摘要:

THE ANALYST. FEBRUARY, 1887. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. THE Annual General Meeting of the Society was held at Burlington House on Wednes- day, the 12th ult. In consequence of illness, Dr. A. Hill: the retiring President, was unable to be present, and the chair was taken by Dr. Muter, one of the Vice-presidents. The minutes of the previous meeting were read and confirmed. The balance-sheet for 1886 was read by Mr. DYER, who announced that Dr. Muter was about to pay over to the Society the sum of &9, that being the amount left over after paying all expenses in connection with THE ANALYST during l88G, in addition to the $6 which he had paid over for 1885. The balance-sheet was then received and approved, and ordered to be printed and circulated, as usual.Mr. DYER read a letter from the retiring President. Dr. Hill stated that he was codned to his bed with bronchitis, and expressed his great regret that he was unable to be present to welcome the new President, and to deliver his retiring address, which was then read by Mr. DYER as follows :- GENTLEMEN, The time has arrived for my putting off both the honours and responsibilities of the office of your President, and, in occupying this chair for the last time, I take the opportunity of saying a few words of acknowledgment and congratulation-acknow- ledgment of the support, assistance, and kindness which, during my two years’ tenure of office, you have uniformly extended to me ; and congratulation and prosperity of the Society. This success is shown partly by the increase of members in the year 1884, and 181 in the year 1886, to 187 in that of detail in the following statement :- 1884 Ordinary members .. .. . . 142 Associates .. .. .. . . 21 Honorary members . . .. .. 10 on the continued success and associates, from 1’73 1886, as shown more in 1885 1886 10 10 149 152 22 25 Ten ordinary members and four associates have been elected ; six ordinary members and one amocia,i% have resigned, while one member, Mr. H. Sugden Evans, of the Inland Revenue Department of Ottawa, Canada, has died. The Balance Sheet, that you have heard read, is the most satisfactory that the Society has yet known. We have nearly &lo0 in hand, and this, in face of the fact that we have a long list of subscriptions in arrear, which, the secrefaries inform us, must, they think, be attributed, in some degree, to ‘‘ bad times,” as more effort than usual has been made, during the past year, to keep down this item in the accounts.The Society has been indebted, during the past year, to Dr. Muter, for a donation of &6, and I have great pleasure in announcing that hs has this evening promised us a further donation of S9.20 THE ANALYST. As evidence of the sustained interest and activity of the Society, I may state that during the year, twenty-three papers were read, as compared with twenty-one in 1885. Eight of them, or more than one third of the whole number, referred to the always important subject of milk, three to water, three to oils, two to soap, and one each to bread, butter, cheese, pepper, starch, and waxes and allied bodies; and finally there was one upon Fuller’s Slide Rule, for facilitating chemical calculations.One event of the year, worthy of Epecial mention, is the adjourned discussion on the Report of the Milk Committee, brought up last year, resulting in the adoption of the report of that committee, after an adjournment of three months, in order to allow all chemists an opportunity of testing the value and accuracy of the Committee’s results. It was, at the same time, recommended that all analysts should use the process ( a modification of Mr. Adams’), in preference to any other. It WM very gratifying to find that members, who, a t first, had hesitation or doubts about the advantages of the process, became fully convinced of their reality, after s sufficient trial of it.I believe that the conclusion arrived at, with only one dissentient voice, will be fully justified in the future; indeed, it has recently received valuable corroboration from the experiments made in the Hanover State Laboratory, with a view to test the respective merits of the Lacto-butyrometer method, Bell’s method, Soxhlet’s areometric method, and Adams’ method. Dr. Baertling sums up the work (an account of which, taken from the “Reper- torium f. Anal, Chem.,” is contained in THE ANALYST for last November), by a report strongly in favour of Adams’ method, on the very sufficient grounds of greater expedi- tion, simplicity, economy, and accuracy ; further, especially on account of its suitability for sour milks, giving the results of analyses of the same milks, both in the fresh and sour condition, and showing them to be practically identical , and, in conclusion, recom- mending the results as a legal standard in Germany. Such testimony as this, coming from a tribunal equally competent and impartial, cannot fail to be most acceptable to the Milk Committee, the Society, and Analysts in general.The influence of our Society has been, during the whole time of its existence, exerted in the same beneficial manner in other directions, notably in the processes of analyses in connection with butter, bread, and other important articles of food and drink, resulting in the elaboration of many perfected out of crude processes, diminished disagreement among analysts, greater certainty of success in legal prosecutions, greater fairness to buyer and seller, and lastly, the practical advantage of progressive diminution of adulteration- the end and aim of the Act.This successful outcome of the operation of the Sale of Food and Drugs Act is evidenced by the Annual Report of the Local Government Board, recently published, in which it is stated that st the time of the inquiry instituted by the Lancet Sanitary Commission in 1854-1856, more than 50 per cent. of the samples analysed were ‘‘ reported against.’’ I n the year 1877, the percentage of adulteration in articles examined was 19.2, and the average percentage for the years 1877-1881 was 16.2 ; in 1884 it fell to 14.4; whilo in 1885 it was found to have fallen to 13.2, which, I believe, is the lowest point ever attained.It is a somewhat remarkable coincidence, and, perhaps, a, satisfactory indication of a general improvement, that the percentage of adulteration in the Borough of Birmingham in 1886 in 014 samples was exactly 13.THE ANALYST. 21 I cannot omit a reference to the country meeting of 1885, inasmuch as it proved to be a source of both profit and pleasure to all those members and their friends who were fortunate enough to participate in it. Through the courtesy and valuable assistance of Mr. Adams, many of the various attractions of Maidstone and its environs were revealed, Several large paper-mills were visited, and the very interesting process of paper-making examined in all its stages. The extensive and modern processes and ap- pliances of a local brewery were also inspected in great detail ; while, to conclude and crown all, a most agreeable trip was made up the Medway, on the kind and hospitable invitation of Mr.Adams. Several of the party subsequently visited Canterbury, where, under Mr. Harvey’s excellent guidance, they ware shown the principal archsological and ecclesiastical monuments of the city, and the new waterworks, where the softening of the water supply from the chalk is carried on. I n conclusion, I congratulate the Society that the presidential mantle is about to fall on such worthy shoulders as those of my successor. The Society, in electing Mr. Allen to the presidency, is doing honour both to itself and Mr. Allen, a gentleman who, by his ability and acquirements, his great practical experience, his excellent analytical work, and his literary productions, possesses a claim to the distinction, which it is a pleasure to recognise, and qualities which cannot fail to act advantageously on the interests of the Society which, I sincerely trust, has before it a long career of constantly increasing usefulness and prosperity.Dr. MUTER said they had listened to the address with great interest, and it needed no words of his to insure their passing a hearty vote of thanks to Dr. Hill for his conduct in the chair during his Presidency. Dr. Hill was one of the country members, and it was often a great inconvenience for those gentlemen to attend in London, but he had been present at nearly every meeting during the time he was President. He had done his duty with great thoroughness, and had conducted their meetings well, and in an orderly manner, and kept up the respect due to the chair.Dr. SEATON seconded the vote of thanks, and said that Dr. Hill was an old Medical Officer of Health. He was the first of the country members to beappointed to the chair of the Public Analysts’ Society, and now the Medical Officers of Health Society had followed their example, and had lately elected him President of that Society. The vote of thanks wm carried unanimously. Dr, BOSTOCK HILL, in returning thanks on behalf of his father, said that Dr. Hill had taken a cold while attending to his official duties, and going out in the late rough weather had made him worse, so that on the 10th he was obliged to take to his bed. He had prepared his address while in considerable pain, and labouring under great difliculty of breathing. Among other reasons why he specially wished to attend was that he felt he ought to be present to welcome the new President, and it was a matter of very great regret to him that he could not be there to do so.Dr. SYKES proposed, and Mr. ASHBY seconded, a vote of thanks to the Vice- Presidents and Council of the Society.22 THE ANALYST. Mr. HEISCH proposed, and Mr. S. HARVEY seconded, a vote of thanks to the Treasurer and Hon. Secretaries. Dr. MUTER proposed a vote of thanks to the Chemical Society for the use of their rooms, and the Secretaries were requested to communicate the same to the Council of that Society. Dr. Bostock Hill and Mr. Johnstone having opened the ballot papers, Dr.MUTER announced that the following gentlemen had been elected as Officers and Council for the ensuing year :- President.-A. H. Allen, F.C.S., F.I.C. Vice-Presidents (who have filled the office of President).-A. Dupd, Ph.D., F.R.S., F.C.S., F.I.C.; C. Hehh, F.C.S., F.I.C.; Alfred Hill, M.D., F.C.S., F.I.C.; J. Muter, Ph.D., M.A., F.C.S., F.I.C. (Who have not filled the office of President).-J. Baynes, F.C.S., F.I.C.; P. Vieth, Ph.D., F.C.S.; C. R. Alder Wright, D.Sc., F.R.S., F.C.S., F.I.C. Treasurer.-C. W. Heaton, F.C.S., F.I.C. Hon. Xecretaries. - Bernard Dyer, B.Sc., F.C.S., F.T.C. ; Otto Hehner, F.C.S., F.I.C. Other Members of Coud.-M. A. Adams, F.R.C.S., F.I.C.; W. Fox, F.C.S.; C. N. Wake, F.T.C. ; C. T. Kingzett, F.C S., F.I.C. ; T. Boverton Redwood, F.C.S., F.I.C.; W.F. K. Stock, F.C.S., F.T.C.; R. R. Tatlock, F.R.S.E., F.C.S., F.I.C. The names of those Members of Council whose term of office has not yet expired, and who consequently do not retire this year, are A. Wynter Blyth, M.R.C.S., F.C.S. F.I.C. ; A. Bostock Hill, M.D., F.I.C. ; R. H. Harland, F.C.S., F.I.C. ; 8. Harvey, F.C.S.; and E. Seaton, M.D., F.R.C.P. The following gentlemen were also elected :- As Member : Mr. Harald Faber. As Associate : Mr. Adolphus Dresel, assistant to Mr. Johnstone. Mr. A. H. ALLEN, the newly-elected President, then took the chair amidst loud applause, and said :- I have to thank you, gentlemen, for the very hearty manner in which you have just expressed yourselves, and I trust I may take it as an earnest of the success I hope to meet with during my time of service.I have the interests of the Society very much a t heart, and shall certainly do all in my power to advance them, and to render the Society even more successful in the future than it has been in the pa&, and I have great pleasure in thinking I shall have, not only the assistance of the Secretaries, but of all the other members of the Council, From the balance-sheet just read we gee we are in a very good financial position, and there certainly does not seem to be any want of interest in the proceedings of the Society, or any falling off the members. The proceedings of the Society are becoming of more general interest, and, in fact, the Society has now established itself as it ought to be. It is in its teens, and I hope to see it yet more flourishing. We can never expect to be a large Society, but we may fairly h o p to see it increase in usefulness, and I shall certainly do all I can to advance its interests in every possible way. The following papers were then read and discusraed :-THE ANALYST. 23 Arsenical Glauber Salts: Its Toxic EEects, by Sir C. A. Cameron, M.D., On the Estimation of Methylalcohol, by Otto Hehner, F.C.S., F.I.C. On a New Pepper Adulterant, by Dr. Campbell Brown. R.C.S.I. Dr. Campbell Brown’s paper mas illustrated by a specimen of Poivrette exhibited under the microscope, by Dr. Muter on his behalf, and it was proposed that the Editor of TEE ANALYST should make arrangements to circulate slides of this adulteration to the members. Full particulars of these arrangements will be found in the present issue. After the meeting the annual dinner took place a t the Criterion, Piccadilly, where the members and several friends spent a very enjoyable and convivial evening. The next meeting of the Society will be held at Burlington House on Wednesday, the 9th February.

ISSN:0003-2654    

DOI:10.1039/AN8871200019

出版商:RSC    

年代:1887

数据来源: RSC

摘要:

THE ANALYST. 23 ON POIVRETTE. BY PROF. J. CAMPBELL BROWN, D.Sc. Bead at the Heetiny) Jan. 12th, 1887. THE substance known in the pepper trade as “ Poivrette,” or ‘‘ Pepperette,” is now so frequently used for the purpose of “ fraudulently increasing the weight and bulk ” of commercial pepper, that the members of this Society ought never to omit a careful search for it in all samples of pepper officially submitted to them. As many commercial analpts do not appear to be yet familiar with poivrette, and as some public analysts have applied to me for specimens, a short account of it may be of use to the Society. It made its fist appearance in Liverpool last summer, when more than one wholesale pepper- merchant brought me samples, and inquired what the substance was, and what were i t E properties.During the last three months I have met with it in between twenty and thirty retail samples of pepper. Poivrette is a pale) slightly buff, or cream-coloured powder, resembling in the bulk the principal middle layers of the pepper-berry, when ground; and when mixed with pepper cannot be distinguished by the eye, nor even by the hand-lens, from particles of pepper. I n the earlier samples the coarser particles could be isolated by spreading the pepper on a s t 8 sheet of paper held in a nearly, but not quite horizontal position ; on tapping this with the Gnger tips, so as to make the larger particles jump gradually to the lower edge of the sheet, the poivrette particles could then be picked out, and easily distinguished from pepper by crushing them between the teeth.Recently, however, it has been so finely ground and sifted that it cannot always be partly separated in this way, although the toughness and hardness of the particles can always be distinguished by the teeth in a mixture. Microscopic examination, with a i t h or i t h objective, shows that it consists of pale dense ligneous cells, some entire and marked with linear air spaces, some torn and indistinct. The following letters (which afterwards appeared in some local newspapers) indicate the country from which it comes : -24 I I Ash. THE ANALYST. Matters solu- Albuminous Wood~ fibre ble hy boiling m $ ~ ~ t h ~ ~ , u - i ~ ~ ~ ~ ~ ~ n in dil, acid. ble in alkali. alkali. Starch. ’ ’ I ‘( The following letter from Leghorn has been received by a local spice house, and similar letters have been circulated throughout the country :- (( ‘ LIVORNO, August 1, l8S6.‘( ‘Dear Sirs,-I send you by this post two samples of an article called ‘ pepperette’ (white and black), which is made of the pulp of a fruit growing in this country, which has the power of retaining the piquancy of pepper when it has been mixed with the same in the proper proportion. This is warranted to consist of this purely vegetable substance, and to contain nothing deleterious, consequently to be in no way detrimental to the health. The price is $8 per ton of 1,000 kilogrammes, goods delivered c.i.f. in Liverpool, packed in 2 cwt. bags ; bags free, no tare, shipping weight ; 2$ per cent. discount for cash. I export my pepperette very largely all over the Continent and to Great Britain, where, on account of its cheapness, it is used very much for blending pepper, which is sold as “prepared pepper,” or “pepper not warranted genuine,” in the same way as is done with mustard, or with ground coffee and chicory (the so-called French coffee).If you desire any references I shall be happy to furnish you any amount in England, as well as on the Continent.-Yours truly u A reply was forwarded, in due course, to the manufacturers of “ pepperette,” asking for further particulars and references, and the following letter was received :- ‘( ‘ Dear Sirs,-I am favoured with your letter, 16th instant, and note contents, ‘ 4 Pepperette.” What you ask me is a question that is very frequently asked me by English houses, but I am always in the impossibility to reply to it; in fact, I mmt cnot do it.When I sell my ‘‘ pepperette” (or “ poivrette ”) to a firm, I bind myself not to mention their name to anybody, and will do so with your good selves, if I have the pleasure of being favoured with your orders. I make it a point of the question of secrecy with all my customers for this article, and cannot make an exception with you. Give me a sample order of a few tons, and I shall execute it to your entire satisfaction; payment after receipt and approval of the goods. However, for your guidance, and according to what I promised with my letter of the 13th inst., I now beg t o subjoin a few English references, who can inform you concerning my respectability, but kindly do not mention to them anything about ‘‘ poivretto,” the same being houses from whom I import English goods (Le., my firm, As already written, I shall be able to send sample of white poivrette of lighter colour by October next.I n the meantime I trust to be favoured with your esteemed orders, and remain, dear sirs, If so desired, the white pepperette can be had much lighter. 2 ). 64 6 9 ,? Z therefore examined, amongst other substances, walnut-shells, almond-shell9 and olive-stones. The cells of walnut-shells are dotted, though otherwise similar t o poivrette j the almond-shells greatly resemble poivretts, and olive-stones still more closely resemble it. Chemical analysis indicates the closest corregpondence between poivretts and olive- stones, 8s the following figures show :- White pepperette .. . 1 1-33 38.32 14.08 48.48 None Ground almond-shells . . Ground olive-stones . . Black pepperette 6 . 2.47 34.55 17.66 47.69 9 9 2.05 23.53 24.79 51-63 9 ) 1-61 I 39.08 15.04 45.38THE ANALYST. 25 The stones of olives, imported in pickle for table use, gave 3.68 per cent. of ash, but well washed olive-stones, thoroughly burnt to a white ash, gave under two per cent. of ash-like poivrette. ‘‘ White poivrette ” is therefore cleaned very pale, and perhaps partly bleached olive-stones, or precisely similar tissue ; black poivrette is the same, mixed with a little black husk. It is to be noted that, although it contains no starch, yet it yields some sugar to Fehling’s solution, after being boiled for some time with dilute hydrochloric acid.The quantity depends on the length of time and strength of mid, but may be stated approximately about ten per cent. It, is important to bear this fact in mind when making a full chemical analysis of pepper containing poivrette. After removing from such a mixture the matters soluble by boiling in dilute caustic alkali, the woody fibre which remains has a yellow colour ; it consists of the poivretto, and some of the cells of pepper-husk and one of the subcortical layers of the pepper- berry. The pepper-cells are made lighter, and the poivrette-cells darker by the alkali, so that the two are more nearly of a similar yellow colour after treatment with alkali. This renders it more dif&ult to distinguish such of the cells as have somewhat similar markings; but it enables us to distinguish more clearly, as poivrette, the many torn particles which have no definite form or markings.The final examination of the com- plete cells k better made with good daylight rather than with artificial light, and in a portion which has been treated with water only. The pepper cells are mostly different in shape, and are coloured, and have generally a dark substance in the interior. They are not numerous, but the quantity varies in commercial samples, owing to the modern practice of decorticating the pepper berry to every different extent possible, and mixing the various portions so obtained, including husks, in every variety of proportion with each other or with ordinary pepper. Each individual analyst must make himself familiar with both kinds of cells, as no description can convey an adequate idea of either. In order to form a judgment regarding the proportions of the different chemical constituents of commercial samples, we require to know the chemical composition of the different layers of the pepper-corn; and I hope soon to communicate to the society some figures bearing on this point, as well as to notice some other substances used in the sophistication of pepper. It is interesting to note that the exemption, mentioned in section 8 of the Sale of Food and Drugs Act, in the case of a label being a&ed to the article sold, intimating that the same is a mixture, does not apply in the case of poivrette, the admixture being made manifestly for the purpose of frauduleratly increasing the weight and bulk. Liverpool, 4th January, 1887.

ISSN:0003-2654    

DOI:10.1039/AN8871200023

出版商:RSC    

年代:1887

数据来源: RSC

摘要:

THE ANALYST. 25 ON THE ESTIMATION OF METHYLALCOHOL IN PRESENCE OF ETHYLALCOHOL. BY OTTO HEHNER. &ead at the Meeting, Januarg 12th, 1887. THE readiest analytical method of which I know for determining the amount of methyl- alcohol, when mixed with ordinary alcohol is that of Dr. Dupr6, described in the ANALYST26 THE ANALYST. of 1876. He oxidises a known quantity of the alcohol with bichromate of potash, acidified with sulphuric acid, distils from an oil bath the acetic acid formed, and estimates by decinormal soda. Only ethylalcohol, according to Dr. Dupr6, furnishes acetic acid, methylalcohol being completely oxidised into carbonic acid. Knowing the total alcoholic strength of the fluid to be examined-the specific gravities of methyl and ethylalcohol being nearly identical--the deficiency of acetic acid obtained indicates the proportion of methylalcohol in the mixture.Dr. Dupr6 also takes the vapour tension of the alcoholic fluid in Geissler’s vapori- meter, the readings on that instrument being higher, if methylalcohol is present, than corresponds to the speci6c gravity. The only test experiment given by Dr. Dupr6, in which 1 per cent. of wood-spirit (or rather 10 per cent. of methylated spirit) was added to a sample of whisky, indicated -42 per cent. of methylalcohol. Having lately to examine a number of methylated spirits for the percentage of wood-spirit contained in them, I took occasion to investigate the subject, and in the following give my results. First, as to the indication of the vaporimeter. A sample of methylalcohol, purchased as pure, sp.gr. -8097, diluted to 10 times its bulk with water, gave a vaporimeter indication of 14.9, ethylalcohol of the same strength requiring 9.7. Rectified wood-naphtha, sp. gr. *8107, similarly diluted, gave vaporimeter indica- tion 12.0, against 9.6 of ethylalcohol. Crude wood-naphtha, swh as is used for methylating, sp. grav. *8233, gave an indication of 11 *5, against 9.3 of ethylalcohol. Ethylalcohol, -7969 sp. grav., showed 10.0 instead of 9.99. Methylalcohol, purified with calcium chloride, boiling at 67 Co, sp. grav. -8i29, vaporimeter indication 9.0, instead of 9.6. This latter result, repeated many times, is not a little remarkable. The alcohol, as found by further investigation, was not quite pure, yet it consisted to a very large extent of methylalcohol, which, boiling at a low temperature, yet gave an indication lower than ethylalcohol of a corresponding strength would have done.Looking at the wide variation of the differences between the vaporimeter indications and the corresponding ethyl indications, I have t o come to the conclusion, that it is not the methylalcohol, but the impurities (acetone, etc.) contained in the methylalcohols, which are measured by Geissler’s instrument, and that this may give, in case of impure me thylated alcohol being employed, qualitative indications of the presence of methyl in ethylalcohol; yet it is quite useless as a quantitative instrument for this purpose. Having some previous experience of Dr. Duprh’s oxidation method, I had ex- perienced the difficulty of distilling off in the oil-bath all acetic acid formed from the tenacious mixture of sulphuric acid and chromium and potassium sulphates.With patience and time, this can be done, but the operation is a troublesome and tedious one. I determined therefore to measure the quantity of chromate reduced,instead of the acetic acid produced, especially as I believed that much more decided indications could thus be obtained, than by a method, by which the most valuable constituent, the methyl- alcohol, was really not estimated at all.THE ANALYST. 27 Theoretically, one equivalent, or 46 parts, of ethylalcohol require two equivalents of oxygen for transformation into acetic acid, whilst one equivalent, or 32 parts, of methylalcohol, want three of oxygen for oxidation into carbonic acid.1 mol. of bichro- mate (295.18) gives off three of oxygen. Hence 100 parts of ethylalcohol want 427.8 parts of bichromate, and 100 ,, methylalcohol ,, 922.4 ,, 9 , I made solutions of bichromate, 80 grms., with 150 C.C. strong sulphuric acid to the litre, and of ferrous and ammonia sulphate, about 240 grms. to the litre. Also, by dilution, a chromate solution ten times more diluted than the one above mentioned. The chrome solution was accurately standardised upon the iron solution, the usual ferri- cyanide reaction being taken as indicator. 1 c.~. of iron solution was thus found to be equal to about -17 to -18 of strong chromate. A quantity of alcohol, of known specific gravity, is diluted, at 60° F., to 100 C.C. ; of this diluted alcohol a volume is taken, containing about *3 grm.of absolute alcohol. 25 to 30 C.C. of strong chromate are mixed with that quantity of alcohol in an ordinary 8 oz. bottle, securely corked, and the mixture heated in the water-bath for at least two hours. An excess of iron solution is then run in, and this titrated back with deci- chromate solution. I found that thus the end-point of the reaction could much more readily be observed by the gradual disappearance of the blue ferricyanidecolour than by the direct titration with iron solution. The volume of iron solution is then calculated into the strong chromate which corresponds to it, and this subtracted from the total chromate added. The remainder, multiplied by 008, gives the weight of bichromate reduced Thus I diluted 5 C.C.of pure ethylalcohol of a8344 sp. gravity, corresponding to 85.5 per cent. by weight of absolute alcohol, to 100 c.c., and took 5 c.c., corresponding to -25 C.C. of the original alcohol. These 9 5 c.c,, therefore, contain 01783 grm. ethyl- alcohol. These were oxidised, for two hours, with 25 C.C. of strong chromate. 85 C.C. iron solution (1 C.C. of which was equal to *188 C.C. chromate), were run in (equal to 15.98 chromate), and the excess of iron titrated back into 3.3 C.C. decichromate. Thence 25-33- 15.98 = 9-35 C.C. of chromate, containing -7480 grm. of bichromate were reduced, corresponding to 419.6 per cent. of bichromate were consumed by the alcohol. Or 98.1 per cent. of the quantity of alcohol taken were found. A sample of the purest methylalcohol which I could obtain, prepared from winter- green oil, and possessing a slight odour of the latter, of *8153 sp. gravity, and boiling at 66OC., heated for half an hour, consumed 829-3 per cent.of bichromate, corresponding to 81.2 per cent. of methylalcohol; in one hour 891.5 per cent., equal to 93.8 per cent. methylalcohol; and in two hours 908.8 per cent. of chromate, equal to 97.3 per cent. of pure methylalcohol, all results calculated u p the anhydrous alcohol, as taken from the ethylalcohol table. Now, strictly speaking, the specific gravities of methyl and ethylalcohol are not alike. Allen calculates, from various sources, that a t 15.5, pure methylalcohol has a density of -8021, corresponding to 97.33 per cent. of ethylalcohol of the same density, which is in absolute accordance with the above result.In the case of mixtures of pure methyl and ethylalcohol, we would have to calculate as follows :-922.4 being the percentage of bichromate used by methyl, and 427.8 by28 THE ANALYST. ethylalcohol, a difference of 494.6 beyond 427.8 would indicate 100 per cent. of pure methylalcohol. Hence subtract 437.8, the percentage consumed by any particular sample, and divide the remainder by 4.946, to obtain the percentage of methylalcohol in the sample, calculated upon the absolute alcohol. By a simple further caloulation we would get percentages on the hydrated samples. Take the case of the following mixtures, in which pure ethyl and pure methylalcohol, the former containing 003567 grm., the latter *03778 grm.in each c.c., were mixed. 1 C.C. dilute ethyl and 4 C.C. methylalcohol (the mixture containing 80.8 per cent. methylaIcoho1, calculated upon the absolute alcohol). Bichromate consumed 808.6 per cent., corresponding to 76.9 per cent. methylalcohol. 2 C.C. ethyl, and 3 C.C. methylalcohol (with 61.3 per cent. methylalcohol) used 720.3 per cent. bichromate, corresponding to 59.3 per cent. methylalcohol; 3 C.C. ethyl and 2 C.C. methylalcohol (with 41.4 per cent. methylalcohol), used 620.3 per cent. bichromate, equal to 38.9 per cent. methylalcohol. On making the allowance OP 97.3 indicated methyl, being 100 per cent. real methylalcohol, and the figures stand as follows :- Found Taken 79.0 . . . . so93 60.9 . . . . 61.3 40.0 , . , , 41.4 These figures show that, for mixtures of the pure alcohols, the method gives results Now as to methylated spirits.Crude wood spirit, such as is used for methylating, required 810.9 per cent. of Various methg lated spirits, purchased at different shops, gave the following of sufficient practical accuracy, bichromate, and contained, therefore, 77.7 per cent. of methylalcohol. results :- Bichromate used, Corresponding to Methylalcohol 466.5 .. .. .. .. 7-8 462.9 .. .. .. .. 7.1 451.9 .. . . .. .. 4.9 450.8 . * .. .. . . 4.7 455.0 .. .. . . . . 5.5 456.3 . . .. .. .. 5.7 456.3 .. .. .. .. 5.7 I have also met with two samples which were decidedly over-methylated ; they used 554.3 bichromate equal to 25.5 methylalcohol. These samples had been exported to Australia, where the excise authorities declared them to be insufficiently methylated.They were, therefore, re-methylated, at the sender's cost. The spirifs had, according to the above figures, a considerable excess of methyl- alcohol. Owing to the variable composition of crude wood-spirit--stated by Allen to contain from 35 to 95 per cent. of real methylalcohol-it is, of course, impossible to calculate the percentage of actual wood-spirit in any of the samples, unless the identical wood-spirit which hm been used in mixing is also analysed. But the figures given furnish an idea of 546.4 ,, ,, 23.9 $ 9THE ANALYST. 29 the composition of methylated spirits, and may form a rough basis of calculation, in case of whiskies or other spirits, that may be found to consume an excessive quantity of bichro- mate. I have not met with any such, although I think an extensive search might furnish interesting results.On the contrary, my experience, as far as it goes, shows that whiskies and brandies, when examined by my method, consume a quantity of bichro- mate decidedly slmrt of the theoretical amount. A whisky, with 005 per cent. of total solids, used 405 per cent. of bichromate, equal to 95.2 per cent. of ethylalcohol in the absolute alcohol of the whisky. Another sample (distilled) used 405 per cent. of bichromate, or 94.7 per cent. of 0th y lalcohel. Another sample used but 399 per cent. of bichromate, corresponding to 93.4 per cent. of ethylalcohol. A fourth sample required 401.1 per cent. = 93.8 per cent. of ethylalcohol, whilst in two other cases 401.1 and 399 per cent. of bichromate were reduced, indicating 93.8 and 93.4 per cent of alcohol. A sample of brandy used 406.2 of bichromate = 94.9 per cent. of alcohol. In the whole of these cases the heating with bichromate was continued for so long a time that I have no doubt of the completeness of the oxidation. In proof of this I will quote duplicate estimates performed upon a sample of alcohol (probably, also, not absolutely pure) this reduced bichromate corresponding to 98.2 and 98.1 per cent. of ethylalcohol. Very many, indeed, of the figures which I have quoted in the paper were confirmed by duplicate experiments. I do not as yet feel myself in a position to give anything like a definite opinion as to the cause of this deficiency. I cannot, however, help thinking that whisky and brandy are far from being fairly pure alcohols, but that they contain tangible percentages of substances of higher molecular weight. I will not fail to investigate this subject with- out delay, and to bring the results before the Society at an early date. I beg to record my obligation to my assistant, Mr. Henry Richmond, who has assisted me in carrying out this investigation,

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DOI:10.1039/AN8871200025

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年代:1887

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THE ANALYST. 29 ON SOUR BREAD AND THE LOGWOOD TEST. BY W. C. YOUNG, F.C.S., F.I.C. Bead at the Meetiny, December 8th, 1886. IN applying the logwood test to bread it frequently happens that a reaction is obtained which further examination shows is not due to the presence of alum. This is more often observable when a pale tint is employed, and then the blue colour is seen on the margin of the stain, or near the outer parts of the loaf. I n cases of this kind I have always felt, in giving a certificate of genuineness, that there was some doubt about it, and although I have repeatedly made special examinations of the sample for iron and other metals, I have never been able to account for the reaction. Quite recently, circumstances occurred which enabled me to clear up the mystery,30 THE ANALYST.and as the results of my experiments are of some interest, and perhaps importance, to Public Analysts, I have thought it adviable to lay them before the Society. On com- menting, in a quarterly report to one of my boards, on some prosecutions for adulterating bread with alum, I was asked by one of the members present, who is a baker in a large way of business, whether it was possible for me to mistake sourness in bread for the presenceof alum. Of course I replied without hesitation that it was quite im- possible. He then said that he had a very good reason for putting the question, as some years ago, having had considerable trouble in making his bread, which frequently became sour, he sent a sample of the flour used and a sample of the bread made from it to a late eminent chemist, in the hope that analysis would afford him some explanation, and suggest some way out of the diEculty.The chemist reported that the flour was perfectly genuine, but the bread contained a large quantity of alum. As he (the member of the Board) was quite sure that no alum had been added to the bread, he concluded that the chemist had mistaken sourness for alum. Some time after this I received a sample of bread from this Board, which had been purchased and submitted for analysis by a private resident in the parish. This sample waa heavy, dark in colour, and sour. Upon applying the logwood test in the umal way a very distinct reaction was obtained, and I felt convinced that it contained a large quantity of alum, but upon analysis I could obtain only aluminum phosphate equivalent to 7.8 grains of alum in 4 lbs., a second estimation giving me 8 p i n s of alum in 4 lbs.It was therefore perfectly clear that the reaction was not due to the presence of alum, and further examination failing to give me any indication of the cause, I certified the bread to be free from alum or other mineral adulterant, but felt strongly that my results were Subsequently I learnt that this sample had been prepared by the before-mentioned gentleman expressly to test my ability to distinguish sour bread from bread containing alum. In order to settle this question I made some bread sour by moistening it with water, and setting aside for a few days, and was surprised to find that in every instance I obtained the blue colour with the logwood test.I got the same result with bread made from sour dough, although the bread con- tained alumina equal to only 6 grains of alum in 4 Ibs. As the acids produced by the fermentation of dour per se give no reaction with the logwood test, the effect must be caused by the solution of the alumina naturally present in the flour by the acetic acid formed, and this seems to be the true explanation. I have moistened twenty different samples of bread, all of which had previously given negative results to the logwood test, with dilute acetic wid (about 1 of acid to 260 of water), and in one hour all of them gave a most intense blue colour. Flour made into a paste with weak acetic acid, and set aside for a short time has invariably given me the alum reaction.The depth of the colour obtained is such as we are accustomed to see when 50 or 60 grains of alum in 4 Ibs. of bread are known to be present, and assuming that the whole of the alumina naturally existing in these samples was dis- solved by the acetic acid, it is surprising that so minute a quantity should give SO decided a reaction. unsatisfactory.THE ANALYST. 31 As a bread, to which say 10 grains of alum in 4 lbs. has been added in the making, giva a much less distinct blue colour than that to which none was added, but which has been moistened with acetic acid, it would seem to indicate that a large proportion of the alumina in the alum in the former case has been rendered insoluble. If this is so it is possible that the whole of the alumina in the alum added to bread may, in some cases, become insoluble, and then the logwood test would fail. This investigation throws grave doubt on the efficiency of the logwood test as an indicator of the presence or absence of alum in bread, as if a reaction be obtained it may be due to acidity, and not to alum, and if no reaction is given, then no proof is afforded that alum has not been added, as it may all have been rendered insoluble.DISCUSSION. The PRESIDENT said the paper was of great practical interest. They had hitherto been led to suppose that the blue colour was always a proof of the presence of alum, but it now appeared that was not so. However, it was an error in the right direction-it was better than looking for alum when it was known to be present, and not finding it.If phosphate of alumina in presence of acid did give the blue tint, then the assumption that the test only acted with alum could not apparently be borne out. He would, with- out himself pronouncing any opinion at the moment, be glad to hear the criticisms of members present on Mr. Young’s remarks. Mr. BODBIER said that he had noticed certain breads free from alum, which gave a dirty date-blue colour something like the alum tint. He would like to know if any member could account for this. By this method gelatine is soaked in the bread paste and then tested with logwood, when it gives a neater reaction. Mr. Young appeared to throw doubts on the appli- cability of the logwood test. According to his own showing, however, it was still a test for alumina, and his explanation was that the acetic acid acted in a solvent way upon the alumina, and so caused the colour. So far as he (the speaker) knew, no one had been able to separate alum as alum in bread, and still the logwood test held good for alumina.All bread contained more or less alumina, and according to this explanation all bread would give the reaction if suiliciently sour, but bread was almost invariably acid, and if it were steeped in water the water would be found distinctly acid. It would be more satisfactory if the spectroscope had been used, because there was a difference in the spectroscopic appearance of the alkaline logwood with and without the real alum colour. Mr. JOHNSTONE inquired what baking-powder had been used for the bread.He had had some powder containing 49 per cent. of alum, the rest being carbonate of soda. As to testing with the spectroscope, he thought it would be better to test quantitatively for the amount of alumina at once. Mr. DYER said that acetic acid did not dissolve phosphate of alumina, which was insoluble, and it was rather a gratuitous assumption that the alumina put into bread was phosphate. It might be true that if they made a watery decoction of the bread they might make it into a phosphate, but it was not certain. Dr. MUTER said that lumps of actual alum could still occasionally be found in bread. He had obtained a piece about five years ago a little bigger than a pea. In reference to the slate colour mentioned by Mr. Bodmer, about fifteen years ago there was a great dispute in the West of England about some bread which was found to have been made with a special tartrated baking-powder, and which, on being tested, gave the slate colour, although free from alum.Therefore, accidental colours, due to other causes than alum, Dr. WYNTER BLYTH said he always tested for alum by the gelatine process.32 THE ANALYST. were no new thing. The simple way w&s to estimate the alumina quantitatively, and not trust entirely to a colour reaction. Mr. YOUNG, in reply, said that each bread had been previously tried with the log- wood test, and gave negative results before acidulating. He thought the question all turned upon whether the alumina was converted into phosphate of alumina or not ; what he admitted to be quite possible was that the phosphate might be in combination with the gluten, and that that compound was soluble. It seemed to him that when they got no reaction with bread in the ordinary way, and then, after having added an acid to it, they did get a reaction, it was only fair to assume that the acid was the muse of the reaction. He had not used any baking-powder in the bread, which he made from sour dough. As to the gelatine process, he had never tried it. He had not seen the slate colour alluded to by Mr. Bodmer.

ISSN:0003-2654    

DOI:10.1039/AN8871200029

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年代:1887

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32 THE ANALYST. ARSENIC I N GLAUBER’S SALT: ITS TOXIC EFFECTS. BY SIR CHARLES A. CAMERON, EX-PRESIDENT, R.C.S.I., V.P., INSTITUTE OF CHEMISTRY. Read at the Meeting, Janwary lath., 1887. IN July, 1884, a farmer, John Donneilan, residing near Castlerea, County of ROE. common, administered a purgative draught, consisting of Glauber’s salt and infusion of senna, to each of his herd of twenty cows. The animals were not sick, but it is usual in Ireland to give an occasional purgative dose to cows, especially after any important change in their diet. I n the course of a few hours all of Mr, Donnellan’s cows became very sick, and on the following day ten of them died. The visceraof one of the cows were forwarded to me for analysis, as were also specimens of the Glauber’s salt and senna, which had been administered to the animals.They and their contents were found to contain small quantities of arsenic. The stomachs were slightly inflamed ; but their coats were not corroded. The senna was found to be pure. The Glauber’s salt received for analysis amounted to about one pound weight, and chiefly consisted of large crystals. It was found to contain arsenious acid, in the ratio of 8.4 grains of h20s por pound of the salt. The arsenic was equably dis- tributed throughout the crystals in the form of sodium arsenite, It is difficult to account for the presence of a sensible proportion of arsenic in Glauber’s salt. In the preparation of anhydrous sodium sulphate or salt-cake, highly arsenical sulphuric acid might be employed, but its arsenic would be volatilized as A@13 at the high temperature of the salt-cake furnace.A salt-cake which was prepared on a small scale, sulphuric acid containing nearly one per cent. of arsenic being employed, proved to be perfectly free from arsenic. Probably, the Glauber’s salt in question was prepared from impure sulphuric acid, employed in producing some such by-product as, for example, the sodium sulphate obtained in treating iodine ley. I made every effort to trace the origin of the Glauber’s salt, but failed. It appears that to each cow one pound of the salt had been given, and assuming that in each dose there was 8% grains of arsenious acid, it seems strange that so small a quantity could prove fatal to a cow. The evidence in favour of the view that theTHE ANALYST. 33 sickness of the cows W&S due to the poisonous salt is, however, very strong. It is certain that the arsenic was in the most favourable condition for rapid absorption into the circulation, and it; is not improbable that this poison, as well as others, may act more powerfully, when administered with aperients so rapidly absorbed as Glauber’s salt is.

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DOI:10.1039/AN8871200032

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年代:1887

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THE ANALYST. 33 NOTES ON THICKENED OR BLOWN OIL. BY WILLIAM Fox AND JAMES BAPNES. Bead at the Meeting, December Sth, 1886. BLOWN or thickened oils are prepared from the various seed oils, by heating the oil in a suitable tank to 70° C., and then blowing air into them through a perforated pipe; the temperature of the oil at once commences to rise, and irritating fumes are given off. The temperature is not allowed to rise beyond 75O C., otherwise the oil becomes of a dark colour. Acetic and acrylic acids are present in the fumes. The blowing is continued from sixteen to thirty hours, or until the desired specific gravity is reached. The changes which take place in the oil during this process are most interesting; from their ordinary fluidity they become of a syrupy consistency ; their specific gravity increases up to 0990; their insoluble fatty acids decrease to as low as 84.12 per cent.The glycerin, determined by the permanganate process, appears to increase about one per cent., except thickened linseed oil, which gives an increase of 2$ per cent.; this increase in the glycerin may be due to some soluble oxidation products of the oil, which become reduced to oxalic acid by the permanganate. No great quantity of free acid is present in these thickened oils ; the amount calculated into terms of oleic acid, in a number of samples, varied from 2 to 5 per cent. The following are mean results obtained from thickened linseed, rape, and cotton oils: Linseed :- On saponification with alcoholic potash the soap is very dark. Per cent. Insoluble fatty acids .. .. .. .. 0 . , . 87.67 Glycerin . . .. .. .. .. .. .. . . 12.85 Free fatty acids . . .. . . . . .. .. .. 2.73 The insoluble fatty acids, titrated with standard potash, gave 258.4 as the equivalent weight of the acid. Cotton :- Per cent. Insoluble fatty acids . . .. .. .. .. . . 85.50 Glycerin . . .. .. .. .. .. .. . . 11-68 Free fatty acids . . .. .. .. .. .. .. 5-35 The insoluble fatty acids, titrated with standard potash, gave 196.0 as the equivalent value of the acid. From the Ba salt, soluble in alcohol, we obtained an equivalent of 188.0. Rape :-- Per cent. Insoluble fatty acids . . a I * . a L . . . 84.70 a1ycerin . * .. .. .. .. .. .. . . 11.32 Free fatty acids . . .. .. .. .. .. . . 3.7034 THE ANALYST. Titrated with standard potash the insoluble fatty acids gave an equivalent of 186.0. The equivalent 186.0, if the insoluble fatty acids were normal, would give the formula C,,H,,02. From the results of a combustion analysis, using fused chromate of lead, a large excess of oxygen was found, so that it would appear that the insoluble fatty acids are oxy-acids of the acrylic series.

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DOI:10.1039/AN8871200033

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年代:1887

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34 THE ANALYST. EXPERIMENTS WITH THE LACTOCRITE. BY A. WYNTER-BLPTIT. Read at Meeting, December 8th, 1886. THE following table gives some determinations of milk fat by the lactocrite, aa compared with estimations of fat by weight according to Adams’ method. The analyses have been made, under my superintendence, by Mr. J. K. Colwell, the laboratory assistant at the St. Marylebone Court House. The table shows the greatest difference between the two estimations to be -14, and the mean difference -05 per cent. of fat in 100 of milk. When it is considered that, with prwtice, as many as four batches of twelve tubes m n be charged, rotated, and read within the hour, it is evident that fat-estima- tions by the lactocrite are more speedy and more accurate than any other volumetric process yet devised. It will therefore prove a valuable instrument for technical purposes. I have to thank Mr. Barham and Dr. Faber for facilities in the carrying out of these experiments. DETERMINATIONS OF MILK FAT BY THE LACTOCRITE. - No. - 1 2 3 4 5 6 7 8 9 10 11 - Specific Gravity. 1033.0 10319 1032 0 1030.5 1032.0 1031.5 1032.5 1030.5 1031-0 1034-0 1035.0 Total Solids. 12-90 14.12 13-12 13.07 12.98 14.27 13.84 13.00 13.51 11.76 9.99 Ash. -80 -80 -77 -74 -76 -76 *78 076 *80 -76 -86 Fat. Lactocri te. 3.40 4.55 3.60 3-90 3.80 4.90 4.20 3.70 4.05 2.10 -45 Adams. 3.44 4.69 3.57 3.99 3.76 4.54 4.26 3.69 4.09 2 07 -502 CwncZcsion of the Society’s ProceecZings. Difference. - *04 - 014 + *03 - *09 + 904 + -06 - -06 + -01 - *04 + 003 - 005 NOTICE TO OUR READERS, OWINQ to pressure of Society matter sevemI original articles and all om abstracts are held over for next issue.

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DOI:10.1039/AN8871200034

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年代:1887

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THE ANALYST. 35 COMMUNICATIONS FROM THE LABORATORY OF THE SCHOOL OF MINES, LEOBEN. BY ED. DONATH AND RUD. GELLER.* 1. DETECTION AND ESTIMATION OF SMALL QUANTITIES OF CHROMIC OXIDE.-The qualitative separation of very small quantities of chromic oxide from much ferric oxide alumina and manganous oxide presents many difficulties, and often fails, when the usual systematic course is pursued, vk, fusion of the oxides with potassic carbonate and potassic nitrate. The following process works much better :-The solution which may contain, besides the metals already mentioned, the salts of the alkaline earths, is poured into a boiling solution of sodic carbonate containing some potassic permanganate. After boiling for a few minutes longer, the excess of permanganate is reduced by addition of a few drops of alcohol and filtered.Ferric oxide, manganic peroxide, alumina, and the carbonates of the alkaline earths are precipitated, whilst the filtrate contains the chromium aa sodic chromate. If present in not too small amount, the liquid is coloured more or less yellow. If colourless, the liquid is concentrated to a small bulk, and ddified with dilute sulphuric acid. A piece of starch which has been moistened with a solution of potassic iodide is now introduced, and if chromium is present, will turn violet. Or the liquid mag be shaken with potassic iodide and carbon disulphide, when the latter will turn violet. For the quantitative estimation we proceed in similar manner. The solution is slowly added to the hot permanganate, and boiled for ten minutes. The filtrate is acidified with hydrochloric acid, boiled with alcohol, and finally precipitated in a porcelain dish with ammonic sulphide.In a mixture of 50 C.C. solution of ferric chloride (1 C.C. containing 000714 ferric oxide), 50 C.C. solution of alum (1 C.C. containing *0068 alumina), and 1 C.C. chromic chloride, containing *0018 chromic oxide, the latter was successfully quanti- tatively estimated. 2. VALUATION OF RICH COPPER OREs.-The usual plan is to first precipitate the copper by metallic zinc, then to redissolve precipitate after washing in nitric acid, and, after addition of ammonia, to titrate with potassic cyanide. The preliminary pre- cipitation with zinc is advisable, aa copper is but imperfectly separated from iron by ammonia. The finely powdered sample is intimately mixed in a porcelain crucible, with double its volume of zinc dust.The lid is put on, and the whole ignited for ten minutes. The ore is by this treatment completely desulphurised, the zinc taking up all the sulphur. After cooling, the mass is boiled in a beaker, with dilute sulphuric acid (1-4), which dissolves the excesa of zinc and the zinc sulphide, also the iron. The copper is left insoluble, but contains, besides small quantities of cupric sulphide, any metals pre- cipitable by zinc which may have been present in the ore, also the gangue. After thorough washing with boiling water, the mass is, as usual, treated with nitric acid, slter'ed, diluted up to a definite bulk, and aliquot parts are titrated with potmsic cyanide. These reactions are more delicate than the test with hydrogen peroxide.The following process will, however, be found more expeditious :- * Repert, Anal. Chemie, 3, 1887,36 THE ANALYST. 3. CHANCEL’S PROCESS FOR THE SEPARATION OF ALUMINA FROM IRON.-The direct separation of alumina from iron is best effected by boiling the neutralised solution with sodic hyposulphite (Chancel). I n practice, the process is but seldom employed, most chemists preferring to weigh the mixed oxides, and then to volumetrically estimate the iron. We have, however, made some experimenta to test the accuracy of the method. A very weak solution of alum, 30 C.C. of which yielded -0768 alumina, was mixed with 25 C.C. of a neutral solution of ferric chloride (= -1785 ferric oxide) diluted with water up to 400 c.c., and boiled down to about 100 c.c., after addition of excess of sodic hypo- sulphite. The following results were obtained :- The precipitated alumina was then a t once filtered off, Number of C.C.of Containing Alumina solution of alum taken. Alumina Fonnd 30 .. .. 00764 .. . . 00730 - .. .. -- .. . . *0730 40 .. .. *lo18 .. . . *0984 .. .. -- .. . . 00956 50 . . .. 01273 .. .. *1220 - As will be noticed, the precipitation of the alumina was in no case complete. The filtrate and washings, of the two last experiments were boiled down to half the bulk, and further precipitates of alumina were obtained, amounting to #0072 and *0068 respectively. This, however, makes the results too high, which is explained by the difficulty of com- pletely expelling the co-precipitated sulphur. The presence of sulphur may be detected by the yellowish colour the mms assumes on ignition.Alumina, free from sulphur, does not turn yellow. Chancel’s process is, however, trustworthy, when the following rules are adhered to : strong dilution, and boiling down to at least half the volume, again boiling the filtrate, and collecting any further precipitate of alumina, and igniting precipitate before the blowpipe until yellow colour disappears. 4. ON THE USE OF HYDRIC PEROXIDE.-Hydnc peroxide is frequently used in analytical work, for instance, to completely precipitate manganese from its ammoniacal solution. We have conducted some experiments, to see whether other metals would interfere with the accuracy of the process. Fifty C.C.of a solution of manganous sulphate, containing *1335 manganous manganic oxide, were mixed with a weak solution of zinc sulphate, mixed with excess of ammonia, and boiled with hydric peroxide. The precipitate was rapidly washed, and ignited before the blowpipe. Two other experiments were made, using nickelous sulphate, and calcic chloride. The following results were obtained :-The first precipitate weighed .1640 gramme, the second -1475 gramme, the third a1376 gramme. As these results were too high, tho precipitates were redissolved in hydro- chloric acid, and again precipitated with ammonia and hydric peroxide, when the follow- ing weightxi were obtained: 01334, *1467, 01341 gramme. From these experiments we may conclude the following :--Manganese may be completely separated ftom zinc by repeated treatment (about four times), with ammonia and hydric peroxide. TWO precipitations will free it from nickel, but from lime the separation is incomplete, Precipitated cobaltous oxide is quickly oxidised to the sesquioxide by ammoniacal hydric peroxide, but nickelous oxide does not alter. Ammoniacal solution of nickel does37 - THE ANALYST. not change on boiling with the reagent, but ammoniacal solution of cobalt colours deep brownish-red. On acidifying with hydrochloric acid and boiling, nearly all the cobalt precipitates as the rose0 compound. This reaction is very useful for preparing pure cobalt compounds from cobalt ores containing nickel. I-I_. -

ISSN:0003-2654    

DOI:10.1039/AN8871200035

出版商:RSC    

年代:1887

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THE ANALYST. 37 REVIEWS. SANI’~BRY EXAMINATIONS OF WATER, AIR AND FOOD: A vade mecm for the Medical Officer of Health. By Cornelius Fox, M.D. Secoad Edition. London: J. and A. Churchill, New Burlington Street, W. THIS concise, but yet distinct, treatise has undergone considerable change and vast im- provement since the first issue. It has the great advantage of having a real rccison d’stre, because it is written on definite lines, and with a fixed purpose. The author’s views on the relative duties of the medical officer and of the public analyst are sound, and ought to be more generally appreciated by health authorities. He holds that, between the duties of the two officers, there is a strict and well defined line. The medical officer should be competent and trained to undertake the examination of water, air, and food from a st&ctZy mmitary point of view; he should be able to make such chemical and microscopical analyses as will enable him to say whether the water and air of any district are or are not in a state conducive to a healthy condition of the inhabitants.I n the domain of food his duties should be limited to searching for any condition dangerous to public health, such as decayed or diseased meat, fish, milk, bad flour, and decomposed or poisonous food generally. There the functions of the medial officer should cease and those of the public analyst commence. It is the duty of the latter officer to examine all food specially for what are strictly adulterations and frauds with the commercial object of extra profit.In a word, the medical officer is to look after the hedth of the people, while the public analyst is the lever whereby the local authorities can prevent their constituents from being swindled in pocket. This being the author’s opinion, he writes accordingly, and with very excellent effect. The information given is of the most recent nature, and in water analysis the bacteriological mode of investigation is fully described. The whole book is well put together, and will form an excellent help to those medical men presenting themselves a t the special examinations in sanitary science recently established at the various universities. The illustrations of water deposita and of parasites in meat, etc., are distinct and well drawn, and the print is of that large, plain style, so delightful to the tired eye of the student.Dr. Fox’s work has made its mark as a real text-book, likely to now run through many editions. OUTLINES OF QUANTITATIVE ANALYSIS. By A. Humboldt Sexton, Professor of Chemistry London : Charles Grsn and CO., The author’s excuse for adding yet one more stone to the pile of works on chemistry is that he has found the want of a book for use in the laboratory sufficiently short and simple for ready reference by students who desire a fair knowledge of the ordinary quantitative work of a chemist, and yet sufficiently comprehensive for all common wes. The plan is something like that of a very reduced ‘‘ Fresenius,” but only one method for each case is dehitely chosen and adhered to. It must be admitted that the processes so selccted are, in most cases, those in actual common use in our commercial laboratories, and that the choice generally has been judicious.It i s certain that, given in the College of Science and Arts, Glasgow. Exeter Street, Strand.TEE ANALYST. --- 38 proper laboratory supervision and oral instruction, the student working by a book like this will become a fairly expert mineral analyst with much 1- trouble than before. His ideas will, of course, be somewhat dogmatic and narrow, but he will hme a really good foundation to start with, and then he can amplify his methods from larger works at his leisure. After taking the estimation of the common metals and acids, both gravimetrically and volumetrically, we have the separation of the chief metals and acids, and the book winds up with a special chapter devoted to the analysis of no l e . than t wenty-three of the*ordinar$minerals and commercial products commonly analysed for trade purposes. We could point out one or two little matters wherein the author could improve the next edition, but we do not want to be hypercritical over B book written with excellent intention, and likely to be exceedingly useful to a large number of students of quantitative analysis.

ISSN:0003-2654    

DOI:10.1039/AN8871200037

出版商:RSC    

年代:1887

数据来源: RSC

摘要:

38 TEE ANALYST. CORREBPONDENCE. [l’lu! Editor is mt ilt aiby ?uay ~8spmtsibk: for opi9tim6s eayrmsed by his corTcspo?bdents.] 5% the Editor of the ANALYST. Sm,-I regret that my absence in Denmark prevented me from being present at the meeting of the S.P.A. on December 8th, when my paper on The Lactocrite ” was read, and I shall be obliged if you will allow me space for a few lines in reply to some remarks made after the reading of the paper. Mr. Adams was not quite correct in seeing in my paper (at least, not directly) a corroboration by the lactocrite to his own method of analysing, because I have used Storch’s method for the analyses quoted, which method has also been used by Mr. Sebelien. The analysea in my paper show a close correspondence between the iactocrite and Storch’s method.Mr. Adams’ remark may perhaps have reference to the equally good results obtained by Dr. A. Wynter Blyth in trying the lactocrite, its he used Adams’ method. But, if both Storcli’s and Adams’ methods correspond with the lactocrite, how can they fail to correspond between themselves, as Mr.Adams says they do ? Fortunately he gives him- self the explanation, as, from his description of Storch’s method, it appears that he has overlooked the most important feature. It is not claimed that pumice-stone, when used simply as an absorbent, is in any way superior to sand, plaster of Paris, or similar media. The advantages found in pumice are that it is brittle and highly spongy, and that it therefore easily can be reduced to a very fine powder. I n this state only should it be extracted, viz.: the milk is thoroughly dried on the pumice gravel, and this is then ground very fine-almost as flour, It is claimed that no fat can escape extraction when this fine powder of milk and pumice is repeatedly treated in 811 extraction tube of the description correctly (riven by Mr. Adams. Mr. Adams has-if I understand his remarks correctly-extracted the coarse purnbice powder (gravel) without pulverising it, and this is the only explanation of the fact that he has found a dif- ference between his own very able method and that of Storch. Dr. Vieth’s remark on the besting of skim-milk with the lactocrite I hope t o be able to answer later on, when I shall give the results of some experiments with the lwtocrite as applied to separated milk.-1 am, sir, yours truly, HABALD FABER. London, January 12th, 1887. BOOKS, &c., RECEIVED, AMKRICAN Analyst ; American Chemical Review ; American Drtiggist ; American Grocer ; American Journal of Pharmacy ; Brewer’s Guardian ; British and Colonial Druggist ; Canadian Pharmaceutical Journal ; Chemist and Druggist ; Country Brewer’s Gazette ; Hospital Gazette ; Illustrated Science Monthly ; Independent Journal ; Invention ; Journal of the American Chemical Society ; Journal of Microscopy and Natural Science ; Justus Liebig’s Annalin der Chemia ; Journal of the Society of Chemical Industry ; Le Mouvement Hygienique ; Medical Frcse ; Medical Record ; The Miller ; Monthly Magazine of Pharmacy and Chemistry ; Nationa,l Druggist ; Pharmaceutical Journal ; Phar- maceutical Record ; The Polyclinic ; Popular Science News ; Repertorium der Analytischen Chemie ; San Francisco News Letter ; Scientific American ; Society of Arts Journal, NO!I’ICES TO CORRESPONDENTS. ALL Communications to be addressed to 326, Kennington Road, London, 8.E.

ISSN:0003-2654    

DOI:10.1039/AN8871200038

出版商:RSC    

年代:1887

数据来源: RSC