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1. |
Obituary notice |
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Analyst,
Volume 25,
Issue January,
1900,
Page 1-1
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摘要:
THE ANALYST. JANUARY, 1900. OBITUARY NOTICE. THE LATE PROFBSSOR HODGES, K D . , F.I.C., ETC. IT is with regret that we have to chronicle the death, on Dee. 13, 1899, at Belfast, of Professor Hodges, who had attained the venerable age of eighty-four years, and was a distinguished member of our society. He was born and educated at Downpatrick, and afterwards studied medicine at Dublin and Glasgow, qualifying at both places. During his stay at the latter city Mr. Hodges made the acquaintance of Professor Graham, who strongly advised him to devote his talents exclusively to chemistry, Mr. Hodges, however, preferred to adhere to his original intention, and commenced the practice of medicine at Newcastle, afterwards removing to Downpatrick. He there evinced much ability as a lecturer, and became so deeply interested in agriculture that this induced him to proceed to Giessen to study chemistry under Liebig, where his ability and diligence so interested the Baron that the two became intimahe friends.At Giessen he took the degree of Doctor of Medicine. Dr. Hodges then returned to Downpatrick, and there delivered a lecture on agriculture, which attracted so much attention that one of its results was the formation of the Chemico-Agricultural Society of Ulster, in 1845, to which Dr. Hodges was appointed chemist. He removed to Belfast in 1844, and shortly afterwards was appointed Professor of Chemistry in the old Belfast College. On the foundation of a Chair of Agriculture in Queen’s College, Belfast, Dr. Hodges was chosen as its first occupant, and also as Lecturer on Medical Jurisprudence there. He was also Lecturer on Agriculture at the Glasnevin Agricultural School. Dr. Hodges wrote many treatises and papers, which had a wide circulation. He was one of the founders of the Royal College of Chemistry, London. He held many important offices. For a long time he was Government Analyst, also Public Analyst for Belfast, and for five Irish counties. He was a corresponding member of the Dublin Natural History Society, member of the Royal Academies of Agriculture of Sweden, and of Turin, and of the Imperial College of Gorygoretzt, Russia; also a Justice of the Peace for County Antrim. Both of these positions he held to the day of his death.
ISSN:0003-2654
DOI:10.1039/AN9002500001
出版商:RSC
年代:1900
数据来源: RSC
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2. |
Note on asafœtida |
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Analyst,
Volume 25,
Issue January,
1900,
Page 2-6
J. M. Martin,
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摘要:
2 THE ANALYST. NOTE ON ASAFmTIDA. BY J. M. MARTIN, B.A., M.B., AND C. G. MOOR, M.A. (Read at the Neeting, December 6, 1899.) A SAMPLE of gum-resin of asafetida having been found to yield a very much higher ash than the standard given by the British Pharmacopoeia, a number of samples were examined to determine the general condition of the commercial article. Twelve samples were examined its to : 1. Matter soluble in 90 per cent. alcohol. 2. Ash of the gum. 3. Portion of ash soluble in HCI.THE ANALYST. 3 I n all the samples, on grinding, much mineral matter was found, in one case a stone weighing 3.4 grammes. The percentage of the gum soluble in alcohol (90 per cent.) ranged from 14.8 to 39.8, instead of the 65 per cent. of the British Pharmacopceia. The ash of the gum ranged from 63.1 to 26.4 per cent., the British Pharmaco- peia figure being 10 per cent.The solubility of this ash in 50 per cent. HC1 varied from 15.7 to 57.9 per cent., but in one case reached 96-4 per cent., nearly the whole going into solution with much effervescence. The British Pharmacopeia directions for making the tincture of asafetida are to extract 200 grammes of the gum-resin with 1 litre of 70 per cent. spirit. Hence, supposing 65 per cent. of the gum were soluble, the tincture should contain 13.5 grammes per 100 C.C. of total solids. Seven tinctures were examined for total solids, and gave results ranging from 4.5 to 8.5 grammes per 100 C.C. The results of the analyses made are as follows : Sample. I. ... 11. ... 111. ... IV. ... V. ... VI. ...VII. ... VIII. ... IX. ... X. ... XI. ... XII. ... Extract. 31.9 30.2 14.9 20.2 18.4 35.4 19.9 23.0 14.8 39.8 37.7 28.9 Ash of Gum. ... 38.6 ... 45.8 ... 62.1 ... 56.3 ... 59.3 ... 40.1 ... 58.4 ... 52.9 ... 63.1 ... 43.4 ... 36.4 ... 47.2 Tinrtirr-eo. Ash insoluble in HCI. ... 82.5 ... 3.6 ... 77.8 ... 84.3 ... 74.2 ... 64.9 ... 74.6 ... 78.2 ... 83-9 ... 42-1 ... 67.2 ... 78-4 I. 8.2 grammes per 100 C.C. V. 5.3 grammes per 100 C.C. 11. 6.2 ,) 2 1 VI. 4.3 y , 9 7 111. 4.5 ,) 2 9 VII. 8 5 ,, 9 ) IV. 7.6 ,, 9 7 I It is, then, evident that commercial samples of the gum-resin of asafetida are very far below the standard given by the British Pharmacopceia, and that they are probably intentionally weighted with worthless material. Consequently, preparations made from the gutn-resin according to the British Pharmacopceia directions fall far below the presumed strength, and the medical profession are prescribing inedicines of uncertain and variable composition.A few other observers have noted this condition of commercial gum-resin of asafetida, yet but little attention seems to have been given to their results. NOERNER ( J o z L ~ . Phayrn. Chirn., March 1, 1888, p. 24) examined a sample, and found 86 per cent. of mineral matter, and only 14 per cent. asafoetida. large pro- portion, on fracture, proved to be alabaster coated with a thin layer of asafetida resin. BUCKNER (14. J. P., 1890) found the ash in a number of samples to range from 19 to 56 per cent.4 THE ANALYST. LLOYD (P. J., i., 243, 1896) said “ash is often higher than the 10 per cent.required by the British Pharmacopceia.” The hTcLtionaZ Dispensatory states that the ash of commercial samples is sometimes as high as 40 per cent. A thirteenth sample was examined which had been specially prepared by a firm of chemists with a view to determining how far it was practicable attempting to produce a sample approaching British Pharmacopoeia strength from this raw material. They succeeded in increasing the matter soluble in 90 per cent. alcohol to 57.5 per cent. (British Pharmacopoeia, 65 per cent.). Although asafetida in its various preparations is now prescribed somewhat less than formerly, yet we certainly ought to have reliable material. The standard of the British Pharmacopmia is too high, unless means can be taken to prevent adulterated resin reaching the market.In this connection it may be remembered that a few years ago many samples of ginger were discovered with an abnormally low soluble ash, and that when attention had been drawn to this, and a few prosecutions followed, such ginger almost entirely disappeared from the market. The ash of this was only 5.8 per cent. DISCUSSION. The PRESIDENT having invited discussion, Mr. CHATTAWAY said that the British Pharmacopeia, in addition to laying down certain regulations as to the proportion of ash, solubility in alcohol, etc., described the physical characters of the drug ; and it would be interesting to know if the samples referred to were in accordance with the Pharmacopoeia in this respect. Mr. E. M. HOLNES said that about a year previously, in his capacity as one of the referees in connection with the compilation of the present Pharmacopcein, he had had analyses made of several samples of asafetida.He was aware that the com- mercial form of the drug was largely mixed with mineral matter, but, at the same time, the gum in the form of “tears ” was almost pure, and he had experienced no dieculty in obtaining it. When the gum was being collected, a certain number of the tears were obtained pure, except for a small quantity of sand attached to their lower surface, where they fell on the ground ; but there was a large quantity of more or less liquid asafetida, which could not be collected in the ordinary way, and this was mixed by the collectors of the drug with a certain quantity of whatever soil might be obtainable in the neighbourhood in order to solidify it.Sulphate of lime, in the form of alabaster, was probably used as an adulterant, not only €or asafoetida, but for benzoin, in which it could be used to represent white tears, a certain proportion of which was normally present in the lump form of the drug. In the samples which had been analysed for him the ash in no case exceeded 8 per cent., but in the crude material in lumps it often ranged from 20 to 60 per cent. He thought that, while for medicinal purposes a drug as pure as possible was desirable, a commercial article was admissible which could be used for drain-testing, or for denaturing tea in the manufacture of caifeine; and a normal standard might be laid down for the crude drug, quite apart from the medicinal point of view.The supply of asafcctida sufficiently pure for medicinal purposes was limited ; but there was a fairly abundant supply of the ordinary form, in which a moderate proportion of mineral matter-say, from 20 to 30 per cent.-was for commercial purposes not of much consequence,THE ANALYST. 5 seeing that for such purposes the article would be bought on the basis of its percentage of active matter. Mr. ALLEN said he felt some dificulty in agreeing with Mr. Holmes’s suggestion to establish two qualities of the drug. The addition of calcium sulphate in the case of the lump asafetida was an intentional adulteration, which it would, he thought, be dangerous to countenance. Even though the adulterated material were intended only for commercial purposes, he did not see why the purchaser should be supplied with calcium sulphate when he might imagine that he was getting pure asafetida.Mr. CRIBB said that he had found the ash in asafetida to vary from 15 to 35 per cent., and the proportion soluble in alcohol was correspondingly low. The samples were purchased indiscriminately in London. As far as he could ascertain, the drug in the solid form was hardly ever asked for except in remote country districts, and it was now rarely employed in medicine in any form. Mr. EKINS said that the drug was very seldom used in the solid form except for veterinary purposes, and the prescriptions in which the tincture appeared were very few. Mr. MOOR said that the samples he had examined were all in the form of a hard concrete mass, which was the only form of the drug to which his experience extended.Regarding the tincture, which was the chief form in which the drug was used medicinally, it was perfectly easy to make the tincture up to the proper standard by taking a suitable quantity of asafcetida. Dr. RIDEAL observed that in the Pharmacopoeia it was directed that, in making the tincture and fetid spirit of ammonia, a certain quantity of the drug should be taken, and it seemed open to question whether the use of a less pure drug in larger quantity would be in strict conformity with the directions. Mr. MOOR said that to sell a tincture of as nearly as possible the proper strength -even though it might be made from a, larger quantity of the drug than the Pharrnacopceia directed-would, he thought, be better than deliberately to sell a weak tincture, and accordingly he would suggest that the tincture itself should be standardized.It would be unreasonable, he thought, too strongly to insist on con- formity with the British Pharmacopoeia tests, and he would suggest that for the present asafetida containing not more than 20 per cent. of ash, and not less than from 45 to 50 per cent. of matters soluble in alcohol, should be accepted. Mr. CHATTAWAY said that the Pharmacopoeia laid down that the drug should be in the form of tears-indeed, the actual size of the tears is specified ; and he thought that the specimens referred to by the author, although they might be admissible commercially, could not be regarded as representing the British Pharmacopeia article, which frequently contained as little as 2 or 3 per cent. of ash. Mr. HOLXES said that, while the British Pharmacopeia limit of ash was 10 per cent., a much smaller percentage was quite common in the drop or tear asafetida. He thought that lump asafetida would be admissible only provided that it contained less than 10 per cent. of ash. The question of purity was merely a question of the price given for the drug, which varied from about 45s. or 60s. for the lump, to 120s. per cwt. for the finest tears. Seeing that the Pharmacopceia intimated that only the pure drug should be used in medicine, he did not think it would be justifiable to use6 THE ANALYST. the drug in an impure state in medicine, and in its purification some volatile active ingredients might be lost, and the British Pharmacopeia standard of strength would not be maintained.
ISSN:0003-2654
DOI:10.1039/AN900250002b
出版商:RSC
年代:1900
数据来源: RSC
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3. |
On some analyses of modern “dry” champagne |
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Analyst,
Volume 25,
Issue January,
1900,
Page 6-9
Otto Rosenheim,
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摘要:
6 THE ANALYST. ON SOME ANALYSES OF MODERN “ D R Y ” CHAMPAGNE. By OTTO ROSENHEIM, PH.D. , AXD PHILIP SCHIDROWITZ, PH.D. (Read at the Meeting, December 6, 1899.) THE authors have recently had an opportunity of examining a number of champsgnes representative of the modern “ dry ” French product, and as there are practically no analyses of similar wines on record, we think it may be of interest to cotnmunicate the results obtained to the Society. The figures obtained by the analysis of wines are to a great extent-as is the case with many other articles of food-dependent on the methods employed, and therefore we thought it advisable to use the standard methods officially adopted in Germany,* in order to be able to compare our results with the data on this subject already in existence.The official German schedule was drawn up as a guide in the analysis of still wines, and therefore no mention is made of the estimation of carbonic acid. We determined the same gravimetrically by absorbing the gas in soda lime after drying with sulphuric acid in the ordinary manner, the last trace being expelled by heating in a water-bath, and then passing a current of air through the liquid. In order to regulate the flow of gas and to prevent frothing over, we made use of one of the well-known hollow champagne corkscrews with an accurately-fitting tap. On the opposite page is a table of the analytical results obtained. With regard to the composition and manu€acture of champagne, Griinhut (2. f: analyt. Clze~t., 1898,231) recentlyput forward the suggestion-based solelyon analytical figures-that this article in general bears the character of a ‘‘ gallisised ” wine-that is, a product which has been unduly diluted by the addition of a weak solution o€ sugar prior to fermentation, and that this is principally evidenced by the low per- centage of ash.The figures we have obtained appear at first sight to corroborate Griinhut’s conclusions, to which he came, however, by an erroneous method of reasoning, He compared his figures with averages obtained from a large number of analyses of German white wines, but there is no justification for this, as the methods of manufacture are so completely different that no strict comparison can be made between the two classes of wine. Practically all better-class champagne is made from blue grapes, and in order to meet the exigencies of the market, which demands a very light-coloured article, the grapes must not be subjected to any preliminary crushing or kneading, and special care is taken to ensure -a rapid separation of the juice from the skins, pips, etc., in the press.This procedure, adopted for the purpose of obtaining a light-coloured must, necessarily tends to prevent the extraction of mineral matter from the skins, stalks and pips, and it is therefore to be expected that the finished article will contain a relatively small percentage of ash. I n the manu- facture of ordinary white wines a preliminary crushing takes place in the vineyard, * German Wine Law, June 25, 1896.o m 2 12 m r' 15 r l r l ; a Q , m r l ! - 1 - I - I - 1 - 'IGSI I , .'26S'L8 THE ANALYST. and the separation of the juice from the marc is not hastened as in the preparation of champagne. In connection with the above remarks, we may add that similar views were expressed by Kulisch (2. f. n?zgciu. Chem., 1898, 573) in criticising Grunhut’s paper. With regard to our own results, it will be observed that both the extract and the ash generally are rather low (compared with Bordeaux or Rhine wines), with the exception of No. 4 (3.76 per cent.), which is due to the high percentages of sugar and glycerin. No. 3 shows a high percentage of ash. I n regard to the sugar percentages, it will be seen that only Nos. 4, 9 and 12 are appreciably above 1 per cent. The relation of ‘( reduced extract ’’ to ash is considerably below 10 per cent.(that being the normal average deduced from a large number of analyses of still white wines), except in the case of Nos. 3 and 10. a r e have already given an explanation for this apparent anomaly, which constitutes an excellent illustration of the fact that it is in many cases extremely dangerous and ill-advised to judge the quality and value of an article of food solely in the light of the figures obtained by analysis. No. 10 shows some features of interest ; it is the only case in which the specific gravity falls below 0.99, but this is probably due to the high percentage of alcohol in relation to the low extract. The total acidity is small, but the volatile acid relatively large. Another noteworthy feature is the high hvo-rotation of No. 6, which indicates a, preponderance of lmulose.The absence of cane-sugar was demonstrated by inver- sion, which did not alter the rotation. According to Neubauer (Bey., x., 827) the proportions of dextrose and lzvulose in a mixture can be calculated according to the following equations : This sample also showed the highest percentage (1.02) of carbonic acid. 1. X = 0.637s +- 0.342~~. 2. Y=S-x. X = dextrose ; Y = lzvulose ; S = total invert sugar found ; w = rotattion observed in 200 mm. tube. Although the results obtainable from these equations are not absolutely correct (for reasons into which we cannot enter here), they are sufficiently exact to permit of the approximate determination of the proportion of dextrose to lzvulose respectively. On applying the above formulx: to the case in point, it was found that the quantity of lzvulose was 7.01, and of dextrose 2-87.In most cases the proportion is as 1 : I, and this indicates that in No. 6 the fermentation of the sugar in the added liqueur ceased after the disappearance of the greater part of the dextrose. D1scuss10x. The PRESIDENT observed that, speaking broadly, it seemed that the proportion of extract in those cases in which it was high rose with the proportion of sugar, which probably depended on the composition of the liqueur that was added to the grape- juice after fermentation. He presumed that there might still remain a certain quantity of unaltered cane sugar, though doubtless most of the augar would be inverted during secondary fermentation. Dr. SCHIDROWITZ said that in those cases in which the determination had beenTHE ANALYST.9 made the sugar present was found to be completely inverted. I t would become inverted very quickly, chiefly owing to the acidity of the liquid in question. Mr. RICHMOND remarked that in it liquid which had undergone fermentabion by means of yeast it was unlikely that there would be any unaltered cane sugar present, complete inversion being brought about by an enzyme secreted by the yeast. The PRESIDENT observed that before the liqueur mas added primary fermentation would be over. Mr. RICHMOND said that the enzyme would still be present in the yeast cells remaining in the wine, and the sugar in course of time must, he thought, surely become inverted. Mr. CRIBB inquired where a description of the German oacial methods of analysis was to be found. Dr. SCHIDROWITZ said that the official methods were embodied in the German Wine Law, dated June 25, 1896, and were to be found in the appendices to most German works on the subject (e.g., Windisch, Die clzemisc7ie Lr7zterszichzing 11. Bezir- theilzmg clcs Wciizcs, p. 45 and e).
ISSN:0003-2654
DOI:10.1039/AN9002500006
出版商:RSC
年代:1900
数据来源: RSC
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4. |
Foods and drugs analysis |
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Analyst,
Volume 25,
Issue January,
1900,
Page 9-12
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摘要:
THE ANALYST. 9 ABSTRACTS OF PAPER§ PUBLISHED IN OTHER J 0 U R N A LS. FOOD§ AND DRUGS ANALYSIS. The Occurrence of Chromates as Preservatives in Milk. A. Leys. (JOUTIL. Piiarrn. Clzzim., 1899, x., 337-34O.)-Dnring the present year the author has frequently met with chromates associated with formaldehyde, most frequently in the proportion of 1 part in 100,000 of milk, though considerably larger quantities are of not unfrequent occurrence. In order to detect traces of chromates the following tests are reconirnended: From 100 to 150 C.C. of the miik are evaporated to dryness, the residue ignited, and the ash extracted with a few C.C. of water, note being taken of the colour of the solution. A reagent is prepared by adding a few drops of indigo carmine solution to con- centrated hydrochloric acid until the liquid has the colour of Fehling’s solution. On boiling 5 C.C.of this reagent with a few drops of the filtered aqueous extract of the ash, the colour is instantly discharged in the presence of the slightest trace of chromate. h second test consists in adding some pure aniline and commercial toluidine to an excess of acetic acid free from furfural, filtering through purified animal: charcoal, and diluting the filtrate to the tint of the extract of milk ash. On boiling equal parts of this reagent and the extract for two or three minutes, a cherry-red colour is produced after a short time in the presence of a chromate.10 THE ANALYST. The two reactions described above are said to be much more sensitive than Schiff’s guaiacum reaction for chromic acid, and point to the presence of an oxidizing agent.I n order to identify t’his as a chromate Barreswil’s hydrogen peroxide reaction may be employed. The aqueous 3xtract of the ash is acidified with a few drops of dilute sulphuric acid and two or three drops of hydrogen peroxide added. The immediate formation of the fugitive blue tint of perchroinic acid indicates the presence of a chromate. ci. Ll. 11. 011 Fruit Juices and their Exaniination, with particular reference to Raspberry Juice. I. Detection of Foreiga Colouring Matter. E. Spaeth. (Zeit. f iir Untemiich. der Nalz?.. w i d Genussmittel, 1899, ii., G33-635.)-The author deals principally with the detection of artificial colouring iiiatter in raspberry juice. One of the principal means of sophistication is by admixture with cherry juice, and though the lead acetate method is said to provide a means for the detection of even sinall quantities, the author canr,ot confirin this, nor is he able to indicate any method at present by which admixture with cherry juice can be detected with certainty.Other vegetable colouring matters used for the purpose are those of the whortleberry, red beet, red poppy, mallow, phytolacca and orseille. Of these, orseille, phytolacca, beet and cochineal can be identified, whilst ia a general way the addition of the juices of such other fruits, as the mhortleberry, the blackberry, and the elderberry, can be detected, though in most cases it is impossible to say which of these has been added, their behaviour with reagents being so similar. Of the tar coloilrs a large and ever-increasing number is made use of, such as rosaiiiline, fuchsin, eosin, etc.The table opposite gives the principal reactions of the various colouring matter3 which the author has studied : Tar colours dissolved by ainyl alcohol can be distinguished from vegetable coloiirs by the colour being removable by means of wool freed from fat. S. fuchsin, however, not being soluble in ainyl alcohol, it is necessary also to submit the diluted juice itself to the wool test. In the sophistication of lemon-juice, tar colours are always used, and the amZ1 alcohol test with the removal of the colour by wool is almost exclusively available. H. H. B. S. Cochineal is also used. The Detection of Saponin i n Lemonade. Frehse.(Jozmz. PJLGWVZ. C’JL~??~. , 1899, x., 13-16.)--In a communication on the composition of the lemonade manu- factured in Lyons in 1898, the author states that from time to time he has found saponin, but that its use is not general, owing to its being readily precipitated and causing a, turbidity in the liquid. It can be recognised by the persistent foam produced on shaking the bottle after the expulsion of the carbon dioxide, but its chemical identification is not easy in the presence of sugar and tartaric acid. The tests based on its conversion into___ .- - - _- Mer- curic Ferrous Chlo- Sulphate. ride. AIu- miniurn Ammo' AT:te 2:;:. Sodium Carbonate. Chalk. ;ray. Magnesia, or Magnesium Carbonate. ----- Grayish- green. KOH). Deco- lorized. Ditto. Ditto. Ditto.Ditto. ------_- Reddish. I'recipitate Light aiid filtrate red. gray- ----- Ditto. Reddiqh. Ditto. _ _ _ ~ _- -~ Reddish. Ditto. Ditto. Reddish. Grayish- Violet. _______ blue. __._ .. Reddish- Ditto. Violet. SG- ish- green. Ditto. Green- ish- Yel- - yellow. _- - Yellowish- -- green. Srownish- green. Green. -____ Dark green. I ~ Yellow- ish- orange. Grayish- red. Grqish- green. filtrate greenish. Grayish-' red. Reddish--- gray. ___ _. ~- Slate-gray, - ._ _ _ _ ~ Gray, filtrate green. - - __ -- - Gray. _._-- Blueish- graY* ZrayislF- green. Green. -h- blue. G&. _-- MgC03= green ; MgO = lorizcd. blueish- violet. green. - Green. Yellow. - Green. . - - . _ - iTi~&O3= violet; , ICOH = red. _---- __ Not Ditto. Very fine Ditto. deco- blueish- lorized. violet. Yellow.Violet. Reddish- Ditto7 - - - - - __ - - -- - violet- pink. _--____ ___ 1 Yellow. Violet. Ditto. Ditto. - - -- lcllow- sh- irown. Brown- ish- red. Ruby- red. I___ NR2C03= violet-red ; KOH= yellow to yellow-green. Na2C03 ruby-red. Ruby-red. __- - _. - -- Reddish- violet. MgO= yellowish. l\lgc03= violet-red- pink. Blueish. Not Blueish- Greyish- Eted- deco- gray. blue. dish lorized. violet. 1 -_ Acids. xed. Red. Red.-- R e d 7 Red, - _- Red. Red.-- - Red. Ruby- red. _ _ _- Red. Light red. Yellom Sodi- u m ?hate. Phos- I Lead Acetate. 1 Hydroxide. Other Solvents. From Alkaline Solution. From Acid 801u- tion. Pale yellow. ish. - ~_ - S i G G Yellow. ish-red I ish-red. Yellow. ish-red. R a - Fine red. -- Pale dueish. red. Juice. Rasp- berry. Currant. Cherrg. Black- Whortle- E l d e r - poppy.berry. berry. berry. Mallow. Phgto- lacca. Red beet. Orseillc. Logwood. B r wood. Cochineal. Direct. - - - Red- dish. Red- dish- violet. Red- dish. Red. Violet- red. - -_- I___- Deco- orized. Ditto. - Ditto. Ditto. - Ditto. Ditto. -_ Ditto. _- Ditto. __- fat aeco- lorized -. Ditto. .__ - Ditto. Ditto Blueish-gray . leddish- rellow. leddish. ireenish- :ray. litto. similar to raspberry, 1 Bltrate blueish. 1 Blueish-green. ' --I Dark blueish-green I orecipitate, greenish filtrate. Blueishgreen ; ah; Bltrate blueish- green. Brownish-gray. ____ -- .- litto. I AYlScarcely auite decolor- -- IU- tense red. Very fine blueislr trayish- (reen. - With lead acetate, violet. -~ - fine green. ?ine green. I I I violet. green. Filtrate BIgco3= fine red: I violet : - --- - _.__-- -- - ___ __ ___ Deco- Nothing Very fine No- lorized, character- reddish- thing but 1 istic. I violet. 1 charac strongly coloured with separation of a reddish-brown pre- cipitate. Precipitate of :olourcd red, Bltrate yellow- ~sh red. Flesh-coloured precipitate. I flesh- teristil D : * l ~- Ditto. 1 ;;;;;ne I Ditto. lorized. I ydlow. Grange-yellow; red- dish-yellow pre- cipitate. - Fine red. Yellow. Yellow. - .~ Light red. Yellow. Yellow i i T finc yellow ish-red Very 6ne red. - Gas--- acetate, reddish- violet. - .- - -- Very fine red.(also i n chloro. form). -______.-- Blueish-violet. Direct and acfd; fine golden yellow in acetic ether. Direct and acid, golden-yellow in acetic ether. The same. Red. Violet. Violet. ired. I -- Ditto.Ditto.. - - MgC03= pink. 1x1 Pink. I Ditto. Ditto. Ruby -red. --_- - I n ether, golden- yellow. Pink. - Very fine red. - Blue, fine red i n chloroform. Direct and acid, in ether, acetic ether and chlorAform, red. Allcanna. chloroform with red colour.1 2 THE ANALYST. sapogenin by warming it with hydrochloric acid is uncertain in the case of lemonade. I t was not found possible to precipitate it with lead subacetate and to liberate it from the precipitate with hydrogen sulphide, since in the presence of saponin the lead sulphide passed through the filter. Extraction of the lemonade with various solvents is useless, owing to the persistent emulsion produced in every instance, while the influence of the saponin prevents the use of fermentation to remove the sugar.The only method by which the author could obtain relatively satisfactory results consisted in evaporating the lemonade to a paste and taking up the residue with acetic ether. On filtering this liquid, again evaporating and repeating the treatment with acetic ether, if required, a residue was obtained which gave a reddish-violet coloration with concentrated sulphuric acid, and which when boiled with dilute hydrochloric acid yielded a precipitate of sapogenin, with, as a rule, an odour resembling that of cedar wood. C. A. M. The Addition of Liquorice Extract to Lemonade. Frehse. ( J O Z L ~ . PIUYWZ. Chim., 1899, x., 347, 348.)-According to the author, extract of liquorice or glycyr- rhizin itself have recently been used to produce a persistent froth in lemonade. The reactions given by saponin (see preceding Abstract) are also given by glycyrrhizin, but the latter may be distinguished by its being precipitated in the cold by hydrochloric acid, and by the chlorides of sodium, calcium, and iron. I n the presence of sugar and of glycerin, which is a frequent constituent of foam headings, the reactions are frequently masked. In such cases subacetate of lead is added, and the precipitate filtered off, washed, and decomposed with hydrogen sulphide. In the presence of the tartaric acid of the lemonade the glycyrrhizin is left on the filter with the lead sulphide. The precipitate is washed with water slightly acidified with hydrochloric acid, then rapidly with water, and is taken up with alcohol, and finally with alcohol containing a little ammonia. On evaporating these solutions the glycyrrhizin is left as a yellow residue, readily identified by its odour and its reactions with hydrochloric and sulphuric acids. C. A. &I.
ISSN:0003-2654
DOI:10.1039/AN9002500009
出版商:RSC
年代:1900
数据来源: RSC
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5. |
Organic analysis |
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Analyst,
Volume 25,
Issue January,
1900,
Page 12-22
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THE ANALYST. ORGANIC ANALYSIS. The Solubility of Volatile Oils and their Constituents in an Aqueous Solution of Sodium Salicylate. (Ball. tlc ~ ' A c c L ~ . 720yale (7e Bclg., 1899, 503 ; through Journ. Phairn. Chim., 1899, x., 353-359.)-The solvent power of an aqueous solution of sodium salicylate reaches its maximum when the liquid has a specific gravity of 1-240, and contains 1 part of the salt in 1 of water, This reagent readily dissolves a large number of alcohols, aldehydes, ketones, and free terpene phenols. On dissolving 1 C.C. of the substance under examination in 4 C.C. of the salicylate solution, and adding water drop by drop, with continual agitation to the solution, the amount required to produce a permanent turbidity M. Duyk.THE ANALYST. 13 varies considerably with different compounds.Thus, under these conditions, eugenol requires 3.5 C.C. ; geraniol and benzaldehyde, 2.5 C.C. ; carvol, 2.0 C.C. ; citral, 1.7 C.C. ; cineol and cinnamic aldehyde, 1.5 C.C. ; and citronellone, 0.5 C.C. Camphor, thymol, and menthol only dissolve in relatively large quantities of concentrated salicylate solution, although the same substances when present in their original oils are much more soluble. The ethereal conipounds of the soluble substances referred to above are not soluble, nor are terpene hydrocarbons, with certain exceptions, such as cyinene, limonene, and menthene, which are slightly dissolved owing to the formation of traces of compounds between the terpene and the sodium salicylate. The author gives the following classification of the principal alcohols, aldehydes, ketones, phenols, etc., of essential oils as regards their solubility in salicylate solution : SUBSTANCES VERY SOLUBLE : Alcohols.-Geranylic (rhodinol, geraniol) ; linalylic (dextro- and lzvo-rotatory linalols) ; citronellic (citronellol) ; bornylic (borneols) ; men- thylic (menthol), A Zdehydes.-Benzoic ; salicylic ; anisic ; cinnamic ; geranic (citral) ; cuminic ; methylpyrocatechuic (vanillin) ; methylene-protocatechuic (helio- t ropin).Ketones. - Carvone (carvol) ; methylheptenone ; pulegone ; methylnonyl- ketone ; menthone ; thujone. Canaplior and cineol. Plzc~zols.-Eugenol; thymol ; carvacrol. (Menthol and ordinary ca.mphor are soluble with difficulty.) SUBSTANCES INSOLUBLE OE NEARLY so : Scsqwiterpeiic Alcohol.-Santalol. P?lC7201 De7.iz~cLtiz~eS.--nethol ; safrol ; apiol. Ester.s.-Bornylic ; geranylic ; linalylic ; menthylic. In applying this reagent to the examination of essential oils, the sample is shaken with a convenient quantity of the solvent and allowed to stand. When the oil is composed exclusively of hydrocarbons, the mixture speedily separates into two layers, of which the upper consists of the unaltered hydrocarbon. Pure essence of terebenthene behaves in this way. If the oil consist of a free oxygen compound, such as oil of bitter almonds (benzaldehyde, with traces of hydrocyanic acid), a clear and limpid solution is obtained. When an essential oil of complex composition is treated with the reagent the oxygen compounds dissolve, while the esters and hydrocarbons separate out.Thus, in the case of oil of peppermint, the menthol and methone are dissolved, whilst the esters of menthol and menthene remain undissolved. When the hydrocarbons or other insoluble constituents are only present in small proportion, they may be dissolved through the influence of the soluble oxygen compounds ; but on adding an additional quantity of sodium salicylate, the solution becomes turbid, and the hydrocarbon eventually rises to the surface. To extract the soluble portion of an essential oil by this means, as, for example,14 TEE ANALYST. carvol from oil of caraway, 100 gramnies of the oil are shaken with 300 C.C. of the reagent for about fifteen minutes, and the mixture allowed to stand until the layers have completely separated, which requires about an hour.The lower layer is then withdrawn, filtered, and mixed with twice its volunie of water in a separating funnel. The oily layer which separates is collected, and the aqueous layer concentrated to its original density on the water-bath, and again used for extracting the insoluble portion of the original oil, which will still contain a little carvol. The carvol can also be recovered from its solution in the sodium salicylate by extraction with ether instead of precipitation with water. I n the case of oils, such as those of peppermint, bergamot, and geranium, which contain alcoholic compouuds partly in the free state and partly in the form of esters, one portion of the oil is treated with the salicylate solution as described above to obtain the amount of free alcohols ; a second portion is saponified with alcoholic seda, the prodnct treated with water and the liberated oil washed, dried, and treated with the sodium salicylate solution as before to extract the total alcohols present.In continuation of the subject (Ball. t7c l',lccitl. royale cle Belg., 1899,503 ; through Jown. Plznrinz. C ~ L ~ ~ I Z . , 1899, x., 406-411) the author gives, as a first instalment, the following particulars of those essential oils found in the Pharmacopccias : Oil 01' Bitter AZ?izoi~t7s, which consists of benzaldehyde, with traces of hydro- cyanic acid, is completely soluble in 4 volumes of the salicylatc solution diluted with 2 volumes of water. Oil of Absiizthe.-The thujone (tanacetone) is readily dissolved ; the insoluble residue should not exceed 60 per cent.Oil of Anise (green).-This is nearly insoluble with the exception of traces of anisic aldehyde. Oil ofBergan~ot.-The author found 12 per cent. of soluble constituents by direct treatment, and 35 per cent. after saponification. Oil of Ca,ept.-This is composed of cineol and hydrocarbons. A sal~iple of undoubted purity yielded 53 per cent. of soluble products consisting of nearly pure cineol, whilst cumene was identified in the insoluble residue. Oil of Cinnamon (Ceylon).-This is completely soluble in the concentrated solution, but is only partially soluble in a mixture of 4 volumes of the reagent with 18 volumes of water. The proportion of insoluble substances in an oil of good quality should not exceed 10 per cent.Oil of Cimnnion (China).-On diluting the concentrated solution by one-fourth, the cinnam yl acetate and hydrocarbons are liberated. Their proportion should not exceed 25 per cent. Oil of Caraway,-On treating this oil with a mixture of 4 volumes of the salicylate solution and 2 volumes of water, the portion dissolving consists of nearly pure carvol, whilst the insoluble part has the characteristics of limonene. The author has treated artificial mixtures of carvol and limonene in this manner, and has obtained results closely approximating to theory. Oil of caraway of good quality should contain at least 40 per cent. of soluble constituents. Oil of Cedar, being composed of hydrocarbons, such as cedrene and cadinene, is insoluble in the salicylate solution.TEE ANALYST.15 Oil of Coi*iartder.-The reagent dissolves the free linalool ; the insoluble portion Oil oj' Cwizi?z.-The salicylate solution removes the cuminic aldehyde. consists of limonene, pinene and linalylic esters. C. A. M. The Action of Formaldehyde on Proteids. C. Lepierre. (BzdL. soc. Chim., 1899, sxi., 729-738.)-The author has studied the action of formaldehyde on certain soluble proteid Substances which do not coagulate on heating. From the results of his experiments he concludes that the action is one of dehydration and condensa- tion, with the fixation of one or more CH,-groups. He finds that proto-albumoses (from muscle, fibrin, and egg albumin) are rendered completely insoluble, and the precipitate does not dissolve in hot water, in a 10 per cent.solution of sodium chloride (exclusion o€ hetero-albumoses), or in sodium carbonate solution. Deutero-albumoses are, in his opinion, not simple substances, but consist of a series of analogous bodies conveniently grouped together. Of these the members of higher molecular weight--i.c., those approaching most nearly in coinposition to the proto-albumoses-become insoluble on treatment with formal- dehyde, whilst those of lower molecular weight, approaching the true peptones, are converted into proto-albumoses, and only after a long-continued action of the reagent are the latter transformed into insoluble derivatives. In like manner true peptones are said to be first converted into substances of a deutero-albumose nature, and these in turn into proto-albumoses. The precipitates obtained from these different proteids are insoluble in cold or boiling water, but when heated for one or two hours in an autoclave at 110" C.are hydrated and rendered completely soluble, the solutions giving the characteristic reactions of the proteids from which the insoluble compounds were derived. Contrary to the experience of Trillat, the author has found that proteids rendered insoluble are not altogether indigestible, but are dissolved by normal gastric juice, although niore slowly than the untreated proteids. With reference to the use of formaldehyde for the separation of gelatin from peptones in analytical work (ANALYST, xx., 44 and 247), it is ststed that a certain amount of the peptones present are ptecipitated simultaneously with the gelatin, the proportion varying with the duration of the action of the formaldehyde and the nature of the peptones.C. -1. M. ~ _ _ _ - _ _ _ _ _ ~ - Separation of the Products resulting from the Action of Pepsin on Albumin and other Proteids. (Chem. Zeit., 1899, xxiii., 770 and 783,)-Tannin produces a precipitate in solutions of albumin, proteoses, or peptones ; an excess of the reagent redissolves the peptone precipitate. If a solution of fibrin is treated with pepsin, and if to the mixture a solution of tannin, prepared exactly as be!ow, is added, the precipitate contains nitrogen (practically) in proportion to the amount of fibrin originally taken. If the reaction between the fibrin and the pepsin is allowed to proceed for increasing periods of time, the weight of the precipitate yielded by J.Effront.16 THE ANALYST. the tannin, and also the nitrogen in it, steadily diminishes, until, finally, no precipita- tion should take place. The precipitate from solutions of egg albumin with tannin contains constantly from 5.9 to 6.1 per cent. of nitrogen; it consists of 37.5 per cent. of albumin and 62-5 per cent. of tannin; extraction with water does not alter its composition; dilute alcohol removes some of the tannin, till about 45 per cent. is left. By treatment with 80 per cent. spirit, a few drops of hydrochloric acid, and ether, the albumin may be recovered pure; but the process is wasteful, and it is better to operate as follows: The precipitate is washed, dried between paper, suspended in water acidulated with a little hydrochloric acid, and dissolved by adding a sufficiency of absolute alcohol.Four or five volumes of water are intro- duced, followed by an excess of phosphotungstic acid. The new precipitate is collected, washed in dilute HCI, dried with paper, suspended in water, dissolved with ammonia, and thrown down with barium chloride. The filtrate is finally evaporated on the water-bath. A pure solution of albuminoids is thus produced, which, giving the xanthoprotein reaction, a precipitate with picric acid, and a deposit on saturation with zinc or ammonium sulphate shows that the original tannin-albumin mixture contained the proteoses. The filtrate from the tannin- albumin precipitate contains the peptones, and may be precipitated with phospho- tungstic acid, whence treatment with barium chloride enables the peptones to be recovered pure.I n their solution neither picric acid nor zinc or ammoniuin sulphate gives a precipitate ; therefore they have been isolated. To separate the various products of the peptonization of fibrin and albumin, two special reagents are needed. Taniziiz SoZutioiz : 50 graninies of tannin are dissolved in 500 C.C. of water, 50 C.C. of normal sodium hydroxide are added, the mixture is diluted to 1 litre, and 15 C.C. of a 10 per cent. solution of tartaric acid are introduced. Phosp7~otzs~zgstic acid: A boiling 5 per cent. solution of sodium tungstate is boiled for 1 hour with 10 per cent. by volume of ‘( medicinal ” phosphoric acid ;* and when cool, 15 per cent. by volume of strong sulphuric acid is added.For analytical purposes, the original solution should contain between 5 and 10 per cent. of albumin. (1) TotaZ nitrogen is determined in 10 or 20 C.C. by the Kjeldahl process, slightly acidifying before evaporation to prevent loss of ammonia. (2) Total Albumi?zoicZs.-5 or 10 C.C. of the solution are poured into 100 C.C. of the phosphotungstic acid. After twelve hours the precipitate is collected on EL nitrogen-free paper, washed with semi-normal HC1, dried on the paper, and kjel- dahled. (3n) Syizto?ziizs.-From 20 or 40 C.C. of the solution, albumin is removed by coagulation under pressure. The liquid is neutralized with 1 : 10 sodium hydroxide ; the precipitate brought on a small filter, washed with water, dried, and kjeldahled. More accurately, however (3b), the solution, freed from albumin as before, is precipi- tated with phosphotungstic acid (a) as it is, (p) after the insoluble products of neutralization have been filtered off. The difference gives a means of calculating the syntonins.I n calculation the factor 6-25 is employed. * The solution of phosphoric acid official in the Iklgian Pharmacopceia contains 50 pa- cent. of H,PO,, and has a specific gravity of 1-35 (squire).-ABs.THE ANALYST. 17 (4) Proteoses.-30 C.C. of the solution are freed from albumin and from syntonins with dilute soda ; the volume is made up to 33 C.C. and filtered. To 11 or 22 C.C. of the filtrate are added 150 C.C. of the tannin reagent ; after twelve hours the precipitate is collected on a nitrogen-free paper, washed five or six times with tannin, dried between paper, and kjeldahled.(5) Peptoiux-The filtrate from the proteose precipitate is mixed with 100 C.C. of phosphotungstic acid, allowed to rest for one hour; the precipitate is collected, washed with semi-normal HCl, dried between paper, and also kjeldahled. I n a liquid where peptonization has not proceeded far, saturation with zinc or ammonium sulphate and precipitation with tannin give nearly the same amounts of proteoses. The further the digestion has gone, the greater the difference between the yields, until, after seventy-two hours at 50" C., one process gives 50 per cent., the other only 33 per cent., of proteoses as the proportion of albuminoids in a solution originally containing 5 per cent. of fibrin. This anomaly is not due to the presence of peptones in the tannin precipitate, but apparently to the fact that some albumoses are thrown down by the sulphates, others not.If an almost unaltered fibrin solution, freed from albumin and syntonin, is kjeldahled, and if the phospho- tungstic precipitate is also kjeldahled, the two results agree completely. If, however, digestion has proceeded far, the total nitrogen of the liquid (prepared as before) is no longer reproduced in the phosphotungstic precipitate. Experiments seem to show that " peptones " are bodies of two distinct kinds, some precipitable by the said acid, others not. I t follows that a determination of peptones from the difference between the total albuminoids- and the syntonins plus proteoses does not always lead to correct figures, the error being the greater the longer the period of peptonization.There- fore, although tannin and sodium tartrate is a trustworthy reagent, and gives accurate results in the estimation of proteoses, the peptones can only be safely determined in fresh liquids; and accordingly the author's process, as a whole, is not satisfactory, if the original solution has been submitted to the action of pepsin for any considerable length of time Phosphotungstic acid is a very untrustworthy reagent. The peptones themselves also appear to be attacked by pepsin. I?. H. L. The Use of Sozoiodol as a Reagent for Albuminous Substances i n Urine. G. Gudrin. (Journ. Phurm. Chim., 1899, ix., 576.)--Sozoiodol, or di-iodo para- phenyl-suiphonic acid, is said to be a very sensitive reagent for abnormal albuminous substances in urine.On adding 10 to 15 drops of a 10 per cent. aqueous solution of this reagent to 8 or 10 C.C. of the filtered urine, a milky turbidity or white flocculent precipitate is produced in the presence of albuminous substances. Alkaline urates and uric acid give no reaction ; whilst albumoses, peptones, and the majority of alkaloids give a precipitate which is soluble on warming. On the other hand, nucleo-albumins give only a slight turbidity in the cold, but on heating become completely insoluble. As the reagent undergoes alteration in the light, it should be preserved in orange-coloured bottles. C. A. M.18 THE ANALYST. The Detection of Alcapton in Urine. G . DenigBs. (BUZZ. SOC. Plmnn. Bordeaux, June, 18'99 ; through A m .d o C'hini. c~nal., 1899, iv., 312, 313.)-A urine containing alcapton is characterized by its optical inactivity (in the absence of sugar), by reducing amrnoniacal silver nitrate, and by changing its colour spontane- ously on exposure to the air. The latter reaction, which is due t o oxidation, has been rendered more intense by the author by treating the urine with an oxidizing agent, such as ammonium persulphate, manganese peroxide, or lead peroxide. From 10 to 12 C.C. of the urine are mixed with 0-5 t'o 1.0 gramme of lead peroxide and 2 to 4 drops of a solution of sodium hydroxide, and the liquid filtered and shaken. I n the absence of alcapton the filtrate remains yellow, but when that substance is present the colour varies from light to dark red.With iiiaiigrznese peroxide used in the same proportion, the colour of the filtrate approaches brown, and with ammonium persulphate, of which a greater quantity is required, there is a similar coloration. c. A. 31. Analysis of Commercial Phenols. S. B. Schryver. (Jozu~z. Soc. C h i l i . Iiid., 1S99, xviii., 553.)-This process is based on the interaction of sodarnide and bodies containing a hydroxyl group, which takes place according to the typical reaction : NaNH, + C,H,OH = NaOC,€I, + NH,. A 200 C.C. wide-necked flask is fitted with a separating funnel, the tube of which passes to the bottom of the vessel, and an inverted condenser connected at its upper end with an absorbing vessel, and thence with an aspirator. About 1 gramme of sodarnide is finely ground, washed two or three times with benzene by decantation, then introduced into the flask, and 50 or 60 C.C.of benzene (free from thiophenj added. The mixture is heated on a water-bath in a current of dry air freed from carbon dioxide for some ten minutes till the last traces of ammonia are expelled. About 20 C.C. of normal sulphuric acid are next placed in the receiver, and the phenol, dissolved in six times its weight of benzene, is brought into the funnel and allowed to drop into the flask. The funnel is rinsed with more benzene, and the current of air is maintained through the boiling liquid for one and a quarter hours. The excess of sulphuric acid is finally titrated with normal sodium carbonate and inethyl orange. With phenol, cresol, and guaiacol (alone), the process gives correct results, provided (1) the apparatus and phenol are perfectly dry-sodamide acts upon water-(2) suffi- cient benzene is employed to hold the sodium salt in solution, (3) the benzene is free from thiophen, and (4) air is aspirated for a sufficient length of time.Toluene or xylene may replace the benzene, but in that case a sand-bath must be used instead of the water-bath. The process is obviously not applicable to the determination of the relative proportions of more than two phenols; but it has been tested on niixtures of phenol and cresol, on wood-tar guaiacol, which is a mixture of guaiacol and creosol, on thymol in oil of thyme, and on eugenol in oil of cloves. Calling the number of C.C. of standard acid that are necessary to neutralize the ammonia given off whenTHE ANALYST 19 1 gramine of a phenol (either simple substaiice or mixture) is treated with an excess of sodainide under the experimental conditions the " hydroxyl value "-which in the iao case of pure phenol is (9.4 ==> 10.63, and in that of pure cresol is (:::=) 9.26, etc.-a table may be prepared for converting the hydroxyl value obtained when a mixture of two known phenols is operated upon directly into the relative proportion between the two ingredients, and the results calculated in this manner from the analysis of materials of the above-mentioned composition appear to be fairly satisfactory. The method is equally available for determining the amount of water in any particula,r phenol, because the reaction between sodamide and water is analogous to that between the amide and a phenol.I t also shows that fused sodium acetate is the best substance to remove the last traces of moisture from ordinary phenol. The process has an advantage over methods involving the use of bromine or iodine, as the results are not affected by the presence of hydroca'rbons, for which reason it should be useful for estimating phenols in a large number of essential oils, etc. Sodaiiiiile acts upon ketones, aminss, eke. (Titherley, Joiim. Cliem. SOC. il'mits., 1897, 460), but t>hese bodies can be readily removed by various suitable reagents. F. H. L. A Critical Examination of the Nethods of Quantitatively determining Salicylic Acid. W. Fresenius and L. Grunhut. (Zeit. anal. Chenz., 1899, xxn-iii., 292-301..)-In their experiment,s on the extraction of salicylic acid by means of a solvent the authors dissoived 0.3017 grainnie of pure sodium salicylate in 30 C.C. of water, and after the addition of. sufficient sulphuric acid to liberate the salicylic a,cid, shook out the solution with four successive portions (25 c.c.) of chloro- form. The united extracts were washed, evaporated at a low temperature, and the residue dried in the water-oven to constant weight. These amounts in percentages of the substance taken were : After 1 hour, 88.51 ; after 5 hours, 84.34 ; after 7 hours, 33-87 ; and after 9B hours, 81.22. (Sodium salicylate contains theoretically 86.23 per cent. of salicylic acid). Thus, while the substance was still moist after 1 hour's dryiiig, the results were too low when the drying was continued.From these results the authors conclude that it is impossible to obtain a constant weight in this way, and that only approximate determinations are possible. Attempts were made to avoid this loss by dissolving the residue in ether before placing it in the water-bath and then employing a lower temperature. But even in this way it was not possible to determine the point at which all the solvent was expelled without any evaporation of the salicylic acid. The results thus obtained when the residue was dried at 100" C. were : After 1 hour, 85-83 per cent.; after 2 hours, 80.76 per cent. As 11. Saupe (Phamz. Cent., xxxi., 314) obtained good result's by drying fatty acids on the top of the water-oven instead of within it, the same process was tried with the salicylic acid, but even after the treatment with ether the residue still had an odour of chloroform, and was considerably too high.In further experiments it was found that the drying could be effected with less20 THE ANALYST. Filtrate sulphate -kcid to 1 Titratsd. used. found. loss when a mixture of equal parts of ether and petroleum spirit was used in place of chloroform for the extraction of the salicylic acid, but that it was necessary to use the smallest possible quantity of solvent and to dry the residue on the top of the wat er-oven. An iodonietric method of estimating salicylic acid has been based on the observa- tion of Messinger and Vortmann (AXALYST, xvi., 75; Berichte, xxii., 2312, and xxiii., 2753) that iodine acts upon phenols in alkaline solution, forming substitution products.In the case of salicylic acid the solution is heated to 50" to 60" C., and an excess of standard iodine solution added. On again warming the liquid to 50" to 60" C. a red precipitate is formed, which increases on acidifying with dilute sulphuric acid. When cold the liquid is diluted to a definite volume, and the residual iodine in an aliquot portion of the filtrate tit'rated with standard thiosulphate. The authors point out that in the first coinmunication by Messinger and Vort- mann 4 atoms of iodine are said to take part in the reaction as in the equation, Solution added. whereas in their second paper they state that the calculation must be based 011 the assumption that 6 atoms of iodine act upon 1 of salicylic acid, whilst Vortmann, in his Aizleitzuzg XZLY Che?it.And. oiynit. Xtofe, gives thg following explanation of the reaction : with Normal c6H4\c0 /OH ON 8 + 3NaOI-I + 61 = C,jH,I.,<~~oNa + 3NaI + 3H,O. The authors give the following results in illustration of their experience with this method, basing their calculations on the assumption that 6 atoms of iodine take part in the reaction : Salicylate I Sodium , Solution. Hydroxide ~ solution. 1 ... 30 ' 12.5 2 ... 1 25 12.5 4 ... I 20 I 12.5 3 ... 20 I 12.5 C.C. I C.C. ' C.C. Per cent. 100 14-30 64.71 250 850 1 100 16.30 74.36 250 I 100 33-89 99-70 250 100 19.60 i 81.61 In the first three determinations the amount of sodium salicylate used was 1.0110 gramme dissolved in 100 C.C. ; in the last two 1.0094 gramme in 100 C.C.In the former 1 C.C. of the iodine solution contained 0.0123215 grarnnie of iodine, and in the latter 0*025600 granime of iodine. From these results the authors conclude that this method cannot yet be relied upon to give even approximately correct results, and that the exact conditions under which it can be used as a quantitative method have yet to be determined. The brorcine method proposed by Freyer ( C l ~ e m Zeit., xx., 820) has been found by them to be the most satisfactory of all the methods tried. This is based on theTHE ANALYST. 21 facts that, on mixing a solution of salicylic acid with bromine-water in excess, a yellowish-white precipitate is formed, C,H4<gtoE + 8Br = C,HBr,*OBr + 4HBr + CO, ; and that, on adding a solution of potassium iodide, not only does the excess of bromine liberate an equivalent amount of iodine, but the tribromphenol bromide also reacts as in the equation : C,HBr;OBr + 2KI = C,HBr,*OK + KRr + 21.Benee, in calculating the results, only 6 atoms of bromine correspond to one of salicylic acid. Freyer stated that an excess of about 100 per cent. of bromine was necessary, but the authors have proved that an excess of from 75 to 80 per cent. is sufficient. They have tested the method with concentrated bromine solutions, using consider- able quantities of sodium salicylate, and have obtained as satisfactory results as Freyer himself. They give the following details of their method of working, in which, like Freyer and Xioppeschaar, they used solutions of potassium bromate and bromide, and liberated the bromine by the addition of hydrochloric acid.The required quantity of the bromine salts solution is diluted with 300 C.C. of water, and decomposed with 30 C.C. of dilute hydrochloric acid (specific gravity 1-10>. Into this mixture is introduced with continual stirring a solution of about I per cent. in strength of the substance under examination. A white precipitate is imniediately formed? and, after this has been allowed to stand for about five minutes with occasional agitation, 30 to 40 C.C. of a 10 per cent. solution of potassium iodide are introduced and the separated iodine titrated with & thiosulphate. I n the most successful results the bromide solution contained 2.5 gramines of potassium b:.omate, and about 10 grammes of potassium bromide in a litre of water.Twenty-five C.C. of this solution corresponded with 25-49 C.C. of thiosulphate solution, and 1 C.C. of the latter to 0-01097505 granime of iodine or 0*00199111 gramme of salicylic acid. The percentage of salicylic acid thus found in the same sample of sodium salicylate as used before varied in four determinations from 86.21 to 86-43 per cent. This method is not applicable to the analysis of tabloids composed of starch and sodium salicylate. I n such cases the substance should be dissolved in 90 per cent. alcohol, the solution brought to a definite volume, filtered from the undissolved starch, and an aliquot part of the filtrate used for the analysis. I n a inixture of 90.91 per cent. of sodium salicylate and 9.09 per cent. of starch, the uuthors found in this way t?,!)-97 per cent. of the former. I n the analysis of wines wbich contain sulphurous acid, aldehyde sulphurous acid, and other substances which act upon bromine, the best method of determining salicylic acid, when present, is to make the liquid alkaline, concentrate it, render it acid, and extract it with a mixture of ether and petroleum spirit. The extract thus obtained is shaken with alkaline water, which removes the salicylic acid, and this aqueous solution can then be used in the bromine method. As regards the colorimetric method of estimating salicylic acid by means of iron22 THE ANALYST. chloride, the authors state that it can only be used when the amount of salicylic acid is less than 2 milligrammes. c. A. 15. Electrolytic Recovery of Copper, Zinc, and Tin from Preserves. Hilger and L. Labaud. (C’?iew. Zcit., 1899, xxiii., 854.)-The organic inntter of the sample is best destroyed by heating with sulphuric acid, as in the Kjeldahl-Halenke method ; but for the estiniation of copper, treatment with 25 per cent. nitric acid is satisfactory. Zinc is deposited from an alkaline solution of its phosphate with a current of 0.3 to 0.3 ampere at about 4 volts. Tin is preferably recovered froin a soiution of ammonium thiostannate, or it may be thrown down with sulphuretted hydrogen, the precipitate dissolved in ammonium sulphide, and the latter liquid electrolyzed. F. H. L.
ISSN:0003-2654
DOI:10.1039/AN9002500012
出版商:RSC
年代:1900
数据来源: RSC
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6. |
Inorganic analysis |
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Analyst,
Volume 25,
Issue January,
1900,
Page 22-27
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22 THE ANALYST. I N O R G A N I C A N A L Y S I S . Separation and Determination of Arsenic: and Antimony iu Ores. 0. C. Beck and H. Fisher. (s’cliool of X1‘ms Qicni*tc?*l,y, 1899, xs., 372.)--This article deswibes an investigation into the various methods proposed for estimating arsenic and autiiiiony in ores, which was instituted to discover the quickest and most accurate process. For the determination of the ax-senic, Pearct.’s method-fusion of the or8 with sodium carbonate and nitrate, precipitation of the arsenic with silver nitrate, and titration of the solution in nitric acid with standard ammonium thio- cyanate, using ferric alum as indicator-gives slightly low resirlts. Evaporating the ore three times to dryness with fuming nitric acid before fusing it, as above, also showed loss of arsenic (probably) by volatilization.Fusii2g the ore similarly in a crucible coated with fused potassium nitrate gave correct results, but the process is too loug. Pischer’s distillation method-decofiiposing the ore in hydrochloric acid and potassium chlorate, distilling the arsenic in presence of ferrous sulphate, and precipitating the distillate with sulphuretted hydrogen--is accurate, but too lengthy. Pattinson’s process-solution in hydrochloric acid and chlorate, reduction of the arsenic with stannous chloride, and precipitation with sulphuretted hydrogen- is accurate and rapid, especially if the arsenious sulphide is titrated with iodine ; weighing the sulphide is less satisfactory, owing to the free sulphur. For the determination of the antimony, sulphide processes come out too high; oxide processes too low, owing to mechanical loss when the sulphide is treated with nitric acid.Jannasch’s ixethod of converting the sulphide into oxide is better, but takes much time, and introduces a large amount of sulphur which must all he oxidized before ignition. Weller’s process-fusion of the ore (according to Rose) with sodium hydroxide, solution of the sodium hydrogen metantimoniate iu hydrochloric acid and chlorate, precipitation with sulphuretted hydrogen, re-solution of the sulphide as before, addition of potassium iodide, and titration of the excess with thiosulphate and starch-and Mohr’s method-reduction of the antiiiionic chloride, prepared, as in Weller’s process, with sulphurous acid, and titration with decinorinal iodine in presence of sodiuin tartrate and sodium bicai-bonate-gave figures which agreed closely one with another.F. €3. L.THE ANALYST. 23 Separation of Gold from metals containing Platinum. E. Priwoenik. (Oesterr. Zeits. Berg. 21. Hiittenw., 1899, xlvii., 356; through Claena. Zcit. Rep., 1899, 233.)--The sample is reduced to filings, and digested with nitric acid (specific gravity, 1.199) as long as silver is dissolved. The liquid is poured off, the metal washed, and an aqua regia composed of 100 C.C. of strong hydrochloric acid, 43 C.C. of strong nitric acid, and 143 C.C. of water (which hardly attacks platinum) is added. When the surface is coated with silver chloride the acid is run off, and the deposit dissolved in weak ammonia.Six alternations hetween the acid and the ammonia leave pure platinum behind. The gold solutions are evaporated with hydrochloric acid till the chloride crystallizes; it is then dissolved in water, and the platinum thrown down with ammonium chloride. The gold is finally precipitated with ferrous sulphate, etc. True alloys of gold, silver, copper, and platinum are first fused with three times their weight of lead, or preferably zinc. The melt is granulated in water, digested with sulphuric acid, and further treated as already described. F. H. L. Separation of Copper from Tellurium. F. Stolba. (Casopis pro prunzysl chemicky, 1899, ix., 11 ; through C'henz. Zeit. Rep., 1899, 233.)-The author's process depends on the fact that invert sugar precipitates the copper from an alkaline solu- tion of copper below 100" C., whereas tellurium is only thrown down on boiling.F. H. L. Separation of Iron from Chromium, Zirconium, and Beryllium by Volatili- zation. F. S. Havens and A. F. Way. (Zeits. anorg. Chem., 1899, xxi., 389.)- Gooch and Havens have recently shown that from a mixture of ferric oxide and alumina the iron may be completely volatilized as ferric chloride by treatment with a current of hydrochloric acid gas containing free chlorine at a temperature of 180" C. (ANALYST, 1899, xxiv., 307). The same process is available for separating iron from any of the metals mentioned in the title. I n order to avoid danger of mechanical losses, the operation is best conducted at not exceeding 200" C., at which temperature 0.1 gramme of iron may be driven off in one hour, but the heat may be raised for a few minutes at the end of the process to remove the last traces of iron.The gaseous mix- ture is conveniently prepared by allowing sulphuric acid to drop into strong aqueous hydrochloric acid containing common salt and a little manganese dioxide. F. H. L. Volumetric Estimation of Manganese i n Permanganates b y means of Arsenious Acid. C. Reichard. (Chm. Zeit., 1899, xxiii., 801.) - This process depends on the fact that permanganates are reduced by an alkaline solution of arsenious acid in the cold, or by a neutral solution of the same reagent at about 50" C. The reacfion proceeds according to the equation : 4KMn0, + 5As20, = 5As,0, + 2K,O + 4Mn0. The method possesses a double advantage : as arsenious acid can be obtained in a state of chemical purity, it serves as a means of standardizing perinanganate solu-24 THE ANALYST.tions, and the precipitated oxide can be treated gravimetrically to serve as a check on the titration. The liquid containing the permanganate to be analysed is mixed with an excess of standard solution of arsenious acid, heated till the manganous hydroxide falls, and then filtered ; the precipitate is washed, the filtrate neutralized with hydrochloric acid, sodium bicarbonate is added, and t,he whole is titrated with iodine and starch. It is not even necessary to filter off the precipitate, for the inanganous hydroxide can be dissolved in sulphuric acid immediately it is reduced, and the liquid titrated with a pernianganate solution which has been previously standardizsd on arsenious acid in the presence of sulphuric acid.The examples quoted are satisfactory. F. €3. L. Gas-Volumetric Estimation of Nitric Oxide. G. v. Knorre and I(. Aradt. (Ber., 1899, xxxii., 2136.)-When nitric oxide and hydrogen are led over red-hot palladium-asbestos, two reactions take place : (a) 2N0 + 5H2 = 2NH, + 2H,O ( h ) 2N0 + 2H, = + 2H,O (2 VO~S. + 5 vols. = 0 V O ~ . + 0 ~01.) (2 vols. + 2 vols. = 2 VOIS. + 0 VO~.) N, The former does not take place quantitatively ; therefore the amount of ammonia, or the contraction in volume, is not under control. But if the gases are passed slowly through Drehschmidt’s platinum capillary tube (Be?.., 1888, xxi., 3245), heated to bright redness, any ammonia which may be produced is instantly decomposed, and the total reaction proceeds according to b.SimiIarly. nitrous oxide and hydrogen react as follows : N,O + H, = N, -1, H,O (1 V O ~ . + 1 V O ~ . = 1 V O ~ . + 0 VO~.) The composition of a mixture containing x C.C. of nitric oxide and y C.C. of nitrous oxide can therefore be calculated thus : z + y = v 1.5 x + y = C (contraction) whence ,T =- 2 (C - V) The process may be checked by measuring the hydrogen required or the nitrogen produced, so that gases composed of NO +N,O + N, NO + N, N,O + N, N,O + 0, etc., are all amenable to treatment. F. H. L. Estimation of Sulphuric Acid in Presencz of Iron. G. Lunge. ( h i t s . aitorg. Chcm., 1899, xxi., 194.)-This article is mainly polemical, being a second reply to Kiister and Thiel, and a discussion of the opinions advanced by those authors, by Herting, and by Meineke (cf.AK’ALYST, 1899, xxiv., 137, 164 ; Zeits. nmd. Chem., xxxvi., 209). Lunge observes that he has never recommended his process for the analysis of burnt pyrites; it was devised for the valuation of the raw ore only. He also makes the point that in Kiister and Thiel’s method it is difficult to tell when the proper amount of barium chloride has been added, because the suspended ferric hydroxide renders the liquid opaque ; moreover, a complete extraction of the hydroxide from the barium sulphate is more troublesome and lengthy than represented by those authors. In order to determine the relative merits of the different processes whenTHE ANALYST. 25 applied to burnt pyrites, the whole question has been reinvestigaked by Lunge’s assistant Bebie, who has obtained the results shown in the annexed table.The methods employed were : (A) the original Watson-Lunge process (Zeit. angew. Chem., 1892, 449) ; (B) Meineke’s process of attacking the material with sodium carbonate and potassium chlorate, precipitating the sulphur with barium ; (C) solution in aqua regia, followed by Lunge’s ammonia method ; (D) solution in aqua regia, followed by Kiister and Thiel’s plan; and (E) solution in aqua regia, and reduction of the ferric chloride with zinc (Meineke). Process. I. 11. 11:. Mean. Time occupied. A 1.98 2.03 1-88 1.96 18 hours B 1-98 2.00 2.01 2-00 8 or 9 hours c: 1.94 1.96 1.92 1.94 9 7 7 , D 1-92 1.97 1.95 1.94 7 , >, E 1.90 1 *93 1-92 1.92 6 hours [Lunge does not refer to Heidenreich’s note (ANALYST, 1899, xxiv., 193); but Meineke’s process (E above) appears to be identical therewith, except that the former author has written of raw pyrites, while Meineke dealt with the burnt substance.(See also following abstract .) -Am.] F. H. L. A Review of the Methods for Estimating Sulphur in Iron, Pyrites, Slags, Coal, Coke, Asphalt, Ca,outchouc, and Gas-purifying Material. 0. Herting. (Chenz. Zeit., 1899, xxiii., 768.)-It is already well known that processes for deter- mining sulphur in iron which depend on treatment with acids and absorption of the sulphuretted hydrogen are incorrect, for part of the sulphur is evolved as an organic compound jmethylic sulphide), and this portion is not oxidized by bromine and hydrochloric acid or by hydrogen peroxide.Phillips, however, has proved that ignition in presence of hydrogen and carbon dioxide is quite efficient to convert the organic sulphur into sulphuretted hydrogen ; and, based on this observation, Cainpredon has proposed absorbing the products of combustion in zinc acetate acidified with acetic acid, titrating the zinc sulphide with normal iodine and thiosulphate ; while Schulte prefers to use acid cadmium acetate, converting the cadmium sulphide into copper sulphide, and weighing the latter in the form of oxide. Both methods are satisfactory ; Campredon’s is somewhat quicker in operation. For the determination of total sulphur in iron, Blair has described a process (ANALYST, 1897, xxii., 279) which is very suitable for occasional employment, and where great rapidity is not essential.For routine purposes the author is engaged in elaborating a colorimetric method with cadmium in Wiborgh’s apparatus, details of which will follow. I t is not possible by carrying out these absorption processes without the intermediate combustion tube, and calculating from the sulphuretted hydrogen so evolved, to ascertain the amount of “organic sulphur ” in iron. Schulte’s results have shown that the proportion of ‘‘ organic sulphur” varies within very wide limits even in the same grades of metal. To determine sulphur in raw pyrites Lunge’s process is quite properly employed. Kiister and Thiel’s modification (ANALYST, 1899, xxiv. , 137), according to Herting, is26 THE ANALYST ‘( worthy of notice.” For practical purposes the plan outlined in Heidenreich’s pre- liminary note (ANALYST, 1899, xxiv., 193) is more serviceable ; but the beaker should be kept well covered and in the dark while the barium sulphate is settling.The method has been improved by Lehnardt, who adopts stannous chloride instead of metallic zinc as the reducing agent, thus saving considerable time. For burnt pyrites fusion processes with alkali carbonates and nitre are the best. Slags from the puddling furnace should be treated like iron ores; blast-furnace slags by solution in bromine and hydrochloric acid. In the latter case the silica should be removed and the sulphuric acid precipitated directly, for the percentage of iron in such materials is generally low. The sulphur in blast-furnace slags may be estimated volumetrically by rubbing down 0.5 gramme in an agate mortar, adding 150 C.C.of warm water and a little starch, then introducing an excess of decinormal iodine and 20 C.C. of hydrochloric acid, agitating for one minute, and titrating with thiosulphate. For coal, coke, and asphalt Eschka’s process as improved by Hundeshagen is the most suitsble, the absorbing material being magnesium oxide mixed with equal parts of sodium and potassium carbonate, or with potassium carbonate only. For indiarubber Unger’s method is to be recommended : 0.5 gramme in very small pieces is carefully ignited with 12 grammes of copper oxide and 2 grammes of sodium carbonate. The melt is taken up in aqua regia, evaporated to remove the antimony, filtered and precipitated with barium chloride ; the barium sulphate is fused mitli sodium carbonate, and the sulphuric acid thrown down a second time.Estimation of sulphur in spent oxide by extraction with carbon disulphide yields results which are too high owing to the presence of tar, etc. The substance should be dried at 75” C., for six hours, ground till it will pass through a sieve of 400 meshes per square centimetre, then exposed to air for one hour. One gramme is next extracted with carbon disulphide, and the dried oxtract is oxidized with 25 C.C. of warm 1.19 hydrochloric acid and a few crystals of potassium chlorate; the excess of chlorine is driven off, and the sulphuric acid determined as usual. F. H. rJ. Determination of Oxygen in Water. F. Zetsche.(Zeit. f iiy Uutersucli. c7cr Nahy. zLnd Ge7zussmitte1, ii., 696, 697 .)--The author has had considerable experience with Winkler’s method for the open-air determination of oxygen in water, and regards it as the most practicable of any method devised for the purpose. His mode of working is as follows : AjyaYatzLs awl Chemicals Reyzbed.-(a) A number of glass-stoppered flasks (according to the number of samples to be taken), measuring from 250 to 300 C.C. capacity, and each containing ten to fifteen small porcelain balls. ( b ) A saturated solution of manganous sulphate (say 50 c.c.). (c) A solution containing 48 grammes of sodium hydrate and 15 grammes of potassium iodide in 100 C.C. of water. (d) 500 C.C. of concentrated hydrochloric acid. (e) Three pipettes, to deliver 1, 2, and 5 C.C.respectively. The capacity of each of the flasks must be accurately deter- mined after the introduction of the balls. ProcecZ?sre.-The flasks are filled to overflowing with the water to be examined, and 1 C.C. of the manganous sulphate solution and 2, C.C. of the alkaline potassiumTHE ANALYST. 27 iodide solution are run in to the bottom of each by means of pipettes. The flasks are then closed and briskly shaken, the movement of the balls insuring complete mixing. When the brown precipitate produced has settled, the flasks are opened and 5 C.C. of hydrochloric acid run in (also to the bottom of the flasks). The flasks are then closed and again shaken, and as soon as the precipitate in each has dissolved, the liquid is transferred to a beaker, and the liberated iodine titrated with iga sodium thiosulphate solution. I n calculating the results, allowance must of course be made for the 3 C.C. of reagents added. H. H. B. S. The Cleaning of Crucibles. F. Wirthle. (Cherrn. Zed., 1899, xxiii., 803.)- Platinum crucibles in which vegetable substances have been incinerated are far more easily cleansed by melting borax in them than by the use of the favourite potassium bisulphate. Porcelain crucibles soiled with silver chloride, lead sulphate, stannic oxide, etc., are readily cleansed by filling them with acid and adding a fragment of zinc ; after a short time the reduced metals can be completely removed. The author suggests that this electrolytic method of decomposing insoluble precipitates should perhaps be quicker in qualitative analysis than the usual plan of fusing them with various fluxes. F. H. L.
ISSN:0003-2654
DOI:10.1039/AN9002500022
出版商:RSC
年代:1900
数据来源: RSC
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Analyst,
Volume 25,
Issue January,
1900,
Page 27-28
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摘要:
THE ANALYST. 27 R E V I E W . THE CHEMISTRY OF ESSENTIAL OILS AND ARTIFICIAL PERFUMES. London : Scott, Greenwood and Go. By ERNEST J. PARRY. Price 12s. 6d. net. Owing to the vigorous manner in which the study of the essential oils has been prosecuted during recent years, and to the enormous number of valuable, and in many cases brilliant, researches which have during that short period been brought to a successful conclusion, we have fully arrived at the point at which the services of a painstaking and careful gleaner become extremely desirable, and this service Rfr. Parry has rendered in compiling and issuing to the world the volume under review. Seeing that no work covering similar ground exists in the English tongue, British chemists will be quite ready to confirm the author in his belief that its appearance demands no apology.Chapter 11. deals with the properties of those compounds which are found in essential oils, but does not treat the subject as exhaustively as one could have wished, seeing that a work of this character must necessarily appeal rather to the chemical specialist than to the general chemist. I t is with the analytical portion of the book that I am now chiefly concerned, but I may remark in passing that cymene is para-methyl-iso-propyl-benzene, and not the normal propyl compound, and that thymol and carvacrol are likewise iso-propyl derivatives. Further, I do not notice any reference to the open chain hydro-carbons which have been found in some oils, and which are of considerable interest. When one remembers the very large trade interests involved, and the ease with which the sophistication of valuable oils could until quite recently (and in some cases28 THE ANALYST. can still) be practised, the need of analytical processes capable of detecting, and so of preventing, these sophistications becomes at once apparent. Moreover, it has to be borne in mind that most essential oils vary in colnposition within certain limits, and that the most variable constituent is often that upon which the value of the oil chiefly depends.Analytical processes are therefore necessary for the evaluation of these oils as well as for the detection of adulteration. Mr. Parry has devoted one chapter to a discussion of certain methods, which are generally applicable to essential oils, dealing with the processes for the estimation of certain special constituents in later sections of the book, an arrangement which certainly makes for convenience.I n the general section some details in regard to the determinations of specific gravities are given, the use of a bottle being recommended for this purpose, a sprengel tube being only employed when the volume of oil at the analyst’s disposal is too small for the former method. But surely it is in the case of liquids, like the majority of essential oils, having high co-efficients of expansion and great mobility, that the superiority of the sprengel tube over the bottle is so evident. We are next treated to the inevitable dissertation on the polarimeter, its construction and use. Both these matters might well have been omitted, seeing that every chemist concerned in the analytical examination of essential oils might well be supposed to be conversant with them.On the other hand, many analysts would doubtless have welcomed some information in regard to the simplest and most convenient apparatus for distillation under reduced pressure. It is the process which has to be carried out prior to the scientific investigation of practically all essential oils, and one that can often be resorted to with great advantage in their analytical examination. A few hints in regard to forms of receivers, distillation in an atmosphere of carbonic acid gas, and other points, might have been of service to many chemists. In this section no mention is made of the “methyl number,” a useful determination in some cases. The special analytical processes are clearly and carefully described, and the book will undoubtedly prove of considerable value to all chemists who are engaged in the examination of these oils.Mr. Parry has evidently spared no pains in selecting from the enormous masses of recorded results those to which the greatest amount of probability attaches, and he has given numerous references to the original papers when they are likely to be of value to the reader. One would like to know for example what is meant by the expression ‘‘ excretionary functions ” as applied to essential oils. The words “under reduced pressure ” should be substituted for ‘‘ in vacuo,” in speaking of distillation, and ‘( rotatory ” for (‘ rotary.” There are many little blemishes of a literary character which, whilst in no way detracting from the real value of the book, yet tend to diminish the pleasure with which one reads it. The book is well printed, and possesses a good index. I n many places, however, the wording is a little loose. Presumably it should refer to the cell. These would doubtless disappear in a future edition. A. C, C.
ISSN:0003-2654
DOI:10.1039/AN9002500027
出版商:RSC
年代:1900
数据来源: RSC
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