摘要:

PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. AN ordinary meeting of the Society was held a t Burlington House on Wednesda,y, the 8th ult., the President, Dr. A. Hill, in the chair. The minutes of the previous meeting were read and confirmed. On the ballot papers being opened it was announced that the following gentlemen had been elected as members :-J. M. H. Munro, D.Sc., F.C.S., of Downton Agricultural College ; A. G. Salamon, A.R.S.M., F.C.S., London; Dr. John A. Voelcker, B.A., B.Sc., chemist to the Royal Agricultural Society. The following gentlemen were proposed for election, and will be balloted for at the annual meeting :-As member, H. Faber, chemist to the Dairy Supply Company ; as associate, Adolphus Dretel, assistant to Mr. W. Johnstone. Mr, Harland and Mr. Johnstone were appointed auditors, to examine the accounts for the pa& year. The following papers were read and discussed :- Notes on the Alcoholic Fermentation of Milk-Sugar, by Dr.P. Vieth, F.C.S. A new Method of ascertaining the amount of Fat in Milk, by H. Faber. Experiments with the Lactocrite, by A. Wynter-Blyth, M.R.C.S., F.C.S. Sour Bread and the Logwood Test, by W. C. Young, F.C.S., F.I.C. On Reichert’s Butter Method : a Correction, by A. H. Allen, F.C.S., F.I.C. Notes on Thickened or Blown Oils, by J. Baynes, F.C.S., F.I.C., and W. Fox, F.C.S. The annual meeting of the Society will be held a t Burlington House, on Wednesday, January 12th, and the annual dinner will take place the sfme evening. The usual notice will be given to members. Mr. Young’s paper on the Logwood Test, that of Memrs. Baynes and Fox on Blown Oils, and Mr, Wynter Blyth’s on the Lactocrite, will all appear in our next k u e .

ISSN:0003-2654    

DOI:10.1039/AN887120001b

出版商:RSC    

年代:1887

数据来源: RSC

摘要:

2 THE ANALYST. NOTES ON THE ALCOHOLIC FERMENTATION OF MILK-SUGAR, BY P. VIETH, PH.D., F.C.S. Read at the Meeting, December 8th,, 1886, A PAPER on (6 The Composition of Mares' Milk and Koumiss," whioh I read before this Society a t the November meeting, 1885, gave rise to a oonversation on the alooholio fermentation of milk-sugar, in the course of which it wm remarked that there exists some difficulty to start alcoholic fermentation in solutions of milk-sugar. I n order to convince myself of this fact, I made the following simple experiment : 5 per cent. solutions of cane-sugar and of milk-sugar were made, and German yeast added fo each of them, in the proportion of 1 gramme to 100 C.C. The solutions were kept loosely covered side by side in a moderately warm place, the temperature of which varied from 16" to 28OC.Samples-5 c.c.-were taken daily, evaporated on the steam bath, dried in the air bath at 100QC., and weighed. The cane-sugar solutions were on the evening of the first day already in active fermentation, and the solids diminished rapidly during the early part of the experiment, viz., about at the rate of 30 per cent. per day, the residue of 5 C.C. of the solution weighing, when freshly made, 02574, after one day *1674, after two days -1150, after three days *0787. I n the solution of milk- sugar, alcoholic fermentation was not perceptible; there wa8, however, also a slight diminution of solids. The solutions contained solids :- I. Series. 11. Series. Cane-Sugar. Milk-Sugar. Cane-Sugar. Milk-Sugar. When fresh . . 5.14 4-96 5.36 5.16 4 days old .. 1.18 4.90 1.38 5-00 8 99 99 . . *62 4-80 -64 4.96 12 1, 9 , . L *52 4.66 058 4.90 From these figures it appears that within twelve days the solids of the cane-sugar solution were reduced to about one-tenth of the original amount, while those of the milk-sugar solution diminished by about 6 per cent. only. I have never tried the experiment to keep a plain solution of milk-sugar, without or with yeast, added to it, for a longer period, and see if alcoholic fermentation would have set in, but done so with a preparation of milk containing as much milk-sugar and as little of the other solid constituents as possible-whey. Milk set in Bhallow pans will turn sour and thick in two or three days, if kept at mean temperature. I f the milk is then slowly heated the precipitated casein is contracted and forms lumps of tough curd, while whey is separated, which, provided poor skim milk had been used, will be almost clear.Whey prepared in this manner in November, 1885, was bottled immediately after having separated and cooled down, the bottles corked and wired and removed to a cool vault. The whey was analysed when it was six and twelve months old; after six months already it was found t o be highly effervescent. The whey contained :- 6 Months Old. 12 Months Old, Total Solids . . 6.28 5.46 Lactic Acid . . 1.73 2-58 Alcohol .. *63 -93 In May last I repeated the experiment, and at the same time put aside isome wheyTHE ANALYET. 3 prepared of sweet milk by means of rennet. The two kinds of whey were analysed when fresh and six months old.The sour whey again was found highly effervescent when six months old, but the whey prepared by means of rennet contained a small quantity of gas only. The results of analysis were as follows :- $our Whey. Sweet Whej. Fresh, 6 Months Old. Fresh. 6 Months Old, Total Solids . . 7-51 5.88 6-84: 6.24 Lactic Acid . . *65 2.38 - 1-41 Alcohol .. - -53 c -20 These experiments show that spontaneous alcoholic fermentation sets in if whey is kept for a considerable length of time, and, in the ms0 of sour whey, develops to a very marked degree. I expected that the fermented whey would act as a powerful ferment on milk-sugar solution, and in order to try it made two 5 per c?ent. solutions of milk-sugar containing twelve months old fermented whey, the one in the proportion of ten and the other of twenty per cent.The solutions were kept loosely covered at a temperature varying from 16” to 28”C., and the solids determined daily. Instead of a decrease, I, during the early part of the experiment, found an increase in solids, due, no doubt, to the evaporation of alcohol introduced with the fermented whey; after a time the solids very slightly diminished. The percentages of solids found mere as follows :- 5 per cent. solution of milk-sugar+ 10 per cent. old whey. Newly prepared . . 5.06 5-40 5 9 8 J J . . 5.12 5 9 2 99 11 ,? . . 5.02 5-06 20 per cent. old whey. After 4 days . . 5.08 5.54 In my paper ‘‘ On Mares’ Milk and Koumiss,” I have mentioned that mares’ milk spontaneously undergoes not only lactic but also alcoholic fermentation, sometimes within a very short time ; I have seen mares’ milk, milked at S a.m., frothing with carbonic acid gas at 6 p.m.of the same day. I n the manufacture of koumiss alcoholic fermentation is supported or effected by the addition of koumiss, which is well fermented. It is well known that a beverage, similar to and having all the properties of mares’ milk koumiss, can be prepared of cows’ milk. During the last few years attention has fre- quently been drawn to a new preparation, consisting of fermented cows’ milk, and known under the name of Kef3.r.” I n this case alcoholic fermentation is started in the milk by the addition of a ferment called kefir grains. These grains contain, according to Dr. Kern, of Moskow, a bacillus, to which he gave the name of Diospora Caucasica, and yeast cells, apparently a modified form of Saccharomyces Cerevisia. Milk, to which kefir grains have been added, and which is subjected to a certain treatment, undergoes alcoholic as well as lactic fermentation within an exceedingly short time.After one day the alcohol four d in kefir amounted to -3, after two to three days to 08, after five days to 1 per cent. I dare say every Public Analyst has made the experience that milk samples kept for some length of time get fermented, developing gaseous products. That the solids in such samples decrease to a considerable degree has frequently been discussed. Some4 THE ANALYST. years ago I brought before the Socisty* some observations relating to the speedy diminu- tion of solids in milk, which is kept in small quantities a t mean temperature, and allowing the free access of air to it.I then suggested that this diminution in solids must be attributed to alcoholic fermentation, and am of the same opinion still. One might think of a decrease caused by the formation of di-lactic acid on drying up sour milk, but supposing the whole of the milk-sugar be converted in lactic acid-which is highly improbable-and the whole of the lactic acid in di-lactic acid, which is impossible under the circumstances-then a loss could be caused only equal to a 4 5 to *50 per cent, in milk containing 4.5 to 5.0 per cent. milk-sugar. I have repeated the experiment of keeping small quantities of milk in platinum dishes exposed to the air in a moderately warm place-about 25" C.-for varying periods of time, and compared them as to the amount of solids with other samples of the same milk kept in a stoppered bottle, but otherwise under the same conditions.At the same time I tried to find out what eEict the addition of yeast-1 gramme to 100 c.c.-would have upon the milk under those conditions. The experiment, for certain reasons, was made with very poor sweet skim-milk. The following results were obtained :- Solids in skim-milk kept in stoppered bottles. Fresh ... ... 9-80 10.08 (Lactic Acid *15) ,, S ,, ... 9.32 9.53 ( ,, 1.16) ,, 11 ,, ... 9-32 9.31 ( ,, 1-21> Without yeast. With yeast. After 4 days ... 9.48 9.70 ( ,, 1.01) Solids in skim-milk kept in platinum dishes. 4 days ... 8.80 9.04 8 ?I ... 8.34 8.40 11 9 , ...8.30 8.10 With regard to the samples taken from the bottles, it must be remarked that particles of precipitated casein stuck to the glass, and could not be removed, not even by violent shaking, a circumstance which accounts for the relatively great difference between the milk when fresh and four days old. On reviewing the facts which have been brought forward we see, on the one hand, the difficulty of starting alcoholic fermentation in pure solutions OF milk-sugar as well as in milk by means of added yeast ; on the other hand, alcoholic fermentation readily developed in milk by a certain ferment ; further, alcoholic fermentation setting in spontaneously in whey and milk, if kept for some considerable length of time ; and a very marked diminution of solids within a very short time, which seems to be at- tributable to alcoholic fermentation, if milk is kept in small quantities exposed to the air in a moderately warm place.I do not think I need apologise for bringing these observations under your notice, as they have a direct bearing on the much-dhcussed question of analysing old samples of milk, but I have to apologise for leaving the question a t a stage where a more close investigation ought to commence. In common with many analysts engaged in practical work, I do not always find time to further investigate into questions, the clearing up of which is very desirable, Without yeast. With yeast. Otherwise, the results want no commentary. * THE ANALYST, 1882, p. 213.THE ANALYST. 5 DISCUSSION. Mr. HEHNER said there was an article in the market something of the nature of a ‘‘ bland,” but it was perfectly transparent, and he understood it was the whey of the milk fermented.It contained no acid, and he should like to ask how it had fermented. Mr. KINGZETT regretted that ha had not heard the early part of Dr. Vieth’s communication, but he thought that a brief description of some results which he had obtained with reference to the fermentation of milk and milk-sugar some time ago might have some general interest for the members. The experiments in question formed part of an exhaustive investigation, made with a special object, and were as follows :- A quantity of fresh milk was taken, and the milk-sugar present in it was determined by first of all diluting 10 C.C. with 90 C.C.of water, and then estimating it by the well-known process which makes use of Fehling’s solution volumetrically. It contained 40422 grammes milk-sugar in each 100 C.C. It was also experimentally proved to be quite free from lactic acid. 50 C.C. of this milk was diluted with 50 C.C. of water, and the mixture placed in a flask loosely covered with filter paper, on July 7th. On July 20th, the mixture was gently warmed, to complete coagulation, and was then filtered, the filtrate being made up to a known volume by washing the coagulnm with warm water, after which the sugar present in the filtrate, and the acidity thereof, were respectively determined. Gugar originally Sugar present Difference due to present. at end. fermentation. Final Acidity. 2.2 1 1 grammes.None. 2 *2 1 1 grammes. 28 C.C. 2 NaHO. A microscopic examination of the fermented mixture revealed the presence of the bacterium Zuctis in great numbers, and the bacteilium termo was also seen to be present in a very active state. As the fermentation of 2-211 grammes of milk-sugar should yield, if entirely fermented into lactic acid, the same weight of that substance, whereas the acidity of the fermented mixture was only equal to 0.253 gramme of that Substance, it was concluded that the lactic acid had itself been resolved by subsequent changes into acetic, butyric and propionic acids, and that, finally, these acids had been split up by oxidation into carbonic anhydride and water ; moreover, as the fermentation was conducted fortuitously, it doubtless was not of a pure character. Experiment 2.This was made with another sample of milk, containing 3.88 grammes milk-sugar in each 100 C.C. ; the mixture being allowed to stand from August 4th to August 13th. Sugar originally Sugar present Difference due to present. a t end. fermentation, Final acidity. I n this experiment the quantity of lactic acid found is greater in proportion to the sugar employed, and, doubtless, this result was due to the fact that the milk was not allowed to stand so long as in the previous experiment. I f the whole of the milk- sugar which had disappeared had been changed into lactic acid, and none of this had been destroyed by subsequent chemical changes, there would have been obtained 096 gramme lactic acid, instead of 0.3375, actually calculated to be present.This experiment was conducted as follows :-Some 245 C.C. of fresh milk was inoculated with 5 C.C. of very sour milk; then the acidity and the milk-sugar of the inoculated mixture were carefully determined ; after which two quantities of milk 50 C.C. each were respectively diluted with 60 C.C. water, and allowed to stand from August 20th to August 24th. 1.940 0.980 -960 37.6 C.C. NaHO Experiment 3. Sugar originally Sugar present Difference due to Original Acidity present. a t end. fcrmentation. acidity. at end. A. 2.155 1.675 -510 0.5 C.C. 44.5 C.C. i$ NaHO B. 2.185 2.654 -53Q 0.5 C.C. 45.7 C.C. $ NaTlO6 THE ANALYST. The results of the examination of the two mixtures are seen to be thoroughly and mutually confirmatory in character. Taking A, the loss of the milk-sugar could produce a maximum of -510 gramme lactic acid, whereas the acidity of the ultimate mixture was equal to ,4005 gramme, leaving apparently only -1095 gramme to be accounted for.It is, however, to be noted that the approximation of the theoretical and practical quantities of lactic acid is much greater than in either of the previous experi- ments, and doubtless the reason is that the mixtures were only allowed t o stand over four days. In order to test the supposition that alcohol might also be found amongst the products, thus accounting for the difference, one half of each mixture A and B was subjected to distillation, and the specific gravity of each distillate after being made up to the original volume, was determined and found to be respectively -99977 and -99973. Alcohol was thus proved to be present in each fermented mixture, in more than sufficient amount to fully account for the deficiency in lactic acid produced. The explanation is this : the alcohol which was found present was all derived from the fermentation of lactose ; whereas a small proportion of the total acidity of mixtures A and B was derived from butyric and other soluble fatty acids, which resulted from the rancidity of the cream or fat contained in the milk, thus swdling the amount of acid which is, as explained, not derived solely from the lactose.Either, then, the 6acterium Zactis performs the chemical changes whereby lactose is resolved both into alcohol and lactic acid, or it was accompanied in these experiments with other forms of microscopic life, which fermented a part of the lactose into alcohol and carbonic anhydride. Dr. VIETH, in reply to Mr. Hehner, said there was no impossibility about having L preparation which might contain whey, and might ferment a t tho same time, but he did not think it was suggested that the preparation referred to consisted entirely of whey. What had principally struck him was, on the one hand, the great difficulty of starting fermentation of milk-sugar by adding yeast as the fermenting power, and, on the other hand, the quick fermentation by adding some other ferment,

ISSN:0003-2654    

DOI:10.1039/AN8871200002

出版商:RSC    

年代:1887

数据来源: RSC

摘要:

6 THE ANALYST. A NEW METHOD OF ASCERTAINING THE AMOUNT OF FAT IN MILK, BY H. FABER, AN apparatus which would render possible an easy, quick and exact determination of the amount of butterfat in milk, has for many years been a desideratum, but all attempts to construct such an apparatus have till quite recently .proved unsuccessful. The simplest way of estimating the amount of fat, which nature itself seems to suggest, is to let the cream rise and notice its volume. This method, which is extensively used by practical men, is however very unreliable, as there is no constant relation between the volume of cream thrown and the percentage of pure fat. An attempt has been made to improve this method by dissolving the fat in ether, as in the Marchand’s Lactobutyrometer, but sufficient accuracy can hardly be obtained in this way.The best apparatus, so far as accuracy is concerned, is undoubtedly Professor Soxhlet’s aerometriml apparatus, by which the specific gravity of an ethereal solution of the fat is taken, the solution being made according to a given method and the gravity takenat a fized temperature. A certain sp. gr, then corresponds to %I certain amount of faf in the Reud at the Meeting, Dec. &he, 1886.THE ANALYST. 7 I__ L-... , , milk, but it may reasonably be objected to this method that it is rather costly, and that such a delicate instrument could not well be worked by a practical dairyman. As far back as 1859, experiments were made by Professor C. J. Fuchs a t Carlsruhe with the view of obtaining a more complete and uniform rising of the fat globules by employing centrifugal force instead of the force of gravitation, as in the srdinary creamometer ; but he failed to produce a sufficiently strong and rapidly revolving machine.In 1881 Professor N. J. Fjord, of Copenhagen, constructed his Control Centrifuge,” especially intended for, and by him mostly used for examining separated milk, for which purpose it worked to great satisfaction. It was never intended to be used by others besides his staff, for which reason he never published any directions for its use ; it was not intended for, nor did he claim that it could be used for analysing whole milk. Nevertheless it has been taken up, exhibited, and a t many places used for analysing whole milk. On account of its favourable reception he has lately altered his apparatus, which is now intended for controlling the supply of milk and enabling dairy factories to pay for it according to the amount of butterfat it contains.The apparatus in its new shape contains fifty-four cylindrical tubes, to hold fifty-four samples of milk. The cream is made to rise in the tubes by making the apparatus revolve about 60,000 times in the Danish Centrifuge, which takes about three-quarters of an hour. The thickness of the cream is thus then measured. There is one objection to be made to this apparatus, viz., that it indicates the amov,nt of cream and not of butteqfat, and although undoubtedly the completeness of the rising of the cream and its uniformity is much greater in this case than in the ordinary creamometer, still this app.must only be considered as one step further towards the ideal, which is to have the puw butterJat isolated by mechanical separation. This is the goal after which Dr. de Ezival, of Stockholm, has been striving, and which he has a t length attained in his new machine, the Lactocrite. I n order to get the fat globules in the milk to unite to one clear mass of fat, it is necessary to render the casein more completely dissolved than it is in the milk in its natural state. There has been, and probably is still, a digerence of opinion as to whether the fat globules m e coated with a membrane or not, but all agree upon the fact that for some reason or other they do not unite as readily as might be expected. The truth seems to be that by a molecular attraction the casein forms zt condensed layer, but not a real membrane, around ths fat globules. To dissolve the casein Dr.de Lava1 at first tried an admixture of alkali, which proved of little avail, He therefore took the opposite course and suc- ceeded in dissolving the casein completely by boiling the milk with acetic acid. As is well known, small quantities of free acetic acid will precipitate the casein while a large excess will redissolve it. By the proposed treatment the serum of the milk is transformed into a perfectly clear and thin fluid, and the fat is apparently not affected,8 THE ANALYST. The apparatus itself consists of a strong round steel disc on a spindle, like that of the separator bowl, and test-boxes of platina-plated brass nith graduated glass tubes.The modus ope~*aruZi is as follows :-lo C.C. of the sample of milk to be tested are run into a small test-glass, afterwards 10 C.C. of glacial acetic acid, containing five per cent. by volume of concentrated sulphuric acid are run into the same glass, which is then closed with a perforated cork-stopper, in which is inserted a piece of glass tube; this serves to prevent a concentration of the contents of the test-glass during the boiling. I n a water-bath, arranged to hold twelve test-glasses, these are heated by steam or gas for seven or eight minutes, after which time the casein has been completely dissolved, while the liquid has acquired a slight violet tinge. The next step is to charge the test-boxes. These consist of a cup in which a perforated stopper fits tightly.The stopper holds the graduated glass tube, as the fat in the milk after boiling with acid has a great ten- dency to rise, the test-glass must be well shaken before its contents are poured into the cup, and when this is filled the stopper must be immediately pressed down in it, whereby any excess of the mixture will escape through the glass tube, and the test box is then filled completely. After the test-boxes have been charged in this way, they are ready to be placed in the disc, which will hold twelve at a time. The disc, which before use must be heated to about l l O o F. by being placed in warm water of this temperature, has twelve cylindrical holes bored from a cavity on the top, radiating and a little sloping. In these the test-boxes are placed (if less than twelve test-boxes are used, there should always be an even number placed so as not to disturb the equilibrium) and the cavity is filled with water, which will keep the liquid in the test-boxes from being pressed out by the centrifugal force.The disc, which fits any stand of a Lava1 separator, is now made to revolve for three or four minutes at ordinary speed (6000 revolutions in the minute). When it is again at rest the test-boxes are drawn out, and the column of fat in the graduated tube is read 06 the divisions indicating immediately tenths per cent of butter- fat by weight. Before entering into the question of comparative analytical results it will be ne- cessary to say a few words of explanation. It has been stated that any method of determining the amount of fat will give corresponding results in the hands of persons working in the same way and in the same laboratory, and that no method will give the same results on the same sample of milk in the hands of different analysts at different places.The first statement may be right, but is of very little interest ; the second would be very serious indeed, if true. Any method which will extract all the fat and nothing else, will give very nearly the same results in the hands of any careful analyst, but it is an essential condition of a good method, that it shall extract cd? the f a t and nothifig ehe. All methods possessing these two qualitieswill give the same results on the same sample of milk carefully worked. To obtain a complete extraction of the fat, the milk must be given a very large surface, but this must not be done on paper containing resinous matter, as something will then be extracted besides the fat, For the same reason the ether used must be redistilled.When using Adams’ method it is indispensable that all the resinous matter shall be extracted beforehand, which does not seem very easy. [I have found in one case that 5 siphonings extracted 0.023 gramme of a coil, but still left 0*020 gramme behind, which were extracted by 8 more siphonings.] With well-washedTHE ANALYST. 9 paper coils I have found thst Adams’ method will give results corresponding very closely with those obtained by the method I generally use, which was first described by Dr. V. Storch, in 1883, but had then been in use for several years.According to this method about 10 grammes of milk are dried on about 10 grammes of pumice stone, ground to the size of lentils, sifted to remove the dust, and heated to a red heat. The dry mass is finely ground in a porcelain mortar and extracted in a very simple extracting tube. 50 C.C. of redistilled ether may be forced to percolate through the finely pulverized milk any number of times so as to remove all fat, and nothing but the fat a n possibly be extracted. In analysing a sample of skim-milk twice by each of these methods I found :-- By Adams’ method ... ... 0.70 0.68 per cent. of fat. By Storch’s do ... ... 0.65 0.64 ditto Below I give some examples showing how far I have found the results obtained bg the Lactocrite t o compare with chemical analysis.Chemical analysis. Lactocrite. 3 73 3-74 3.7 3.75 3-15 3.8 3.8 3.85 3.8 3.8 3.S2 4.08 4.07 4.1 4.2 4.2 3.86 3.8 4.0 3.9 3.9 At least equally good results have been obtained by Mr. John Sebelien, lecturer to the Agricultural College, Ultuna, Sweden, and superintendent of the Dairy Labora- tory of the same place. From his report I quote :- ChemiLal analysis. Lactocrite. 3.68 3.65 3.65 3-70 34’0 3-70 3.6’7 3.67 3-70 3.70 2 76 2.77 2.80 2.77 2.80 2.80 2-75 2.70 2.65 2.70 2-65 2.70 These samples, which are by no means picked, will show that the Lactocrite is abls to give b very close estimation of the amount of fat in milk. I think it may fairly be claimed for the Lactocrite that it will give an estimation within 0.1 of the amount of fat in whole milk.When skim-milk is treated in the Lactocrite the results will fall somewhat below those of the analysis, as seen in the following examples : Chemical analysis. Lactocrite. 1.14 1.17 1.05 1.0 1.07 1-05 0.87 0.90 0.75 0.s 0.76 0-8 0 s 0.75 0.S 0-65 0.82 0.75 0.8 0.8 Separated milk, from the cream separator, having but very little fat left in it, cannot he tested by the Lactocrite in the usual way, as many trials have shown the results to be about 0.2 per cent. too low, which difference in analysing separated milk of course cannot be allowed, Equally low results have been obtained from buttermilk10 THE ANALYST. Sour milk, even curdled, may be treated in the Lactocrite just as well as sweet milk, as the strong acetic acid will dissolve the casein of sour milk as easily as that of sweet milk.The only difficulty lays in the measuring off the 10 C.C. of a true average quality. One great advantage of the Lactocrite is the very simple way in which it is worked, so that no skill is necessary, but any dairyman may obtain as good results as the apparatus is able to yield. I n order to illustrate this I give below the results obtained by two persons a t their first attempts; the first person is a dairyman used to heavy work. By way of a check I myself made some tests of the same milks :- Bp myself. Dairyman. 3.1 3.1 3.2 3.2 3.2 Failed 3.3 3.3 3.2 3.1 3.3 3.2 2.65 2.65 2.6 2.6 2.65 2.65 3.6 2.65 These very favourable results are of importance as showing that in the Lactocrite is a t last found the long wished-for apparatus, possessing the two qualities not hitherto combined-simplicity of construction and working and sufficient correctness for all practical purposes.The Lactocrite will, no doubt, be found invaluable for butter dairies, or dairy factories buying milk from different farmers, by enabling them to carry out the system of paying for the milk according to the amount of butterfat which is the only fair system. At present, both in England and in other countries, the farmer whose milk will make butter at zt rate of 3 lbs. per 100 lbs. of milk gets the same price as the farmers whose milk is so rich as to give 5 lbs. of butter per 100 lbs. of milk, which of course is most unfair. When milk is paid for according -to the fat contained in it, the temptation to skim it i.s done away with, and besides, a great encouragement is given to the pro- duction of rich milk, The Lnctocrite will also prove of use for analysts who have access to a septLrator stand, as it will give in a short time a more exact determination of the amount of fat than any other apparatus.I n this connection it will bs of interest to know that a special construction of it has been adapted to fit Dr. de Laval’s small Rand Heparator, worked by hand and requiring no foundation. DISCUSSION. Dr, VIETXX said he had listened with great interest to the papers, and he thoughC himself that instruments and methods for determining the most valuable constituent of milk-fat-which can be worked outside the chemical laboratory, and yet give correct results in tho hands of non-chemists were of the utmost importance to dairy-farming and dairy-industry.From what he had heard that night, and learned previously, he had no doubt that the Lactocrite was a very useful apparatus, and that the results obtained were highly satisfactory. He was astonished to see so close an agreement with result@ r e l a h g to skim m.ilk, because the inventor distinctly states that if skim milk ia examined with the apparatus -2 per cent. must be added to the result in order to bring lap the fat t o the percentago actually present. With regard to the cooling down of theTHE ANALYST. I1 - - ~ ____---- --_ ___ tat-tubes, while reading off the results, he did not think that a matter of great conse- quence, as the tubes were made of pretty thick glass, He might mention that the Lactocrite was not the only apparatus of its kind, but that there also exists a centrifugal control-apparatus in connection with the Danish cream separator.Each apparatus appears to have some merits of its own; but there was scarcely any occasion for a close comparison of the two, as they would never compete with each other. The Lactocrite cannot be used where the Danish separator is being worked, nor can the Danish control apparatus be employed in connection with the Swedish separator. A h . ADAMS was highly gratified to see the remarkable corroboration the Lactocrite afforded to his own method of analysis. He had been favoured by Mr. H. Faber with some particulars respecting the other mode of analysis employed by him, and referred to in his paper, also with specimens of the apparatus which Mr. Faber makes use of, consisting of a conical tube some 6 or 8 inches long, plugged at the bottom or smaller end with wool, through which a small glass fubo passes, the space between it and the conical tube being filled with pumice stone broken to a coarse powder-which pumice takes the place of the sand, powdered glass, or plaster of Paris of other methods. The pumics is first. ignited, then placed in IL porcelain capsule, charged with the milk, which, when dried, is transferred to the tube to be extracted by ether under an upright condenser. The speaker’s experience of the process, as compared with his own, was that the yield of f&t is *29 per cent. below truth, and besides its failure to extract the whole of the fat, he finds the pumics an unwieldly, disagreeable material to use as an absorbent, it being, in his opinion, much inferior to sand, glass or plaster, not only by reason of its ineffectiveness, but also because of its bulk and the difficulty of detachment from the porcelain capsule without loss of substance, and the destructive action it has on the capsule by scratching of the enamel.

ISSN:0003-2654    

DOI:10.1039/AN8871200006

出版商:RSC    

年代:1887

数据来源: RSC

摘要:

THE ANALYST. I1 NOTE ON REfGHERT'S DX8TXLLATION PROCESS, BY ALE'RED H. ALLEN. Read at the Meeting, Decernbe?. 8th, 1886. IN a paper read before this Society in the spring of last year, and published in the ANALYST for June, 1885, I described my experience of Reichert's method of assaying butter-fat, and gave a number of figures illustrating the results obtained with oils of various kinds. These figures professed to represent the volatile acids in terms of butyric acid, and were obtained by multiplying the numbsr of centimetres of decinormal alkali required for neutralising the distillate from 2.5 grammes of fat by the factor 0,312. I am indebted to Mr. W. F. K. Stock for pointing out an error in this factor, which should be 0.352." As the erroneous factor was used in calculating the figures already referred to, it follows that they are all too low in the proportion of 312 : 352, or 39 : 44.A further experience in the employment of Reichert's process for examining fats h a s led me to abandon the expression of the results in terms of butyric acid, in fa,vour of a atatcment of the weight of caustic potash neutralised by the distillate from 100 grammes N *0088 x 100- 10 2.5 * 1 c,c, of - alkali neutralises 0.0088 gramme of butyric acid, and -- - 352. The erroneous €aetor may have resulted from the fraotion-- -0078 x 100- - -812.19 THE ANALYST. of the oil. by the distillate from 2.5 grammes by the factor 0.2244.* This is obtainable by multiplTing the volume of decinormal alkali neutralised The following table contains a number of results expressed in both ways :- Fatty Oil.Butter or Milk-fat; COW’S . . 9 7 ,, Ewe’s . . 9 9 ,, Goat’s . . Y ? ,, Porpoise’s Cocoanut oil . . . . . . Palmnut oil . . . . .. Palm oil . . .. . . Cacao butter . . .. . . Butterine and oleomargarine . . Whale oil . . . . . . .. J 9 Porpoise oil . . Sperm oil . . Bottl.enose oil . . Menhaden oil . . Codliver oil . . Sesame oil . . Cottonseed oil . . Castor oil . . .. . . . . .. .. . . .. . . . . . . . . . . .. * . 0 . . . . . . . N 10 3.C. of - alkal -equired by 2.5 gi 12.5 to 15.2 13.7 13.6 11.3 3.5 to 3 7 2.4 0.8 1.6 0-2 to 1.G 3.7 12.5 11 to 12 1-3 1.4 1-2 1.1 to 21.1 2 *2 0.3 1.4 KHO required b 100 parts of oil. 2.80 to 3-41 3.07 3.05 3.51 0.78 to 0.83 0,64 0.18 0.36 0.04 to 0 ~ 3 6 2.80 2.47 to 2.69 0.29 0.31 0.27 0 24 to 0.47 0.07 0-31 o m 0.48 Observer.Reichert, Caldwell, Moore, Allen, etc. Schmitt Allen Reichert, Moore, Allen Allen Moore Caldwell, Moore, Allen Allen I , ) ? 9 , 9 9 11 9 , Y, Y, 9 , Moore Allen From these results, it is evident that the fats of different kinds of milk (butter-fats) are sharply distinguished from nearly all other fats by the large proportion of soluble volatile fatty acids they yield by Ileichert’s process. The most remarkable exception is presented by porpoise oil and some samples of whale oil. I n porpoise oil I have found 5 per cent of valeric acid, and Chevreulobtained as much as 9.63 per cent. I n a recent paper I pointed out that in porpoise-butter the glyceride of valeric acid appeared to replace the butyrin characteristic Qf the butter of terrestrial mammals.Some of the chemists who have employed Reichert’s process take the precaution to filter the distillate before titrating it, so as to get rid of any volatile acids which may be insoluble or very sparingly soluble in water. This plan may sometimes be adopted with great advantage. Thus when the solution of the soap obtained by saponifying cocoanut or palmnut oil is acidulated and distilled, a notable proportion of lauric acid passes over and solidifies in the condenser or on the surface of the distillate; and by adding water to the contents of the retort, again distilling, and repeating this process several times, a very considerable proportion of volatile fatty acids can be obtained from cocoanut oil. I n assaying butter the appearance of insoluble acids in the distillate would *00561 x 100 = .2244, * 1 C.C.of & alkali contains 0.00561 gramme cf KHO ; and 2.5THE ANALYST. 13 furnish a valuable indication of the presence of cocoanut oil, and they should be removed by filtration j or the distillate will be found t o neutralise so‘ large a volume of alkzli as considerably to diminish the practical value of the process as a means of dist,inguishing butter from butter-substitutes, as has been pointed out by Moore and others. Latterly, I have adopted the plan of filtering the distillate in all cases, washing the filter with cold water, and then immersing the filter, with any adhering insoluble acids, in alcohol, which is then titrated with decinormal alkali and phenolphthalgin.I n the case of ordinary butters and butter-substitutes the insoluble woolatile acids only neutralise about 0.2 C.C. of decinormal alkali. The question having recently been raised, the following experiments were made at my request by Mr. William Barraclough on a sample of butter-fat, in order to ascertain the variation in the results of Reichert’s process produced by modifications in the methods of conducting the saponification and distillation. 1. 2.5 C.C. of butter-fat was saponified by alcoholic potash in an open basin, the alcohol evaporated off completely at a steam heat, the residual soap dissolved in water, the solution acidulated with sulphuric acid in slight excess, diluted to 75 c.c., and dis- tilled gently in a globular flask with side-tubulure adapted to a condenser, until 50 C.C.had passed over. The flask held 460 C.C. up to the side-tubs, and some fragments of pumice-stone coiled round with platinum wire were added to the contents, to promote evolution of vapour. 2. An exact repetition of No. 1 experiment. 3. Saponification was effected in a flask furnished with a long tube and heated by 4. Saponification was effected in a well-closed bottle placed in the water-oven. Other 5. Manipulation exactly as in experiment 3, except thnt the distillation was con- 6. Conducted as in experiment 3, except that the distillation was conducted in a 7. Blank experiment with the alcoholic potash employed in the previous experi- The alcoholic potash was steam. manipulations unchanged. ducted in a flask fitted to the oondenser by a cork and bent tube. retort. ments, the manipulation being like that in experiment 3. brown and not very recently prepared. The subsequent manipulations were the same as in experiment 1. Experiments. Decinormal Alkali Decinormal Alkali for 2.6 grammes. for 2.5 grammes. No. 1 L . . . 11.80 C.C. No. 5 . . . . 12.40 C.C. No. 3 .. . . 12.40 ,, No. 7 . . .. 0.25 ,, No. 4 . . . . 12.50 ,, These results show that a sensible loss occurs if the saponification be conducted in On the other hand, This No. 2 . . , . 11.85 ,, No. 6 . . * . 12.45 ,, an open basin, doubtless owing to the formation of butyric ether. the exaot nature of the distilling apparatus appears to be of little importance. latter conclusion is not in accordance with the experience of some other chemist& Conclusion of the Society’s Pmceedings,

ISSN:0003-2654    

DOI:10.1039/AN8871200011

出版商:RSC    

年代:1887

数据来源: RSC

摘要:

14 THE ANALI’S’P. A NEW PROCESS OF ESTIMATIXG GLPC ERIN I N FERMENTED LIQUIDS. BY L. EEGLER.* 1. THE process for the determination o€ glycerin in wines, as decided on by the Bsrlin Committee, has of late been improved, but there are still great sources of error, chiefly the loss of glycerin in the process of its purification by ether-alcohol. Pure glycerin is certainly soluble in a mixture of 1 volume of alcohol and 2 volumes of ether, but when other insoluble bodies are present they retain a not inconsiderable amount of glycerin, sometimes as much as 20 per cent. of the total. Repeated treatment with the ether- alcohol fails to completely remove all the glycerin, The process which I now recommend is based on the following principle :- The carbon of glycerin may be readily oxidized to carbonic acid by means of sulphuric acid and potassic dichromate. By using a Wills carbonic acid apparatus, and estimating tfhe loss in weight, we can calculate the amount of glycerin.The one flask contains the glycerin mixed with a saturated solution of potassic dichromate, the other contains, as usual, strong sulphuric acid. After the apparatus has been weighed, a little air is drawn out, which causes some of the acid to mix with the chromate. A regular evolution of carbonic acid soon sets in, but must be assisted towards the last by gently boiling. The flask containing the sulphuric acid must be kept cool. When no more gas bubbles are formed, the apparatus is cooled by partial immersion in cold water, and the remaining carbonic acid is expelled by a current of dry air.The apparatus is now reweighed, and the loss represents carbonic acid. The following equation shows the action taking place :- 3 C,H80, + 7 K,Cr207 + 28 H,SO, = 7 Kc,SO, + 14 Cr,(SO,), + 9 CO, + 40 H,O One part of glycerin therefore requires about 7.5 parts of K,Cr,07 and 10 parts of H2S0,, but an excess of each is of course used. The dichromate must be purified by re- crystallization. I n using a delicate balance 1 have a smaller apparatus made on purpose, and can then operate on -26 gramme of glycerin, but 1 also can work on -75 or 1 gramme ; if the balance is still sensitive to -01 or -005 grammes. The operation takes about one hour for every -25 gramme of glycerin. The following test analyses show the accuracy of the method. The glycerin actually weighed had a specific gravity of 1.2339 at 15°C.; and according to Lena’s tables contained 8608 per cent. of pure glycerin. Pure glycerin taken. Carbonic anhydride. Qlycerin founcl. 1.00 grammes. . . . . 1.445 grammes. . . . . 1.007 grammes. -500 ,, . . .. *725 ,, * . . . *505 j 9 *500 ,, . . , . *710 ,, . . . ,495 ,, 9 5 0 ,, . . .. .360 ,, . . . . *244 ,) *248 ,, . . ,. -3562 ,, . . .. *2483 ,, 950 ,, . . . . -3610 ,, .. .. ,2515 ,, -24s ,, . . . . -3587 ,, .. ,. 9600 f , The last three analyses were done with the aid of a delicate bttlance. 2. Estimation of glycerin in wine :- The crude glycerin obtained from 100 C.C. of wins, after evaporation with 3 C.C. milk of lime and 4 grammss of quartz, and extracting the inass with alcohol of 96 per * Zlepert.Anal, Chemie, 47, - _ITHE ANA4LYST. 15 -. - - -.- - -. -. -_ - -_ ___._ cent., is, after weighing, diluted up to a definite bu€k, and a!iquot parts are taken for the ash and the oxidation process. A white wine, containing 8.54 per cent. of alcohol and 2.07 per cent. solid matter, gave in 100 C.C. 1.4 grammes crude glycerin with -1278 ash. 25 C.C. of the glycerin diluted up to 50 c.c., yielding a 7 2 5 grammes GO, = 1.10 per cent, of glycerin. A duplicate experiment gave 1.47 crude glycerin with ~136 ash, *710 CO, = -99 per cent. glycerin; the average thus being 1 per cent., and the relation between alcohol and glycerin as 100 : 11.7. 3. Estimation of glycerin in wine after it has been purposely added. Three lots of 100 C.C. each of the same wine were mixed respectively with -125,950, -500 grammes of glycerin, and analysed as before.The results were as follows :- Crude glycerin. Ash. COS (28 C.C. from 50 c.c.) Glycerin in 100 C.C. 1155 . . .. ,1496 .. . . .so . . . . 1.115 1-75 , . .. -1400 .. , . *go .. . , 1.264 2 4 7 . . ,. ,1172 .. . . 1.07 . . . . 1.492 Allowing for the 1 per cent, of natural glycerin in the sample, we obtain -115, ,254, and ~492 per cent, of glycerin, The cthromate solution from the two last experiments was afterwards submitted to distillation, ond yielded about el6 grm. of acetic acid, derived from impurities in the crude glycerin. 4. Suppose it could be taken for certain, the process removes such bodies as sugar, tartmio, malic, citric, and tannic acids, which would interfere with the accuracy of the oxidation process, it would still be necessary to ascertain if there are other bodies in the orude glyoerin which would yield carbonio acid, From the experiments it would appear such a quantity of carbonic acid is constant.To separate any of these bodies, the diluted crude glycerin was mixed with an ammoniacal solution of lead acetate, the pre- cipitate filtered off, washed, dissolved in acetic acid, and this fluid, after heating to expel GO,, submitted to the oxidation process. A precipitate obtained from 100 C.C. of wine yielded an amount of carbonic acid equivalent to -035 grm. of glycerin. The true amount in the sample was therefore 1-00 - -035 = 0965 per cent, 5. Comparison of the old process with the oxidation process. 100 C.C. of the same wine treated by the old process gave the following weights of glycerin ;- After the first extraction -7177 including 0015 ash.,, swond ,, *1488 ?, -0123 ?, The residue weighed -3819 ,, -096 ,, The oxidation of these residues gave an amount of carbonic acid corresponding with -6300, 01295, and -1662, total -9257 grms. of glycerin, from which must be deducted *035. From these figures it will be seen the oxidation process is the best, the results obtained by the old process being too high, on account of small quantities of fatty and nitrogenous matters, and of organic acids, which cause the ash to contain potassic carbonate. The total glycerin, 09257, differs *0383 from the *965 grm. previously found, and this difference is due to loss during the drying of the glycerin after purifying with ether-alcohol.16 THE ANALYST.I have also got promising results with beer and sweet wines. 100 C.C. of Lager beer with 5.5 per cent. of extract, yielded after evaporation with 8 C.C. milk of lime and 5 grm. of quartz, q069 grm. of glycerin. The same beer mixed with *25 grm. glycerin gave ,308 grm. The quantity of recovered glycerin was therefore -308 - ,069 = a239 grm. For sweet wines I have introduced a modification based on the fact that glucose or invert-sugar are completely decomposed by boiling with strong alkaline fluids, like baryta water, and forms salts insoluble in spirits of wine. A quantity of wine as will yield about 3 grammes of solid residue is evaporated, first in a large basin, finally in a smaller one, with excess of baryta water, containing about 7.8 grammes of Ba2HO. Calcium hydrate does not answer so well, as too much of it is required, and the bulk is inconveniently increased.When no more water vapour is given off, the mass is mixed with 8 grammes of quartz, and then extracted four times in succession with 80 C.C. of alcohol of 85 per cent. The mixed alcoholic extracts are dis- tilled, and the residue is then ready for the oxidation process. If the wine contained cane-sugar, this must first be inverted by boiling with HC1. To test the accuracy of this process, I separated any barium from the fluid, by passing a current of CO, and adding a few drops of ammonia. After filtering and evaporating to a syrup, the residue, when dissolved in water, gave but a faint pre- cipitate with ammoniacal solution of lead acetate. Both filtrate and precipitate were subjected to the oxidation process. A sweet wine, with 15.17 per cent, alcohol and 15.91 per cent. extract was analysed, with the following result- 1. 20 C.C. = *320,-C02=.223 glycerin. 2. 20 c.c.+*496 added glycerin= 1.02 00, = -711 glycerin. Glycerin recovered, ~ 7 1 1 - -223 = *488. When Jirst treated with ammoniacal lead acetate, precipitates were formed, which I yielded an amount of CO, corresponding with no113 and 00146 grammes of glycerin. hope t o soon publish the results of further experiments.

ISSN:0003-2654    

DOI:10.1039/AN8871200014

出版商:RSC    

年代:1887

数据来源: RSC

摘要:

16 THE ANALYST. MONTHLY RECORD OF ANALYTICAL RESEARCHES INTO FOOD. A NEW TEST FOR PICRIC ACID AND BINITROCRESOL. K. FLECK. Repert. Anal. Chem., 1886, No. 48.-As many makers of farinaceous foods are in the habit of colouring them, it has been thought they may occasionally use picric acid. This suspicion is, perhaps, not well founded, as picric acid would communicate a bitter taste, and so render the products unsaleable. As it is, however, possible picric acid (Welter’s Bitter) may be unintentionally substituted for binitrocresol (Victoria yellow), which is largely used in the trade, it becomes important for an analyst to be able to positively distinguish these two colouring matters, which hitherto has only been possible by tasting the alcoholic extract. If a solution of picric acid is concentrated in a small porcelain dish, and mixed withTHE ANALYST. 17 a few C.C. of 10 per cent. hydrochloric acid, the colour is at once destroyed. Binitro- cresol is also decolourized after a few minutes. I f now a piece of zinc is introduced, and allowed to act for one or two hours, the picric acid turns a fine blue; but binitro- uresol turns blood red. To apply the reaction to foods, they must be powdered and extracted with alcohol. The residue obtained after evaporating off the spirit must be oarefully tasted for bitter, and then treated with hydrochloric acid and zinc as described. L. DE I<.

ISSN:0003-2654    

DOI:10.1039/AN8871200016

出版商:RSC    

年代:1887

数据来源: RSC

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THE ANALYST. 17 MONTHLY RECORD OF GENERAL RESEARCHES I N ANALYTICAL CHEMISTEY. ESTIMATION OF THE DECOLOURISING POWER OF AKIMAL CIIARCOAL. G. LAUBE. Repert. Anal. Chem., 1886, No. 49.-Analysts, unless engaged in sugar refineries, are not often called upon to perform this analysis, and therefore do not as a rule possess the required costly apparatus. The author therefore thinks an easy and practical process will be of some service to them. As a rule the questmion is merely whether a char has already been used or not. The first thing is to select a sample of undoubtedly genuine char, t o remove any whitish or suspicious-looking particles, then to powder and pass through a sieve. The powder is dried at 110" C., and kept in a stoppered bottle. It is labelled Standard Animal Charcoal.100 grammes of the commercial article, which has about the thickness of honey, are dissolved in 100 C.C. of water, then mixed with 100 C.C. of alcohol, and diluted with water up to one litre. After standing for a day or two, it must be filtered.. It is labelled Standard Colouring. The decolourizing power ( = 100) of the standard charcoal is now determined as follows :-Five grammes are put into a not too small flask, mixed with 300 C.C. of water, and heated to boiling. 10 C.C. of the standard colour are now added, and the whole again boiled for ten minutes, under an upright condenser, to avoid loss by evaporation, The fluid is now filtered through a double filter ; the filtrate, which must be quite clear, is, after cooling, mixed with a drop of solution of caustic soda, and put into a cylindrical glass. 200 C.C. of water, and a drop of caustic soda, are now put into another cylinder of exactly the same diameter, and as much standard colour is now added as will give it the same depth of colour aa the filtrate from the char. Suppose 2.1 C.C. were required, the char would have absorbed 10 - 2.1 = 7.9 C.C. standard colouring. If now a suspected sample should, when similarly treated, absorb 10 - 4.5 = 5.5 c.c standard colour, its decolourizing coefficient mould be- A solution of caramel is now prepared. 5.5 x 100 - 70. -- 7.9 As the decolourizing power also depends in a slight degree on tlie state of division, the same sieve must be used. L. DE R.

ISSN:0003-2654    

DOI:10.1039/AN8871200017

出版商:RSC    

年代:1887

数据来源: RSC

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18 THE ANALYST. CORRESPONDENCE. [Th Editor is not in any way reqionsible for q&-hiw eapressed by his correspondents.] To tlle Editor of the ANALYST. SIR,--I find in the last number of the ANALYST, in the report of the discussion on my paper, some remarks by Dr. Alder Wright on the plummet-method of taking specific gravities. I answered his criticisms on the occasion of the meeting, and uilderstood that such parts of the discussion as would appear in the ANALYST were all replied to in the nbst’raot of my remarks published on page 230. This, however, is not the case, as no reply appears to Dr. Wright’s criticisms. I shall therefore be obliged if you will allow me space for the following comments. In the first place there is a dist-inct practical advanta.ge in comparing with water at the ordinary temperature taken as unity the figures obtained with oils a t the boiling-point of water.This is in con- sequence of the construction of the Westpbsl Balance, and similar pieces of apparatus, and the weights used therewith. Practically, the numbers I give as expressing the densities of oils are the relative weights necessary to be used to counterpoise a plummet which is counterpoised by 1 gramme when immersed in distilled water at 1 5 O C. If the figures which were the actual result of observation were to be com- pared with water at the boiling-point as a standard, a troublesome calculation would be necessary, and, as Dr. Wright points out, the results would be vitiated to R certain extent by well-known causes. But I would point out that the value of the figures as accurate expressions of the relative weights of equal measures of liquids a t the boiling-point of water, compared wit4 thab of an equal measure of water at the ordinary temperature, is a very different thing from the oolutancy of tl@$pres obtained.Thus, it may not be zt fact that a cubic centimetre of butter-fat at 9gP C. weighs %80 gramme, but it is a fact that a particular sample of butter-fat which gives an indicated density of ‘8680 at 9 9 O C. by the Westphal balance will, on repeating the experiment, give a figure not varying by more than *0002 from that first obtained. Practically, what we desixe to know is the in&ioated cmnparativs density under the conditions in question. In the present condition of chemistry there is absolutely no useful deduction to be drawn from the density of a liquid fat, except in comparison with the density of other fats ; and if the observations be so made as to render all the results comparative, every object having either a theoretical or practical interest is attained.If any one have any desire for a more complicated mode of expression by all means let him adopt it, but I feel sure that analysts generally will prefer to employ figures obtained by directly reading off the indications of the balance, than certain other figures derived from the last by a somewhat complicated series of considerations, and which, in case of necessity, it would be perfectly impossible to get the average magisterial or lcgal mind to follow. I fully agree with Dr. Wright in his objection to such expressions as ‘‘ specific gravity a t 1OOQ compared with water at 159,” and have indicated my views pretty strongly elsewhere (“ Commercial Organic Analysis,” vol.i., page 7). The difficulty is to find some short mode of expression which would have a chance of being generally adopted by chemists, and which would express what was really meant. As pointea out by Dr. Wright, owing to the expansion o€ the plummet, the actual weight indicated would not be accurately the weight in grammers of 1 cubic centimetre at the boiling-point. In default of a better, I would suggest the term “ i n d i c a t e d p Z ~ ~ t . ~ ~ a ~ ~ ~ t ~ ” for expressing densities indicated by the plummet method, and would add the temperature of the liquid in each case ; it being understood that the plummet is one which indicates mnity when immersed in water at 15O C.Thus the ‘‘ indicated plummet-gravity ” of butter-fat at 999 C. ranges from -8670 to WOO, with an average of .8680 ; while butterine usually indicates between *8585 and -8625 under similar conditions. -1 am, sir, yours truly, ALFRED H. ALLEN. 1, Surrey Street, Sheffield, December 21st, 1886. “ADDING SALT TO MILK.” To thc! Bditor of the ANALPBT. DEAR SIR,-With reference to the footnote on the above case, this is not the first conviction in Scothnd for a similar offence. I enclose a newspaper report of the case which was tried on March 12th, 1876. Kindly return the inclosure, and make the correction in your next issue.-Yours truly, 86, Raglan Road, Smethwick, near Birmingham, 16th December, 1886. W.MCCOWAN. BOOKS, &c., RECEIVED. AMERICAN Analyst ; American Chemical Review ; American Druggist ; American Grocer ; American Journal of Pharmacy ; Brewer’s Guardian ; British and Colonial Druggist; Canadian Pharmaceutical Journal ; Chemist and Druggist ; Country Brewer’s Gazette ; Hospital Gazette ; Illustrated Science Monthly; Independent Journal ; Invention ; Journal of the American Chemical Society ; Journal of Microscopy and Natural Science; Justus Liebig’s Annalin der Chemie; Journal of the Society of Chemical Industry; Le Mouvement Hygienique; Manual for the use of the Board of Health of Massachusetts ; M e d i d Press ; Hedical Record ; The Miller ; Monthly Magazine of Pharmacy and Chemistry ; National Druggist ; Outlines of Quantitative Analysis, by A. Humboldt Sexton ; Pharma- ceutical Journal ; Pharmaceutical Record ; The Polyclinic ; Popular Science News ; Repertorium der Analytischen Chemie ; San Francisco News Letter ; Sanitary Examination of Water, Air, and Foal, by Cornelius B. Fox, M.D. ; Scientific American ; Society of Arts Journal. NOTICES TO CORRESPONDENTS. ALL Communications to be addressed to 325, Kennington Road, London, S.E.

ISSN:0003-2654    

DOI:10.1039/AN8871200018

出版商:RSC    

年代:1887

数据来源: RSC