalate, which I had the honour to read before this Society in June last, a method of estimating moisture by means of calcium carbide was mentioned, and it was stated that experiments were in progress to apply the method more or less generally. These experiments having been now completed, I beg to lay the results before this Society. With this object animonium oxalate was chosen, as affording the most convenient and A series of experiments was first undertaken to standardize the process,THE ANALYST. 214 accurate method of weighing out a definite quantity of water, since the proportion it contains is accurately known (12.67 per cent.), and there is no tendency to loss by evaporation during weighing.Various weights of the salt, from 0.25 to 0.56 gram, equivalent to 0.03 to 0.07 gram of water, were taken, the quantity being weighed out in a tube of about 1 em. diameter and about 12 ems. long; the salt was then covered with a thin layer of sand,* and calcium carbide filled in to a depth of about 5 cms. The tube was then connected with a nitrometer containing a saturated solution of common salt, and the apparatus adjusted to zero with the tube brought to a known temperature by immersion in water. The tube was then immersed in a water-bath at a temperature of 100" C, to a depth of 7 or 8 cms., and the heating continued until no further evolution of gas could be observed.The tube was then brought back to the original temperature and the volume of acetylene measured, the temperature and pressure being noted. As the mean of ten experiments, in the last three of which the water was weighed out direct, it was found that 1 C.C. of acetylene at N.T.P. was equivalent to 0.001725 gram of water. The theoretical number would be 0.00162, but at the temperature of boiling water the hydrate of lime formed retains a small pro- portion of water above the one molecule. As, however, the amount of hydrate of lime formed is always proportional to the amount of acetylene evolved, the relation between the amount of acetylene produced and the excess of water retained is always the same.The following table gives the results obtained; it will be seen that the variations are small, and that the process is therefore of adequate accuracy : Weight of Amount of Oxygen taken. 0.2430 gram 0.3003 ,, 0.3160 ), 0,3235 ,, 0.4890 ,, 0.5020 ,, 0,5565 ,, Weight of Water. 0*0308 0.0380 0.0401 0.0410 0.0620 0,0636 0.0705 0.0651 0,0298 0-0627 - Amount found. I Error. I 0.0311 0-0378 0.0400 0.0413 0.0619 0.0634 0.0703 0.0649 0.0301 0.0625 + 0*0003 - 0.0002 - 0.0001 + 0*0003 - 0-0002 - 0.0002 - 0*0002 - 0.0002 + 0-0003 + 0.0002 The moisture in cordite was then estimated in exactly the same way, cordite, ground as for analysis, being substituted for the oxalate, and from 1 to 2.5 grams being taken. The total volatile matter in each sample was estimated at the same time by the official method.cause loss of acetylene a t ordinary temperatures. See paper on ammonium oxalate. The following are the results : * The sand is used to prevent contact betneen the oxalate and the calcium carbide, which mightTHE ANALYST. - _- \-.- 215 I - Nature of Sample. Cordite M.D. ... ... Cordite M.D.. ... Cordite returned from India First sample after softening with acetone for grinding.. . Cordite hlk. 1, recent, size 20 Cordite Mk. 1, size 20, old ... Cordita M.D., recent ... Cordite M.D., old ... ... .. ... Total Volatile Matter. Per Cent. 0.41 0.72 0.36 5.39 0.27 0.40 1-04 090 Moisture. Per Cent. 0.29 0.24 0.23 0.60 0.11 0.10 0.34 0.44 Acetone. Per Cent. 0.12 0.48 0.13 4.79 0.16 0.30 0.70 0.36 In order to test the accuracy of these results the following experiments were made : ( a ) Two samples were examined, each in duplicate, in order to see whether the results were concordant.( b ) A sample was taken and the moisture estimated as before ; the experiment was then repeated with another portion, to which a drop of acetone had been added after weighing, to find out the effect, if any, of the presence of this body. (c) A portion, previously dried, was weighed, exposed to moist air and again weighed, and the moisture so absorbed estimated as before. The results were as follows : Sample I. Sample 11. ... ... 0.148 per cent. ... ... ... 0.146 ,, First experiment Second experiment 0.114 per cent. 0.118 ,, Sample 111. Direct ... ... ... 0.416 per cent.+ acetone ... ... 0.419 ,, Sample IV. Water absorbed Water found . . . . ... 0.344 , j ... 0.345 per cent. - The method has also been applied to other substances, and found very useful in the case of a, mixture containing a volatile constituent, such as naphthalene or camphor.216 THE ANALYST. For instance, about 0.25 gram of naphthalene was taken and 0.0255 gram of water added ; the moisture estimated by the above method came to 0.026 gram. Again, in an explosive containing such ingredients as ammonium oxalate or magnesium sulphate, the total moisture can be rapidly estimated by this method, whereas it takes a long time-several days in many cases-for these salts to lose all their water of crystallization in 'uacuo, especially in such explosives as gelignite.The water present as moisture can readily be calculated when the proportion of the salt has been estimated. Experiments are now in progress to find out whether the method can be applied to volatile liquids, 0 10 20 30 40 50 60 70 80 90 100 110 120 TIME IN NIIINUTES. Experiments made in yet another direction with the view of distinguishing, if possible, between water not in combination and combined water have yielded results which may prove to have some useful application. These experiments were carried out exactly as described in the paper on ammonium oxalate, except that the salt was taken in a moist condition, a known weight of water having been added, and the curve, representing the rate of loss of water at constant temperature, obtained. The results show that the proportion of uncombined water can be separated very approximately from the combined water by means of a sharp change in the steep- ness of the curve, which occurs directlyall the uncombined water has been driven off.I t might be thought a t first sight that a salt when so heated would lose added water only until all this had been driven off, and that it would only then begin to lose combined water. From the few experiments made, however, this does not appear to be the case ; but, on the contrary, combined water commences to be lost at once, theTHE ANALYST. 217 loss continuing during the whole period taken for the uncombined water to the driven off. Also, this loss appears to take place at an average rate, during this period, of one-half the rate of loss of crystalline water after all uncombined water has gone.The chart on p. 216 gives the results obtained. The black lines represent the observed volumes of acetylene, the observations being taken every five minutes and each marked by a circle. The dotted lines represent the heights at which the breaks the curves should, theoretically, have occurred, calculated from the amounts of uncombined water taken and allowing for temperature and pressure, and also making the allowance above stated for the loss of crystalline water. The rate of loss taken is one-half that indicated by the curve after the break. Weight of Uncombined Weight calculated Water taken. from Curves. 0.0080 ,, 11. 0.0825 ... ... ... ... ... 0.0323 ,, 111. 0.0275 ... ... ... ... ... 0.0274 ,, IV.0.0325 ... ..I ... ... ..* 0.0325 CURVE I. 04080 ... ... ... . * r ... DISCUSSION. THE PRESIDENT (Mr. Bevan) having invited discussion, Mr. GUTTMANN said that the differentiation of the various volatile matters in cordite was not so unimportant as might at first be thought. Having regard to the important r6le that any volatilizable matter in a powder must play as far as ballistic results were concerned, it would be easily realized what an enormous digerence there was between water and acetone. When it was remembered that 4 per cent. of moisture might make an explosive absolutely unexplodable, while with & per cent. it might still be explosive, and having regard to the narrow margin allowed by official specifications and shooting tests, the great influence of even a per cent.of moisture would be readily understood. He remembered a paper by Mr. A. Marshall in the Journal of the Society of Chemical Industry, in which special means were described for condensing the nitro-glycerin, which would also be evaporated in the process. Mr. Dupri! had not alluded to this, but presumably, at the temperature to which the cordite was heated, a good deal of nitro-glycerin would come off, and one wondered what happened to it. If so, these results would need bringing into order by some further work, and if Mr. DuprA could succeed in differentiating between the nitro-glycerin and the acetone-either by applying Mr. Marshall’s process or in some other way-he would make his method complete. Mr. A. MARSHALL said that the first attempt to find a satisfactory method of determining the total volatile matter in cordite was made by a cousin of Mr.Dupr6 at Waltham Abbey. The details of the method were not altogether satisfactory, but further experiments which he (Mr. Marshall) had carried out at Waltham Abbey had resulted in its improvement. The method brought forward by Mr. Dupr6 advanced the question a stage further, as it enabled one to distinguish the water from the acetone or other volatile solvent used in manufacturing. Mr. DuprA’s results brought out the interesting point that in cordite of uniform composition the amount of water was almost constant. Dr. Robertson, at Waltham Abbey, had by an entirely different method obtained similar results. The question arose whether that was really the Was it included with the acetone?218 THE ANALYST, proportion of water in the cordite as used for firing, or whether it might not depend upon loss or gain of moisture from the atmosphere during the necessary process of grinding the cordite to powder.He had found that ground dried cordite exposed to the air absorbed just about the same amount of moisture in a few minutes, and as the preparation of the sample took at least several minutes, he thought that the constancy of the moisture might perhaps be accounted for in that way. Mr. DUPRE, in reply, said that no doubt a certain amount of nitro-glycerin was volatilized; but he had heated some carefully-dried cordite in the apparatus for ten or fifteen minutes without the evolution of any measurable amount of gas, and he had therefore concluded that whatever nitro-glycerin might be driven off was not decomposed in its passage through the carbide, but was condensed again probably at some part of the tube between the cordite and the nitrometer, and did not affect the volume of gas in the latter. The acetone distilled off would also be condensed, and a small allowance was made for it in the vapour tension. He might say that the method he had used was not intended in the least to supersede the official method of estimating the volatile matter, but it had struck him that it might be useful if the moisture and acetone could be separated. I t was certainly possible that Mr. Marshall’s explanation with regard to moisture might be correct, but in that caae one would have t o assume that 0.26 per cent. was the most that the cordite would ever take up, which from some of the results quoted does not appear to be the case.

ISSN:0003-2654    

DOI:10.1039/AN906310213b

出版商:RSC    

年代:1906

数据来源: RSC

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218 THE ANALYST. THE ESTIMATION OF FAT IN HOMOGENIZED MILK. BY H. DROOP RICHMOND, F.I.C. (Read at the Meeting, &fay 2, 1906.) HOMOGENIZED milk, or milk in which the fat is broken up into very small globules, not usually exceeding 0.001 mm. in diameter, is now an article of commerce, It is obtained by forcing milk under a pressure of from 200 to 400 atmospheres through very small openings ; there are several machines made for this purpose, differing from each other chiefly in the method of formation of the small openings. The cream in homogenized milk no longer rises freely, but remains to a, very great extent distributed throughout the whole volume. The process is chiefly applied to sterilized milk, which is often required to stand for a, long time before being used, and from which it is an undesirable thing for the cream to separate ; but milk which has t o stand--e.g., on refreshment-bar counters- is also sometimes homogenized.I t is therefore quite possible that some of the samples of milk taken under the Sale of Food and Drugs Act may be homogenized. As it appeared more than probable that the estimation of fat, especially by dry extraction processes, would be rendered more difficult by the fine state of division of the fat, I have made a few comparative experiments by different methods. The methods chosen were those in common use by public analysts, together with the Kieselguhr method. I n the Gottlieb and Werner-Schmid methods theTHE ANALYST. 219 original plan of taking an aliquot portion was not followed, but the whole of the fat was dissolved out by repeated extraction.The Adams method was carried out by extracting a blank coil into a flask tared against the flask in which the fat was weighed. I n the other methods the flask was, after weighing, washed out with petroleum ether, and weighed again with any residue of substance not soluble in petroleum ether. Very slight residues were almost always obtained, but so small, if due cire had been employed, that the percentage of fat was barely affected. The following are the results : Gottlieb. Kieselguhr. Werner- Schmid. Adams . Gerber. 3-79 3 -80 3.81 3-58 3-78 3.70 3.70 3.74 3.52 3.70 3.66 3-66 3.67 3-53 3-70 3-46 3.46 3.45 3.32 3-47 3.86 3.87 3 -88 3.66 3.89 3-93 3.94 3.98 3.81 3-95 It is seen that though the Werner-Schmid method has a tendency to be a trifle higher than the others, the first three methods are in almost perfect agreement, while the Adams method is always low.The Gerber method also gives good results with homogenized milk. Microscopic examination shows that the fibres of the paper used for the Adams coils are very many times larger than the fat globules, while the diatoms of Kieselguhr have openings which are much smaller. Though the Adams coil provides sufficient surface to insure that the thickness of the film of milk solids is of the some order as the size of the fat globules in ordinary milk, and thereby exposes them to the solvent action of ether, it fails to do so when homogenized milk is extracted. The film is of sufficient thickness for some of the fat globules in homogenized milk to be completely surrounded with a layer of solids insoluble in ether. With kieselguhr there is a much larger surface, and the layer of milk solids is not thick enough to completely surround the globules. The advent of homogenized milk renders it necessary to remove the Adams method from the position it has so long occupied as a standard method. I n my laboratory it has for some time been discarded in favour of the Gottlieb method, which for ease and accuracy appears to be the best method we have, and I have little doubt that it will be in the future almost universally used.

ISSN:0003-2654    

DOI:10.1039/AN9063100218

出版商:RSC    

年代:1906

数据来源: RSC

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THE ANALYST. 219 THE ANALYSIS OF DRIED MILK. BY H. DROOP RICHMOND, F.I.C. (Read at the Meeting, May 2, 1906.) MILK which has been evaporated to dryness is sold as dried milk or milk-powder, The methods of drying milk vary. The milk in one process is passed over polished steel rollers heated to a temperature above that of boiling water, and the film frOm which most of the water has been evaporated is taken off by knives set in a suitable position ; in another process the milk is condensed in a vacuum pan to one-third or220 THE ANALYST. ' 4-92 27.98 34-16 1-25 24.59 6.24 one-fourth of its bulk, and is then dried in a vacuum chamber in thin layers ; in a third process the milk is, after a preliminary concentration, dried on hot rollers ih vacuo ; and there are other methods which have not come into extensive use.The analysis of these milks requires a few slight modifications of the methods used for ordinary milk. The sample should be ground and well mixed to secure uniformity. Fat cannot be estimated by direct extraction, as the results are always low. The Werner-Schmid method is suitable. If there is no sugar except milk-sugar, the fat, after drying, should be dissolved in petroleum ether, and any residue weighed and subtracted from the total weight. In the presence of much of any other sugar, it is preferable to mix the ethereal solution with an equal bulk of petroleum ether, and shake out with water rendered slightly alkaline with ammonia before the solution is evaporated. fVdk-sugar may be easily and quickly estimated polarimetrically ; 10 grams of milk-powder are ground up in a mortar with sufficient hot water to make it into a paste, which is gradually thinned with hot water, and the solution made up to 100 c.c.; a little ammonia may be added if the milk-powder does not all go into solution.Unless this procedure is followed, incomplete extraction of the sugar may result. Ca?ze-sugar may be conveniently estimated by the method described by Harrison (ANALYST, XXX., 123). Proteids are calculated from the total nitrogen by Kjeldahl's method by the factor 6.87. Ash, Linze, a d Phosphoric Acid as usual. Acidity is estimated by grinding up about 1 to 2 grams with hot water, and The table below gives the analysis of seven samples : Noistwre is estimated by drying about 1 gram in the water-bath.. The usual method is then followed.titrating with & alkali, using phenolphthalein as indicator. Moisture . . . ... ... Fat ... ... ... .. . Milk-sugar , . . ... ... Cane-sugar . . . ... ... Proteids ... ... ... Ash ... . m , ... ... TABLE ~.--COMFOSITION OF DRIED MILK. 6-39 27.35 31.42 27-48 6.00 - _ _ - Water of hydration ... Total ... ... Change of temperature on - - 1.65 100-29 ~ ~~ ____ ____. _ _ .___ __I_ . -__ Total ... ...I 98.64 1 99.14 1-80 100.94 - 3 ._ - - 3.30 23.97 37-32 1.53 26.38 6-19 98.69 1-96 100.65 - 0.2" ~- ~ - ~_ .- - 4 .__ 3-55 2.55 45-60 2-80 35-45 7-89 97-84 -__ 2-40 100.24 - 0.4" 5 4.74 29.16 32.24 26-66 5.63 - 98-43 1-70 100.13 5-15 6-03 19-90 1 25.60 34.96 , 32-83 - ' 2.00 31.10 ' 23-84 7-11 6.44 - 98.22 96-74 1.84 ' 1.73 100*06 98-47 ~- - -THE ANALYST, 221 I t is noticed that none of the analyses add up to 100 per cent., but are con- siderably low ; the milk-sugar has been calculated as anhydrous sugar, and here, I think, is the reason for the deficiency.On shaking the solid residue obtained by drying milk on the water-bath, in which the milk-sugar certainly exists as anhydrous sugar, with water a rise of temperature always takes place ; anhydrous milk-sugar mixed with water always causes a rise of temperature, whilst hydrated milk-sugar causes a fall of 0.55" if more than can be at once dissolved is added. The milk-powders examined, with one exception (No. a), all caused a fall of temperature, and it is seen that the addition of the water of hydration to the total gives figures which are but slightly in excess of 100 per cent.; both the change of temperature and the slight excess over 100 per cent.indicate that the bulk of the milk-sugar, though not all, exists as hydrated sugar. Sample No. 2 differed in appearance from the others, being a heavy powder, instead of being light and flaky, and had doubtless been more dried, and probably contains a considerable proportion of anhydrous sugar ; it is noticed that the addition of the water of hydration would make the total nearly 101 per cent. Sample No. 7 gives a low total, which I believe is accounted for by the presence of invert sugar. I t will be noticed that samples 2, 3, 4 and 7 contain small quantities of cane- sugar; this in sample 2 was admittedly added in the form of saccharate of lime, and was certainly so added, judging from the analytical figures, in No.7. This is used to render the dried milk more soluble, and additions of sodium phosphate and other alkaline substances are made with the same object. I n Table 11. the composition of the original milks, on the assumption that they contain 9.0 per cent. of solids-not-fat, are given. TABLE II.-~OMPOSITION O F ORIGINAL JfILKS. ~ F a t ... ... ... ... Milk-sugar . . . ... ... Proteids . . Q ... ... Ash ... ... ... ... CaO ... ... ... ... P,?,. . . ... ... ... Acidity . .: ... ... 1 3.79 4-36 3.81 0.83 0.19 0.23 8 . 4 O 2 3.88 4.73 3.41 0.87 0.21 0-24 13-2" 3 3-09 4.81 3-40 0.80 0.17 0-23 16.8" 4 0.26 4.62 3.58 0.80 0.17 0.23 16.5" 5 4.07 4-50 3-71 0.79 0.17 0.23 19.6" 6 2-45 4.30 3.82 0.87 0.19 0.29 - 7 3.65 4.68 3.40 0-92 0-27 0.24 11.4" From this table it is seen that No.4 is made from separated milk, and No. 6 from milk deprived of a portion of its cream. The milk used to prepare No. 3 is only just above the Government standard. The normal percentages of lime and phosphoric anhydride in milk are 0.11 per cent. and 0.23 per cent. respectively, but vary some- vhat with the proteids, and the normal acidity is not far from 20". From a con- sideration of the results, it would appear that Nos. 2 and 7 have received an addition of saccharate of lime; and No. 6 has received an addition of a phosphate. Nos. 3 and 4 contain cane-sugar, but there is no evidence of the addition of saccharate of222 THE ANALYST. lime. No. 1 has probably received an addition of sodium carbonate, as the lime is not high enough, considering the high proteids, to indicate an addition of this substance; and No.5 appears to have received no addition whatever. DISCUSSION. The PRESIDENT (Mr. Bevan), in inviting discussion, said that he could not quite understand how it was that, in the case of homogenized milk, the Adams process gave low results as compared with the Werner-Schmid and other methods. He should have thought that the breaking-up of the fat globules would have caused them to be more readily soluble. He should be interested to hear by what process the samples of dried milk referred to were made. Mr. W. PARTRIDGE asked whether any unusual difficulty had been found in extracting the fat with ether in the case of homogenized milk.He had had occasion to examine some samples of condensed homogenized milk in which the degree of homogenization was stated to be very high, and, using the Werner-Schmid process, his results were similar to those of a Norwegian analyst who had examined the same milks; but a London analyst who had also examined them, by Bell's process, had obtained results which were regularly 1 per cent. lower. Mr. HEHNER said that he had made some time ago a few comparative experi- ments with regard to fat extraction in the case of dried milk prepared by the Natmaker process, and had found in every case that a larger proportion of fat was obtained by extracting the powder itself with ether than by any other means. When plaster of Paris and other like materials were used lower results were invariably obtained.I n the Hatmaker process, as in all others, alkali was added in the form of sodium carbonate, which would account for the somewhat high ash. He wondered why Mr. Richmond was so anxious that his analyses should add up to 100, seeing that there must necessarily be a number of undetermined constituents-for instance, there would be about & per cent. of citric acid in the milk, which, of course, would represent about qV per cent. in the dried product. He thought that the reason why, in the case of homogenized milk, the fat was not well extracted from paper was not quite satisfactorily explained by the photographs shown. When milk was mixed with an absorbent it evaporated, and the.fat remained more or less adhering to the surface presented to it.I t could not surely make much difference whether the absorbent was in small or large particles. The question must be whether the surface on which the fat was, so to speak, plastered was large enough to subdivide it completely, and he could not see why the surface presented by one material should be less favourable than that presented by another. Mr. M. WYXTER BLYTH said that, from some experiments which he had made with certain foods for infants, he could confirm what Mr. Richmond had said as to the difficulty of extracting the whole of the fat by the Adams process. I n one case he could only extract about 2 per cent. of fat, whereas a modification of the Werrrer- Schmid method, which he had used on Mr. Richmond's suggestion, yielded 8.24 per cent.of fat. The low results given by the Adams process in such cases were explicable by the fact that, especially with malted foods, a dry mass of sugar wasTHE ANALYST. 223 obtained which was very diflficult to deal with. I n the case, however, of milk in which the fat globules had been broken up, he quite agreed with Mr. Rehner that the reason why the fat could not all be got out was difficult to understand. Dr. LEATHER inquired how long the extraction with ether was carried on. Mr. E. R. BOLTON asked whether the fat extraction was carried out in a Soxhlet apparatus or in one of those extractors in which the solvent dripped down and trickled straight through. He had found that in the case of oil-cakes all the fat was extracted much more quickly in such an extractor than in the Soxhlet apparatus.MY. WYNTER BLYTH said that in his case an ordinary Soxhlet apparatus was used, and the extraction carried on for five hours. Mr. RICHMOND, in reply, said that the milk-powders referred to were obtained by the various processes described in the paper, but he did not know in all cases which process had been used. Some of the samples were very finely ground, and had been dried to a greater extent, and probably contained a larger amount of anhydrous milk- sugar. I t seemed to him that the photographs went a long way towards explaining the lowness of the Adams results. It must be borne in mind that the photographs (not reproduced) were on different scales. Had they been on the same scale the enormous difference in the total surfaces exposed to the milk would have been more apparent.I n the case of kieselguhr the layer was of the same order of thickness as the fat globules, and consequently they were all exposed to the action of the ether. Probably, also, the grinding-up of the milk and kieselguhr had some effect. In the determinations by the Adams method extraction was carried on for at least five hours in a Soxhlet apparatus. I n some cases extraction was carried on for so long as sixteen hours, but the full proportion of fat was still not obtained. He had not found any difficulty with the Werner-Schmid process. He never made more than four extractions, and at the fourth there was generally practically no fat left to take out. He had compared various methods of extracting, and had found four extractions at the outside to be sufficient.This applied also to homogenized condensed milk. Mr. PARTRIDGE asked how much ether Mr. Richmond used for each extraction. He himself used about 15 or 20 C.C. Mr. RICHMOND said that he used perhaps a little more, but not very much. In the case of homogenized milk he thought that the Gottlieb method had advantages over the Werner-Schmid. I t took much less trouble, and the fat came out more cleanly and easily. With regard to the addition of alkali, he thought that sodium phosphate was used quite as often as sodium carbonate. Mr. HEHNER said that he had been consulted as regards the manufacture of dried milk both on the Continent and in America, and had never known any alkali but sodium carbonate. to be used.Mr. RICHMOND said that he knew that sodium phosphate had been used in England. With regard to the milk-sugar, having obtained distinct evidence from the change in temperature on mixing with water that there was some water of hydration, he thought it only right to include this. He did not, of course, suggest that these analyses ought necessarily to add up exactly to 100. As Mr. Hehner had mentioned, there was citric acid present, which, however, was partly compen-224 THE ANALYST. sated for by the fact that a portion of the phosphoric acid was included both in the casein and in the ash. Analyses of dried milk should, however, not be 14 to 24 per cent. low. Mr. FAIRLEY asked what, if the Adams process failed when the milk was spread over a oertain surface, was to prevent its being spread over a larger surface by dilution if necessary, and whether, in the Werner-Schmid determinations, any attempt had been made to find out whether any fixed residue was contained in the fat, because, after all, these discrepancies were minute, and a very small amount of impalpable mineral matter in the fat might make all the difference. Mr. RICHMOND said that there was really nothing to prevent the milk being spread over a larger surface. The fat in the Werner-Schmid determinations was tested to see if it contained anything insoluble in petroleum ether, but was not ignited to see if there was any non-volatile matter. Note.-In the Journal of Analytical Chemistry, vol. iv., part i., I stated : t 6 From the data given by Adams (ANALYST, x., 46), I calculate that on paper the thickness of the film of milk solids is less than 0.0002 inch, and from my own measurements af kieselguhr, I conclude that the film dried up on this medium is about 0.0000005 inch. . . ."I % @ % @ % H. D. R.

ISSN:0003-2654    

DOI:10.1039/AN9063100219

出版商:RSC    

年代:1906

数据来源: RSC

摘要:

224 THE ANALYST. NOTE ON A RECENT PAPER BY R. STEINEGGER ON THE “ALDEHYDE FIGURE” OF MILK. BY H. DROOP RICHMOND, F.I.C., AND E. H. MILLER. (Read at the Neetivzg, May 2, 1906.) WE have been induced to refer to this paper by the fact that the method (ANALYST, xxxi., 46) proposed is likely to be of considerable use. The author first shows that formalin. added to milk hinders and finally prevents curdling by rennet. Next he discusses the increase of acidity on the addition of formalin pointed out by Hanne and Hesse, and shows that the acidity increases with the amount of formalin used and attains a maximum when about 5 per cent. (at least 1.8 per cent. of formaldehyde) is added, whether the addition is made all at once or in successive amounts. He then gives the variations in the milk of singZe cows, and it is not pointed out in the abstract that $he maxima and minima given are in the milk of single cows.Next he shows that the increase of acidity is not due to the action of a ferment causing oxidation to formic acid, as had been suggested by Hesse, and that it remains constant whether rennet is added to the milk or not. I n addition to giving figures that show that the aldehyde figure is proportional to the total nitrogen in the milk, and that the total nitrogen (and therefore the percentage of proteids) can be calculated from the aldehyde figure, he gives some experiments with tyrosine and leucine, which show that the acidity is produced by the conversion of the amino groups into methylene-amino groups by condensation, with the consequent conversion of the amphoteric nature of the amino-acid into an acid one.THE ANALYST.225 We think this paper important because- 1. The method appears to give an approximate estimation of the amino-nitrogen 2. I t gives an indirect but very easy method for proteid estimation. 3. It adds another figure to those which can be easily determined in milk analysis, and thus will yield corroborative evidence. Our first experiments were made with a view to see if we could obtain definite evidence of the combination with the amino-groups, and experimented with whey produced by the action of rennet and acid respectively. of the proteids. Our results were : Treated with Benzene- Diazotized and combined diazonium Chloride. with @-naphthol. Acid whey ... . . . Dark red colour Bright yellow precipitate Acid whey + CH20 " .. . Dark yellow colour No reaction Rennet whey ... ... Bright red colour Light yellow colour Rennet whey+CH,O ... Light yellow colour No reaction I n each case the wheys effervesced in the cold on treatment with nitrous acid, whilst after treatment with formaldehyde there was no gas given off in the cold. The amount of gas given off from the rennet whey corresponded to 0.013 per cent. of amino-nitrogen, while the increase of acidity corresponded to about 0.01 per cent. of amino-nitrogen on the assumption that each molecule of NH, corresponded to one equivalent of acidity. These results show the presence of both aromatic and fatty amino groups in milk which condense with formaldehyde. We next experimented on a casein solution containing 0.2596 gram nitrogen by Kjeldahl per 100 C.C.; this gave an aldehyde figure of 9.8 C.C. Tc soda per 100 c.c., and combined with 0.0394 gram CH,O per 100 c.c., which ie equivalent to 13.2 C.C. & alkali. Ten C.C. of this solution gave 0*1601 gram casein by precipitation with acetic acid, and 0.1608 gram after the addition of formaldehyde. These results show that the aldehyde figure " is not a complete measure of the amino-groups nor of the formaldehyde condensed. Proteids certainly contain both amino and carboxyl groups, and when alkali is added (e.g., soda) the following reaction takes place : RCOOH+NaoH NH2 * RCOONa NH2 +OH,. The point of neutrality to phenolphthalein is, on account of the presence of the basic NH, group, much nearer to the acid than to the sodium salt, The action of formaldehyde is probably- RCO&+CHOH N H + RZG;$,+OH,.and the reaction in the presence of a large excess of formaldehyde is probably complete and very rapid. The methylene-amino acid reacts with alkali thus :226 THE ANALYST, and the point of neutrality is probably very close to the salt on account of the feeble basicity of the inethylene - amino group. The “ aldehyde figure ’) measures the difference between the points of neutrality of the two reversible reactions (1) and (3). It is figure.’’ soda and The therefore by no means certain that all alkalies will give the same t L aldehyde We have measured in four samples of milk the aldehyde figure’’ with strontia respectively. The results are expressed as C.C.N alkali per litre. ALDEHYDE FIGUXES WITH Soda. s tron tia. 1. 17.4 . . J ... ... 20.2 2. 20.1 ... ... ... 21.6 3. 18-8 ... 0 . . ,.. 20.2 4. 21-8 ... ... ... 22.6 strontia aldehyde figure )) is always higher than the soda figure, and the mean ratio is 1.1. We also find in mixed milk that soda gives a mean ‘‘ aldehyde figure )’ of 18.4, while strontia yields 20.2, also in the ratio of 1.1. Steinegger, who used the Soxhlet - Henkel method of determining acidity, probably used soda as his alkali. We find that with soda 1 C.C. & alkali corresponds to 0.0265 gram casein nitrogen, and 0.053 gram albumin nitrogen, Steinegger finds that on the average 1 C.C. & alkali corresponds to 0.0303 gram of the nitrogen of milk (I degree Soxhlet-Henkel= 2.5 C.C. & alkali per 100 C.C. = 0.0758 gram N per 100 c.c.), whilst, taking the mean proportion of casein to albumin to be 7 : 1, we find 0,0298 gram using soda and 0,0271 gram using strontia. As the titration is rather sharper with strontia than with soda, we prefer the use of the former solution. The mean of 113 determinations gives 19.9 C.C. N strontia per litre of milk as the mean aldehyde figure,” with 22.6 C.C. as a maximum and 18.1 C.C. as a minimum. As showing the relative constancy in milk from a herd, we give the highest figures, the lowest figures, and a mean figure. All figures were on different dates : Aldehyde Figures. Mean Solids-not-Fat. Highest herd ... ... 21.0, 22.0, 22.0, 22.6 9-16 Mean herd ..- ... 19.6, 20.2, 19-6, 19.6, 19.6 8.97 Lowest herd ... ... 18.1, 18.6, 18.1 8.61 We have also made a number of experiments on the change in the aldehyde figure when milk is acted on by micro-organisms, and on the amino groups in milk proteids. These will be discussed later.

ISSN:0003-2654    

DOI:10.1039/AN9063100224

出版商:RSC    

年代:1906

数据来源: RSC

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226 THE ANALYST, ANNIVERSARY DINNER OF THE SOCIETY OF PUBLIC ANALYSTS. THE anniversary dinner of the Society took place on Wednesday evening, June 13, at the Trocadero Restaurant, under the chairmanship of the President, RIr. E. J. Bevan. Among the guests present were Sir Thomas Elliott, K.C.B., Secretary of the Board of Agriculture and Fisheries ; Nr. John Lithiby, C.B., Assistant Secretary ofTHE ANALYST. 227 the Local Government Board ; Professor Percy F. Frankland, LL.D., F.R.S., Presi- dent of the Institute of Chemistry; Dr. Divers, F.R.S., President of the Society of Chemical Industry ; Mr. R. A. Robinson, President of the Pharmaceutical Society ; Mr. Montague Baird, President of the Institute of Brewing; Dr. T. Cooksey, Deputy Analyst to the Government of New South Wales; Sir William Ramsay, K.C.B., F.R.S. ; Professor J. Millar Thomson, LL.D., F.R.S. ; Professor W. A. Tilden, D.Sc., F.R.S. ; Dr. Buchanan ; Mr. F. W. Beck ; Mr. Richard B. Pilcher, Secretary of the Institute of Chemistry ; and Mr. Aubrey W. Rake. The loyal toasts having been duly honoured, the following toasts were pro- posed : ‘‘ Government Departments,” by Sir William Ramsay, responded to by Sir Thomas Elliott and Mr. Lithiby ; The Society of Public Analysts,” by Professor J. Millar Thomson, responded to by the President ; ‘( Kindred Societies,” by Mr. Bertram Blount, responded to by Professor Frankland and Dr. Divers; and ‘‘ The Guests,” by Mr. A. Gordon Sitlamon, responded to by Dr. Buchanan and Mr. R. A. Robinson. A choice selection of music, tastefully rendered by a select party of glee singers, added much to the enjoyment of the evening.

ISSN:0003-2654    

DOI:10.1039/AN9063100226

出版商:RSC    

年代:1906

数据来源: RSC

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THE ANALYST. 227 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. (Zeit. UfentZ. Chem., 1906, xii., 167, 168.)-A preparation, sold to confectioners, under the name of artificial milk, has recently been examined by the author and found to consist essentially of sesame oil, sugar, and albumin. Milk Substitute, R. Racine. The results of the analysis were : Total solids ... ... ... ... ... 85-90 per cent. Ash ... ... .., ... ... ... 0.16 ,, Oil (sesame) ... ... ... ... ... 47.10 ,, Sugar (as invert sugar) ... ... ... 34.00 ,, Albumin ... ... ... ... ... 4-51 ,, The preparation was of a syrupy consistency, and, when mixed with water in any proportion, gave milky solutions from which the oil separated very slowly. w. P. s. Adulteration of Butter with Casein.R. Racine. (Zeit. oflentl.. Chein., 1906, xii., 169-170.)-A sample of butter was found by the author to have the following composition : Fat, 69-01 per cent. ; water, 24.73 per cent. ; ash, 0.77 per cent. ; casein, 5.49 per cent. This form of adulteration is readily detected owing to the large quantity of coagulum obtained on melting the sample. It will also be seen that an excessive quantity of water was contained in this butter. w. P. s. The Detection of Bleached Flour in Wheat Flour. E. Fleurent. (Compte.9 RE~C~US, 1906, cxlii., 180 ; through Jour~z. Pharm. Chinz., 1906, xxiii., 499, 5OO.)-Thc228 THE ANALYST, only processes of bleaching flour that have an industrial value are those in which nitrogen peroxide is used as the reagent. Pure oxygen or ozone.does not affect tbe colour, and although ozonized air has a, bleaching effect, it is only when it is simul- taneously charged with nitrous products.Moreover, flours treated with ozone acquire a repulsive odour, which destroys their commercial value. The quantity of nitrous vapours in terms of nitrogen peroxide absorbed ranges from about 15 to 40 C.C. per kilogm. of flour. The nitrogen peroxide forms an addition compound with the fat, the iodine value of which is correspondingly lowered. The action of ozone, however, causes an increase in the iodine value and the formation of volatile fatty acids. The fixation of the nitrogen peroxide by the fat affords a means of differentiating bleached from normal flour. Fifty grams of the sample are extracted with petroleum spirit (benzine), the extract evaporated at a low temperature, the residue of oil dissolved in 3 C.C.of amyl alcohol, and the solution shaken with 1 C.C. of a 1 per cent. alcoholic solution of potassium hydroxide. In the case of a normal flour the resulting soap solution is of the same pale yellow colour ; but when the flour has been bleached the colour changes to reddish-orange, the depth of shade depending upon the amount of nitrogen peroxide that had been fixed by the fat. The test is capable of detecting the addition of 5 per cent. of bleached flour to ordinary flour, The bleaching process has no action upon the diastase or other enzymes of the flour, but the fat becomes acid more slowly than that which has not combined with nitrogen peroxide. I t is in this sense only that the bleaching process can be said to have any preservative action upon the flour.C. A. M. A Study of the Proteids of Beef-Flesh. P. F. Trowbridge and H. S. Grindley. (Journ. Anzer. Chem. SOC., 1906, xxviii., 469-505).-The results of their previous work (ANALYST, 1905, 89) led the authors to the conclusion that much additional information regarding the proteids of flesh could be obtained by extracting the flesh successively with cold water, with a 10 per cent. ammonium sulphate solution, and finally with & potassium hydroxide solution in the cold. An investi- gation on these lines was therefore carried out, together with a study of the acidity of the flesh, with the following results: The total acidity of aqueous extracts of flesh varies between comparatively wide limits, the minimum being 0.66 per cent., the maximum 1.07 per cent., and the average 0.85 per cent., calculated as lactic acid and expressed in terms of the fresh meat.Whilst the residues of flesh which are left after complete extraction with cold water are distinctly acid to litmus and to phenolphthalein, the insoluble proteids of flesh upon digestion with 2c hydrochloric acid, at the ordinary temperature, combine with the latter, neutralizing its acid properties. The analyses show that 13.56 per cent. of the total proteids existing in lean flesh is soluble in cold water. Of this, 90.04 per cent. is coagulable by heat from a neutral solution, 840 per cent. exists in the form of albumoses, and a very small quantity apparently as peptones.It is not at present supposed that the albumoses and peptones exist as such in the original flesh, During the coagulation of an aqueous extract of flesh there is an increase in the acidity of the same. Reduction of the acidity of the extract facilitates the coagulation of the proteids, the separationTHE ANALYST, 229 of the coagulable proteids being more complete with one-fourth neutralization (to phenolphthalein) of the acidity of the extract than it is on further neutralization. The partial neutralization of such extracts causes the precipitation of some proteid matter at the ordinary temperature. There is no well-defined temperature at which different coagula of flesh extracts separate. The complete removal of the proteid coagulating at any definite temperature requires long application of heat , and the lower the temperature at which a coagulum is separated, the longer the time required to effect the separation.Of the total proteid of a cold water extract of flesh, 11-71 per cent. is separated by neutralization, 36.65 per cent. is coagulable below 50" C., 39.99 between 51" and 75" C., and 11.71 between 76" and 85" C. The chemical composition of the different fractional coagula is remarkably constant, and, judging from the results of their hydrolysis, their chemical constitutions are quite similar. Raw flesh which has been completely freed from proteids soluble in cold water contains two classes of proteid substances-those which are soluble in 10 per cent. ammonium sulphate solution and those which are insoluble, Of the total proteids of lean flesh about 16 per cent.are insoluble in cold water, but soluble in 10 per cent. ammonium sulphate solution. The latter solution extracts from flesh at least two individual proteids or groups of proteids which differ in physical properties, and to some extent in chemical composition. The residue left after extracting raw flesh with cold water and 10 per cent. ammonium sulphate aolution is almost entirely soluble in & potassium hydroxide solution, and has the same chemical composition even when separated from the solvent by different means and purified by widely different treatment. w. P. s. The Presence of Sodium Arsenate in Preserved Meat. A. Andouard. (Journ. Pharm. Chiin., 1906, xxiii., 417,418.)--Sodium nitrate has gradually replaced potassium nitrate as a means of giving to preserved pork the rosy colour of the fresh meat.In the author's opinion, it is less injurious than nitre, but he considers that the use of any alkaline nitrate for such purposes should be prohibited, both on account of their active medicinal properties and of the risk of poisoning from the use of impure salts. Several 'instances of such poisoning have come under his notice, and in three cases the supposed sodium nitrates used for colouring the flesh were found to contain sodium arsenate. C. A. M. Determination of Fat Oin Cocoa. A. Kirschner. (Zeit. Untersuch. Nnhr. Genussm., 1906, vol. 11, pp. 450, 451.)-The following manner of applying the Gottlieb process (ANALYST, 1898, 259) to the determination of fat in cocoa is described : A weighed quantity of about 1.5 grams of the cocoa and SO C.C.of alcohol (50 per cent. by volume) are shaken together in a graduated cylinder. The latter should have a capacity of 75 or 100 c.c., be divided into divisions of 0.5 c.c., and be of such a diameter that the height between the 0 and 75 C.C. marks is not less than 30 cm. ; 25 C.C. of ether are then introduced, and the mixture shaken for fifteen minutes, when 95 C.C. of petroleum spirit are added and mixed by carefully inverting the cylinder230 THE ANALYST. a few times. The cylinder is now set aside for one hour to allow the solvent to separate, 45 C.C. of the ethereal layer being then withdrawn, evaporated, and the residue of fat weighed. As the presence of the cocoa prevents the total volume of the solvent being read off, a blank experiment is made, in which the above-mentioned quantities are used, but the cocoa omitted, and the volume thus ascertained.To the total volume found in this manner is added the weight of fat obtained, 1 C.C. being added for each gram. The amount of fat in the cocoa is then found by a simple calculation. From the results given the process Care must be taken not to form an emulsion. appears to be trustworthy. w. P. s. The Determination of Foreign Substances in Cocoa and Chocolate. F. Bordas and Touplain. (Comptes Reizdus, 1906, xlii., 794 ; through Journ. Pharvz. Chirn., 1906, xxiii., 502, 503.)-Foreign substances are usually searched for with the microscope in the insoluble residue left after extraction of the fat with ether and of the sugar with water.To simplify the process, the authors have devised a mechanical method of separating the different substances by treating the residue successively with mixtures of carbon tetrachloride and petroleum spirit (benzine), ranging in specific gravity from 1,340 to 1.600. Preliminary experiments have shown that the different substances that may be in the insoluble residue behave as follows on treatment with the different mixtures : Specific Gravity. Insoluble Residue of- 1.340 ... ... Arachis cake 1.435 ... ... 9 , 1.400 ... ... Cocoa germs 1.440 9 , 1.440 ... ... Pure cocoa 1.500 ... ... 1.500 ... ... HUE& 1.530 ... ... 1.510 ... ... Piiato starch 1.525 ... ... $ 9 1.600 ... ... Mineral matter ... ... Be haviour .... ".. Sinks ... ... Floats ... ... Sink ... ... Float ... ... Sinks ... ... Floats ... ... Sink ... ... Float ... Sinks ... ... Floats ... ... Sinks ... C. A. M. A Reaction of Theobromine. G. Gerard. (Journ. Pharrn. Chim., 1906, xxiii., 476, 477.)-A small quantity (0.05 gram) of the alkaloid is mixed with 3 C.C. of water and 6 c.c: of sodium hydroxide solution (Zessive des savomiers), and the tube allowed to stand until the liquid becomes clear, after which 1 C.C. of ammonium hydroxide and 10 C.C. of a 10 per cent. solution of silver nitrate are introduced. The mixture on shaking forms a colourless transparent mass, which becomes fluid at 60" C., and sets to a transparent jelly when cooled again. If the heating be done too rapidly, too concentrated solutions of the alkaloid yield opaque jellies.I n the author's opinion, the reaction is probably due to the formation of a silver precipitate of theobromine in a gelatinous state similar to that of precipitated silica. Caffeine does not give the reaction. The test is very sensitive, and it is possible to obtainTHE ANALYST. 231 evident solidification with 0.01 gram of theobromine in 10 C.C. of liquid. When once formed, the jelIy can be kept for several weeks without undergoing any alteration. C. A. M. Detection of Sugar in Mace. E. Spaeth. (Zeit. Unterszcch. Nahr. Genussm., 1906, vol. 11, pp. 447-450.)-Notwithstanding the fact that mace contains naturally a small quantity of sugars (c$ ANALYST, 1905,207), the presence of added sugar may be detected by the following test, described by the author some years ago (1896) : Ten grams of the sample, previously freed from fat by means of petroleum spirit, are shaken with chloroform and allowed to settle.After decanting the greater part of the latter, the last few c.c., together with the sediment, are evaporated on the water- bath, and the residue dissolved in a little warm water. The solution is clarified by the addition of lead acetate and aluminium hydroxide (the latter alone is usually sufficient), diluted to 50 C.C. with water, filtered, and the filtrate examined by the polarimeter. When thus treated pure samples of mace yield no polarizing substances, and, consequently, the presence of added sugar is readily detected. w. P. s. The Ash of Pepper and Cinnamon. H. Luhrig and R.Thamm. (Zeit. Uizterszuh. Nahr, Genussm., 1906, xi., 129-134.)-The following results were obtained on the analysis of specimens of Malabar, Tellicherri, and Singapore peppercorns, 9 samples in all being examined. The figures represent percentages on the sand-free dry substance. The amount of sand present varied from 0.040 to 0-265 per cent, : ALKALINITY OF ASH : C . C . N ACID PER 100 GRAMS OF PEPPEK. ASH. >-- c A \ MTater- Water- Water- Water- Total. soluble. insoluble. Average ... 5.02 3-19 1.83 52.4 26.2 26-1 Lowest ... 4.67 2.46 1-49 49.1 15.7 20.5 soluble. insoluble. Total. Highest ... 5.60 3.57 3.14 54.9 28.6 38.3 Average ... 5.28 1.56 4-72 92.2 14.7 77.5 Eight samples of Ceylon cinnamon gave the following results : Highest ... 5-96 1.84 4.32 104.5 18.1 88.6 Lowest ...4.30 1-26 3.00 72.9 11.0 70.5 under : Two samples of cassia bark-a common adulterant of cinnamon-gave results a s 1. 2.36 0.90 1.46 34.5 5.95 28.6 2. 2-37 0.96 1.41 35.6 6.14 29.4 For the determination of the soluble alkalinity of the ash, the latter, after being weighed, was washed into a 100 C.C. flask with about 50 C.C. of water, boiled for ten minutes, then cooled and made up to the mark. The solution was filtered, and 50 C.C. of the filtrate boiled with the addition of an excess of $ N acid. The excess of the latter was then titrated back with t N alkali solution. The whole of the contents of the 100 C.C. flask were now brought on to the filter, washed with a large volume of boiling water, and the insoluble ash determined as usual. The samples of cinnamon contained very little sand--viz., from 0.02 to 0.08 per cent.w. P. s.232 THE ANALYST. The Detection of Soap-Wort in Mineral Waters. J. Vamvakas. (Ann. de Chim. anal., 1906, vol. 77, 161-163.)-A decoction of soap-wort root (Saponaria OficinaZis) is a common addition to mineral waters, and various preparations con- taining it are used to produce frothing when the bottle is opened. One of these, of English origin, examined by the author, was sold under the name of “Liqueur Lautain.” It was a, brown liquid with an odour of banana, an acid reaction, and a density of 1.140 at 15” C. It consisted, in the main, of an aqueous extract of soap- wort root, and contained 1.6 per cent. of sugar. When diluted with water, boiled, cooled, and treated with a few drops of Nessler’s reagent, it gave a bright yellow to deep orange-coloured precipitate, which became greenish-gray after a few hours, and finally leaden-gray.A similar reaction was obtained with decoctions of soap-wort root and with mineral waters containing it. If the liquids were boiled after the addition of the Nessler’s reagent, a gray precipitate, changing immediately to blackish- gray and greenish-gray, was formed. The addition of a few drops of nitric acid or of a concentrated solution of tartaric acid prevented the formation of aoy precipitate by the reagent. The following method of applying the test to lemonade and other mineral waters is recommended : 100 C.C. of the liquid are boiled to expel the car- bonic acid and the free ammonia in the water, diluted to the original volume again, and treated with lead subacetate.The white precipitate is filtered off, sus- pended in water, and decomposed with a current of hydrogen sulphide, abundant frothing being produced if the original liquid contained soap-wort extract. The liquid is now filtered, and the filtrate and washings boiled until quite free from hydrogen sulphide, cooled, and divided into three parts. One of these is tested with Nessler’s reagent and allowed to stand, the second boiled with the reagent, and the third tested with a few drops of 8 concentrated solution of tartaric acid in the hot as well as in the cold sdution. If the drink contained soap-wort, a yellow precipitate will be obtained in the first case, a greenish or grayish-black precipitate in the second, and no precipitate at all in the third. The reaction is not applicable to sparkling wines or to beer.C. A. M. The Acids occurring in Raspberry Juice. R. Kayser. (Zeit. ofentZ. Chem., 1906, xii., 155, 156.)-The following organic acids were detected and their quantity determined in (1) a sample of raspberry syrup, and (2) raspberry juice preserved with alcohol. The figures express grams per 100 C.C. after allowing for the amounts of sugar and alcohol respectively present : 1. 2. Tartaric acid . . . ... ... ... 0.220 0.180 Citric acid ... ... 0.756 0.655 Malic acid (by difference) . . . ... 0.220 0.300 Volatile acid (as acetic) ... ... 0.060 0.045 w. P. s. Composition of Raspberry Juice. Hefelmann, P. Mauz and F. Muller. (Zeit. offentl. Chem., 1906, xii., 141-155.)-The average results of the analyses of fifty samples of 1905 raspberry juice were found to be as follows :I 00.2F 16.9 42.0 96*9Z 96.9Z 4I.LC234 THE ANALYST, acetate (2 molecules of mercuric acetate to 1 molecule of camphene).The crystalline precipitate formed after thirty days’ contact is readily purified owing to its insolu- bility in most neutral solvents, and the camphene can then be recovered by means of hydrogen sulphide. C. A. M. The Lemon-scented Ironbark and its Essential Oil. R. T. Baker and H. G. Smith. (Pham. J O Z L ~ , 1906, vol. 76, pp. 571, 572.)-This small tree (Eucalyptus staigeriana) which is only at present found in Queensland, is a species with distinct characteristics and is not easily confounded with any other eucalyptus.The leaves examined by the authors yielded 2.484 per cent. of essential oil, having a light lemon colour and an odour of citral and geraniol. The rotation of the oil in a 100 mm. tube was - 43-1 ; the specific gravity at 16” C. was 0.8708, and the refractive index at the same temperature 14871. The approximate composition of the oil was: Limonene, 60.00; geraniol, 12.72; geranyl acetate, 8.32; citral, 16.00; undetermined, 2.96 per cent. From the physical properties of the fractions obtained on distillation, it is seen that nearly the whole of the terpene present was h v o - limonene. w. P. s. Peru Balsam Oil. Haensel. (HaenseZ’s Report, 1906 ; through Pharm. J O Z L T ~ . , 1906, V O ~ . 76, p. 642.)-Genuine balsam contains about 30 per cent. of essential oil which is dark yellow in colour, has a slight dextro rotation, and a specific gravity of 1.083 at 25’ C.The amount of cinnamein in this oil is 84.4 per cent. w. P. s. Determination of Camphor in Camphor Liniment. J. Lothian. (Pj2a?..~12. J0211”12., 1906, vol. 76, pp. 493, 494.)-Results of analyses are given showing that the camphor is completely volatilized from camphor liniment by heating a thin layer of the latter in a shallow, flat-bottomed basin for one hour on the water-bath. The size of the basin employed should be such that about 4 grams of the oil form a layer in it 1 mm. in depth. Under these conditions the olive oil itself does not gain in weight, w. P. s. On a Reaction of Morphine. C. Reichard. (Pham. Centralh., 1906, xlvii., 247 ; through Chenz.Zeit., 1906, xxx. [Rep.], 142.)-The formaldehyde reaction for morphine is usually carried out in the presence of concentrated sulphuric acid ; the author finds it better to add a trace of stannous chloride instead of the acid. As modified t h s , the reaction is a delicate test for either morphine or tin. A. G. L. A New Reaction of Morphine. D. Radulescu. (Bull. SOC. Sci. d. Buczmsci, 1905, 14, 602 ; through Pharm. Journ., 1906, vol. 76, p. 501.)-The following colour reaction is stated to be peculiar to morphine : A filtered decoction of the substance to be examined, as free as possible from colour, is treated with a crystal of sodium nitrite and sufficient acid to liberate the nitrous acid. Before effervescence has ceased an excess of potassium hydroxide solution is added. I n the presence of morphine a pale rose to ruby-red tint develops, according to the amount of morphineTHE ANALYST. 235 present. The kind of acid employed is immaterial, and any alkali may be used. The red colour is not removed by shaking with immiscible solvents nor discharged by boiling the alkaline solution, but is decomposed by strong acids. It also decom- w. P. s. poses in the presence of much alcohol. On the Precipitation and Quantitative Determination of Alkaloids by means of Solutions of Potassium Bismuth Iodide. D. Jonesen. (D. ~ I Z ~ L T T ~ Z . Ges. Ber., 1906, 130; through Chem. Zeit., 1906, xxx. [Rep.], 156.)-Thorns has shown that potassium bismuth iodide may be used, not only to detect organic bases, but also for the precipitation of certain alkaloids. The reagent is added to a sulphuric acid solution of the alkaloid, and the precipitate washed with dilute sulphuric acid. From the precipitate the alkaloid may be recovered by treatment with a mixture of sodium carbonate and hydrate (which treatment requires t o be prolonged in some cases). In this way, from 1 gram each of quinine, caffeine, and antipyrin, 0.9405, 0.9546, and 0.9273 gram respectively was recovered, showing the precipitation with the potassium bismuth iodide reagent to be fairly compIete. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9063100227

出版商:RSC    

年代:1906

数据来源: RSC

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THE ANALYST. 235 ORGANIC ANALYSIS. The Determination of Methyl Alcohol in Formalin. 0. Blank and H. Finkenbeiner. (Berichte, 1906, xxxix., 1326, 1327.)-Nethyl alcohol is an ordinary constituent of the commercial (40 per cent.) solutions of formaldehyde, an addition of IS to 18 per cent. being made to prevent the liquid becoming permanently turbid when exposed to cold. The author bases a method for its determination on the amount of oxygen consumed when a weighed quantity of bhe formalin is oxidized by means of chromic acid and sulphuric acid- H.COH + 0, = CO, + H,O CH,.OH + 3 0 = GO2 + 2H,O. Qne gram of the sample is introduced into a mixture of 50 C.C. of chromic acid solution with 20 C.C. of skrong sulphuric acid, and the whole allowed to stand for about twelve hours a t the ordinary temperature, or about one to one and a half hours if the liquid be heated cautiously, care being taken not to let it evaporate below a third of its volume.The liquid is then made up to a litre and 50 C.C. withdrawn, and, after the addition of a crystal of potassium iodide, titrated with a sodium thiosulphate solution. From the result the total amount of oxygen consumed can be calculated, and, the amount of formaldehyde in the original solution being known, the percentage of inethyl alcohol can be obtained indirectly. In a test experiment described the result obtained was identical with the amount (7.65 per cent.) of methyl alcohol added t o a 20 per cent. solution of formaldehyde. c. A!!. 31. New Method for the Determination of Acetone. S. J. M.Auld. ( J o z ~ r ? ~ . S'oc. C'lzem. I n d . , 1906, xxv., 100, 101.)-The acetone in wood spirit, crude acetone, etc., is converted into bromoforrn, the latter decomposed with alcoholic potash, and236 THE ANALYST, the residual potassium bromide titrated with silver nitrate solution, the hydrolysis being represented by the equation- 3CHBr, + 9KOH + C,H,OH = 3CO + C,H4 + 9KBr + 7H,O. A quantity of the solution containing 0.1 to 0.2 gram of acetone is pipetted into a 500 C.C. round-bottom flask, diluted with a little water, and mixed with 20 to 30 C.C. of a 10 per cent. potash solution. The flask is attached to a long reflux condenser, and is fitted with a dropping funnel containing a solution of 200 grams of Br and 250 grams of KBr per litre. This solution is allowed to flow into the mixture until it has acquired a faint yellow tinge, the flask heated on the water-bath at about 70" C.for half an hour, and more bromine solution added drop by drop until the slight coloration is permanent, any excess being removed by boiling with a little more potash. The mixture is then distilled until the distillate is free from bromoform, water being added to the contents of the flask if necessary, and the condenser rinsed with a little alcohol. Distillate and washings are mixed with 50 C.C. of alcohol and sufficient solid caustic potash to make an spproxirnately 10 per cent. solution, and the mixture heated on the water-bath under a reflux condenser until the bromoform is completely decomposed, which occupies about three-quarters of an hour.After evaporating to smaller bulk, if necessary, the liquid is cooled, neutralized with dilute nitric acid, diluted to 500 c.c., and an aliquot part titrated with TG silver nitrate, using K,CrO, as indicator ; 240 parts of bromine correspond to 58 parts of acetone. Pure bromine must be employed, as crude bromine frequently contains bromoform. W. H. S. The Determination of Acetone. A. Jolles. (Berichte, 1906, xxxix., 1306, 1307.)-The method is based upon the fact that acetone combines with sodium bisulphite (1 molecule : 1 molecule), forming the sodium salt of a sulphonic acid siailar to that obtained with furfural (ANALYST, xxxi., 116)- The standard bisulphite solution is added to the acetone solution in a quantity three or four times greater than the theoretical amount, and the excess is titrated with standard iodine solution after the mixture has been allowed to stand for not less than thirty hours.A blank determination with the sodium bisulphite solution should be made simultaneously to obtain the correction for any changes it may undergo during the experiment. C. A. M. Experiments made with Dettmarsch's Apparatus for Testing Oils. Richard Kissling. (Cherm. Zeit., 1906, xxx., 152.)-The author has made over 500 tests on the Dettmarsch apparatus (shown in the figure) for testing the lubricating power of oils. The apparatus consists essentially in two heavy fly-wheels, a and b, connected by a shaft revolving in a journal between them, to which the oil to be tested is fed from the reservoir (h, situated just under the right-hand bearing), where it is heated electrically.The fly-wheels are driven by the motor, c, and canTHE ANALYST. 23 7 be instantaneously disconnected from the latter by releasing a spring, d. The method of working is to impart a certain measured velocity to the fly-wheels, then to release the spring, and to measure the time taken for the revolution to stop entirely. From these data a “coeflicient of friction ” gives results in good agreement with is calculated. Although the apparatus often tb.e viscosity determinations and the results t obtained in practice, the author has obtained so many totally inexplicable results with it (apparently attributed by him to the presence of an imperfection in the apparatus) that he condemns it entirely. E e believes the only way to determine the lubricating power of an oil to be to test it in situ in the machine for which it is to be used.A. G. L. Preparation of Aldehyde-free Ethyl Alcohol for Oil and Fat Analyses. F. L. Dunlap. (Jozwuz. Amer. Chem, Xoc., 1906, xxviii., 395-398.)-Alcohol yielding a colourless potash solution may be obtained by adding to 1 litre in a glass- stoppered cylinder a solution of 1.5 grams of silver nitrate in 3 C.C. of water, mixing thoroughly, then pouring in slowly, and without shaking, a solution of 3 grams of potash in 10 to 15 C.C. alcohol. The finely-divided silver oxide precipitated gradually distributes itself through the alcohol, and after standing overnight completely settles, when the clear, supernatant liquid is filtered or siphoned off and distilled.W. H. S. On the ‘‘ Milkiness” of Paraffin Wax. H. Mittler and R. Lichtenstern. (Chem. Bev. Fett. ZL. Harx-I?zd., 1906, xiii., 104, 105.)-Transparent paraf5n wax fetches a higher price than ‘( milky ” wax, and the greater value of the clear products j s due to more than their better appearance. Neustadtl concluded that ‘‘ milkiness ” was caused by differences in the melting-points of the different constituents of the paraffin ; but the authors contest this, and point out that transparent paraffins with238 THE ANALYST. melting-points as far apart as 57" and 42' C. can be mixed together without rendering the product opaque, though in some instances a bluish shade may be produced. They attribute the '' milkiness " to the presence of paraffin oil, and have isolated that oil from (I milky " paraffin by extraction with a mixture of alcohol and ether, and have rendered transparent paraffins " spotted " or milky " by adding oil in the proportion of 0.5 to 3 per cent.The addition of smaller quantities up to 0.3 per cent. has little or no effect upon the transparency. C. A. M. Constants of Carnauba Wax. L. G. Radcliffe. (Joz~m. SOC. Clzem. Itzd., 1906, sxv., 158.)-The following figures have been obtained with a sample of Gear& wax : Melting-point (in capillary tube), 84" C. ; acid value, 2.9 ; acid value deter- mined by dissolving 3 grams in 120 C.C. of boiling amyl alcohol, 5 ; saponification value (5 grams dissolved in 60 C.C. amyl alcohol, and boiled for six hours with 50 C.C. alcoholic potash containing 60 grams of potash per litre), 88.3 ; ester value, 854 ; iodine value, 13.17.The bleached wax melted at 61", and had an acid value in amyl alcohol solution of 0.56. W. H. S. On the Proportions of Pentosan and Methylpentosan in Plant Products. John Sebelien. (Clzem. Zeit., 1906, xxx., 401.)-P. Sollied has continued the work done by the author and others to show that in the great majority of cases the amount of methylpentosan occurring in plants is considerably less than that of the pentosan also present. Sollied's results are given in the following table, Tollens and Ellett's method (Bey., 1905, 492) having been used : Oak-wood, fifteen-year-old tree Oak-bark, eighteen-year-old tree Cedar-wood ... ... ... Fir-wood ... ... ... ... Beech-wood ... ... ...Ash-wood ... ... ... ... Fucus vesiculosus ... ... Ditto, younger ... ... ... Ditto, younger branches ... Hay ... ... ... ... Ascophyllum nodosum ... ... Rye-bran ... ... ... ... Rape-seed cake ... ... ... Carrots (dry substance) ... ... Kohlrube (ditto) ... ... ... Oats ... ... ... ... Linseed cake ... ... ... Cotton-seed cake.. . ... ... ... ... ... ... .*. ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... Methylpentosan, Per Cent. 2.26 2.31 2.08 2.54 2 90 4.70 2.68 2-95 2.13 3.16 3.47 1.75 1.09 1.72 2.62 1.72 2.59 2.93 Pentosan, Per Cent. 19-06 18-60 14.21 12.85 12.36 10.03 23.59 17.24 17.43 6.32 8-46 20.93 12.76 6.25 9.73 6.23 8-43 6.67 A. G. L.THE ANALYST. 239 Linaloe Oil. W. Naumann. (Chemist and Druggist, 1906, lxviii., 619.)-The following results were obtained on the analysis of three samples of oil shipped direct from Mexico and guaranteed by the shippers to be pure oils : Specific gravity at 15" C.... ... Rotation in 100 mm. tube ... Refractive index at 20" C. . . . Esters ... ... ... ... Linalol ... ... ,, 195" C. ... ... 7 , ,, 200" c. ... ... ,, 205" C. ... ... ... ... Distilling beiow 190°C. . .. ... ,? ? S No. 1. 0-8785 1.4635 -8" 30' 4.3% 66% 7% 25% 45% none No. 2. 0*8800 14633 4.7% 68% none 570 350,; 40% - 1 2 O No. 3. These results are similar to those obtained by Parry and Bennett (ANALYST, 1906, 20l), and accordingly the above oils belong to the best class now obtainable. w. P. s. On the Chemical Examination of Kerosine. K. Charitschkow. (Westizik shirozo., vii., 14 ; through C'hem.Zeit., 1906, xxx. [Rep], 142.)-Dehnstedt and Geisler have recently shown the presence of neutral sulphuric esters in various petroleum oils imported at Hamburg. The author now shows that similar esters are sometimes present in Russian petroleum, the quantity varying inversely with the amount of acid used in the purification of the oil. The esters may be recognised by treating the oil with aniline, aniline sulphate being insoluble in kerosine. On burning oil containing sulphuric esters, sulphurous and sulphuric acids are formed and the lamp- wick is charred. A simple method of determining sulphur in petroleum consists in distilling it over potassium, potassium sulphide being formed and determined in the usual manner. The quantity of unsaturated hydrocarbons present in kerosine should always be determined, as they yield a flame of unpleasant colour.A. G. L. Collaborative Work on Tannin Analysis. F. H. Small. (Joumz. XOC. Clzenz. Ind., 1906, xxv., 296-298.)-The American Leather Chemists' Association have formulated the following methods for the estimation of tannin in raw materials and analysis of the tannin solutions obtained therefrom. The material is ground to a specified fineness, and the tannin extracted in a copper Soxhlet apparatus so constructed that the extractive is removed from the action of heat, as prolonged boiling of the liquor converts part of the tannin into some compound not tannin, probably gailic acid. The analysis of the tannin solution is conducted on a solution containing 0.35 to 0.45 gram of tannin per 100 C.C.The residues obtained from the evaporation of 100 C.C. each of the solution before and after filtration give the amounts of total and of soluble solids respectively. The tannin is removed from another portion of the solution by treatment with hide-powder, which is then filtered off, and the clear240 THE ANALYST+ filtrate evaporated to dryness, the residue being the soluble non-tannins. By deduct- ing these from the total soluble matter the proportion of tannin is readily obtained. The hide-powder employed is first treated with a dilute solution of chrome alum, washed free from uncombined salts, excess of water squeezed out, and the moist powder added to the tannin solution, a correction being made for the water added with the hide-powder.Dificulties have arisen owing to failure to obtain clear filtrates, and to the retention of part of the tannin by the filter-paper, but by following prescribed conditions concordant results are obtainable. To avoid decom- position during evaporation and drying of the residues, a special copper steam-bath has been devised, with a solid top on which the dishes rest, and fitted with a steam- jacketed cover provided with openings for ventilation. W. H. s. Analysis of Ebonite Articles. R. Thal. (Chewz. Zeit., 1906, XXX., 499.)-As supplied to the Russian army medical service, ebonite cases for instruments and bottles must fulfil the following requirements : The ebonite must be made from best Para rubber and sulphur.The quantity of the latter may vary from 27 to 30 per cent., but should preferably be 29 per cent. The vulcanization must be even throughout, and the ebonite must be free from surrogates. The amount of ash must not exceed 0.60 per cent. On warming the ebonite with fuming nitric acid, a clear or nearly clear solution should be obtained. The material should be black, capable of being polished, and be free from cracks, indentations, porous or coloured spots, etc. ; it must be sufficiently hard, and yet not too brittle to be worked by tools. The cases must not break or crack on allowing them to fall by their own weight when empty on to a stone floor, OF on knocking them together. The analysis of ebonite is carried out by the methods usual for rubber. Moisture may be determined by drying for two hours at 100" to 105" C.; longer drying results in oxidation of the material. For the test with fuming nitric acid, 0.5 gram of the ebonite in small pieces is gradually added to 20 C.C. of the acid, and the whole is warmed until nitrous fumes are driven off. A turbid solution indicates an amount of ash greater than 0.6 per cent. I n testing for surrogate, a correction must be made €or the weight lost by the filter-paper on treatment with 8 per cent. alcoholic caustic soda. For accurate work corrections must also be made for the amount of sulphur extracted from, and the quantity of soda, retained by, the dried residue. The author has previously found this to be 5.5 per cent. A. G. L. Grading of Glues and Gelatines. J. Alexander. (Joz~riz.Xoc. Chew. I ~ z d . , 1936, xxv., 158-161.)-The author recommends the determination of the reaction to litmus, viscosity, grease, foam, set," jelly strength, adhesive strength (under actual working conditions), and keeping properties. The viscosity is measured by noting the time of efflux at 80" C. from a 45 C.C. pipette of solutionsicontaining 25 grams of glue in 100 C.C. of water. The effluent tube is 7 cm. long, and has external and internal diameters of 9 and 6 mm. respectively, the smal1est:dianieter of the outlet being about 1.5 mm. The length of the bulb is 9.5 cm., and its outside diameter 3 em. The amount of grease is approximately proportional to the spots appearing when the glue solution is painted on white paper with a little aniline or dry colour.THE ANALYST.245. Foam is estimated comparatively by agitating with a rod or mechanical agitator, and " set " is the speed with which the jelly hardens. Jelly strength is well measured by pressure with the finger-tips; but a special instrument, more reliable than the shot test, has been devised for the purpose, consisting of a brass cylindrical vessel supported like a gas-tank by four vertical rods, against which it slides with almost frictionless roller-bearings. This rests on a truncated cone of jelly, and shot are poured in until a definite expression of jelly is observed, two vertical brass uprights 3.5 cm. high connected with an electric-bell circuit being placed beneath the CUP, SO that when this reaches their level the bell rings. Keeping properties are observed by exposing the uncovered glue solutions for some days at room temperature.arbitrary series of standards has been devised, based upon the viscosities, sixteen nearly equidistant grades having values assigned of 10 to 160, 10 points being allowed bdmeen each grade. The grades specially adapted for particular purposes are mentioned. W. H. S. Conditions affecting the Foaming and Consistency of Glues. So R. Trotman and J. E. Hackford. (JOWL. XOC. Chem. I d , 1906, XXV., 104-107.)- Foaming of glue is increased by overboiling, by prolonged boiling with alkalies, and by the presence of peptones, of soda or lime, of soap beyond a certain limit, of carbolic acid, and of suspended matter. From the influence of the last-named, loaded glues, such as Russian, may be expected to give considerable foam.The amount of foam is reduced by rise of temperature, by the addition of lubricating, bone, Or cod oil, or of hydrochloric, sulphuric, acetic, salicylic, or oleic acid. The mineral constituents of water used in glue-making would not affect the quality of the resulting glue. The consistency of glue is not injured by small quantities of peptone SO long as they do not replace albumose nitrogen, but is seriously reduced by alkalies and acids, though in a less degree by small quantities of carbolic or boric acid, A small amount of soda or potash soap does not diminish the consistency. The foaming has been measured by means of a graduated tube about 70 ern. long, and of such diameter that each division is 1 cm. in length and has a capacity of I C.C.This is half filled with a 10 per cent. solution of the glue, placed in a water-jacket at 60" C., and after allowing the glue solution to attain this temperature, withdrawn, and the level of the solution adjusted to zero. The tube is then corked and shaken vigorously for one minute, replaced in the water-jacket, and the height of the foam read off. Consistency has been determined by noting the time taken by spheres to fall through a column of the given glue solution. H. J. Watson (ibid., 1906, XXV., 209-211), from independent experiments on the same lines, concludes that foaming is not materially increased by the presence of free alkali or acid, except sulphurous acid. Mucins increase the foam, and zinc sulphate lengthens the time it takes to die away, but heat appears to be the all-important factor in producing foaming glue, probably due to hydrolysis of the gelatin to gelatone.By reducing the period under heat to the shortest possible, practically foam-free glue should be obtained. This author measures the foam by shaking 50 C.C. of a 10 per cent. solution of the glue at about 50" C. in a stoppered graduated cylinder 2.5 cm. in diameter, and reading the height of the top of the foam as soon as the height of the solution reaches 45 C.C. SV. H. S.242 THE ANALYST, The Determination of Urea. B. Glassmann. (Berichte, 1906, xxxix. , 705-710.-The following modification of Liebig’s and Pfliiger’s methods is claimed to give very accurate results, and to be more easily applied than any other method.The urea is precipitated from the solution, which has been neutralized with sodium carbonate, by means of a known excess of standard solution of mercuric nitrate, the precipitate filtered off, the filtrate acidified with nitric acid, and the excess of mercury determined by titration with & ammonium thiocyanate solutiorr, iron ammonium sulphate being used as indicator. From the amount of mercury that has been taken up the urea is calculated by means of the equation- 2CON2H, + 4Hg(NO,), + 4H,O = [2CO(NH,), + Hg(NO,), + 3HgOJ + 6HN0,. The conditions for the determination of the urea in urine by this method are the same as those required in Liebig’s original method--viz. : (1) The urine must not contain more than traces of albumin, which otherwise must be precipitated with acetic acid. (3) It must not contain leucine or tyrosine. (4) I t must not contain abnormal amounts of alkali chlorides, bromides, or iodides, or of benzoic, salicylic, or hippuric acids. (5) If too darkly coloured it should be treated with animal charcoal. (2) I t must not be in full alkaline fermentation. C. A. M. Simplified Ultimate Analysis for Technical Purposes-11. M. Dennstedt. (Zeits. a.lzgew. Chenz., 1906, xix., 517 ; cf. ANALYST, xxx., 135, 348, and this vol., 122.)-The author has given up the use of platinized quartz, which occasionally scratches the combustion- tube, and now uses rolled-up pieces of platinum foil, or, better, platinum- foil “stars” (Fig. l j , weighing 1 or 2 grams, which may For the introduction of the double current FIG. 1. be obtained from Hereaus, of Hanau. of oxygen, the arrangement shown in Fig. 2 is recommended, as it very seldom requires renewal. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9063100235

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年代:1906

数据来源: RSC

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THE ANALYST. 243 INORGANIC ANALYSIS. On the Quantitative Determination of Arsenic by the Marsh Method. G. Bertrand and Z. Vamossy. ( A m . Chim. Phys., 1906, 523; through Chem. Zeit., 1906, xxx. [Rep.], 141.)-The method gives good results, provided that the authors’ instructions ( A m . Chim. Phys., 1903, 242) are used with the modification that a length of 40 cm. of the tube is heated and that the tube has a bore of 2 mm. For quantities of 0.01 gram arsenic and more, the gas, after leaving the apparatus, is passed through a solution of silver nitrate, The arsenic mirror should be dissolved in sodium hypochlorite and not in nitric acid. A. G. L. On a Method for the Detection of Very Small Quantities of Yellow Phosphorus. R. Schenck and E, Scharff. ( B e y . , 1906, 1522; through Chem.Zeit., 1906, xxx., [Rep.], 156.)--Yellow phosphorus, even in very small quantities, ozonizes air, and hence may be made to discharge an electroscope ; phosphorus trisulphide, even when luminescent, does not possess this property, and does not yield any phosphorus trioxide on glow com- bustion at moderate temperatures. The authors make use of the apparatus shown for the detection of small amounts of yellow phos- phorus. By means of a tube passing through the ground-glass stopper of the tube (a) a slow current of air is led over the sub- stance to be examined, which is placed at the bottom of the tube. The air then passes through the vessel (c), which communicates by means of its removable stopper (d) with an electroscope (b). A piece of sodium in the tube (e) serves t o keep the electroscope dry and sensitive.A. G. L. Determination of Small Quantities of Copper in Water. E. B. Phelps. ( J o z ~ m . Amey. Chem. SOC., 1906, xxviii., 368-372.)-The copper is separated electro- lytically from an acid solution, dissolved in dilute acid, and, after neutralizing, determined colorirnetricslly as sulphide. Sufficient water to contain 0.1 to 1.0 mgm. of copper is evaporated to 75 C.C. and washed into a platinum dish, which serves as anode, adding 2 C.C. of dilute sulphuric acid for clear and soft waters, 5 C.C. for those rich in organic matter or clay. The cathode, consisting of a flat spiral of stout platinum wire, is then suspended in the solution parallel to and about $ inch from the bottom of the dish, and the circuit closed. After electrolysing for four hours with occasional stirring, using it current of 0.02 amphe, the cathode is removed without244 THE ANALYST.first opening the circuit and immersed in dilute nitric acid previously heated to boiling. The spiral is washed and the liquid evaporated to dryness on the water-bath, a few drops of hydrochloric acid being added if silver is suspected. The residue is then dissolved in water, washed into a Nessler glass, made up to 100 c.c., and 10 C.C. of an alkaline solution of potassium sulphide, prepared by mixing equal volumes of 10 per cent. potash solution and a saturated aqueous solution of sulphuretted hydrogen, added. A similar tube is prepared by adding 10 C.C. of the reagent to a tube of distilled water, and then running in, 0.2 C.C. at a time, a standard solution containing 0.2 gram copper per litre. This method gives good results in the presence of sewage and industrial waste, iron, lead, silver, and tin, and in highly-coloured surface-waters. W. H. S.

ISSN:0003-2654    

DOI:10.1039/AN9063100243

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年代:1906

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244 THE ANALYST. APPARATUS. Apparatus for the Continuous Registration of the Results of Gas Analysis and Precipitation in Liquids. (Chenz. Zeit., 1906, XXX., 347.)-B. Stollberg has patented (in Germany).the apparatus shown in the figure. It consists essentially of a number of flasks, containing suitable re- agents, connected with each other and mounted on separate pendulum - balances, which rotate graduated paper discs at speeds corresponding with their weights. On these discs a pencil worked by clock-work marks off minutes. By mean$ of a pump (not shown) worked by a falling-weight mechanism determined quantities of the gas (from a chimney, etc.) to be analysed are drawn through the flasks, and the increase in weight of each flask in a given time is read off from the discs. By means of suitable modifications the apparatus may also be made to give a continuous record of the specific gravity of a liquid, the amount of suspended or precipitated matter in it, and the like.A. G. L. Modified Westphal Balance for Solids and Liquids. F. M. Williams. (Jozmz. Arne?*. Chem. Xoc., 1906, xxviii., 165-187.)-The balance is adapted for solids, particularly cements and minerals, by lengthening the pointer, upon which, at a distance equal to the length of the other arm, is suspended a support carrying two pans, one above, the other below, the surface of the liquid, by means of which the object may be weighed first in air, then in the liquid. A two-piece counterpoising weight movable along the threaded portion of the pointer facilitates adjustment, and a cam device for raising the beam and locking it in place tends to prevent wear uponTHE ANALYST.245 the knife edges. The insertion of a hinge-joint in the upright standard arm allows - - the instrument to be folded up within a small space. W. H. A Burette Top for the Absorption of Carbon Dioxide and other Gases (Chem. Ztg., 1906, xxx., 459).-Gustav RIuller, of Ilmenau, has devised the apparatus shown, which is designed to prevent the absorption of carbon dioxide by caustic alkali solutions in the burette. The apparatus fits in the top of the burette, which is widened to admit it, by means of a ground- glass joint. It contains a solution of caustic alkali, through which any air entering the burette has to bubble, the path of the air being shown by the arrows.A piece of solid potash may also be placed in the bulb (d). I n filling a burette for the first time with the standard solution, the apparatus is placed on the top of the burette and filled with potash. It is then turned so that a groove (f) at the ground-glass joint is opposite a hole (9) in the burette. The standard solution is then run in from below, the air from the burette escaping through (9). The top is then turned so as to shut off cornmunication between (g) and (f), and kept in this position. Any air entering the burette has then to bubble through the potash, whilst in filling the burette afresh the potash is simply forced up into the bulb (d). A New Electrolytic Apparatus. S. F. Acree. (Anzer. Chern. Journ., 1906, vol. 35, pp. 313-316.)-The essential feature of the apparatus is that by means of a rotating, propeller-like anode all the liquid is continually circulated through the 4 n cathode K, which is of platinum gauze, 50 meshes to the linear inch, and consists of an outer ring 2.5 inches in diameter, forming one piece with the arm G, and an inner removable ring which holds the gauze in position, the two rings being kept firmly together either by fine platinum wire or by four small drops of gold.The arm G is held in position by a binding-screw attached to the glass rod F, and supports K half an inch above the bottom of the beaker H. A glass cylinder, I, rests on the outer ring of K, its upper edge being at least 8 quarter of an inch beneath the surface of the liquid. The anode J, of heavy platinum foil, is riveted to the platinum rod E, which is sealed into the glass tube C, and the latter rotated in the glass tube B by means of a pulley, A, and a Rabe water turbine or a small electric motor.A platinum strip or stout wire, D, connected to a binding-screw on F brushes against E, making good contact. The distance between J and K is adjustable, and depends entirely upon the voltage and strength of current required. -.,,, -'I W. H. S.246 THE ANALYST+ New Form of Potash Bulbs for Estimation of Carbon Dioxide from Combustions. S. F. Acree. (Amer. Chenz. Jozmz., 1906, vol. 35, pp. 309-311.)- A modification of Soxhlet’s alkali apparatus, in which the two bulbs B and D are filled and surrounded with glass wool saturated with 50 per cent. KOH solution, the mixture of gases from the combustion- tube being thereby brought in contact with a very large surface of alkali solution, insuring almost perfect absorption.The glass wool around the bulbs is kept in position by four small glass projections E, which extend from the lower bulb nearly to the wall of the outer vessel, and the exit tube from the lower bulb dips into the potash solution F. A calcium chloride tube is attached by means of a ground-glass joint at A. The efficiency of the apparatus is proved by the fact that on passing through two of them in series ( a ) a stream of nearly pure CO, for fifteen minutes, ( b ) a mixture of one-third CO, and two-thirds air, in neither case was the amount of CO, absorbed by the second apparatus as much as 0.10 mgm. Porcelain-lined Bomb for General Laboratory Use.S. F. Acree. (Amer. Chewa. Jown., 1906, vol. 35, p. 309.)- The bomb E is of soft steel, about Q inch thiok, and tested to 250 atmospheres water pressure, its entire inner surface up to the threads at the neck being lined with white porcelain -& inch thick, which may be of acid or of alkali-proof material. The stopper B is of hard bronze, has a square head, and screws into the neck of the bomb with heavy threads, the ring C, of very hard rubber or lead, making a gas-tight joint. The handle I, attached to the screw A on a square head, serves as a valve, the screw fitting into the stopper with gas- tight threads and packing, and having a tip, D, of very hard rubber or lead, which closes the bomb so tightly that liquid carbon dioxide cannot escape.The inlet or outlet G has a cap, and is threaded to fit carbon dioxide cylinders. The bomb rests in 8 detachable ring base, H. w. H. s. W. H. S. Dougal Assay Tube.-This, which is a modified flask, will be found useful for “part- ing,” dissolving metals, minerals, etc., solution proceeding quietly, as the double opening pro- vides a free escape for the evolved gases. The apparatus may be obtained from Messrs. J. J. Griffin and Sons. W. J. S.THE ANALYST. 247 A New Rheostat for Electrolytic Analysis. G. Pascalis. (Mon. Xcieizt., 1906, 4 Ser., 20, 168; through Chenz. Zeit, 1906, xxx. [Itep.], 104.)-The small adjustable resistance shown in the figure on the top of the electrolytic stand has been designed by the author in conjunction with GrBsy. Its height is only 80 to 100 mm., the diameter being 50 to 60 mm. A casing protects it from fumes. By means of the screw on the top the strength of a current at 4 to 6 volts may be regulated from 0 to 1 ampitre in -& ampAre stages. A. G. L. Struthers Syphon Pipette possesses the following advantages-compactness, less danger of liquid pipette being sucked up into the mouth, no necessity for using tip of finger in stopping flow, mark more exactly and easily caught, easy regulation and stoppage of flow, which is effected by simply tilting the pipette; it always discharges the same volume, as the bulb completely empties itself. The pipette is manufactured by Messrs. J. J. Griffin and Sons. W. J. S.

ISSN:0003-2654    

DOI:10.1039/AN9063100244

出版商:RSC    

年代:1906

数据来源: RSC

摘要:

THE ANALYST. 247 REVIEWS. THE CYANIDE INDUSTRY. By R. ROBINE and M. LENGLEN. Translated by J. ARTHUR With an Appendix by C. E. MUNROE, PH.D. (New York: London : Chapman and Hall, 1906. The manufacture and utilization of cyanogen compounds have undergone rapid development in recent years, and the work under review is an attempt to classify the various methods employed at the present time. The book comprises four sub- divisions, the first of these dealing with the chemical reactions involved, together with the preparation and properties of the more important single and double cyanides. Part 11. is practically a directory of the works at which the cyanide industry is carried on, whilst Part 111. is devoted to the manufacturing processes in general use. LECLERC, PH.D. Wiley and Sons.Price 17s. net.)248 THE ANALYST, The commercial application of the different cyanogen compounds is discussed in the last section, and an appendix contains a digest of the United States patents relating to the recovery of precious metals by means of cyanides. The descriptive matter as a rule is concise, and the processes of manufacture are clearly explained. The authors point out that the application of cyanides to the treatment of auriferous materials is the immediate cause of the progress realized by the industry during the last fifteen years, whilst the discovery of cyanide compounds in the bye-products of the manufacture of illuminating gas has also widened the field of investigation towards synthetic processes. I n the small space allotted in the book to analytical properties the usual tests for cyanides are included, but the information given in reference to quantitative deter- minations is rather meagre. Although the book will probably prove useful to the manufacturer as a r&sum& of the ordinary methods employed in the production of cyanides, its value to the analytical chemist is somewhat problematical.P. A. E. R. LES INDUWRIES DE LA CONSERVATION DES ALIXENTS (The Food-preserving Industry). This book is divided into seven chapters, respectively treating of historical sketch, the causes and effects of changes due to putrefaction, preservation by heat, by cold, by desiccation, by antiseptics, and by the prevention of the entrance of micro-organisms into such naturally sterile products as eggs.There is little or no analytical information, the whole subject being treated of from a technical point of view ; but the work is well up to date, and gives a fairly complete description of the various methods of food preservation. As is natural in a French work, the processes and details of packing and transport are chiefly those used in France, but these are fairly typical, and in most cases will give the food analyst a good general idea of the technology of the food-preserving industry. One passage taken from the report of Dr. Bordas, adopted by the Congress of Hygiene, is worth quoting in extenso .- (‘ En r6sum6, l’addition d’antiseptiques dans les denrdes alimentaires produit les resultats suivants : ‘* 1. Elle est susceptible de nuire A la sante. ‘* 2. Elle peut perrnettre de conserver des &l&ments ayant d&j& subi un ‘( 3. Elle modifie le plus souvent la composition des 6ldments organiques. L L I1 y a lieu d’interdire l’emploi des antiseptiques quels pztils soient, noc$s ou non, dans toutes les matibi*es alimentaires.” H. D. R. By X. ROCQUES. (Paris, 1906. . Pp. xii+506. Price 15 francs.) commencement d’alt &ration.

ISSN:0003-2654    

DOI:10.1039/AN9063100247

出版商:RSC    

年代:1906

数据来源: RSC