摘要:

INCLUDING THE PROCEEDINGS OF On Butter Fat, by Dr. Dupr6, F.R.S., etc. , 87 Discussion on do. . . ., . . 91 Addendum, by Dr. Duprk . . . . 93 Wood Oil in Copaiva Balsam. . . . 94 THE “ SOCIETY OF PUBLIC ANALYSTS.” Review-Chemical Notes in Rhyme . . 97 Ergot of Rye . . . . . . 98 Cane Sugar in Wine, by C. A. Cameron, M.D., F.R.C.S., etc. . . . 99 PUBLISHED M 0 NT HLP. [No. 5.3 31st JULY, 1876.[PRICE 6d. 9%$2$,?$%:$~%t.] CONTENTS. A. H. ALLEN, F.C.S. J. FALCONER KING. A. WYNTEB BLYTH, M.R.C.S. OTTO HEHNER. C. A. CAMERON, M,D. E. W. T. JONES, F.C.S. C. H. PIESSE, F.C.S. I?. J. LLOYD, F.C.S.INCLUDING THE PROCEEDINGS OF On Butter Fat, by Dr. Dupr6, F.R.S., etc. , 87 Discussion on do. . . ., . . 91 Addendum, by Dr. Duprk . . . . 93 Wood Oil in Copaiva Balsam. . . . 94 THE “ SOCIETY OF PUBLIC ANALYSTS.” Review-Chemical Notes in Rhyme . . 97 Ergot of Rye . . . . . . 98 Cane Sugar in Wine, by C. A. Cameron, M.D., F.R.C.S., etc. . . . 99 PUBLISHED M 0 NT HLP. [No. 5.3 31st JULY, 1876. [PRICE 6d. 9%$2$,?$%:$~%t.] CONTENTS. A. H. ALLEN, F.C.S. J. FALCONER KING. A. WYNTEB BLYTH, M.R.C.S. OTTO HEHNER. C. A. CAMERON, M,D. E. W. T. JONES, F.C.S. C. H. PIESSE, F.C.S. I?. J. LLOYD, F.C.S.

ISSN:0003-2654    

DOI:10.1039/AN8760100085

出版商:RSC    

年代:1876

数据来源: RSC

摘要:

THE A N A L Y S T . THE COMPOSITION AND ANALYSIS OF BUTTER FAT. BY A. DUPRI~, Ph.D. F.R.S., Lecturer on Chemistry at the Westminster Hospital. Read before the 8ociety of Public Analysts, June 14th, 1876. UP to the year 1814 butter fat was regarded as consisting, like other fats, of a mixture of tri-stearate, palmitate, oleate, &c., &c., and with only a trace, 2 per cent. at most, of butyrine.On the strength of this assumption no attempts were made to distinguish butter-fat chemically from other fats, as it was felt that a maximum difference of 2 per cent. gave far too small a margin for safe conclusions t o be drawn. In July, 1874, however, Messrs. Kehner & Angell published a small pamphlet in which they showed that butter-fat yielded only about 86 per cent. of fatty acids insoluble in water, whereas, on the above assumption, it should yield, like most other animal fats, about 95 per cent.Here, then, was a difference, apparently, at once constant and of sufficient magnitude, to be available for the detection of adulteration of butter-fat, with at least such fats as are more commonly used for this purpose. The value of this alleged fact, for the purpose of detecting adulteration, depends chiefly on the constancy of the alleged proportion of insoluble fatty acids, and is independent of the nature of the substance making up the remainder.Nevertheless, it is of advantage to know the nature of this remainder, if for no other reason than to demonstrate why the insoluble acids should be as low as alleged.Measrs. Hehner and Angell accordingly made some attempts to supply this deficiency, and came t o the conclusion that it corsisted, besides, of course, the necessary glycerine residue, of fatty acids soluble in water, butyric acid chiefly. The method by means of which they endeavoured to show this was, however, open to objection and their explanation was therefore not generally accepted.I n the summer of 18'75, I in con'sequence undertook a series of experiments, in order, if possible, to clear up this point, which seemed t o me of considerable interest. The work was frequently interrupted and therefore progressed but slowly. A t our meeting in January, 18'76, I gave, however, a short description of some of these ex- periments, which seemed to me to demonstrate that butter-fat really did contain a con- siderable proportion of fatty acids, soluble in water, as Hessrs. Hehner and Angell had alleged.The experiments, it may be recollected, consisting in heating butter-fat either with water alone, or with water and a known amount of alkali in closed tubes, to a temperature of 500° F. I n the first case the fat splits up into soluble and insoluble fatty acids and into glycerine, in the second case the soap produced may be decomposed by means of a known amount of acid, the insoluble fatty acids collected as usual, while the soluble fatty acids are estimated in the filtrate by standard alkali.None of the experiments then recorded were, however, quite satisfactory, as owing t o constant leakage of the tubes, some loss had taken place in each case.Since then I have over- come this difficulty and now beg to lay the results of these later experiments before you, About 5 grammes of the dry filtered butter fat were enclosed in a silver tube, with about 80 cub. cent. of water, and heated t o a temperature of from 500 to 550Q F for a period of 4 t o 5 hours, After cooling, the tube was opened and the contents waBhed into a beaker, or latterly a flask, as recommended by Dr.Muter, and the insoluble fatty acids thoroughly washed, dried, and weighed without removing them from the flask or beaker. The silver tube was washed out with ether, and the Heating with water only.88 THE ANALYST. amount of fatty acids thus obtained, added t o that found as above. The aqueous filtrate containing the soluble fatty acids and glycerine, was neutralized with barium carbonate, boiled, filtered and evaporated, at first on a water bath, finally in vacuo over oil of vitricl.The residue obtained was then weighed and the glycerine present extracted with alcohol, or expelled by prolonged heating to a temperature of 1308 C, and the rest again weighed, the loss being taken as glycerine.Finally the residual barium salt was converted into sulphate, from which the amount of soluble acids present could be calculated. Neither of these processes is, however, quite satisfactory; in the first some barium salt is dissolved by the alcohol, in the second the glycerine cannot be all expelled without danger of decomposing some of the barium salt. (Owing to this I have not as yet been able to estimate the exact equivalent of the soluble acids present, but; I believe that it is verynear to that of pure butyric acid, I am now engaged in some experiments to settle this point more conclusively). In some of the experiments I therefore weighed the mixed residue of glycerine and barium salts, added sulphuric acid, evaporated, ipited and weighed again.On the assumption that the soluble acid present is butyric acid, we are then able t o calculate both the acid and the glycerine contained in the residue. The general results of the experiments I have already stated, via. :-that they show the presence of a notable proportion of soluble fatty acids. I may, however, give one experiment in full. Dry filtered but.ter fat taken ...L.. ... 4.800 grammes. Insoluble fatty acids obtained ... ... ... ... 4.202 ,, Mixed glycerine and barium sslt ... ... ... ... 1.059 ,, Sulphate of barium ... ... ... ... ... 0,3395 ,, ... This gives the composition of the fat as follows :- Insoluble fatty acids ... ... .. > ... ... 87.54 Soluble ,, ,, ... ... ... ... ... 5-33 Glycerine . , . ... ... ... ... ... 12.62 This still leaves a deficiency, due in part, I have no doubt, to an under estimation of the insoluble fatty acids, owing t o difficulties of manipulation, in part to the fact that the soluble acid is not, as assumed, pure butyric acid.I n three other experiments, each made with a different sample of butter, I obtained soluble fatty acids 5.3, 6-4 and 5.8 per cent. mean of the four 5-70 per cent., and glycerine 10.86, 11.5 and 11-8 per cent.mean of the four experiments 11-69 per cent. Heating with standard aqueous alhaZi. Tho same amount of butter fat as previously given was heated with 25 cub. cent. of normal soda solution, generally with the addition of some water, in the closed tube as before, to a temperature of 5OOQ F. for four hours. The resulting soap was decomposed by 25 cub.cent. standard acid, slightly stronger than the alkali used, and the insoluble fatty acids washed, dried and weighed as usual. I n the filtrate the acidity was estimated by a deci-normal soda solution, and after subtracting the excess of acid added the rest was calculated as butyric acid. Some of the results obtained were very good, but as I found that unless the soda solution used for saponi- fication was very much stronger than that given above, which, of course, is very objection- able on other grounds, nothing was gained by substituting soda solution for pure water, except! perhaps, that the experiments could now be performed in an iron instead of in a silver tube.In either case I had t o heat to at least 5009 F., €or not less than four hours to ensure decomposition. I therefore abandoned this method also, but will give two experiments performed in this manner.THE ANALYST.89 Twenty-five cub. cent. of the standard acid added to 25 cub. cent. of the standard soda required 3.8 cub. cent. deci-normal soda to produce exact regularity. let Exp. Butter fat taken ... ... ... 4.041 grammes. Insoluble acids obtained .. . ... 3-519 ,, Cubic cent. deci-nomeal soda used ... 28.5 From this we have- Insoluble fatty acids ... ... 87.08 Soluble ,, ,, ... ... 5.37 Finally I have adopted the following method which, I believe, desired on the score, either of facility of execution or of accuracy, of the dry filtered butter fat are weighed into a small strong flask. 2nd Exp.* 3-599 grammes.3.166 ,, 25.8 87196 5.38 leaves nothing to be About 5 grammes (I alwnss me one of the small assay flasks), 25 cub. cent. of a normal alcoholic soda solution are added, the flask is closed by means of a well fitting caoutchouc stopper, firmly secured by a piece of canvass and string, and heated in a water bath for about one hour. I think a much shorter time would be sufficient, but hitherto I have always heated for one hour.When cool, the flask is opened, the contents, which are semi-solid, carefully liquified by heat and washed into a flask with hot water. This flask is now heated for some time on a water bath to expel the alcohol, some more hot water is added and 25 cub. cent. of diluted sulphuric acid, somewhat stronger than the alkali used, are run in.The contents are now allowed to cool and the acid aqueous solution below the cake of fatty acids is passed through a filter. The fatty acids in the flask are washed by hot water in the manner recommended by Dr. Muter, i.e., each time allowed to cool ; all the washings are passed through a filter. I use no cambric, but pass everything through paper. With care scarcely any of the fatty acid will find its way into the filter.At first I used to dry the fatty acids in the flask and on the filter paper separately, making use of a counterpoised filter. I found, however, that the fatty acids evaporate from the filter paper even at a temperature of 105O C., and I now, after the washing with water is completed and the flask drained, wash any fatty acid that may be on the filter into the flask, by means of a mixture of alcohol and ether, boil off the alcohol and ether, on a water bath, and finally dry the fatty acids in the flask at a temperature of 105 Q C.The drying can be done readily if the melted fat is now and then shaken bris'kly, so as to subdivide the water as much as possible. In this way tthe acids, when once in the flask, are not taken out until their weight has been taken, thus reducing the risk of loss to a minimum. Meanwhile the acidity of the aqueous filtrate and washings is estimated by deci-normal soda solution.Subtracting from the amount required the proportion necessary to neutralize the excess of acid added in decomposing the soap, the rest represents the soluble fatty acids con- tained in the butter taken, and on the assumption of its being butyric acid, we can, of course, calculate the amount of this acid present.When once the equivalent of the soluble acids present in butter is fairly determined, this, of course, will have to be substituted for that of butyric acid. The results thus obtained are, I believe, very accurate, and the process is very simple in execution.I have satisfied myself by repeated experiments that *the alkalinity of the alcoholic soda solution by itself is not altered by the process. At one time I had hoped that the process might be conducted in open flasks, but the following experiments will show that a loss of soluble acid is thus occasioned, ~ ~- * This was a different sample of Butter.90 THE ANALYST which renders it necessary to use a closed flask.When once the decomposition of the fat is complete, the alcohol may be boiled off without loss. This boiling off of the alcohol is not, I believe, absolutely necessary, for, if we add a sufficient amount of water before adding the sulphuric acid, the fatty acids separated are practically insoluble in the very diluted spirit. As, however, the boiling off is, as far as I can see at present, no disadvantage, it may be as well to do it.Five portions of the same sample of dry filtered butter fat were treated each with 25 cub. cent. alcoholic soda solution; the first three, contained in open flasks, were heated on a water bath for a 9 hour, Q hour, and 1 hour respectively, the last two were heated in closed flasks for 1 hour in a water bath.In one of the latter experiments, No. 4, the alcohol was allowed t o remain; in the other, No. 5, the alcohol was boiled off previous to the addition of the acid. The following are the results :- Experiment I.-: hours heating, soluble acid found . . . . . . . . . 5-38 per cent, ,, 2-1 ,, ,, ,, . . . . . . . . . 4.90 ,. ,, ,, . . . . . . . . . 4.86 ,, Y ? 3-1 Y, ,, 4-1 9 , ,) ,, ), .. . . . . . . . 5.49 ,, , I 5-1 9 , ,, ,, ,, . . . . . . . . . 5.50 ,, ,? 7, ? Y 7, 2 9 9 The series clearly shows that prolonged heating in an open flask occasions a serious It may perhaps be useful t o give one of the above experiments in 25 cub. cent. of the acid addcd to 25 cub. cent. of the alcoholic soda required, 29.1 loss of soluble acid. full. per cent.deci-normal soda solution to produce perfect neutrality. I will give No. 5: Dry butter fat taken . . . . . . . . . . . . . . . . . . . . . Insoluble acids obtained . . . . . . . . . . . . . . . . . . 3.885 ,, Deci-nomeal soda required . . . . . . . . . . . . . . . . . . 56.5 cub. cent. 56.5-29.1 leave 27.4 deci-normal soda neutralized by the soluble fatty acids present. 4.380 grammes From this we obtain :- Insoluble acids .. . . . . . . . . . . . . . . . . . . . 88.69 per cent. Soluble acids . . . . . . . . . . . . . . . . . . . . . . . . 5-50 ), The same butter fat had previously been examined, in the nsual manner, for in- soluble fatty acids only, when 88-56 per cent. had been found. As a further illustration of the process I will give the analysis of the butter used in the above experiments, and those of the six last samples of butter received in my district, and will add for comparison the specific gravity of the melted fat taken at a temperature of looo F.compared t o water at the same temperature. Sp. Qr. at 1000 F. My own butter 9 12.4 District butter, No. 1 912.3 7, 9 , ?, 2 912'6 9 , Y, 7, 3 913.1 9 9 9 9 2, 4 913.0 9 , 9 , 7, 5 912.3 9 , :Y 9 , 912.3 Insoluble Fatty Acid.. 88.69 87-83 87.61 87.31 87-40 88-10 88.03 Soluble Fatty Acid. 5.50 5.40 5*73 5.66 5161 5.25 4.92 Calculating the amount of glycerine residue in each of the above c.ases, and adding it to the sum of acids found, we do not in any case come up to 100. This is, as before observed, no doubt due in part to the fact that the soluble fatty acid is ca?culated as butyric acid, whereas some higher acids are also present, in part, however, also to the fact that butter fat, as obtained by simple drying and filtering, does not consid of pure glycerides.THE ANALYST.91 The results given in the foregoing show? I think conclusively, that butter fat really does contain from 5 t o 6 per cent. of soluble fatty acids.It will be seen that the fat, whether decomposed with water only at a temperature of 500Q F., or with diluted alkali at the flame temperature, or with alcoholic soda in an open flask at a temperature not exceeding 1 7 6 O F., or, finally, with alcoholic soda in a closed flask at a temperature of 212O F. yields substantially the same products. The amount of glycerine found also agrees with this assumption, although but little stress can be laid upon that, as the glycerine cannot be estimated with sufficient accuracy.I am inclined to put more stress on the fact that the amount of glycerine residue calculated, added to the amount of acid found, falls short of 100. I n what exact state of combination this soluble acid is contained in butter fat must be decided by future experiments. In conclusion, B few words in regard t o a process (the spec.gr. of the fat taken at 100 F.) first employed by Mr. Bell, and since then strongly recommended by Dr. Muter, who even thinks, going in this somewhat beyond Mr. Bell, that a reputed sample of butter may safely be passed over as good if it shows a spec. gr. above 911. Kow, I am sorry to say, I cannot endorse this last statement. I believe that the spec.gr. of the fat is, as one of several factors, of great value in judging of the genuineness of a given sample of butter, but it cannot be safcly taken as the sole guide. Within the last week or so, I took the spec. gr. of a sample of mutton dripping, obtained about nine months ago out of my own kitchen, and since kept in my laboratory, and found it to be 917.3. The spec.gr. was taken several times, and otherwise checked, and there can be no doubt of its correctness. On my mentioning this fact to Mr. Bell, he suggested to me that the dripping had probably been strongly heated. I accordingly procured a fresh sample of mutton dripping from my kitchen, and this time found the spec. gr. t o be 904.8, when, however, this same sample was heated in a flat porcelain dish, for some time t o a temp.of about 300 C., the spec. gr. was raised t o 914-4, thus confirming Mr. Bell’s suspicion so far. I think it very probable that prolonged exposure to the action of the air, even at ordinary temperature, may have a similar effect. This clearly shows, that taken by itself, spec. gr.cannot be absulutely relied on as showing the genuineness of a sample of reputed butter. On the other hand, I think it will be found that whenever a sample of reputed butter shows a spec. gr. below 911 it may safely be pronounced adulterated. I must express my strong conviction that, as far as I can see a t present, no single property of butter fat, taken by itself, is of absolute value as a guide for judging of the genuineness of a given sample of butter, and I would, therefore, advise every one to submit each sample that comes before him t o as many tests as possible before he pronounces an opinion. Dr.Muter had listened to Dr. Duprd’s paper very attentively, as it showed an ad- vance in butter analysis to the extent of saponifying in a closed tube, and apart from that, it confirmed his, (Dr.Nuter’s,) process for the estimation of both soluble and insoluble acids, and of the standards he had laid down. The history of the modern system of butter analysis, was as follows :-In the years 1870-71, he, (Dr. Muter,) began to examine butter, which he did by saponification, first with alcoholic potash, and afterwards with lime and distillation of the whole ley with tartaric acid, so as to estimate the soluble acids. Want of time prevented him from fully publishing his results, and subsequently Messrs.Angel1 & Hehner saponified with potash decoinposed with acid, and estimatedTHE ANALYST. 92 the insoluble acids, pnblished their results, and fixed a standard, this standard Dr. Muter considered too low, and therefore published his process for taking both the soluble and insoluble acids, pointing out the importance of washing in a flask instead of on a filter, giviug as a standard for calculation of Soluble Acids .. . . . . . . . . . . 6.0 Insoluble Acids . . . . . . . . . . . . 88.0 Total ... 94-0 - As represcnting a fair low class butter, lookingas he now did at Dr. Dupre’s results done on early summer butter, Dr.Muter was pleased t o see therein a complete confirmation of the safety of his insoluble standard. I n his paper he had given the barium method of estimating the soluble acids as being, although the most tedious, yet the most accurate, but in the discussion he had mentioned two alternative ways of working, via, (1) The use of standard alcoholii! potash for saponification, and subsequently standard sulphuric acid and (2) The evaporation and ignition of the solution after exact neutralization with standard acid, and the estimation of the alkalinity of the ash an6 calculation to butyric acid.He saw that Dr. Dupr6, had been all along adopting the first of these methods, and he confessed that in practice he himself worked by it to save time, having first carefully standardized his solutions by the barium process.He, however, considered that it was essentially a dangerous method, except in the most practised hands. It was a necessity to save bulk to use a normal solution of potash each C.C. of which represents -056 KHO., so that even the slightest unsteadiness of hand and one drop too much put in, there is at once an appreciable excess of potash which when calculated t o per centage of butyric acid gives an enormous error.As the tendency is in this direction, the soluble acids thus estimated come as a rule too low, and he (Dr. Muter) thus viewedDr. Dupr6’s results as he rarely appeared to get the total up to 94, without which the speaker con- sidered that no analysis of butter mas perfect.He was much gratified with Dr. Dupre’s approval of his flask washing, which he was certain would commend itself to highly competent men like Dr. Dupre, for its simplicity and accuracy. Dr. Muter, also from practical experience, upheld the fact that by long boiling in an open vessel, butyric ether is formed and lost during saponification, and although he had not yet gone so far as actually saponifying in a perfectly closed flask, he had, in practice, reduced the boiling to a minimum and partially closed the flask, and had, no doubt, of the value of Dr, Duprd’s absolute closing principle.As t o Mr. Bell’s specific gravity process he entirely differed from Dr. Dupr6, and held that (especially when expressed in id actual density,” as modified by himself) it was a very useful process indeed for indicating what butters were worth the trouble of analysis.Mr, Bell’s results were, he understood, based on a long course of experiments, as also were his own in confirmation, and he unhesitatingly stated that there was no fat which had a gravity so great as butter. He especially took exception to the case of mutton dripping given, both as regards its gravity and acids, and was certain it could not have been pure.He had again and again examined dripping prepared by his own hands direct from the animal fat, and had found it to have a gravity of about 903 to 904, according to Mr. Bell’s system, and that it never, under any circumstances, showed less than 95 of insoluble acids. The lightest fat in the market was the so called ‘ I margarine,” which had a gravity of 901 to 901.5, and showed when quite fresh 93 per cent, andTHE ANALYST.93 when stale and after prolonged melting (the artifically added volatile portion having become dissipated) it yields 95 per cent. This gravity of 901 (= -903 actual density) is strikingly characteristic of the French artificial butter of which he had lately had occasion to examine many samples for members of the butter trade. He did not consider that this one experiment on dripping taken from a kitchen, and which might have really contained an admixture of butter, sihould weigh for a moment against the results obtained by Mr.Bell and confirmed by himself on undoubtedly pure samples. Mr. Allen quite agreed with a previous speaker as to the primary importance of the determination of the soluble fatty acid. I n confirmation of Dr.Muter's statement that he had been working for some years on the examination of butter by the estimation of the volatile acids, he might remind the Society that in an article contributed some four years since t o the Food Journal, by Dr. Nuter, the author distinctly stated that he was then working on and hoped to perfect a method of determining the butyric acid in butter.Dr. Dupr6s anomalous result of 92-46 (?) per cent. of insoluble fatty acids in dripping, Mr. Allen thought, might possibly be due to the employment of butter by the cmk. Addendum. Since the foregoing paper was written, I have effected the saponifica- tion, decomposition of the soap, and the washing and.drying of the fatty acids, at ordinary temperature, thus still further reducing the risk of breaking up the higher into lower acids. The saponification is readily effected by using a sufficiency of alcholic soda. Between four and five grams. of the dry butter fat were shaken up, for several minutes, with 100 cub. cent. of normal alcoholic soda. The butter soon dissolves, but after a time the solution gelatinizes t o a clear transparent jelly.(The temperature of the laboratory at the time of these experiments ranged between 22 and 2 5 O . ) This jelly is now allowed to stand over night, during which time the smell of butyric ether, very strong at first, entirely disappears. In one of the experiments the alcohol wag allowed to evaporate spontaneously, before the acid was added, in the other (made with a different sample of butter), the soap was dissolved in.about half-litre of water, and at once decomposed by the addition of hydrochloric acid. The fatty acids, which separated in white curdy masses, were thoroughly washed on a filter, with cold water, about 4 litres, dried in vacuo over oil of Titrio1 and weighed.The following are the results :- 1st E X ~ . Butter fat taken 4.545 grammes, insoluble fatty acids obtained 3,888 grammea. 2nd 97 77 1, 4,982 7 9 9 , 77 9 , . 4,299 9 , Ditto ,, 9 , 7, ,, 2nd Exp. 86.3 ,, Percentage of insoluble fatty acids found 1st Exp. 85 5 per cent. Butter fat, therefore, yields the same proportion of insoluble fatty acids, whether For the sake of completeness, I give the analyses of the samples of mutton dripping saponified with or without the aid of heat.referred t o in the paper. Spec. Gravity at Insoluble fatty Soluble fatty looo F. acids. acids. 1st Sample ... ... ... 917.3 92.43 1.69 2rd Sample, after heating 914.4 93.64 0.78 2nd Sample, before heating 904.8 95.44 0.09 It has been suggested, that the addition of alcohol or ether t o the fatty acids, and the subsequent drying, might give either too high a result by the formation of non volatile ethers, or too low a result by the production of volatile ethers.I find, however, that such is not the case. The fatty acids, when alcohol or ether have been added,94 THE ANALYST. certainly require a longer time of heating before the weight becomes constant, than is necessary when no such addition has been made, the ultimate amount found is, however, the same in either case.A report on “Butter hnaljsis,” by Mr. J. Bell, dated May 31st, 1876, has just been presented to the House of Commons, which contains some useful details, and I hope to return t o it at some future time. Meanwhile, I would take this earliest opportunity t o refer to two points in this report.Firstly, Nr. Bell is under a great misapprehension in supposing that Messrs. Hehner and Angell’s process ever fell practically into abeyance. On the contrary, it was at once taken up by a number of Public Analysts, and at the time of the report was, I believe, adopted by every Public Analyst, who had at all worked on the subject of butter. As evidence of the interest taken in this question, I need only refer to Dr. Muter’s paper, published with the discussion in the Analyst for March ; and my short note read at the meeting of Public Analysts, in Jamarg. Se,condly, I should like to ask Mr. Bell, if the per centages of fixed fatty acids given in Table III., and from which it is inferred that this per centage increases with the age of the butter, are in each case the results of two or more concordant analyses, or represent a single analysis only? If the latter is the case, the table is I fear of little or no practical value, since the results are then, in four at least out of the six cases given, within the limits of experimental error. A. D. A TEST FOR THE PRESENCE OF WOOD OIL I N COPAIVA BALSAM, THE ethereal oil of Dipterocarpus Balsam, otherwise known as Gurgun Balsam or wood oil, according t o Fluckiger, hkes a splendid violet colour, when dissolved in about 20 parts of bisulphide of carbon and a drop of a cooled mixture of equal parts of sulphuric and nitric acids added. Fish liver oil and oil of valerian also give a violet colour, but it is transient whilst the colour with wood oil is permanent for some hours. In order to exclude fish oil, a few drops of the liquid may be distilled over and the test applied. A. W. B.

ISSN:0003-2654    

DOI:10.1039/AN8760100087

出版商:RSC    

年代:1876

数据来源: RSC

摘要:

94 THE ANALYST. A NEW SOCIETY. ON the 13th instant there was gatkered at St. James’ Hall, a select company presided over by the Duke of Northumberland, their object being the formation of a “ Sanitary Institute of Great Britain.” We cannot but commend the objects of such a society, and they are multiform, including the improvement of the water supply ; the treatment of sewage ; the preren- tion of the emission of noxious vapours by manufacturers; the prevention of the pollution of rivers, &c., &c.After the opening address of the noble Duke, Mr. Gardner read a paper (‘ On the necessity for further sanitary legislation, with special reference t o Mr. Sclater Booth’s Pollution of Rivers Bill.” I n the full discussion which followed the reading of this paper, Messx Towle, Beal, Wood, Bartlett, and other gentlemen took part. Eventually an influential preliminary Committee was formed, with infitructions to report as to the further steps it is desirable to take, t o an adjourned Meeting t o be held in October. We wish this society every success, and may mention for the information of such of our readers as may feel interested in the objects it is intended to promote, that the offices are at 11, Spring Gardens, and that the Secretary is Mr. W. T. Xarchant.

ISSN:0003-2654    

DOI:10.1039/AN8760100094

出版商:RSC    

年代:1876

数据来源: RSC

摘要:

THE ANALYST. 95 ON MERCURIC IODATE ; ITS PREPARATION AND REACTIONS. By C~~ARLES A. CAMERON, M.D., F.R.C.S., Professor of Chenzistry and Zygiene, R. C.X.I., Medical Oflcer of HenZt7$, and Aianlyst for Dublin? &c. Read before the Society of Public Analysts, June 14th) 1876. SOMETIME ago, I introduced ferric iodate as a therapeutic substitute for the unstable ferrous iodide, having found from the results of some experiments conducted at the Lock Hospital, Dublin, that the medicinal properties of both compounds were nearly identical.Having had occasion whilst engaged in these experiments to prepare some iodates, I found that the descriptions of some of these compounds given is the larger treatises on chemistry, were both meagre and inaccurate. I n the present paper, I propose t o describe new methods of preparing mercuric iodate, and to detail several interesting reactions which I observed in connection with this substance. The only chemists who appear to have studied mercuric iodate are Rammelsberg and Pleischl : they state that it can only be prepared by digesting rFcently precipitated mercuric oxide with iodic acid ; and that neither iodic acid nor alkaline iodates precipi- tate mercuric salts.This is an erroneous statement, for though iodic acid fails to precipitate with mercuric chloride, it throws down precipitates from other salts of dyad mercury. Iodic acid added t o a hot solution of oxycyanide of mercury in the ratio indicated by the equation : -Hg. Cyz + Hg.0 + 2HJ0, = Hg 210, + Hg. C~72 + H20-gave a white amorphous precipitate, almost insoluble, which was with difficulty attacked by nitric acid, but which readily dissolved in hydrochloric acid.Exactly similar precipi- tates were obtained by mixing iodic acid and iodate of potassium with nitrate, and acetate of dyad mercury. The white precipitate thas procured mas dissolved in excess of pure potassium iodide solution, and on being acidulated yielded iodine corresponding to 46.32 per cent.in the form of iodic anhydride, the proportion required by theory in mercuric iodate being 46.18 per cent. ; the precipitate was completely volatilised by heat, and in other respects comported itself like Rammelaberg and Pleischl’s iodate. Mercuric iodate is, I find, soluble in solutions of alkaline chlorides, bromides, iodides, cyanides and cyanates, of disodic hyposulphite, and of chlorides of zinc arid manganese when dilute. Hydrochloric acid, even when highly diluted dissolves it : b u t when it is mixed with hydrobromic acid, bromine is set free, and it liberates iodine from hydriodic acid; in both cases the mercury salt is dissolved.Mercuric iodate is insoluble in soda, potash, ammonia, hydric disodic phosphate, borax, corrosive sublimate, and alkaline iodates, chlorates, bromates, and sulphitee, and in acetic, fluoric, and silicofluoric acids.It is with difficulty attacked by strong nitric acid. Mercuric bromate reacts with hydrobromic and hydriodic acids in the same way as mercuric iodate, but it is not soluble in alkaline chlorides, bromides, &c., which, however, decompose it.Mercuric iodate, dissolved in ammonium chloride solution, yields with ammonia a white precipitate, insoluble in excess of the latter, and solution of the iodate in disodic hyposulphite, gives with hydrochloric acid a red precipitate, soluble in excess of the acid. The nature of these precipitates has yet to be ascertained.96 THE ANALYST. To a solution of potassium chloride, mercuric iodate was added until it ceased t o be taken up.The crystals which first made their appearance contained the merest trace of mercurr, and yielded on analysis 58-78 per cent. of iodine, the amount required by theory, assuming the crystals to be potassium iodate, being 59.34 per cent. in the form of iodic acid. These crystals, therefore, consisted of slightly impure potassium iodate.To a solution of ammonium chloride, mercuric iodate was added in the proportion of two molecules of the former t o one of the latter. The solution was filtered from excess of mercuric iodate, evaporated, and the substances therein contained crystallized out, in four fractions. A relatively large amount of the substance separated in this fraction, and proved on analysis to be almost absolutely pure ammonium iodate. The solution was filtered and evaporated.Fraction 1. Fraction 2 was identical with Fraction 1. Fraction 3 contained a trace of mercury and consisted of slightly impure ammonium Fraction 4 consisted of a mixture of mercuric and ammonium iodates. The mother liquor gave with potash a yellcw precipitate, not soluble in cold dilute nitric and hydrochloric acids, but soluble in them by the aid of heat.Mercuric iodate dissolves in three molecules of ammonium chloride, sodium chloride, and potassium bromide, in the cold, and in two if the solution be boiling. Four mole- cules of potassium iodide, dissolve one molecule of Mercuric iodate. When mercuric iodate is dissolved i n Bay4 molecules of iodide of potassium, and the solution evaporated, potassium iodate separates, leaving in solution the crystallizable double salt, HgI, + 2EI.A great many double salts of mercuric chloride with alkaline chlorides, bromides, &c., may be formed in this way. A mixture of mercuric iodide, potassium chlorate, and water, heated to 170° C., in a sealed tube, undergoes no change, but at about 200° C., and especially with excms of chlorate, the brilliant scarlet color of the mixture soon vanishes.The tube, on being cooled, will be found filled with tufts of colorless crystals, completely soluble; OIL evaporating the solution of the contents of the tube, potassium iodate separates, leaving in solution mercuric chloride. It is a rule, that two soluble compounds will decompose each other, when by an interchange o f their constituents, an insoluble substance can be formed.The production of a precipitate under such conditions may, however, be prevented, by the formation of a soluble double salt, composed of an insoluble (per se) salt, combined with a soluble one. For example, solution of mercuric chloride fails to produce a precipitate when added to an excess of solution of potassium iodide, because the mercuric iodide formed in the solution, and insoluble in w a k , forms with potassium iodide the soluble salt, 2K1 + Hg.1,.The behaviour of mercuric iodate with soluble iodides, bromides, &c., is, however, quite different €rom that of the iodide of mercury ; the latter dissolves in solutions of certain iodides, &c., but the double salts thereby formed are readily pro- curable by the evaporation of their solutions. On the othei hand, mercuric iodate dissolves in solution of, say, ammonium chloride, but when the solution is evaporated it is neither the insoluble mercuric iodate, nor a double salt of mercuric iodate with ammonium chloride, which appears, but merely ammonium iodate.iodate.THE ANALYST. 97 As mercuric iodate would undoubtedly in the stomach become converted into mercuric chloride, this iodate cannot be employed for medicinal purposes. I n the present paper I have not exhausted the subject of mercuric iodate and its reactions, but I hope soon to lay before the Society the results of further experiments with this and other iodates, on which I am at present engaged. * VAN VOORST, Paternoster Row.

ISSN:0003-2654    

DOI:10.1039/AN8760100095

出版商:RSC    

年代:1876

数据来源: RSC

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THE ANALYST. 97 REVIEWS OF BOOKS, &c. DISCURSIVE CHEMICAL NOTES IN RHYME.* B y the Author of the Chemical Reuiew.” CHENISTBY and Poetry are not generally considered to be natural allies. The Scientist, as a rule, looks upon the poet as a mere trifler, and regards him with a feeling of pity tinged with contempt. On the other hand the poet has a certain fear of the Scientist--a man who weighs and measures and calculates everything to a fraction- and, admitting his usefulness, d ~ e s not desire his acquaintance.In the little book before us, however, we have Chemistry done into rhyme and very fair rhlme. It abounds in playful badinage and we feel sure that neither of the eminent chemists referred t o in the following lines will feel offended by this very good humoured attack :- ‘ I Anomalies are common : Abel will Doubtless be handed to posterity, For teaching men the readiest way to kill.A kindly man who would not harm a dy, With peaceful face, and voice as soft as silk, While fire-eating W anklyn writes on milk ! One studies missiles and torpedoes grim ; The other works on tea and chocolate, And tranquil water is a friend t o him, Of which, I think, we’ve had enough of late.The man of peace extols the means of slaughter j The fighting man is full of mi& and water! ” The Byronic style is of course apparent, and though we should be extremely sorry to be supposed for a moment to compare Professor Abel, to a Greek pirate, we must say :- The Chemistry is good, but the verse is better. ‘‘ A kindly man who would not harm a fly, With peaceful face and voice as soft as silk,” Irresistibly reminds us of ‘‘ The mildest mannered man, We commend this little brochwe to our readers. and amusing; and if not the former, certainly the latter. That ever scuttled ship or cut a throat.” They may find it both instructive Q VAN VOORST, Paternoster Row.

ISSN:0003-2654    

DOI:10.1039/AN8760100097

出版商:RSC    

年代:1876

数据来源: RSC

摘要:

98 THE ANALYST. ERGOT OF RYE. BY PROFESSOR DRAGENDORFF. Phcwmaceut Journal fNo. 312, p . 1001, 1076). PROFESSOR Dragendorff, in connection with Herr Stud Padwissotsky, has been engaged in the chemical examination of Ergot, and believes he has isolated the active principle. 1. Coming specially under consideration as an active constituent of ergot is ( a ) Scbromucin, a slimy substance which goes into solution upon extraction of the ergot with water, and which is again precipitated by 40 to 45 per cent.alcohol. It is colloidal, after being once dried it is with difficulty soluble in water, and it holds with the greatest energy constituents from which it might not have been freed. It contains nitrogen, but gives no albuminoid reaction, nor any reaction of an alkaloidal or glucosidal body.It gave to analysis :- 8.26 per cent. Water. 26.8 ,, Ash. 29.0 ,, Carbon. 6.44 ,, Hydrogen. 6.41 ,, Nitrogen. (6). A substance Dragendorff calls Xclerotic acid. This is a feebly acid substance, easily soluble in water and dilute and moderately concentrated alcohol. It passes in association with other constituents of the Ergot extract into the diffusate, when the extract is submitted t o dialysis, but after its separation in a pure state it is like sclero- mucin colloidal.It is precipitated by 85 to 90 per cent. alcohol together with lime, potash, soda, silica and manganese, but after macerdtion with hydrochloric acid the greater part of the ash constituents can be separated by a fresh precipitation with absolute alcohol. The sample analysed contained only 3 t o 4 per cent.of ash and gave- 40.0 per cent, Carbon. 5.2 ,, Hydrogen. 4-2 ,, Nitrogen. 50.6 ,, Oxygen. Sclerotic acid forms with lime a compound that is not decomposed by carbonic acid, and which upon combustion leaves 19 to 20 per cent. of calcium carbonate. I t s reactions, both qualitative and quantitative, are similar to those of scleromucin. The subcutaneous injection of 0.02 t o 0.04 grams brings frogs gradually into a state of perfect palsy, accompanied by a peculiar swelling, that may last six or seven days..Professor Dragendorff particularly insists upon the peculiar fitness of sclerotic acid *for therapeutic use, from its easy solubility in water and from the fact that it occasions no kind of disturbance in the cellular tissue if injected under the skin, and he further states that Professor Ton Holst, has used it in midwifery practice for a year and a half, injecting it under the skin in doses of from *04 to .05 grams.2. The red colouring matter, professor Dragendorff names Sclererythrin, he suspects that it is a derivative from anthraquinone, standing in near relation to chrysophanic acid and alizarine.Sclererythrin is insoluble in water ; but easily soluble in dilute and strong alcohol, ether, chloriform, dilute solutions of caustic potash, ammonia, &c., its solutions in alkalies are of a beautiful murexid colour, and when these are decomposed by an acid and shaken up with ether, the sclererythrin is taken up by the ether. Alcoholic solution - * It may be obtained from Dr.F. Witte Rostock, Mecklenburg, Germany.THE ANALYST. 99 of sclererythrin gives with aluminium sulphate, and with zinc chloride a splendid red mixture; with salts of calcium, barium, and many of the heavy metals it gives a blue precipitate. The amount of sclererythrin is very small, not more than /o or i0 of a part per thousand. 3. With sclererythrin is obtained a small quantity of another colouring matter, which, because it dissolves in concentrated sulphuric acid, with the productim of a handsome blue violet colour, the author has named Scleroiodin, its analyses gave- 5.5 per cent.Elydrogen. 3.87 ,, Nitrogen. Scleroiodin is not soluble in alcohol, ether, chloroform, or water, it dissolves in potash solution with the production of a splendid violet colour ; from this solution it is again precipitated by acetic acid.It is present in ergot in the proportion of about one to one thousand. 4. From ergot powder treated with aqueous solution of tartaric acid, after the two colouring matters have been separated by alcohol by treatment with ether, two crystalline substances can be obtaiued, both of which are without physiological action upon frogs, the one is in needle shaped colourless crystals, almost insoluble in alcohol and water, with difficulty soluble in ether, but dissolving in caustic ammonia and potash solutions, it has probably the composition C,, HIO 04, and the author names it Sclerocrystallin, the other crystalline substance has been named Scbroscanthin, and appears to be an hydrated compouhd of Sclerverystallin, into which it can be converted by heating with chloroform.Sclerverystallin can also be artifically brought back t o scleroxanthin, the formula of the latter is probably 2ClO H,, 0, + 3H2 0. The author also states he has isolated a yellow amorphus substance and a brown resinous substance, neither of which appeared t o have any physiological action upon frogs. He has also isolated Wenzel’s alkaloids (ergotine and ceboline), but found them almost inactive. Taurets crystinin was also prepared but found not to be a pure substance containing sclererythrin, to which perhaps its action on frogs is to be attributed. 64.88 ,, Carbon. 25.50 ,, Oxygen. A. W. B.

ISSN:0003-2654    

DOI:10.1039/AN8760100098

出版商:RSC    

年代:1876

数据来源: RSC

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THE ANALYST. 99 NOTE ON THE OCCASIONAL OCCURRENCE OF CAXE SUGAR IN PORT AND SHERRY WINE, SUPPLIED TO IRISH WORKHOUSES. BY CHARLES A. CAMERON, M.D., F.R.C.S. HAVING occasion t o examine very frequently wines supplied to the Infirmaries attached to Workhouses, I have on several occasions met with Cane Sugar in specimens of Port and Sherry, sent in by contractors t o those Institutions ; in one instance I found that the so-called Port Wine supplied, contained the enormous amount of 12 per cent.of solid matters, of which nearly one-half consisted of Cane Sugar. As Cane Sugar added t o Wine soon becomes conrerted into invert sugar, I have no doubt that nearly the whole of t,he Sugar in this wine was originally Cane Sugar. The Wines which are known as (‘ Hambro,” contain a large amount of alcohol, a small amount of solid matters, and a relatively much smaller proportion of acid and of mineral matters than are usually met with in genuine wines.In the fictitious wines manufactured at Hamburgh, and probably elsewhere, Cane Sugar may be detected for a much longer time than when it is added to genuine wines, such for example as sparkling Champagne and Moselle. This is owing to the small amount of free acid contained in the spurious wines. I have never found Cane Sugar in claret, nor do I believe that it is to be found in the wines imported from Spain and Portugal.The best way to determine the amount of sucrose in wines, is by the polariscope, Mr. Wigner, who has great experience in sugar analysis, reccommends for this purpose Duboscq’s. Those who do not use the saccharimeter will find the volumetrical copper method sufficiently accurate ; ten minutes’ boiling with the dilute acid mill be sufficient to convert the cane into invert sugar, and the matters usually present in wines will not sensibly interfere with the accuracy of the results.

ISSN:0003-2654    

DOI:10.1039/AN8760100099

出版商:RSC    

年代:1876

数据来源: RSC

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100 THE ANALYST. PROSECUTIONS UNDER THE SALE OF FOOD AND DRUGS’ ACT. A SPECIAL Petty Sessions was held at Duntser to hear a case in which Mr, William Burnell, grocer, &c., of Wootton Courtney, was charged by the inspector of weights and measures with selling as pure one ounce of pepper which was adulterated. Mr. Cooper, wholesale druggest and chemist, of Exeter, who supplied the defendent with the article in question, appeared and contended that it was not adulterated. Mr.Durham proved purchasing the pepper at the shop of the defendant and taking it to the county analyst, Mr. W . W. Stoddart, of Bristol, who returned a certificate stating that it was adulterated with 10 per cent. of starch. Mr. W. Stoddart stated that he analysed the pepper in question, and found that it contained at least 10 per cent.of starch from the flour of peas or beans. He produced the starch extracted from 30 grains of pepper. H e had since received a sample of pepper direct from the defendant for analysis, and found that it also con- tained the same percentage of starch. I n answer to Mr. Cooper, witness said that the glass produced also contained pure pepper-starch.For the defence, Mr. Buroett stated that he added nothing whatever to the pepper, and that he sent a sample of it, by Mr. Cooper’s request, to Professor Attfield, of London. John Middlewick, miller. of Exeter, proved receiving two sacks of peppercorns. He did not add anything whatever to the pepper, blit replaced it in the bags. The Stones were kept for other uses. Before the pepper the last things ground were beans.A small quantity of the bean-flour might have remained on the stones and so got mixed with a slight portion of the pepper. Mr. J. Attfield, professor of practical chemistry to the Pharmaceutical society, stated that on the 30th May last he received a sample of pepper by post from the defendant. He analysed it, and found no pea-meal, pea-starch or bean-starch in it.He was well aquainted with the operation of drug-grinding, and the previous witness’s statement that some bean-meal might get mixed with the pepper was correct. From the description which had been given by the miller of the process which he adopted in grinding he was of opinion that a small portion of the ground pepper would contain bean-meal. H e explained the finding of starch by Mr.Stoddart and not by himself by the suggestion that the portion sold to the inspector was a portion containing the bean-meal. The complete admixture of a little bean-meal with the whole bulkof pepper ground would be extremely unlikely. The bench were of opinion that the provision under section 6 of the Act of 1875, to the effect that no conviction could take place when an act of food or drug was mixed with extraneous matter in the process of preparation or collection, could not shield the defendant.There was no doubt that the starch was in the pepper, but they thought it was not wilfully put there ; still its presence was not unavoidable. The fine would be merely 6d. and costs, and they expressed an opinion that the case had been conducted in a very straightforward manner.The following charges for selling adulterated tea came before the magistrates at the Petty Sessions held at Newport, Isle of Wight.-Miss Winefred Long, grocer, of Calbourne. David Davis’s evidence was to the effect that he went to the defendant’s shop and purchased a quarter of a pound of tea at 2s. per lb. a e forwarded a portion of it to L)r.Hassall, the public analyst, whose certificate he now produced. The result of the analysis disclosed that the sample was one of “adulterated black tea” containing the following foreign ingredients :-Mineral matter 11.13 per cent., including small stones 5’60 per cent. ; lie tea 2.68 per cent. Adulterated with stores and lie tea. The lie tea was made up of dust of teadleaves, sand, and starch ; it is most likely derived from the caper tea in the sample.Mr. Blake called Mr. Maurice Dear, who stated that he had been in business at Cowes 50 years. Defendant was a customer of theirs ; the tea in question was sold by them to her. The chairman said they must, as the law stood, convict the defendant, but they would not inflict a heavy penalty.Fined 5s., and &1 9s. costs. Mr. Benjamin Wheeler, grocer, of Shanklin. Police-sergeant Chapton deposed visiting defendant’a shop and asking for a quarter of pousd of gunpowder tea. Defendant said he had none, but he had some young hyson. Witness consented to take a quarter of a pound of that. He sent the whole for analysis to Dr. Hassal, whose certificate he now put in. This document stated--“ This is a sample of young hyson tea containing mineral matter 6.5 per cent,, prussian blue and China clay a small quantity.Observations : This tea is strongly painted or coloured with Prussian blue and China clay.” Defendant said he would submit this sample to any experienced tea dealer in Hewport ; it was the purest green tea be could procure ; he sold it just as it came to him.The chairmau remarked that this Act was framed to protect the public from Adulteration, and those in the trade like the defendant should take steps to secure themselves. Fined 5s., and $1. 10s. costs. - _ _ _ _ ~ F O R S A L E . --%- ---- One pair of Balances by OZrtling.-Agate Planes and Edges, stops under pans. 1/200 grain when loaded with 1,000 grains, in perfect order. tube and thermometer packed in oak case, in excellent condition.Show One Hoffman’s Polariscope with Jellett’s eye-piece, 4 tubes for solutions, inversion Address S., care of Mr. Boot, 7, Nark Lane, E.C. Cost $14. Cost $24.THE ANALYST. 101 - BUNGE’S BALANCE. This Balance is designed for use in Chemical Analysis, and for all purposes where Extreme Exactness in weighing is necessary. MR.BUNGE’S great improvement in Analytical Balances is now so far recognised that several eminent balance makers have adopted the principle, and one maker at least has imitated Mr. Bunge’s pattern exactly, and even copied his prospectus and description, merely changing German into English. We mention this to show that the merits of Bunge’s Balance are now thoroughly accepted.The features of the Balance are as follows :- It is in very many respects a great improvement on the best constructed Analytical Balance of the ordinary form. It is much more sensitive. I t is much more rapid in its action. It is less liable to derangement by wear, or the action of corrosive gases. These advantages are obtained by two means, namely :- 1st-By a design as nearly as possible mechanically perfect in every detail.2nd-By the most exquisite workmanship. The Beam,-One of its principal distinguishing features is its rShort Beam; this is of the form of a right-angled triangle. The portions which represent the sides of the triangle act as trusses to the main portion of the beam, which represents the triangle’s base ; this construction, together with the very tough material employed for the trussses, namely,Aluminium Bronze, combines thr: greatest possible rigidity with the least possible weight j it is capable of‘ carrying an uncommonly heavy load without appreciable flexture.[OVER.102 THE ANALYST. The knife edges and bearings.-Among the numerous improved details may be mentioned the kn$e edges and the planes on which the knife edges turn ; these are all of Rock Crystal, a material harder than Agate.The edges touch the planes on a very long line, by which means great dura- bility is obtained ; and any adjustment is provided which precludes any possible deviation from perfect parallelism of the knife edges, and which is a means of obtaining maximum sensitiveness. Riders.-The contrivance for weighing by means of riders is novel and extremely convenient :-A divided scale, attached to the beam, is projected in front so as to be easily seen, and to permit of the placing of riders on any division of the devided scale by means of only orne sliding arm, which works from the right hand side, and takes the whole range of the beam from oae end to tpe other ; this arm lifts off the rider vertically, and its actions is facilitated by a counterpoise, which carries it out of the way of the beam when it is let go.&tion.-The mechalzism for putting the beam in and out of action is peculiarly efficient :-By turning a crank handle (on the left of the base) with a forward movement, the supports under the pans are lowered, and by a limited reversal of the movement of the handle, the pans can be quieted without otherwise interfering with the balance ; on turning the crank further forward) in continuance of the initial movement, a bearing, on which the pans hang when out of action, is lowered, and in its descent, places the pan-suspensions upon the termind knife edges of the beam ; a still further movement of the crank puts the balance in complete action by raising the central axial bearing. The beams and pan are gilt.The glass-case opens on every side. The base is of thick glass wbich gives great stability. The beam carries a very long index and the scale it traverses is so divided as to indicate a definite weight-value for each division of the scale. Load capable of being earried ......... Grainmes .........2000 ......... 500 ......... 200 ......... 20 Beam turns with ........................ Hilligrammes ... 0.2 ......... 0.1 ......... 0.1 ... 0.02-001 PRICE . . . . . . . . . $26 ........ $18 ......... $14 ... $12 10s. AGENTS FOR ENGLAND- X A W S O N & SWAN, MOSLEY STREET, NEWCASTLE-ON-TYNE. -THE ANALYST. BALANCE. To carry 20 grammes in each pan ... 12 Guineas 2, 200 2, 92 14 1, 1000 9 , 25 9 9 Y9 9 99 500 9 , 18 :; 103 GRAMME WEIGHTS (in Mahogany Boxes).From 10 grammes to 1 milligramme 18 Guineas 7, 100 71 I 2 2 9 9 ,Y 500 Y, 9 9 Y, 3, 9 , 200 9 , p 9 9 WOLTERS’ BALANCES.104 THE ANALYST. case is very different with the beam; here the number of vibrations in a given time augment in the ratio of the squares as the beam shortens, so that a beam one-third the length of another would perform nine vibrations to one vibration of the longer, while the loss of sensitiveness on that score only amounts to one-third.We can, therefore, by using such short beams, afford to restore the requisite sensitiveness bv lessening the distance between the points of gravity and suspension, and still retain to a great degree the advantage of quick action.Another consideration of importance in this respect is the extreme light- ness of the beam as compared with the long one. The friction being much less, this would also cause a greater freedom cd action, and tend to accelerate tbe vibrations. The capabilities of this balance are such that it yields to the tenth part of a milligramme with the greatest precision, and has a working range up to one thousand grammes.The appliance by which it is worked will be found extremely convenient. When not in use, all the knife edges are disengaged. By turning the handle, which is visible in the figure opposite, all the acting parts come into play one after the other. The whole range of motion of the handle is about one-half of a turn. Beginning the operation, the pans are freed first; they are easily brought to rest by gently bringing their stoppers in contact with them by carefully turning the handle back again once, or twice if necessary.When they are perfectly quiescent, the further turning of the handle engages the suspension pieces by gently and simultaneously bringing their knife edges in contact with their supports ; the end of the handle motion suspends the beam, and the balance is ready for use.After use the handle is turned back again, by which everything is set out of action. This arrangement, besides the great convenience it affords, prevents all unnecessary wear of the acting parts. In order to enable the final operation to be performed in the perfectly closed case. a parallel action and sliding rod serves to lift the rider and place it in the required position with the greatest ease, The rider can be used the whole length of the beam.To ensure greater strength the whole is fixed to a stout glass plate which is supplied with two spirit levels. The Balance is so arranged that it can easily be taken to pieces and put together again. The pieces, when apart, fit in a box, and can be carried about without any fear of injury in the transport.The knife edges and their supports are made of agate, and most carefully finished. The form I have adopted for the smaller weights from 0.5 downwards will also be found very con- venient. They are made of wire, turned up into a flat spiral, the inner end projecting and forming a little upright by which it can easily be taken hold cif.The number of coils indicates the number of anits in each decimal, and the decimals themselves are distinguished by different thicknerrszs of the wire. An inspection of this Balance is respectfully solicited at my office, 55, Upper Marylebone Street, Portland Place, London, W. 0. WOLTERS, (Many years with L. OERTLINB,) Hanufactaver of Weights, C%emical, Assay and Bullion Balances.~ _ _ _ _ _ ~ _ _ _ _ _ _ ~- LATTNERS QUALITATIVE AND QUANTITATIVE ANALYSIS WITH THE BLOWPIPE. P Profusely illustrated, 515 pages, Svo., new, 1875. Published at 21s. Offered for a short time at 6s. 6d. LETHEBY on Noxious Trades, 1s. post free. London : HENRY EIMPTON, Medical Publisher and Bookse\ler, 82, High Holborn. LETHEBY on the Right Use of Disinfectants, Is.post free. Circulating Library, 21s. per annum. List of Works on Chemistry, &c., gratis. In Wrapper, 2s. 6d. On Roller and Varnished, 6s. \OOD CHART, giving the Names, Classification, Composition, Alimentary Value, Rates of Digestibility, E Adulterations, Tests, &c., of the Alimentary Substances in General Use. By R. LOCKE JOBNSON, L.R.C.P., L.R.C.S., &c. One of the most useful publications of the time.”- tYeehZy Rmiew. London : HARDWICHE & BOGUE, 192, Piccadilly, W. PRICE 2s. CLOTH. HE MICROSCOPICAL STRUCTURE OF CERTAIN FRUITS AND ROOTS T to be met with in the Jams and Preserves of Commerce. By ARTHUR ANGELL, F.B.M.S., Public Analyst, County of Hants. To be obtained of GILBERT, High Street, Southampton. PROCEEDINM OF THE SOCIETY OF PUBLIC ANALYSTS,” Vol. 1, 1876. CLOTH, 2s. 6d. BY POST, 2s. lO+d, ELLIOT STOCE, 62, PATEBNOSTER Row. THE ANALYST. Subscription-3s. 6d. per annum, post free. Allliterary matter to be addressed t o G.. W. WIGNER, 79, Great Tower Street, London, E.C. Business communications, Advertisements, &c., to J. H. SCOTT, at the same address. Printed by ALFRED BOOT, 7, Mark Lane. E.C., for the Proprietors ; and Published by ELLIW STOCK, 62, Paternoster Row, E.C.

ISSN:0003-2654    

DOI:10.1039/AN8760100100

出版商:RSC    

年代:1876

数据来源: RSC