摘要:

THE ANALYST. FEBR UARY, 189 1. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. Tan annual meeting was held a t Burlington House on Wednesday, the 14th January, The President, Mr. Adams, in the chair. The minutea of the previous meeting were read and confirmed. The report of the auditors (Messrs. Cassal and Harland), was read, showing a balance in hand of S114, besides arrears due, whereupon Dr. MUTIIR moved, and it was carried unanimously, that the report be adopted and circulated among the members, and that another &lo0 be invested in Consols as soon aa convenient, Mr. Thomaa Hughes, Public Andyst for Cardift and Newport, was proposed as a member. The President (Mr. Adams) then delivered his valedictory address as follows :- &wrLEMEN,-In the first phce allow me to wish you a Happy and Prosperous New Year, This is, I beiieve, our 16th anniversary, and according to custom it is my duty to report to you the position of our Society, and in a brief manner to review the course of our proceedings during the year just expired.We have on our rolb nine honorary members, 169 ordinary members, twenty-seven associates. Eleven new members and two associates were elected during the year, & have resigned, and we have suffered the loss of one other by death, namely, Dr. Henry Smith, Barrister-ablaw and Public Analyst for Plumstead. He was a comparatively new member of much promise, and had he been spared might have become a useful and mtjve one. We have added a A100 to our l?'hancia,lly our position is quite satisfactory.32 THE ANALYST. funded property, and still have a good balance at our bankers; in point of fact we are some 363 richer now than at this time last year.We have held eight ordinary meetings, and besides Committee meetings there have been eight meetings of Council. The contributions to our transactions have included the following papers :- Date. PAPERS IN 1890. Author. Dr. Seaton and H. D. Richmond Dr. Vieth Nitre ” . . . . .. .. a . . . . . . . Dr. Muter Jan. 8. Feb. 12. ‘‘ A Rapid Method of Estimating Quinine in Medicines ’’ “ On the Composition of Milk and Milk Products ” “On the Detection of Methylated Spirit in Sweet Spirits i f “ On the Detection of Cotton Seed Oil in’lard ” . . “ On the Solubility of Phosphate of Alumina in Acetic Acid ” . . Marl6 12. ‘‘ On the Analysis of Disinfecting Pou7ders Containing Com- ,, .Dr. Muter and .. .. 1, L. L” T-VLLI.gLL W. C. Young mercial Carbolic and Sulphurous Acids ” . . . . . . Dr. Muter 99 ‘6 On the Chromate Test for Lead in Water ” . . . . . . S. Harvey ‘’ On the Determination of Rosin in Soap ” “Notes on the Bitter Principle of the Hop ar;d Meihods foE Distinguishing Between it and the Bitter of Hop Substitutes ” “On some Recent Advances in our Knowledge of the Sugar “ Some Points in the Analysis of Milk ” “ Notes on the Chemistry and Detection’df *Ce;t’ain Hip Sub- I‘ On the Adulteration of Fodi with’ Boracic’ Acid’; It. Williams M. A. Adams May)i4. June 11. Group” ., . . . . . . Dr. W. J. Sykes ,, u On the Nitrogenous ‘donstitkmts ‘df Maitm9’ . . . . . . Dr. W. J. Sykes H. D.Richmond ;; A. H. Allen and stitutes . . . . . . . . . . . . . . . . W. Chattaway Nov. 12. ‘‘ On Food Preservatives ” . . . . OttoHehner ,, C. E. CasBal Cream ” . . . . . . . . . . . C.E. Caw1 other Compounds ’’. . . . . . . . . . . . . . Dr. Ashby Dec. 10. On the Composition of Butter ” . . . . . . . . . . Dr. Vieth *, ‘‘ On the Detection and Estimation of Boracic Acidjin G l k a n i ‘‘ The Detection of M&h&:t’ed Spirits in Tinctures, Spirits, or 9, The country meeting, which was to have been held at Gloucester, was abandoned because too few names were sent in to give hope of a successful meeting. With this exception the ordinary meetings have been well attended and the discussions well sus- tained. The only remark I would venture under this head is the hope that in the future more of our younger members may be induced to contribute papers.Of the matters that have engaged the attention of your Council, some have been of great importance, and perhaps that which is most important of all relates to the qualifi- cation that should be required of candidates for the office of public analyst. On more than one occasion it has come to the knowledge of the Council that personsinadequately qualified have been appointed. I n some such cases it has bsen argued that becauae the district for which the appointment wag mada was small, and the payment for the work required was also small, it was impossible therefore to command the services of better qualified men. If not a mere evasion of the point a t issue the folly and error of thia argument is obvious.They proceed upon the a3sumPtion that the holder of an oflice of public analyst must of necessity reside within the district for which he is appointed.THE ANALYST. 23 Of course, if a duly qualified man can be found within the district, it is an advantage in many respects that he should be chosen. But in the alternative case, where such a man is not to be found, there seldom or never is much difficulty in obtaining the services of a well-qualified man in some neighbouring district able t o execute the duties just as well as though he lived within the district. But it is well known that there are other and more potent reasons that bring about In small places it often happens that interested motives rule in the selection of the public analyst, some of the individual items constituting tho appointing bodies not seldom being themselves the chief among the transgressors against the Food and Drugs Act, have an unwholesome fear of competent and independent officers, because, on their own personal accounts, they have so much reason to dread the efficient discharge of the functions of the public analyst.With the object of preventing these unfit appointments, so injurious t o the public interest and the regutation of our profession, your Council has memorialised the Local Government Board. Let us hope that the memorial may receive, not only due atten- tion, but also that it may result in the promulgation of some definite regillations as to the minimum standard for education and credentials to be required of future candidates before confirmation of any appointment to the offi:e of Public Analyst can be obtained of the Local Government Board.This naturally leads to a consideration of the question-How is it possible in some cases for a local or the central authority to decide upon the qualifications of a hitherto untried man? Our department of applied chemistry, during the last ten or fifteen years, has developed into a distinct specialty, and has attained so high a position as a technical art that none but those who have been trained to it can hope t o be sufficiently proficient to be safely entrusted with the exercise of a public function which in incompetent hands is liable to deal mischief and injury broadcast. The best available remedy for this state of things would appear to be an examinational test, specifically designed to dis- cover the practical knowledge of candidates in our own special department.It is not surprising that this necessity should have arisen; we find in other professions a similar necessity has arisen. I n the profession of medicine, for instance, until within the last ten or fifteen years, hygiene, or State medicine, as it is called, had few followers and fewer teachers, and no organised examinations; now, this department has developed into a large and most important branch, with its separate schools, teachers, and examiners, and it is likely in the near future to rank higher in importance even than curative medicine. As a con- sequence, not only are men found to devote themselves specially t o its cultivation and these unsatisfactory appointments. No such public test at present exists.24 THE ANALYST.praqtice, but also Parliament has deemed it necessary to impose special examinational tests as guarantees to the public thah practitioners of state medicine shall be duly and specially qualified for its practice before they shall be permitted to undertake the duties of medical officer of health. The case of the public analyst in all respects presents an exact parallel with that of the practitioner of public health ; the one is a State chemist and the other is a State physician, and both should be equally furnished with satisfactory credentials for fitness, each for their respective callings. Turning to another matter, you will remember that at about this time last year an overture emanating from the Institute of Chemistry reached this Society, having for its object an amalgamation of our Society with that body.The scheme met with partial favour ; some thought advantage would accrue from such an arrangement, providing always that effective provision could be devised to safeguard the special interests and promote the special objects for which our Society exists ; some thought an almagamation would strengthen our influence, support us in our dealings with public bodies, and give more weight to our counsel when applied for for legislative purposes, and that it would also provide a larger audience at our meetings, and, as a consequence, widen the interests and possibly increase the participation in our transactisns.All most desirable objects in themselves. But some, on the other hand, mistrust any idea of amalgamation, fear- ing not only that such a course would fail of these purposes, but that it would also be fraught with serious risk of a complete destruction of the influence and advantages which, as a separate Society, we have built up for ourselves and now enjoy. They believe that if our small Society cmeented to sink its separate identity in the general mass of the members of the Institute of Chemistry, that we should lose all cohesion and concentration of purpose, and in the end become absorbed into a large and unsympa- thetic body that certainly might, and probably would, give but scant attention to our special labours or particular interests. The negotiation, however, has not advanced beyond the preliminary stage of pro- posal, and if it bas not by this time actually dropped out of consideration, certainly it has not gained ground during tbe past year.If, however, the scheme should be resuscitated, it is important that ail of us should bear in mind what, as public analysts, we owe t o this Society, which bas been our rallying-place, our workshop, and our recreation-ground ; where we have taken counsel of one another, and made many friendships; where, to the immense advantage of our craft, we have contended in professional rivalry, but with personal amity; where crude notions have been tested, and sometimes forged into valuable weapons ; where accumulated stores of knowledge have been stocked, and models for our future guidance welcomed as to a home.I say God speed to t4he Society; may i t go on and prosper, and inspire all of usTHE ANALYST. 25 ~~~~ ~ ~- with a determination not to relax our hold one iota upon the profits, privileges, and pleasures it brings to us. The scrutineers of the voting-papers then reported that the following geiitleman had been elected as officers and Council for the year 1891 :- PRESIDENT-0 tto Hehner. VICE-PRESIDENTS (who have filled the offic3 of President)-M. A. Adams, F.R.C.S. ; A. H. Allen; A. Duprh, Ph.D., F.R.S. ; C. Heisch ; Alfred Hill, M.D. ; J. Muter, Ph.D., M.A., F.R.S.E. (Who have not filled the office of President)-R. R. Tatlock, F.R.S.E.; W. J. Sykes, M.D., D.Ph.; P. Vieth, Ph.D. TREASURER-C. W. Heaton. HON. SECRETARIES-R.H. Davies ; Bernard Dyer, B.Sc. OTHER MEMBERS OF COUNCIL-A. Ashby, M.B., F.R.C.S. ; T. P. Blunt, M.A. ; Sir Chas. Cameron, M.D., F.R.C.S. ; C. E. Cassal ; G. Embrey ; John Hughes; T. Stevenson, M.D , F.R.C.P. The names of those Membsra of Council whose term of office has not yet expired, and who consequently do not retire this year, are S. Harvey ; G. H, Ogston ; Bmerton Redwood, F.R.S.E. ; E. Seaton, M.D., F.R.C.P. ; and E. W. Voelcker. The following gentlemen were also reported to have been duly elected as members :- F. H. Perry Coste, F.C.S., Analyst, Lmdon ; LBO. Taylor, F.I.C., Analyst, Waltham- stow. Mr. ADAXS then said :-B2fore I reign this chair, gentleaen, t o the worthy s u e cessor you have chosen to follow me, I heartily thank you one and all for the support and courtesy you have accorded to me during my two years of office.Mr. HEHNER, having taken the chair as President, thanked the Society for the honour they had conferred upon him. He conld only assure them, perhaps he need not assure them, that he should do his best to uphold the interests of the Society and its independence, and to be just and right to every member of it, so that when the time came for him to give up €he chair to his successor, it should not be said that the position had suffered in his hands. With regard to the future meetings of the Society, Mr. Hehner subsequently stated that in order to suit the convenience of the new secretary, Mr. Davies, the Council had arranged to hold them on the first Wednesday instead of the second in each month, with the exception of that in this month (February), which will be held on the 11th inst.The President then moved, and it was unanimously carried, that vote of26 THE ANALYST. thanks be passed to the President and Council of the Chemical Society €or the use of their rooms during the past year. Mr. ALLEN having congratulated Mr. Hehner on his election, said he rose to move a vote of thanks to their retiring President, Mr: Adams, €or the manner in which he had presided over them during the past year, and for the admirable and eloquent address he had given them. These addresses were exceedingly important, for they enabled the President to bring before the Society subjects which were very im- portant, though not suitable for papers. He congratulated Mr. Adams on the able manner in which he had laid the various points in his address before them, and they would all read the address with great attention when they had the opportunity of seeing it in print. With respect to Mr. Adarns’s conduct in the chair, the speaker was sure they would agree with him that; he had shown himself to be the right man in the right place, with his aauvity of manner and his power of showing, when neces- sary, that he could put his foot down, as he had done when he had to stop discursive discussion. Dr. SPKES seconded the motion, which was carried unanimously, and Mr. Adams Mr. G . Embrey read the following paper : -U A Comparison of English and Ameri- can Cider, with Suggestions for Estimating the Amount of Added Water.” The Annual Dinner was afterwards held at the Hotel Continental, Regent Street, when a large number of members and friends spent a very pleasant and convivial evening. (Conclusioln of the Society’s Proceedings.) briefly returned thanks.

ISSN:0003-2654    

DOI:10.1039/AN891160021b

出版商:RSC    

年代:1891

数据来源: RSC

摘要:

26 THE ANALYST. PURTHER NOTES UPON THE ANALYSIS AND COMPOSITION OF BUTTER-FAT. BY WILLIAM JOHNSTONE, Ph.D,, F.I.C., 3l.C.S. IN the June number of the ANALYST of 1889, I roughly described a method whereby the soluble and insoluble fatty acids of a butter-fat could easily be determined with accuracy, and since the publication of that paper the correctness of the process has been confirmed by the, independent researches of Messrs. Eondzynski and Rufie, and recorded by them in the Zeitschr. Annal. Chern. (2901-6’). Since the publication of my previous paper I have introduced several improvements in the various manipulations, and the process is now carried out as follows :- The butter-fat is carefully clarified and saponified with a known quantity of standard alkali. The eaponification is carried out in the following manner.Instead of saponifying in a closed flask as previously stated, and which required to be repeatedly shaken, I now carefully weigh out 2.5 grams. into a stout glass tube with flat bottomTHE ANALYST. 27 (7 inches high and 2; inches wide), practically a narrow, strong beaker, then add 2 ozs. of N 95 per cent. neutral alcohol and 1 oz. of ether, and finally run in 25 C.C. of ___ NaHO solution, attach the tube t 3 an upright condenser, and heat by means of a water-bath until saponification takes place, the time generally required being about one hour. When saponification is complete, the tcbe is removed from the condenser, 3 02. of proof spirit added, and the titration immediately commenced, uaing phenolphalein as an indicator, the temperature of the soap solution being maintained at a temperature of between 80Q and 9 5 O F., the following being the actual figures obtained in three duplicate analysis operating in the above-described manner :- Fat taken Pu'aHU added H,su, added N aHO consumed Acid required t o complete titration N N - N N - l o t l a so4 N - Total NaHW consumed Average 25.00 25.00 12.00 12.00 - - P 3 .OO 13.00 11-61 11.50 11 50 IT.2.5 m o o 25.00 12.00 12.00 - -- 13.00 13.00 10.90 = 1 09 10.60 = 1.06 - - 11.91 11.91 11 92 Beef fat. 2.5 25.00 25.00 12.00 12.00 - 7 13.00 13.00 10.51 10.57 10-56 Working in this manner, an accurate estimation of the amount of alkali required for saponification is obtained, and from which the Koettstorfer number of the fat is readily calculated. The titration of the alcoholic soap solution requires, as stated, t o be made a t a temperature of between SOo and 90", otherwise results are obtained which a t present I do not venture to account for, but simply record them until I have time to fully in- vestigate the cause, as it is apparently not due to dissociation as is ordinarily accepted, as otherwise we should have more alkali consumed at 90° F.than at 60' F., whereas we have more consumed at 60° F. than at 909 F. Butter-fat taken 2.5 grms. 2.5 grms. Alkali taken -5- 25 -00 25.00 25-00 25.00 NaHO 12.00 12.00 12.00 N Acid added -- H,SO, 13.00 13-00 13.00 13.00 Acid required to com- N plete titration 10- 6.20= 0.62 6.50= 0.65 6 40= 0.64 6 . 6 0 ~ 0.66 H2S0, 60° I". . . .. .. 12.38 12-35 12.36 12.34 Thus :- 'liT -- 12*00 I__- Total alkali consumed at The above, upon standing a few minutes, begin t o show alkaline reaction, and de- posib a precipitate of fatty acids, the solution a t the same time evolving a continuous stream of small bubbles; if the solutions are now heated in the water-bath to a tem-28 THE ANALYST.~~ ~~~ ~~ ~ perature of 90' F., the precipitate that has formed redissolves, and the following quan- tity of acid is required to again render the solution neutral, which, upon standing any length of time, remains clear and also neutral. Total alkali required at 60° F. 12.38 12.35 12.36 12 34 N ,4cid required at 90° F. lo---, 3.42 = 0.34 3.20 = 0-32 3.20 = 0.32 3.30 = 0.33 12.04 12.03 12 04 12.01 I_ __ H2W Average of & a t 60° F.12-03 12 02 aHO 11.92 mtions . . * . .. * l o __ 9 7 9 , -~ at 909 F. NaHO Difference between the two esti- 11.92 *10 Beef-fat, or similar triglycerides, do not behave in the above-described manner. After the titration is completed, the alcoholic soap solution is carefully washed into a porcelain basin, the alcohol evaporated off, excess of acid added so as to decompose the soap, then gently heated until the fatty acids are melted. The insoluble fatty acids are now filtered off through an unweighed filter in the usual manner, thoroughly washed with boiling water until the washings are neutral, when the filter containing them is set aside in a moderately warm place and allowed to air dry. When the filter is sufficiently dry, it is transferred to a Soxhlet extraction- tube, and thoroughly extracted with drg ether, tbe acids being received in an acurately- weighed flask of sufficient capacity, so as to allow the Eltimate titration of the insoluble fatty acids to be made in the same flask; the washing out of the insoluble fatty acids with alcohol from the extraction-flask now becomes unnecessary.When the extraction is complete, the ether is evaporated ofF, and the flask and contents are placed in the water-oven, and when dry, allowed to cool and finally weighed. Thus :- Insolubb fattyacids and flask 32.4376 28.3180 32 4500 29.0433 27.3704 29.5244 .. .. . , 30.2942 26.1744 30.2948 26.8856 25.0144 57.1613 Flask Insoluble fatty acids of 2.5 grms. .. . . 2.1434 2.1436 2.1552 2,1577 2.3560 8.3631 + 40 = per cent. . . . .85 736 85.744 86.205 86,308 94.240 94.524 Average , . .. . . 85.74 86.25 94.38 When the percentage of insoluble fatby acids have been ascertained, add sufficient normal alkali to the flask, heat gently, when saponification rapidly takes place; then add 3 oz. of 85 per cent, alcohol, and titrate again with standard acid, and estimate the amount of alkali now consumed by the insoluble fatty acids, from which the Koettstofer number of the insoluble fatty acids can be calculated. HaHO taken 12.00 12.00 12.00 12.00 12 00 12.00 H,SjO, required 38*0=3.80 3 8 . 4 ~ 3 . 8 4 34*60=3.46 33.60=3*36 14.54=1*46 14*70=1*47 8.20 8.16 8 54 8.64 10.55 1053 _ - _ _ _ _ - - - Thus :- N N 7 - - - - - Average 8.18 859 1054TIIE ANALYST. 29 Then N 1va ti0 N consumed by 2.5 grms.butter 11.51 l i 50 11.91 11 94 10.54 10 57 8*20 3-16 8.54 8.64 10.55 10.53 _ - _ _ - _ _ _ - ,, by fatty acids NaHO Average, 3 32 3.33 0.02 3.31 3.34 3 37 3 30 ‘01 + -04 - N - required by soluble fatty acids of 2.5 grms. of butter-fat calculated into C,H,O,. NaHO -_ - 11 #651 11.756 11.776 11.616 Average, C,H,02 11.70 11-69 Working in the manner indicated, we obtain an accurate estimation of the total soluble and unsoluble fatty acids contained in a butter-fat ; as the accuracy OF Koetts- torfer’s process has never been questioned, it stands to reason that if the saponification number can be accurately determined in the original fat, it can also be accurately determined in the insoluble fatty acid, and any difference between these two determina- tions must be due to soluble fatty acide.The process as described is simple, rapid and accurate, only requiring ordinary care; No complicated apparatus or delicate reagents are necessary, such as those required for the Reichert Wollny process-a process which has been described by Mr. Otto Hehner (now the President of the Society of Public Analysts) as follows :-“ Vhatever compara- tive results Reichert’s process was capable of furnishing, ;f always performed in the same manner. Yet analysts should not on principle tolerate aprocess by whioh only aportion of the substance to be estimated was obtaintd ; but in all cases where a real and accurate estima- t i o n was possible, such rough and ready methods shoatld not be admitted by carpful analysts.’) I n my previous paper I expressed some doubts as to the nature of the soluble volatile fatty acids ; but from the results obtained in the following experiment all doubts in my mind upon that point has now been removed.Considerably over one pound of butter- fat was saponified with NaHO, the resulting soap decomposed, and the soluble fatty acids again neutralised with NaHO (after the separation of the insoluble fatty acids had been accomplished), and evaporated to crystallisation, the glycerine drained off, the salts redissolved in water and recrystallised, the crystals obtained being washed with a mixture of alcohol and ether (two parts of 90 per cent. alcohol and one part of ether) to remove any adhering glycerine and water, and then air-dried. The purified crystals were then placed in a retort, water added to dissolve them, and finally H2S04 added, and distillation conducted by means of an oil bath, until vapours of H,SO, began to appear in the retort.The distillate obtained was neutralised by BaH,C), solution, and then a current of CO, passed through the solution, which was afterwards heated, and finally filtered. A portion of the liquid was then evaporated on the water-bath, to dryness, and finally dried at 260” F., thus- Barium salt dried at 260” F. + Basin .,, 40*2200 Basin ... ... ... ... ... 39.82711 Amount of barium salt taken ... ... -392230 THE ANALYST, Redissolved in water and evaporated with dilute H,SOa, and again evaporated to dryness, and igniting gave Basin + BaSO, ... ... ... ... 40.1224 Basin ... ... ... ... ... ... 398276 BaSO, ...... ... ... . , , -2946 A 100 parts of the above barium s d t yielding 75.19 per cent. BaSO, A 100 ,, Ba(C4H702L 9 9 74-93 per cent. BsSO, Further research in this direction was not continued. The glycerine and mother liquor obtained in purifying the barium salt was now examined for the possibility of it still containing a soluble non-volatile fatty acid, but with negative results, as far as the investigation in this direction was carried. I now directed my attention to the volatile fat acid which collects in the condenser when a Reichert Wollny test is being made. Some of the fat thus collected was dis- solved in 95 per cent. neutral alcohol, and then carefully neutralised with an alcoholic solution of BaH,O,, which caused a heavy white precipitate which was filtered off from the solution it was formed in, then carefully washed with alcohol and ether, and finally dried over sulphuric acid.A portion of the barium salt thus formed was taken and dissolved in dilute sul- phuric acid, and evaporated to dryness in the water-bath, ignited and weighed, which gave the following results :- Amount of barium salt taken = 02525 Weight of BaSO, produced from amount taken *1222 A 100 parts of above barium salt yields BaSO, 48-39 A 100 ,, ,) Ba(C,,,H,,0,)2 ,, BaSO, 48.64 Consequently the above result proves the fat collected in the condenser consists mostly of capric acid. The results of the analysis of the two butters as given in this paper were obtained from June butters ; the first was received from Norfolk, the second from Ireland.The insoluble fatty acids in both instances being the lowest I had ever obtained with correspondingly high soluble fatty acids, as butyric acid, and at the same time giving results unaccountable when reviewed as follows, I determined, if possible, t o secure more of the butter for further examination, as there was no doubt whatever as t o their genuineness, both samples being from private country dairies, the cows not being kept, in a commercial point of view, more than for domestic consumption of large private establishments. Insoluble fatty acids ... ... ... 85.74 86.25 Butyric acid.. . ... ... ... ... 11.82 11.69 Gfyceryl ... ... *., ... ... 5.82 6.03 103.38 103.97 -- The above figures, however, are not correct as regards the glyceryl, as the glycerine has been very carefully estimated in duplicate by the well-known method of Messrs.Benedikt and Zsigmondy, and gave the following results :- C,H& 12.08 12.23 12.24 12.19 = C,H2 4.98 5.05 5.05 5.03 Average for C,H, 5.01 5.04THE ANALYST. 31 proving that the glyceryl cannot be correctly calculated in a butter-fat from its saponifi- cation equivalent. I am now engaged upon the examination of the insoluble fatty acids when pressure of outside business does not interfere with same, and the results already obtained suggest to my mind the following explanation, namely, that there are two kinds of butter, one a compound tri-glyceride, giving insoluble fatty acids as lorn as 85.81 per cent., and one a mixture of two compound tri-glycerides, giving insoluble fatty acids up t o 90 per cent. The first may be represented by this formula :- C18H3302 1 C,,H,,O, C,E5 = 748 At.Wt. ~,,Hl,O, i Iso-oleo-palmito-capriate of glycerine the first radicle having the following con- stitution :- The iso-oleo-palmito-capriafe of glycerine may be represented iis follows :- Theory. C,,H2,0 26.33 CH 1.73 C,H70 9.49 yields upon C,,H,,O 34.09 saponification C,,H,,O 22.86 C,H, 5.47 99.97 Theory. Found. C,,H,,O, 28.60 CH, '1 2-13 C,,H,O, 34.22 C1,H2,0, 2 2.9 9 C,H,02 11.76 11.70 C,HsO, 12.30 12.23 11 2.00 From the above formula it will be at once apparent that I am assuming that a butter-fat yielding 85.81 per cent, of insoluble fatty acids is a tri-glyceride wherein the first radicle of t.he tri-acid compound is a compound acid of the formula c13'E;12'0 } CH, (iso-oleic-acid ?) tridecatoic methane butyrate, the second radicle being palmitic acid, and the third radicle capric acid, forming a molecule of butter-fat.When a compound such as tridecatoic methane butyrate is saponified with an alkali in 95 per cent. alcohol, the following equation may be taken as representing the change which takes place, thus :- C,,H,,O, + 3NaHO = CI3H2,NaO2 + C,H7Na02 + CH3NaO+H2 Iso-oleic- Sodium Sodium Sodium Sodium c, H7 0 acid. hydrate. tridaco tic. butyrate. methylate. Hydrogen. The second butter spoken of is a mixture of the above tri-glycerine with tri-nonde- catoic acid. Thus :- C18H3302 I C,,H,,% \ c, HI402 1 C16H3102 C3R5 019H3702 1 C19H3702 C3H5 Of course, I advance the above theory with all due reservation, but from the results obtained I think I am warranted in advancing it, the correctness of which, of32 THE ANALYST. course, will be proved when a closer examination of the insoluble fatty acids have been made an investigation, which I have now well in hand, and the results already obtained in that direction are so far favourable to supporting it. The two samples of butter-fat at present under examination are so very much alike in composition that I shall now draw your attention to the three samples of butter-fat mentioned in the June number of the ANALYST of 1889, and then the difference between these samples when viewed by this theory immediately became apparent.I f the C,H 0, found is calculated into the iso-oleo-palmito-capriate of glycerine we get the following results :- A.Fatty acids. W. Fatty acids. Y. Fatty acids. Thus in sample Iso-oleo-palmito-capriate 1 62-47 = 53.61 53.21 = 45.66 65.19 = 85.95 of glycerine 37.53 36.00 46.79 44.88 34-81 33.39 100*00 89.61 100*00 90.54 100-00 89.31 Fatty acids actually found 89.95 90.00 89.83 It now becomes apparent that the radicle of cenanthylic acid might replace one of nondecatoic acid in the tri-glyceride, and form the di-nondecatoic cenanthylic of glycerine, which apparently is the case in sample marked W, for when calculated as di-nondecatoic cenanthylic the insoluble fatty acids came to 90.12 against 90.00 found ; a result well within the limit of error, as the process has been rendered more accurate since the temperature was taken into consideration, and which was previously not con- sidered of so much importance. The difference between the amount of iso-oleo-palmito- capriate of glyceride and 100 I put down as tri-glyceride of nondecatoic acid (as I have results which point to such being the case) the following peculiarity will be observed, namely, that starting with butyric acid we have every fourth acid of the series in butter- fat up to nondecatoic.I n concluding this paper, I add the following detail, obtained from the butters mentioned in this investigation, so that they may be also put on record :- Sp. gr. at 37W'C . , . . 90'7.80 904.74 0906.63 -913.85 -912.96 Melting point .. . . 36*5@C 36.5OC 36*OoC 30 8@C 31.2"G Sp. gr. fatty acid at 15*5QC . . 96335 96349 96325 797.58 797.66 Melting point fatty acids . , 41.5OC 41.5"C 41.0°C 3 8 ~ 3 ~ C 3S*5*C Since writing the above an unexpected confirmation of the amount of butyric acid contained in a butter yielding 85.80 per cent.of insoluble fatty acids has turued up. I find from my laboratory nute-book that on the 3rd February, 1887, I received a sample of butter which gave 85.80 per cent. of insoluble fatty acids, and had the follow- ing specific gravity and melting point :-- Sp. gr. a t 378°C 913.83 Pilelting point. 29.4OC. A portion of this butter, 3.9971 gramF., were saponified with lime in a flask, 100 C.C. of water containing phosphoric acid added, and then 500 C.C. of water, and then 500 C.C. distilled. The addition of the 500 C.C. and distillation was repeated five con- secutive times, the last 200 C.C. coming over perfectly ncJutlral; the varioun distillates were then titrated, and gave volatile acid calculated as C,H,02. 1 Distillate 3-845 - - - - -- - (CI9H$702)3C3H5 '1 A. \V. Y . I. IT. 2 77 3.192 3 7 7 2 425 4 5 ) 1.210 5 1 7 1.100 -- Total C,H,O, 11.772 against theoretical 7.76THX ANALYST. 33 The subject is one which has up to the present been beset with great difficulties, so I have ventured to record a few preliminary results, for if I might so write this investigation is merely in its infancy; a largo amount of tedious and laborious work will require to be undertaken before I can thoroughly establish tho correctness of my theory, consequently I have been induced to advance the same in its embryo in the hope that others with more leisure than myself may be enticed toinvesti- gate the subject in the direction indicated, and help to solve the question of butter analysis, as it certainly is in a most unsatisfactory state at present.

ISSN:0003-2654    

DOI:10.1039/AN8911600026

出版商:RSC    

年代:1891

数据来源: RSC

摘要:

THX ANALYST. 33 STUDY OF A METHOD FOR THE QUANTITATIVE DETERMINATION OF SUCROSE, INVERT-SUGAR AND DEXTROSE, OR LEVULOSE. BY F. G. WIECHMANN, PH.D. (Concluded from page 19.) The dextrose used in the following experiments was anhydrous crystallised dextrose, The levulose was prepared under the writer's directions in the following manner : prepared under the Behr patent. . . .. .. 18 gramme.. Inulin . . .. Sulphuric Acid (sp. gr. 1.840) .. . . 36 cc. Water . . . 9 . . . . . . 516 ?? This solution mas set aside for nine days, then judt neutralised with barium hydrate, filtered, and the filtrate evaporated to a solution having a density of 1.0043. The levulose solution was examined by the polariscope, and tested with Fehling's solution, and was found by both tests to possess the properties of chemically-pure levulose.The invert-sugar solution was prepared by dissolving 13.024 grammes of chemieally- pure sugar (sucrose) in about 75 C.C. watsr, adding 5 C.C. hydrochloric acid, and heating in a water-bath up to between 670 C. and 10* C. When the contents of the flask had attained this temperature, they were kept a t this point for five minutes more, with fre- quent agitation. Then the contents of the flask, after having been caoled down to 1'1.5" C., were made up to 100 C.C. with distilled water. Fifty C.C. of this solution were removed, placed in a litre flask and made up to 1000 C.C. Twenty-five C.C. of this solution correspond to 0,1628 gramme dry substance. This amount, or whatever amount be taken for the analytical determination, must', before mixing with the copper solution, be neutralised by a solution of sodium carbonate, which is prepared by dissolving 1.7 grammes of the anhydrous salt in 1 litre of water.A preliminary test made of the Sieben process on pure invert-sugar was the following : Placed 25.0 grammes granulated sugar in 1 litre of water. Of this solution took 50 c.c., added 5 C.C. concentrated hydrochloric acid and made up to 100 C.C. Heated for five minutes between 67" and 6gC C., cooled, neutralised with sodium carbonate, and made up to 500 C.C. Of this solution 5 C.C. = 0.125 grammes dry substance were used for the determination,34 THE ANALYST. Thie gave before Sieben’s treatment . . .. 0.243 copper. Copper that should have been found after Sieben’s treatment , , .... . . 0.1215 Copper found . . .. .. .. 0.1 200 EXPERIMENT I. Determinations made : 1. Invert-sugar separately. 2. Anhydrous dextrose separately. 3. Mixture of invert-sugar and dextrose in known proportions, 4. Mixture of invert-sugar and dextrose, after Sieben’s treatment. 1. Took 13.024 grammes chemically-pure sugar, dissolved in 100 C.C. flask, inverted Fifty C.C. of the inverted solution were Twenty-five C.C. of this solution equal 0.1628 grammea dry sub- This was neutralised with Na, Go3, and the invert-sugar determined by the Result .. ., .. .. 0.311 gramme Cu. Ten C.C. of this solution, corresponding to 0.25 gramme dry substance, were used for the copper determination. with 5 C.C. HCl (German Government Nethod). made up to 1000 C.C. stance. copper-test.2. 12.5 grammes anhydrous dextrose were dissolved up to 500 C.C. water. This determination was made three times. Results : Determination No. 1 .. .. = 0.473 CU. 9 9 7, 3 . . . . = 0.473 ,) 19 9 9 3 . . . . = 0*4?5 3. Two hundred C.C. of solution No. 1 (= 1.3024 gmmmes dry substance) were mixed with 80 C.C. of solution No. 2 (= 2.000 grammes dry substance). OF this mixture, 35 C.C. were taken for the copper determination. These 35 C.C. represent, of solution No. 1,25 C.C. (= 0,1628 gramme dry substance), and, of solution No. 2, 10 C.C. (= 09500 gramme dry substance). Hence, if this mixture of invert-sugar and dextrose should reduce copper in the same proportion as these sugars do separately, the amonnt of Cu reduced here should be equal to the sum of the copper reduced by determination No. 1 + determination No.2 given above, and equal to 0,784 gramme Cu. This determination was also made three times. By two minutes’ boiling there were found : Results: Determination No. 1 . . . * = 0.764 gramme Cu. 9 , $ 7 2 .. . . = 0.769 ,, $ 9 ,? 9 9 3 ‘ 9 .. = 0.772 ,, 9 , Repeating this experiment once more, but boiling €or three minutes, there wero found 0.7’75 gramme Cu. 4. Took, of solution No. 3, 212 C.C. (= 2.5 grammes dry substance). Heated for three hours with 60 C.C. six times normal strength HCI, cooled, neutralised with six times normal strength sodium hydrate, made up to 500 c.c., and used 50 C.C. of this solution (= 0.25 gramme dry substance) for the copper determination. These 50 C.C. consisted of : Inverb-sugar . . . ... * . 0.09 86 1 grammes. Dextrose . . .. . . ., 0515143 ,, 0.09861 invert-sugar reduces . . . . 0.138 Cu. 0.15143 dextrose reduces .. . I 0.286 ,,THE ANALYST. 35 One-half of the invert-sugar is dextrose; hence we should expect a yield of : 0.188 + 2 = 0.094 CU. 0.286 ,, 0,380 and there were found : CLI = 0.3836 grammeg. EXPERIMENT 11. Determinations made : 1. 2. 3. 4. 1. 2. 3. CU. duced Invert- sugar. Levulose separately. Mixture of invert -sugar and levulose in known proportions. Mixture of invert-sugar and levulose as in No. 3, after Sieben's treatment. Proceeded exactly as in No. 1 (Experiment I.) and found as there : Result = 0.311 10 C.C. of a levulose solution equal to 0*180 grammes dry substance re- Used 250 C.C. of Solution 1 = 1.628 grammes dry substance and 100 C.C.of .. .. .. .. 0.275 grammes Cu. Solution 2 = 1.8 grammes dry substance (of which 93.3 per cent. are levulose), or levulose = 1.6794 grammes. Of this mixture took 35 C.C. ; these contained : 0.1628 grammes invert-sugar (wh.ich is the dry substance of Solution No. l), and 0.1679 grammes levulose (which is the dry substance of Solution No. 2). These together shozikl reduce copper . . 1 . .. .. 0.586 The 0.1628 invert-sugar = 0.311 Cu. The 0.1679 levulose = 0.275 Cu. 0.586 There were found : 0.5868 grammes Cu. Determinations made : 1. Mixture of sucrose, invert-sugar and dextrose, 2. Mixture of invert-sugar and dextrose. 3. Total dextrose in No. 1, after Sieben's treatment. Test A'o. 1. EXPERIMENT 111. Cu reduced. Used : Sucrose 0.26048 grammes .. .. 0,4975 grammes. ,, Xnvert-sugar 0.013024 grammes .. 0.0249 ,, ,, Dextrose* 0*0052096 ,, . . .. 0-0095 ;, Inverbed sucrose , . .. .. .. 0.4915 Invert -sugar .. .. .. 0.0249 Dextrose , , .. .. .. .. 0.0095 Xolution No. 1.-Copper reduced by : 0-5319 Cu. * Anhydrous crystalline dextrose.36 THE ANALYST. SoZution X o . 2.-Copper reduced by : Invert- su g a r . . ., .. .. 0 0249 Dextrose . . .. .. .. .. 0.0095 -- 0.0344 Cu. Solution iYo, 3.-Copper reduced by dextrose, after Sictben’s treatment . . .. . . a . .. 0 269 CLI. .. C~dclc~~icctio72. No, 1 .. * . . . . . Less No. 2 . . 1 . . . .. 0.5319 0.0344 No. 3 . . * . . . .. Less .. . . . . . . 04975 A 2 =0.2287 0 2690 0.2487 0.0203 x 2 =0.0406 This value 0.0406 is greater than NA 3 ; hence there is free dextrose present.No. 3 .. .. .: .. 0-0344 Less . . . . . . a . 0 0803 0 0141 x 2 ==0*0282 N3. 2 . . . . .. 0.0 ?44 Less .. . . .. 0.0282 0 0062 Cu due to:free dextroie. Cu dueto free dextrose pluced in the solution = 0,0095 Cu due to free dextross, found = 0.0062 Difference = 0.0033 -- The difference is equal to only 3.3 milligrammes, but as such small quantities were This experiment was, therefore, worked with, the percentage of error is too great. repeated, but greater amounts of substance w x e used. Test a-0. 2. Cu reduced. Used : Sucrose 0.26048 I . .. .. . . = 0.4975 ,, Invert-sugar 0.026048 . . .. . . . . = 0.04975 ,, Dextrose 0.013024 . . .. . . .. = 0.0246 XoZt&n H o . 1.-Cu reduced by : Inverted sucrose . . .. .. . . . . 0,4975 Invert-sugar . . .. .. ... . 0.04975 Dextrose . . . . .. .. . . . . 0.0246 0.57185 Cu. Solution J7o. 2.-Cu reduced b~ : Jnverc sugzr 9 . .. . . . . . . 0.04975 Dextrcse . . . . .. . . . . . . 0.0246 0.07435 Cu. 0.2968 Cu. Solutiom Xo. 3.--Cu reduc3d by dextrose after Sie5en’s treatmentTHE ANALYST. 37 Calculntio n. No. 1 * . .. .. .. . . 0.57185 LeJs No. 2 . . .. . . . . 0.07435 No. 3 . . . . . . . . . . 0.2968 Less . . . . . . .. .. 0.2487 0*0481 x =20*0962 This value, 0.0962, is greater than No. 2 ; hence free dextr0.e is present. No. 2 . . . . .. * . .. 0.07435 L8.S . . .. . . . . . . 0*04&10 0.02625 x =20*05250 NP. 2 . . . . ... . . . . 0.07435 Lesi . . .. . . . . . . 0.05250 0 03185 Cu due to free deli rose. C;I due to free dextrose placed in the solution . . .. = 0 02460 Cu due to free dextroaafouwd .. ,. . . = 0 02185 Diffdrence .. . . .. .. .. = 0.00275 The diffa-ence is equal t o 2.75 milligrammes; whereas in the first test only 65 3 per cant. of the added dextrose was found, in this test 88.8 per cent. were recovered. As the differences encountered have never exceeded 3.5 milligrammes of copper, and have generally fallen below that figure, it is probable that working with larger amounts will decrease materially the percentage of loss. EXPERIMENT IV. Determinations made : 1. Mixture of sucrose, invert-sugar and levulose in known proportions. 2. Mixture of invert-sugar and levulose. 3. Total dextrose in No. 1, after Sieben’s treatment. 1. Uded : Sucrose . . . . . . . . . . 0.1638 . . . . 0.01628 ,, Invert-sugar . . . . ,, Levulose .. .. . . . . .. 0.0107415 0.1898’215 This should have reduced copper : . . 0.3110 Inverted sucrose . . - - . . .. Invert-su gar .. .. . ., . . . . 0.0311 Levulose . . * . .. . . . . . . 0.0088 0.35053 Cu. Calculating over to . . 0 4625 copper. There were found in Tdst 1, 0 3572 Cu ; ir, test 2, 0,3550 Cu. There were found on 0.25 gramme dry substame : Test 1, 0.4704 Cu. Test 2, 0.4675 Cu. 0.25 gramme dry substance there shozcld have been reduced . .38 THE ANALYST. 2. Used : Invert-sugar .. .. .. . . 0*01628 ,, Levulose . . .. .. .. .* 0*0107415 0.0270215 This should have reduced copper : Invert-sugar .. . . .. . * . . 0.0311 L3vulose . , .. .. .. . 0*0088 0.0399 Cu. There were found Cu = 0.040. 3. Used : Same as Solution No. 1, This should have reduced copper, 0.2388 (based There were found by proceeding as directed by Sieben, i.e., by using 60 C.C.HCl of This proved that all the levulose was not destroyed, and indicated that either more Both Time of boiling, three hours. Time of boiling, six hours. on 0.25 grammes dry substance). six times normal strength, and boiling for three hours 0.2934 Cu. acid must be used or that the solution would have to be boiled for a longer time. devices were tried, and both gave very satisfactory resultre. Copper reduced, 0,233. Copper reduced, 0,235. Test 1.-Used : 120 C.C. HCl (6 x normal strength). Test 2.-Used : 60 C.C. HCl (6 x normal strength). To briefly resume, the foregoing data are here once more given in tabular form : ~ x p . 1.-Invert sugar ~ .. .. Dextrose . . .... . . Ratio of invert-sugar to dextrose, as 100 : 154. Copper that should have been reduced Copper found .. .. .. Exp. 2.-Invert-sugar. . .. .. Levulose . . .. .. . . Ratio of invert-sugar to Ievulose, as 100 : 103. Copper t h a t should have been reduced Copper found .. .. .. Exp. 3. -Invert -sugar .. .. Dextrose .. .. .. . . Ratio of invert-sugar to dextrose, as 100 : 2. Copper that should have been reduced Copper found .. .. .. Exp. 3 a. --Inver t -sugar .. .. Dextrose . . .. . . . . Ratio of invert-sugar to levulose, as 100 : 4 5 . Copper that should have been reduced Copper found .. -. .. Exp. 4.-Invert-sugar. . .. .. Levulose . . .. .. Ratio of invert-sugar to levulose, as 100 : 6. Cormer that should have been reduced , . CGper found after three hours’ boiling Copper found after six houra’ boiling Copper found after three hours’ boiling with double amount of acid .. .. .. .. 0 . * * . . . . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . . .. .. .. .. . I . b . . .. .. .. .. .. .. .* t . .. .. .. 0.09861 0.15143 0-3800 0.3826 0.1628 0.1679 0.5860 0.5868 0973504 0*0052096 0.0095 0.0062 PZOE 10.0 *82!29880 0.02460 0 02185 0.17908 0*0107415 0,2388 0.2934 0 235 0.233 As shown by these data, the proportion between the invert-sugar and the dextrose, or levulose, respectively, was made to vary between wide limits,THE ANALYST. 39 The work thus far given shows that this method devised for the determination of sucrose, invert-sugar, and dextrose or levulose, respectively, is perfectly feasible and practicable. It, however, also discloses the fact that the directions given by Sieben for the destruction of the levulose-the process upon which this method of analysis depends wholly for its accuracy-do not meet all the possibilities. A careful investigation will therefore have to be made of the various conditions affecting the destruction of the levulose before judgment can be passed on the value of the method here under considera- tion. Experiments to this end are now in progress, and the results obtained will be given in Part 11. of this paper. For valuable aid received in the execution of the analytical work here recorded, the writer wishes to express his obligations to his assistants, Messrs. Ziebolz and Brainerd.

ISSN:0003-2654    

DOI:10.1039/AN8911600033

出版商:RSC    

年代:1891

数据来源: RSC

摘要:

THE ANALYST. 39 REPORT OF RECENT RESEARCHES AND IMPROVEMENT8 fN ANALYTICAL PROCESS. ESTINATION OF IRON AND ALUMINA IN PHOSPHATES. (Zehech f. Anyew Chrnie, No. 1, '91).-The author having thoroughly tried Glaser's process (see ANALYST, 1890), thinks it may be improved by lessening the amount of sulphuric acid. The original process recommends 45 grammes of the strongest acid, but even if the sample solely consisted of calcic oxide, two grammes would be amply sufficient. As the memur- ing of strong sulphuric acid is troublesome, the author uses 10 C.C. of an acid which has been five times diluted. The author further thinks the quantity of phosphate used for analysis (-4 gramrnes) is too small, at least one gramme should be used. The actual procesEl is, then, as follows :- 10 grammes of the phosphate are dissolved in nitrohydrochloric acid, and the solu- tion diluted up to 500 C.C.50 C.C. (= 1 gramme) areevaporated to half the bulk, and while still hot, mixed with 10 C.C. of dilute sulphuric acid. 150 C.C. alcohol are next added, and the mixture allowed to settle for at least three hours. Claser thought half an hour sufficient ; but the author found this to be not long enough. The sulphate of lime is collected on a filter and washed with alcohol, the filtrate being collected in a Erlenmeyer's flask of half a litre capacity. The washing is finished when 10 drops of the washings, after dilution with an equal bulk of water, do not colour with methyl-orange, The filter and the precipitate is put into a platinum dish, the spirit is burned of, and the mass finally ignited and weighed, The alcoholic solution is distilled off to recover the alcohol (which, however must be re-distilled over potash), and the residue rinsed into a beaker.Slight excess of ammonia is then added, and this again completely boiled off. This is very important, a8 it prevents the co-precipitation of magnesia. The precipitate, consisting of ferric and alumina phosphates, is carefully collected on a filter, and washed four times with boiling water without disturbing it too much. If the washings should be turbid, washing with a very weak solution of neutral ammo- nium nitrate must be resorted to. The filtrate contains phosphoric acid, magnesia, beside#, of coume, sulphuric acid, and may be alkalies. The magnesium phosphate & R, JONES.40 THE ANALYST.sepamted by addition of ammonia, and weighed; but the phosphoric acid and alkaliea are best estimated in aliquot part of the original solution. Many analysts prefer to remove the phosphoric acid by molybdate, and finally weigh the pure oxides. The author thinks this a very good plan, providing the phos- phates of iron and alumina have been first isolated by Glaser’s process before treating with molybdate. The phosphate must, however, be free from organic matter, otherwise a little of the alumina will escape precipitation. L. DE I(. ESTIMATION OF NITROGEN IN PURE AND MIXED NITRATES. A. SULLWALD. (Chem. Zed., No. 99, 189O).-The author’s process (really a modification of Jodlbauer’s method) is as follows :--5 gram. of pure nitre, or 1 gram.of a mixture is put into a 150 C.C. flask and moistened with 05 C.C. of water. The addition of water serves to easier dissolve the substance, and. also to prevent the mass from getting too hot; by means of a long funnel 20 C.C. sulphophenylic acid (20 grams. of phenol in 500 C.C. sulphuric acid) are slowly added. After thoroughly cooling 2.5 grams. of zinc-dust are added, and after a quarter of an hour some mercury is added, and the whole gradually heated to boiling. The ammonia is finally estimated as usual. If a sufficiently large and suitsble flask is at disposal it is as well to distil off the ammonia from the same. Although this process gives perfectly correct results, it ia, according to the author, not quite so simple as the one proposed by 0. Farster, which is as follows :-*6 gram.of the nitrate is mixed with the usual precautions, with 15 C.C. of a 6 per cent. sulphuric acid solution of salicylic acid. When all is dissolved 5 grams. of hyposulphite of soda are added, and finally 10 C.C. of pure sulphuric acid and a little mercury. f;. DB E. ASSAY OE‘ COM~EROUL ALUMXNIUM. F. REGIELSBERCISR. (Zed& f. Angew Chm& NO. 1, 1891).-Klemp’s process, based on the volume of hydrogen evolved when the metal is dissolved in potash-ley, is not correct, because all samples of commercial aluminium contain silicon, which also liberates hydrogen. For instance, a cornmeraid sample aon- faining 98 per cent. Al., and 1.5 per cent. Si., will give a volume of hydrogen corre- sponding with 99.9 per oent, of aluminium. The author thinks it far better to carefully estimate the impurities in the metal, but if a direct estimation is required he proceeds as follows ;-Two grams. of the murmple are dissolved in a solution containing 15 grams. of pure caustic potash in a platinum vessel, and finally made up to 200 C.C. 50 C.C. ( = -5 grm.) are now boiled with a alighf excess of neutral ammonium nitrate, and the precipitated alumina collected and treafed as usual. Allowance must of course be made for any alumina or silica the reagents may contain. The alumina must be of oourse tested for silicat, h3C!LAImdER.-Mr. W. H. Stanger and Mr. Bertram Blount, of the Broadway Laboratory and Testing Works, Westminster, desire to correct a rumour which has become prevalent, by stating that the Mr. William Fox who is at present associated with them at the above a.ddress, is a member of the Institution of Civil Engineers, and not a practising analyst.

ISSN:0003-2654    

DOI:10.1039/AN8911600039

出版商:RSC    

年代:1891

数据来源: RSC