摘要:

THE ANALYST. NOVEMBER, 1888. SPECIFIC GRAVITY AT looo F. OF FAT WHEN CLEAR, AND ALSO WHEN CLOUDED WITH CRYSTALS. BY E. W. T. JONES, F.I.C. SOME time ago I was taking the specificgravity of some lards at 100° F. with a bottle, when some of the samples, through being left just about 100" F. for some hou~s, became more or less granulated or clouded with crystals ; they were still fluid enough to pour into the bottle, and upon taking the specific gravity in this state I found them all un- duly high, and I became suspicious, the abnormally high specific gravity was due to the crystalline state, hence I made the following experiments, which prove it to be so. A sample of genuine lard was melted quite clear, and then the temperature allowed to fall whilst stirring with a thermometer till the proper temperatures was attained, and the specific gravity at 100" F.taken. (i.) 905.87 (ii.) 905.72. I now allowed this melted fat t o remain at the temperature, about looo F., for some hours, by which time it had become somewhat granulated or clouded with crystals, then carefully adjusting the temperature, I took its specific gravity a t looo F., still in its clouded condition, getting (i.) 910.40 (ii.) 910.30, this shows the increase due to its crystalline state. I then took another sample of lard, this was softer, and did not granulate to the same extent as the former one, and so the difference in the specific gravity of the clear and clouded fat is not so great. Clear, 906.10 Clouded, 908.47. The fat remaining quite clear, it gave I do not suppose recording these facts will be .of much practical use to Public Analysts, but from a scientific point of view they are very interesting.

ISSN:0003-2654    

DOI:10.1039/AN888130201b

出版商:RSC    

年代:1888

数据来源: RSC

摘要:

~- 202 THE ANALYST. A METHOD FOR THE ANALYSIS OF BUTTER, OLEOMARGARINE, ETC. BY H. N. MORSE AND W. M. BURTON. (Concluded from page 193.) The Reagents. 1. A solution of hydrochloric acid of such strength that one cubic centimetre of it 2. A solution of hydrochloric acid one-tenth as strong as the first. 3. A solution of potassium hydroxide in 95 per cent. alcohol approximately equiva- 4. A solution of potassium hydroxide in 95 per cent. alcohol one-tenth as strong as is equivalent to 20 milligrams. of potassium hydroxide. lent to the first acid. the preceding. The Mode of Procedure. The dry and filtered fat is well stirred during solidification, to prevent the separa- tion of the lower from the higher melting constituents. Any convenient quantity of the material, between one and two grams,, is placed in an Erlenmeyer flask having a capacity of 250 cubic centimetres, and treated with that amount of alkali which is found to be equivalent to 40 cubic centimetres of the acid No.1. The flask is then placed upon the water-bath, and heated to the boiling point of alcohol for twenty minutes. The excess of alkali is determined by acid No. I, with the use of phenolphthalein as the indicator. Thus the number of milligrams. of KOH 'required for the neutralisation of all of the acids in the fat is found. The flask is then returned to the water-bath, and heated until all of the alcohol has been expelled. During the evaporation of the alcohol, the soap, which in the first place was neutral, becomes alkaline, owing doubtless to the evaporation of a small amount of volatile acids in the form of ethers ; but the ioss from this cause is very slight." When the odour of alcohol is no longer perceptible the soap is treated with that quantity of acid No.1 which is necessary to exactly liberate all of the acids contained in it. This quantity is, of course, the difference between 40 and the number of cubic centimetres required to neutralise the excess of the alkali used in saponi- fication. The flask is again returned to the water-bath, and heated until the liquid becomes clear. But, in order to prevent loss of volatile acids, it is now supplied with a stopper carrying a glass tube about 5 millimetres in diameter, and 400 millimetres in length. The upper end of the tube is bent downwards, and to it is attached a small U-tube containing a few cubic centimetres of water.The contents of the flask are filtered through double thick paper which has been wet with hot water, and then washed with boiling water until the volume of the fdtrate equals a litre ; care being taken to wash thoroughly the flask itself. The contents of the condensing arrangement are washed into the filtrate. The funnel containing the washed insoluble acids is placed in the h s k in which the, saponification, etc., were effected, the paper pierced, and the contents washed through with hot 50 per cent. alcohol. * This:loss may be made good by bringing the solution to a neutral condition by means of very dilute acetic acid. The quantity of acetic acid thus introduced is, of course, equivalent to the acid which has been lost during the evaporation of the alcohol.We are under the impression that there is no such loss of volatile acids during saponification, owing to the presence of a considerable excess of alkali.THE ANALYST. 203 We thus have the soluble and insoluble acids separated, and it only remains to determine the amount of alkali required to neutralise each. The soluble acids can bo directly determined by the weaker solution oE the alkali j but to determine the insoluble acids it is better to add the quantity of alkali which was required for tho saponification, and, after warming upon the water-bath, to titrate back with the weaker acid. It will be observed that a determination of the insoluble acids alone by this method suffices t o distinguish butter from other fats and mixtures, and that if these only are to be deter- mined it is not necessary to use the condensicg arrangement.Moreover, it is not necessary to use the condensing arrangement. Moreover, it is not necessary to know the exact strength of the solutions employed, sinc3 a knowledga of the relation of the acids t o each other and to the alkalies is all that is needed to enable us t:, determine, it1 the fat, the relation of the soluble to the insoluble acids. Hence it is pracbicablo to tlis- pense with the use of the bdanca altogether. It is frequently recommended to rn~~ko blank determinations, in order to control the error introducad by ths action of the alkali upon the glass of the flzsks. Bixt a little reflection will cmvincs one that this practic? may itself be the cmse of considerable error, inasmuch as the extent to which the glass is affdcted by the alkali depends upon its quality and upm the treatment to which i t has previously been subjected.I n order that the results of the blank may be applied to the correction ol those of the determinations, it is necessary that the glass employed in the two cases should be the same in respect to c3mposition and previous use i n tho laboratory. It is better, acm-uling to our experience, to discard the use of blanks, and t a boil out with strong alkali all flasks employed in such work. The subssquent action of dilute alkali upon glass which has been treated this way is very slight. The water and alcohol employed in making the standard solutions should, of cmrse, be thoroughly boiled, and afterwards protected from the carbon dioxide of the oil by keeping them in bottles or flasks, which are supplied with stoppers carrying tubes filled with mda-lime. The use of blanks is then not necessary on account of any carbonic acid contained in the solution.

ISSN:0003-2654    

DOI:10.1039/AN8881300202

出版商:RSC    

年代:1888

数据来源: RSC

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THE ANALYST. 203 LARD : ITS ADULTERATION WITH COTTON-SEED OIL AND DETECTION THEREOF. BY MICHAEL CONROY .* TIIE purity of lard for us5 as an ointment basis is a matter of some importance, nnd consequently the British Pharmacopceia directs it to be made from the perfectly fresh internal fat of the abdomen of the hog ; and, according to the same authority, i t should respond to the following characters and tests : “ A soft,, white, fatty subxtance, melting a t looo F. (37.5 C.) ; has no rancid odour ; dissolves entirely in ether. Distilled water in which i t has been bailed, when cooled and filtered, gives no precipitate with nitreto of silver, and is not rendered blue by the addition of solution of iodine.” Theso tests are very good so far as they go, but they are, unfortunately, not sufficient for the misapplied ingenuity of the present day.It has recently been shown by the United States press that attowseed oil is used to an enormous extent for the adulteration of lard, which may be seen by the opposition _-- >k Ph U,YIIL~C:C zit ic(d I Jo icriuz 1.204 THE ANALYST. given to a Bill introduced into Congress for the prevention of this adulteration. The Mississippi Legislature passed resolutions against the Bill ; the merchants and Cotton Exchanges of New Orleans sent protests to Congress against it ; while the New Orleans Times calls it a Bill to reduce the value of cotton-seed 50 per cent. The following tit- bit is from the itration : ‘‘ We cannot see any diffarencs bstween this Bill and one which should seek t o put a clog on new inventions.The discovery that butter can be made from the fat of a slaughtered ox as easily as from the cream of a living cow was a great boon t o mankind, and one which cannot be suppressed, although it may be temporarily crippled by legislation. The discovery that the sun’s light and heat work the same result in the production of edible fats in the seed of the &ton plant as in the fruit of the olive or in the bodies of swine is akin to it, and is ,likewise a benefit to the human race. Why should Congress undertake t o prevent the diffusion of this blessing ? If the pro- posed Bill does not prevent it, the measure will b3 useless t o those who clamour for it.” The value of these quotations is apparent when we consider the vast quantity of American lard that is imported into this country.I have no statistics at hand, but I think it is under the limit t o place it at one-half the total consumption, and we are told by the American Oil and Drug Reporter of April 4th last that the pure food laws of England have in no way interfered with the sale of American refined lard, and no com- plaints have come t o the surface, which is good evidence that the article gives satisfaction under the rigid scrutiny of exacting foreign buyers.” Since this date, however, a change has come over the spirit of the Reporter’s dream, for the matter has been vigorously taken up and several prosecutions have been carried, but as the adulteration is a paying one, it is not likely t o be easily crushed. Fortunately, the presence of cotton-seed oil in lard is easily detected, and my object in bringing the matter under your notice is to lay before you some of the tests that I have myself tried.The first is the nitric acid test, which some years ago I had the honour of reading a paper on before the Liverpool Chemists’ Association, in connection with the adulteration of olive oil. It consists in heating and stirring well about half an ounce of lard with one-tenth its weight of strong nitric acid, specific gravity 1.42, in a porcelain dish of about S ounces capacity until brisk action commences, when it should be removedfrom the source of heat. Pure lard sets in about an hour to a pale orange- coloured solid, like citrine ointment, but if adulterated with cotton-seed oil it takes a more or less deep orange-brown tint, according to the extent to which that oil is present.There are two drawbacks t o this test, the first being that lard sometimes contains a small amount of water, which reduces the strenth of the acid, causing the acid to be less energetic, and thus leading to error ; the second is that the difference in colour between pure and adulterated samples is not sufficiently definite when the adulterant is under 5 per cent. I have also tried the test proposed by M. Labiche, who says that when cotton-seed oil is treated with subacetate of lead and caustic alkali, it gives almost immediately an orange-red reaction. The author mixes equal parts of the oil and a saturated solution of neutral acetate of lead and adds ammonia, stirring briskly. The acetate of lead decomposes and the nascent oxide reacts upon the oil, causing it to turn red.If 20 per cent. of cotton-seed oil be present the sample is said to turn red a t once, lesserTHE: ANALYST. 20 3 quantities show after some time. I n my hands this test has proved an utter failure, but I think it may be due to the fact that the cotton-seed oil which I used in my experiments was highly refined, and it is quite possible that the crude oil would give this reaction. The next test is by Ernest Milliau, and was proposed by him for the detection of cotton-seed oil in olive oil. It is as follows :-In a porcelain capsule, holding about 1 litre, 15 C.C. of the sample in question are heated to l l O o . Then, whilst still continuing the heat, we pour upon the oil a mixture of 15 C.C.of a solution of soda of 40O Baum6 in distilled water and of 15 C.C. of alcohol of 92 per cent. When the mass has become homogeneous we add, drop by drop, so as not to cool the paste and form clots, about half a litre of distilled water. After boiling for a few minutes the fatty acids are separated by means of pure sulphuric acid diluted to one-tenth. As soon as the separation is complete and the sulphuric acid is in slight excess, 5 C.C. of the hydrated fatty acids are collected with a silver spoon and poured a t once into a test tube, about 3 c.m. in diameter and 13 in length. We add 20 C.C. of alcohol of 92 per cent,, and heat slightly in the water bath to dissolve the fatty acids. When the solution is effected, 2 C.C. of a solution of silver nitrate (3 grams.in 100 C.C. of distilled water) are added, the tube is placed in a warm bath and heated until about one-third of the mass is evaporated. The tube is then removed from the water bath. Whatever the origin of the sample, its fatty acids remain unaltered if the sample be pure. But if cotton-seed oil is present the silver is reduced and blackens the fatty acids, which rise to the surface. I n this manner 1 per cent of cotton-seed oil can be detected in olive oil. I n using this test for lard instead of for olive oil, as intended by its author, a brown colouration instead of a black one is obtained in samples containing cotton-seed oil, while pure samples remain perfectly white, and I find it better, instead of adding the half- litre of cold water, '' drop by drop," to use boiling water.For delicacy and reliability this test leaves nothing to be desired, and its only drawback is the time it takes t o per- form. Another test for the detection of cotton-seed oil in olive oil, dependent upon tho nitrate of silver reaction, is given by Bechi as follows :--6 C.C. of the oil are mixed with 25 C.C. of 98 per cent. alcohol, and 5 C.C. of silver nitrate solution (prepared by dissolving 1 gram. of the nitrate in 100 C.C. of 98 p3r cant. alcohol), the mixture is heated t o 84" C. If cotton-seed oil be present, the mixture becomes cdoured, but not so if the oil be genuine. It is necesary to avoid heating by the direct flame, as other oils which may be present, such as linseed, colza, etc., will give colourations. This, unlike the previous test, is not quite suitable for the detection of cotton-seed oil in lard, because lard sometimes contains traces of sodium carbonste, due to the fact that this substance is commonly used in washing lard that has become rancid.Slight traces of sodium carbonate decompose the silver nitrate, and the subsequent heating reduces it, causing samples of genuine lard to become darkened in such a manner that they might possibly be condemned as impure. For several weeks past I have tried these and other tests with the object of finding It is an excellent test and quite applicable to lard.2OG THE ANALYST. ~~ ~~~ the most reliable and expeditious, and my experience is, that those dependent upon the reduction of silver nitrate are the best, and the following nzoclzcs operandi has given me results that are entirely satisfactory and reliable, and only requires a few minutes time :- 1.Make a test solution containing 5 parts of silver nitrate and 1 part of nitric acid (specific gravity 1.42) in 100 parts of rectified spirit (specific gravity *83S). 2. Melt a small quantity of the lard to be tested in a water bath and pour about 100 grains of it into a dry test tube, about half an inch in diameter. To this add 20 grain ‘;neasures of the above-mentioned test solution, and place the tube in boiZing water for Eve minutes, taking care that no water enters it. Pure lard remains peyfectly white, but if adulterated with cotton-seed oil, it assumes a more or less olive-brown colour, according to the amount present. The colour is best seen when the lard sets, and it saves time t o put the test tube direct from the boiling water into a vessel of cold water. The presence of 5 per cent. of cotton-seed oil in lard gives a very decided olive-brown colouration with this test, and 1 per cent. gives a colour quite distinct from genuine lard. The addition of nitric acid to the test solution is intended to neutralize any traces of alkali or alkaline carbonate that may be present, and i t also prevents a slight reduction of the silver nitrate which takes place in genuine lard. It must not be forgotten that some samples of lard might possibly contain sodium chloride, though I have never met with any, in which case the silver nitrate would be precipitated as chloride instead of reacting on the oil, but this would be a t once seen by the white curdy precipit,ate that would be formed.

ISSN:0003-2654    

DOI:10.1039/AN8881300203

出版商:RSC    

年代:1888

数据来源: RSC

摘要:

2OG THE ANALYST. SYSTEMATIC EXAMINATION OF SULPHATE AND HYDROCHLORATE OF QUININE. BY c‘. HIELBIG.* THE examination of these quinine salts has caused quite a number of processes to be devised, but not one of these can be relied upon in furnishing a positive answer regarding the purity of these salts, To frame a method which allowed the presence or absence of the more frequently occuring impurities, such as quinidine, cinchonine and cinchonidine, t o be proven in a simple and comparatively rapid manner, the majority of the published processes were carried out and their merits and defects ascertained; as the result the following compilation liss h e n found to work successf ully. JTW L . V Q I J l f f t C . FOY ?Z!jdyoi/ilorntc. 1 gm. and n solution of 0.4 gin. so- dium sulphztte in l C.C.water, with 30 C.C. distilled water me agitated for five minutes, and filtered. To the filtrate is added 0.5 gm. Rochelle salt, agitated f o r five minutes, allowed to stand five minutes and filtered; the precipitate of tartrates is collected on a small filter and reserved, the filtrate for the Detection of quinidine and cinchonine is divided into two portions, one of A. 1 gm. with 15 C.C. B.THE ANALYST. 307 which is reserved ; to the other add one drop of water of ammonia, and allow to stand for a few moments. 1. The solution remains clear ; absence of quinidine and cinchonine, p-roceed E. 2. The solution becomes turbid ; presence of quinidine and cinchonine or both ; C. Detection of Quinidine. To the reserved portion (see B), add 0.5 gm.KI, shake 1. The solution remains clear., if quinidine i 3 absent ; proceed D. 2. The solution becomes turbid or deposits tenacious re +lous precipitate. I n thid case cinchonine must first be tested for according to D and then u. I n absence of cinchonine, the turbidity with KI indicates the prasenca of quinidine ; proceed E. b. I n presence of cinchonins, the ammoniacal solution in 13 is filtered, the precipitate washed with distilled water and the thalleioquin reaction* carried out with the precipitate. If the intense green colour is produced there is quinidine present ; if the green colour is not produced quinidine is absent. Proceed E. The liquid afher addition of KI is filtered and one drop water of ammonia added ; set aside for a few minutes ; there results : proceed C.for five minutes, allow to stand for name time. Observe either D. Detection of Cinchonine. 1. Perfectly clear solution, in absence of cinchonine. 2. Turbid solution, if cinchonine is present. E. Detection of Cinchonidine. If in the foregoing examination cinchoniuo or quinidine is found, the precipitate of tartrates (see A) is carefully washed with 15 to 30 C.C. Rochelle salt solution (I to 20) ; were these alkaloids not found this washing is superfluous. The precipitate is dissolved off the filter by use of 3 C.C. dilute H2,YO, (1 to 30) ; to the solution 2 C.C. ether and 1 C.C. water of ammonia are added, the mixture is well shaken for one minute and allowed to stand a t rest for five minutes. This shaking and allowing to stand is repeated several times (the time allowed not to exceed a half-hour).Notice : 1. The ethereal layer and the sides of the test tube remain perfectly clear in absence of cinchonidine. 3. The ethereal layer and the sides of the test tube become cloudy, if cinchonidins is present. Rsmarks referring to Quinine containing Quinidine. By this method one-fourth or one-half per cent. quinidine cannot be detected. Often 1 or 2 per cent. quinidine will give no reaction with KI, but the presence can be ascartained by the addition of water of ammonia, which is a more delicate test. I n the examination of quinine with 10 per cent. quinidine nothing extrawdinary is noticed, but in presence of 15 per cent. and more of this alkaloid it is noticed on addition of Rochelle salt that the tartrates are not precipitated ; this does not, however, interfere with the further detection of quinidine.Should more than 15 per cent. quinidine be suspected, more KZ must be used, otherwise it must be feared that the quinidine is not thoroughly precipitated and later may he mistaken for cinchonine. As a large percentage of quinidine prevents the separation of the tartrates and, as was found by special experiments, quinine sulphate mixed with quinidine sulphate is more difficultly soluble than the pure salt, there appars to exist a dependency between the two alkaloids. Remarks referring to Quinine containing Cinchonidine. One-half per cent. of cinchonidine is easily detected within half an hour. Should the per cent. of cinchonidine be so minute that a precipitate cannot ba clearly distinguished, absence of the alkaloid must be decided upon, as the reaction is so characteristic that there can * Excess of chlorine water prevents the thalleioquin reaction, while excess of ammonia favour:, It.Proceed E. Proceed E. --20s THE ANALYST. absolutely be no mistake. With 1 per cent. the reaction is more decided; with 2 per cent. there appears a deposit in the ether. Cinchonidine is recognised by the capillary rising of the precipitate beyond the ethereal layer, immediately after shaking the solution. Care must be exercised that not every slight turbidity at the line of contact of the two liquids be pronounced as cinchonidine; only in case the precipitate is capillarily attracted by the side of the test tube can there be no doubt regarding its presence. If the quinine contains 10 per cent. cinchonidine there appears at the line of contact of the two liquids a white cretaceous ring. Cinchonidine, in the absence of quinine, is separated as a white precipitate in the ethereal layer. Remarks referring to Quinine containing Cinchonine. One per cent. cinchonine is easily recognised ; the more cinchonine present in the quinine the greater the precipitate with water of ammonia. When more than 5 per cent. cinchonine is present there forms on addition of KI a turbidity of cinchonine hydriodate, which can easily be mistaken for separated quinidine; 10 per cent. causes a precipitate of a tenacious character similar to quinidine hydriodate.

ISSN:0003-2654    

DOI:10.1039/AN8881300206

出版商:RSC    

年代:1888

数据来源: RSC

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20s THE ANALYST. ~ ___--- NOTES UPON METHODS FOR ESTIMATING THE QUANTITIES OF HOMOLOGOUS ACIDS PRESENT I N ARTIFICIAL SALICYLIC ACID.” BY ERWIN E. EWELL AND ALBERT B. PRESCOTT. OF the homologous phenols associated in the distillates of coal-tar the first member is the chief constituent of ordinary carbolic acid, but, it is well known, the higher membersare not altogether absent. Considerable percentages of higher phenols are common in car- bolic acid. Since salicylic acid is in greater part manufactured from carbolic acid by Kolbe’s process,? inquiry naturally arises as to what becomes of the higher phenols of carbolic acid used in this manufacture. It had been found, some time ago,$ that when the higher phenols of carbolic acid are treated as they are in Kolbe’s method they are changed into homologues of salicylic acid ; the cresols into hydroxy-toluic acids ( C7H,.0H.C0,H), and the xylenols into hydroxy-xylenic acids (C8~18.0H.C02H) just as phenol proper is changed into a hydroxy-benzoic acid.§ The presence of some other acids besides true salicylic acid (ortho-hydroxy-benzoic acid) in the article of salicylic acid of commerce was reported by Mr.Williams in 1878.11 H e found the calcium salt of the foreign acid to be much more soluble in water than calcium salicylate is. By neutralising a hot aqueous solution of salicylic acid with calcium carbonate, causing the salicylate of calcium to crystallise out as completely as practicable, and then acidulating the mother liquor, the unknown acid was obtained. I n certain physical characters this acid was found to be distinctly different from salicylic acid, * PJbarm. Record.t Kolbe, 1874 ; Joz6r.yrakt. Chern. [2] 10, 89 ; Jour. Chem. Soc., 28, 260 ; Watts’s Did. Chem., 7, gchmitt, 1885 : Jour. prakt. Chern., [2] 31, 397-411 ; 1065 ; Proc. Am. Phar. ASSOG., 23, 374 ; 27, 463. Jour. Chem. SOC., 48, 982 ; Pharm. Jour. Trans., [3] 5,421. $ Biederman and Pike, 1872 : Ber. d. CJtcnz. Gess., 5,323 ; Wktts’s Dict., 7, 394, 8, 2023. S The ortho-compound, C,H,.OH.CO,H (OH : CO,H= 1 : 2). The isomers and their homologues 11 J. Williams, 1878 : Phar. Jour. Trans. [3] 8, 786: Proc. Am. PJiar. dssoc., 26, 536. are given in Prescott’s ‘‘ Organic Analysis,” pp. 394, 434, 443.THE ANALYST. 209 and from the other two hydroxy-benzoic acids. I n the leading chemical relations, howeveiz, the unknown acid was found to agree with salicylic acid and the isomers of the latter.The acid liberated from the crystals of calcium salt, after purification, was found to agree in all points with true salicylic acid. Mr. Williams concluded that the acid not salicylic formed fifteen to twenty-five per cent. of the better grades of salicylic acid of the market. Very little further investigation of the presence and proportion of the homologous acids has been reported. I n 1883 Dr. E. R. Squibb" gave the opinion that '' the better grades of the well-crystallised acid of the market contain four to five per cent. of some- thing which is not salicylic acid," and for which, he says, he knows no test. The physiological and therapeutic value of the homologous acids in medicinal salicylic acid are certainly deserving of careful study, in view of the large doses in which the agent is used, and the somewhat variable effects reported of these doses.1.-A Method by Aciclimetry. The molecular weights of the homologous acids show the following differences, those Salicylic acid (hydroxy-benzoic acids), C,H,OH.CO,H = 137.67. Hydroxy-toluic acids, C,H,OH.CO,H = 15 1.64. Hydroxy-xylenic acids, C,H,OH.CO,H = 165.61 And of hundredth normal solution of alkali (-K) needed to neutralise thoso 1 grm. of salicylic acid requires 726.3 cxm. 1 grm. of a hydroxy-toluic acid requires 659.4 c.cm. 1 grm. of a hydroxy-xylenic acid requires 603.8 c.cm. I n the application of this method it was assumed that hydroxy-toluic acids, C,H,O,= 151.64, fairly represent the total acids of molecular weight above that of salicylic acid. This can be justified both because there can be only a very small quantity of xylenols in carbolic acid of respectable quantity, and because a given percentage of the xylenol product mould indicate a larger percentage of the less objectionable crosol product.Thus, of the (iz) alkali solution to neutralise 1 gram. of the acid, of CH, = 13.97, in arithmetical increase. acids and form monobasic salts : Hydrouy-toluic acids take 66.9 c.cm. less than salicylic Hydroxy-xylenic acids take 132.5 c.cm. less than salicylic. One per cent. of a hydroxy-xylenic acid would indicate 1.8 per cent. of a hyclmxy- Then the saturating cupacitg of urticles of '( salicylic ucicl " made from car- toluic acid.bolic acid will stand as follows :-310 THE ANALYST. I n making trial of the calculated saturating powers of salicylic acid and its homo- lopes, potassa and soda were found to work equally well in the standard solutions and phenol-phthalein proved thoroughly satisfactory as an indicator of the end- reaction, while litmus is wholly incapable of being used in this estimation. The titrations are to be made as follows :- About 3 grm. of the acid to be tested, dried a t or below 65" C. to constant weight, is accurately weighed, placed in a beaker of about 3 litre's capacity, some drops of the (alcoholic) solution of phenol-phthalein added, and (without adding water for solution) the hundredth-normal solution of alkali is run in from the burette, while stirring, until the end-reaction is approached, The beaker is now placed upon wire cloth over the flame (or otherwise promptly heated) while gently stirred, only long enough to complete the solution of the acid, and without decided boiling, when the heat is removed, the beaker-sides rinsed down with a little distilled water, and the titration completed.The weight taken : 1,000 :: c.cm. required : x=c.cm. for 1 grm., to be compared with the table above. I n drying salicylic acid for a constant weight it was found that this could be attained at 65" C . , while a t TOo to 75* C. there was a constant loss, in a short time sufficient t o be registered by the balance. A portion of the purified acid from oil of wintergreen, placed between watch-glasses, arranged for sublimation, and heated to 116" C., promptly gave a sublimate of colourless crystals of good size.In aqueous solution, it suffers loss by boiling a t common air pressure, Acidimetry under the directions given above was tried upon a sample of purified acid from oil of wintergreen, a sample prepared for the purpose, in the way followed by Williams:* one ounce of oil of wintergreen was saponified by potassium hydrate colution, the liquid cooled and acidulated with hydrochloric acid, the precipitate four times crystallised from boiling water, the hot solution filtered through strictly purified animal charcoal and re-crystallised, and lastly twice re-crystallised from alcohol. The average of several titrations of this purified salicylic acid agreed very closely with the calculated quantity, 726.3 c.cm. (:G) alkali for 1 grm. of the acid. Applying the same volumetric reagents in the same way to a sample of salicylic acid of the ordinary market,? in four titrations an average of 714.3 c.cm. was obtained -corresponding to a proportion of 15 to 20 per cent. of homologous acids calculated as a hydroxy-toluic acid. With titrations of good ordinary care, using verified instruments of such delicacy as every chemist requires for analyt,ical work, acidimetry can reveal quantities of hyilroxy-toluic acids as low as 4 or 5 per cent., other interfering impurities being absent. (To be continued.)

ISSN:0003-2654    

DOI:10.1039/AN8881300208

出版商:RSC    

年代:1888

数据来源: RSC

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310 THE ANALYST. ON TE-IE EEIJATIVE VALUE OF DIFFERENT PEPSIN TESTS. BY J A n m H. STEBBINS, JR. (Continued from page 198.) Lately my attention has been called to a, new pepsin test, which I will designate by its author’s name, the “ Manwaring test.” I n this test Nanwaring has tried to avoid as much as possible the bad points of the U. S. P. test; but in doing this he has ritumbled ? p i n s t other sources of error which I wil1 try to make clear farther on. _____ - _ _ - _ _ _ _ _ _ _ _ ~ ~ * I’liay. Jow. Ilkanu. [?I, 8, 785. t In apptarancc the sample was an hdistinctly crystalline powder of a slightly pinkish colour.THE ANALYST. 211 The test can best be described in the words of its author :- ‘ I The design of the following mode of testing the dissolving power of pepsin is t o conform as nearly as possible to the U.S. P. test, which, contemplating the testing of the saccharated form, makes no provision for the proportion of acidulated water to be used with a pure pepsin. ((On the basis that 1 part of a pure pepsin is capable of dissolving 1,000 times its weight of coagulated egg albumen in six hours, a saccharated pepsin made with a pure pepsin of U. 8. P. strength would contain 5 per cent. of pure pepsin; therefore if 1 grain of a U. S. P. saccharated pepsin is to be tested in the presence of 500 grains of acidulated water, then 1 grain of a pure pepsin should be tested in the presence of 10,000 grains acidulated water, to equal the same proportion of water and acid used for the actual quantity of pure pepsin contained in a U.S. P. saccharated pspsin when tested according to the U. 8. P.” In order to render the weighing of small quantities of pure pepsin as easy as possible t o the pharmacist, Manwaring recommends that it shouId be saccharated, and for this purpose he gives the following recipe :- E. Saccharated pepsin, consisting of- Pure pepsin . . .. .. .. .. .. . . 1 grm. Milk-sugar . . .. .. .. .. .. * . 19 ,, To make the test, take of the above saccharated pepsin 0*3 grm. (= 0.015 grm pure pepsin)- Coagulated egg albumen . . .. .. .. . . 22.5 grms. Acidulated water, consisting of- - } . . . . .. . . 154 C.C. Distilled water, 100 C.C. Hydrochloric acid, U. S. P., 1.25 The egis are to be boiled for fifteen minutes, and the whites pressed (by means of a spatula) through a (preferably flat) 30-mesh sieve.For the sake of uniformity, the egg whites should be cut into small pieces and thoroughly mixed before being passed through the sieve. The mixture should be maintained a t 100-105° F. for six hours, and agitated thoroughly about every half-hour. At the end of six hours the temperature of the bath should be quickly run up above 145O F. to destroy the pepsin, then the bath with contained bottles allowed to remain undisturbed over night, that the undissolved albumen may settle. If the test bottle has been kept securely corked during the test, or if by previously weighing bottle and contents and afterwards making up with water any loss from evaporation, the quantity of albumen dissolved may be easily determined as follows : From the settled contents of the test bottle pipette off 10 C.C.and evaporate to dryness-until weight is constant--in a watch glass. From this dry residue figure as follznvs (1 pt. of peptone or intermediate products representing 1 pt. of original albumen) : Suppose 10 C.C. of the liquid = 0.2 grm. dry residue; qr times its weight = the quantity of water contained in the 10 C.C. that was derived from the albumen dissolved ; 10 C.C. of liquid less 1.4 C.C. of water Jeaves 8.6 C.C. water taken from the 154 C.C. of acidulated water in making the test.212 THE ANALYST. 1.6 grms. or 8 times 0.2 grm; dry residue = the quantity of albumen in its natural state as originally used, that has been dissolved in the 10 C.C. of liquid evaporated to dryness. Therefore, if 8.6 C.C.acidulated water holds 1 *6 grm. egg-albumen, Then, as 0.015 grm. pepsin dissolved 28.5 grms. coagulated egg-albumen, 1 pint would dissolve 1900 times its weight. The use of the multiplier 7 and 8 is based on the fact that egg-albumen averages 12 per cent., or Q dry. As will be seen, this test is quite a departure from the U. S. P. test, and, in some respects, is an improvement upon the latter, but I object to it on several points, viz. : 1. It makes no provision for other than concentrated, or, as Manwaring calls them, pure pepsins, while in reality the number of these is small compared to the saccharated pepsins. A person desiring to essay a saccharated pepsin by this test would be at an utter loss to know how much pepsin should be weighed out, or how much acidulated water should be employed, unless he knew that the pepsin under examination was of U.S. P. strength. This cannot be ascertained without submitting the sample to a complete chemical analysis, and hence a great deal of trouble and erroneous results are apt to ensue. I have encountered this very trouble myself, as may be seen from the foilowiag figures : A sample of pepsin, purchased as a pure pepsin (pepsin C in the tables), but which in reality was a eaccharated pepsin, gave by this method 420, Le., it is supposed to dissolve 420 times its weight of coagulated albumen. Not knowing the strength of this saccharated article in pepsin, I was at a loss to know how much should be used in the test, and therefore decided to look upon it as a concentrated pepsin. In consequence of this decision on my part the pepsin was saccharated according to M.’s directions, and 0.3 grm. of this resaccharated pepsin used in the test, with the above result. The result obtained undoubtedly does the pepsin injustice, for it is propable that if I had not resaccharated the original article, and con- sequently diluted it to a much greater extent, that a much higher test would have been recorded. The same applies also to the following pepsins, which were in the sacchayated con- dition when bought and were resaccharated by me before testing. then 154 C.C. ,, 7, Y, 28.5 7, 99 Grs. Albumen dissolved Brand of Pepsin. in six hours. Pepsin A . . .. .. .. .. . . .. . . 550.6 .. .. .. .. . . . . . . 516.6 .. .. .. * . * . . . . . 420. .. .. .. .. . . . . . . 398.6 Y, Be. 9 , (2.. 97 D - * (To be Co?atinued.)

ISSN:0003-2654    

DOI:10.1039/AN8881300210

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年代:1888

数据来源: RSC

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THE ANALYST. 213 ON SOURCES OF ERRORlIN DETERMINATIONS OF NITROGEN BY SODA- LIME, AND MEANS FOR AVOIDING THEM. BY W. 0. ATWATER. (Continued from page 196.) The experiments cited by Mr. Ball and myself in the previous article of this series bear striking testimony to the danger of loss if there is not sufficient contact between the gaseous distillation products and the heated soda-lime. I n determinations of casein by our usual method (which involvesclose packing of the soda-lime in the tube, the use of coarse particles of soda-lime for the anterior layer, heating the anterior layer before the distillation products begin to be developed, and keeping it well heated until the combustion is finished), the whole of the nitrogen, 12.43 per cent., was obtained as ammonia. But when a channel was left in the tube (and fine soda-lime was used for the anterior layer), so that there was less contact between distillation products and heated soda-lime, the nitrogen obtained as ammonia amounted to only from 12.25 to 11.65 per cent.of the weight of the casein instead of 12.43 per cent. ; that is to say, from 1.4 to 6.4 per cent. (on the average 3.3 per cent.) of the whole nitrogen escaped ammonification. When, again with the channel, the anterior layer was made shorter, 7.5 cm. instead of 12 cm., the nitrogen obtained as ammonia fell as low as 10.51 per cent., the rest, 15.4 per cent. of .the whole, escaping ammonification. The average loss under these last conditions was 6.4 per cent. of the whole nitrogen. Even more striking illustrations of the failure of distillation products to be changed to ammonia are given in the experi- ments with strychnine described in the same article.In these but a fraction, at times very small, of the total nitrogen was obtained as ammonia, although especial effort was made to secure complete ammonification. But little consideration of the matter is needed [to show that the formation of volatile nitrogenous products which would escape arnmonification by the soda-lime and detection in the acid is a very natural occurrence. The protein compounds when subjected to destructive distillation yield a great variety of products, among which are, besides water, carbon dioxide, hydrogen sulphide, and hydrocarbons, a great variety of volatile nitrogenous compounds, including ammonia, ammonia salts of the fatty acids, amines derived from the paraffins, members of the aniline and pyridine series, pyrrol, etc., etc." By heating in the presence of alkalies and other reagents a great variety of other compounds, with the rest a number of acids of the fatty acid series and amido acids belonging to this and the aromatic series, among which lahter are leucine and tyrosine.By the action of enzymes and microbes, products akin to the alkaloids are formed. The alkaloids break up into compounds such as were mentioned above, and numerous o thers, including members of the quinoline series. Now these nitrogenous products vary greatly in respect to their volatility and the ease with which they are changed to ammonia when heated in presence of soda-lime (i.e,, of water vapour at high temperature).The specific data a t hand regarding the ease with which they are ammonified are meagre. There are, however, observations bearing upon this point. For instance, Goldberg finds that some of the more complex azo- * See Handw. d. Chem. 2, 1161-1173, and E. Salkowski, Ztschr. anal. Chem. 16, 1877, 261 and408.214 THE ANALYST. compounds, with soda-lime, yield all their nitrogen as ammonia, while the simpler ones fail to do so, part escaping." There is nothing more natural than that in soda-lime combustions such volatile nitrogenous products should be formed and escape ammonifica- tion. A fact of interest here is that some, at least, of the compounds which are most difficult to determine by soda-lime are the ones that me most readily broken tip into very volatile products.Such are guanidine, kynurenic acid which may yield quinoline, leucine, and quinine and other alkaloids. It is also worth noting that some of the alkaloids, tho nitrogen of which it is so difficult t o transform entirely into ammonia by soda-lime, manifest a similar behaviour in treatment with sulphuric acid and other reagents by Kjeldahl's method,? and perhaps for similar reasons. I n looking over the literature of the subject, which is quite extensive, one cannot help being impressed by the fa& that certain nitrogenous compounds very frequently, and othersalmost uniformly, fail to yield all of their nitrogen in the form of ammonia when heated with soda-lime. Whatever may be the differences of manipulation of different experimenters, nearly all find it impossible to get all of their nitrogen in that form from such substances as leucine and some of the alkaloids.But in some cases, as, for instance, those of Miircker and Abesser above quoted, the nitrogen has been obtained by precipitating platinic chloride even when i t was not obtained by titration. Leucine$ is, in this respect, an especially refractory compound, though chitin,$ gluten-protein,/] and, in some instances, casein7 (milk) and peptones"" have given trouble in this way. The interesting researches of SchutzenbergerS? have indicated that the protein compounds (albuminoids and gelatinoids) are made up of a variety of simpler compounds, among which leucine and another, or perhaps several other compounds closely allied t o it, are among the important constituents, That is to say, under the influence of various agencies the protein compounds split up into a large variety of simpler compounds, among which leucine .and its congeners play an important part.That these latter might be easily formed from protein compounds in the breaking up which occurs in the ordinary heating with soda-lime is a very natural inference from the facts a t hand. But from its constitution, leucine might be expected to readily be split up into volatile nitrogenous compounds. Such observations as those of Miircker and Strecker, above quoted, would seem to give reasonable assurance that it actually does so. I n view of these facts it will be easy t o assume that in ordinary * Ber. d, chem. Ges.25, 46. f Ztschr. anal. Chem. 22, 1883, 379. $ 3.g. Mtircker and Abesser, loc. cit.; Ritthausen and Kreussler, J. prakt. Chem. 111, 1871 ; $ Biitschli, Ztschr. anal. Chem. lG, 1877, 409. 11. Mtircker and Abesser, loc. cit.; Krenssler, Landm. Vs. St. 31, 1881, 248. S:e also Ritthausen, 'I[ Lehmann, Ztschr. anal. Chem. 15, 1876, 113 ; Muss3, ibiil. 16, 1877, 413 ; Menozzi, Jsb. Agr. ** Gruber and Peder, Ztschr. f. Biol. 16,1880,351. tf Bull. SOC. Chim. 23-30, 1875-1878, and Chimie GBnBralc: 131, 407. Ritthausen, ibid. 116, 1874, 17. loc. Clt. Chem. 31, 1878,474 ; Kreussler, loc. cit.THE ANALYST. 216 combustions by soda-lime there is a tendency to the formation of nitrogenous distillation products, such as come from leucine and analogous compounds, and which would escape ammonification.-t.Such being the case, it is easy to see how volatile nitrogenous com- pounds might often escape ammonification unless the greatest pains were taken to insnre the most perfect contact between them and the heated soda-lime (heated water vapour) and that sometimes the ammonification might be incomplete despite the greatest care. If this be correct, the difficulty of getting 'all of the nitrogen of peptones into form of ammonia would accord with the fact that the peptones are products of change of the albuminoids, which change, carried further, results in the cleavage of the latter into leucine and other allied products. It would also be easy to theorise regarding the constitution of the alkali albumins and casein, and to imagine that they might likewise be on the way toward the process of cleavage by which leucine and its decomposition products are produced.Of course this is speculation, but it at least helps us to see how the observed facts might occur ; and irrespective of any such hypotheses, the known facts are sufficient to warrant the assumption that under the influence of high heat in the presence of soda-lime, numerous volatile nitrogenous compounds might be expected to be formed, some of which would resist ammonification; and that certain classes of protein compounds would be especially prone to such decomposition, even though, in the present state of our knowledge, we are unable to say just exactly what thosecompounds are, or what are the processes of cleavage they go through, or what are the nitrogenous products that resist ammonification.An illustration of the difficulty of ammonifying some of these volatile compounds is found in the above-mentioned case of strychnine in the experiments detailed in the previous article of this series. Neither the most pains taking effort to secure contact between the gases and the soda-lime by the Will-Varren- trapp method, nor by the greatest care in heating by that of Kjeldahl, sufficed to convert all the nitrogen into ammonia. On theother hand, the results with casein, when means were taken to secure adequate contact with soda-lime and to avoid dissociation, were most satisfactory. But when a channel was left in the tube so that the distillation products were not brought into close contact with the soda-lime, the loss was at times very large. The lesson which all these considerations teach, and which is enforced by those cited in the previous articles, is tho importance of providing intimate and sufficient contact between the distillation products and the heated soda-lime. This is done by fine pulveri- sation and intimate mixture of substance with soda-lime ; by having the tube closely packed with soda-lime to avoid open spaces; by providing a long enough anterior layer of soda-lime, and by heating this layer well before the gases are disengaged, and keeping it well heated until the combustion is finished. At least such seems to me the just inference from the facts at hand. t See also Hofmann, Ann. Chem. (Liebig) 79, 29 ; Wertheim, Jaw. prakt. Chem. 5.1, 481 ; Williams, loc. cit. 76, 353 ; and Michael, this Journal 7, 182, for decompositions of alkaloids and otzer compounds, bearing upon this question. (5% be continued.)

ISSN:0003-2654    

DOI:10.1039/AN8881300213

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年代:1888

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216 THE ANALYST. ~ ~ ~~ ~~ MONTHLY RECORD OF GENERAL RESEARCHES INTO ANALYTICAL CHEMISTRY. REMOVAL OF FUSED MASSES FROM PLATINUM CRUCIBLES. L. L. DE KONINCK. Zeitschr. f. angew Chemie, No. 20.-When fusions are performed in large dishes, no particular trouble is experienced in dissolving the fused mass; but if done in deep crucibles it is better to first empty them. Many devices have been proposed, but they generally only succeed with new crucibles, and are apt to spoil them in the long run. The author now operates as follows :-As soon as the fusion is completed, the coiled end of a platinum wire is put into the mass, which is then allowed- to cool. The wire is about 10 cm. long, and ends in a loop, so that it may be suspended from a hook. When suspended, the crucible is brought at about half an inch distance from a pipeclay triangle, and then suddenly heated.In a few seconds the crucible will detach itself and drop into the triangle, whilst its contents stick to the wire. The small quantity of salts still adhering to the crucible may, of course, be removed by suitable means. The wire is now made to slip into a beaker filled with water or acid, when, owing to the salts being on the top of the fluid, solution takes place with great rapidity. L. DE K. TESTS FOR CARBOHYDRATES. L. V. UDRANSZKY, Zeitschr. J’. Php. Chem., May, 1888.-Undoubtedly the furfurol reactions furnish the most delicate tests for the carbohydrates. H. Schiff uses a test paper made by immersing paper in a mixture of equal volumes of xylidin and glacial acetic acid diluted with alcohol and drying.A small quantity of the substance to be tested is heated with a slight excess of concen- trated sulphuric acid and the test paper held in the evolved vapours, a beautiful red colour is produced owing to the formation of the furoxylidin. It will detect as little as O9OOOO7 gm. glucose in an *aqueous solution. The author uses a furfurol reaction, even more delicate than the above, detecting 0.000028 gm. glucose in solution. One drop of a dilute solution to be tested is mixed with two drops of a 15 per cent, alcoholic solution of a-naphthol in a test tube and $ C.C. concentrated sulphuric acid is carefully poured in to form a distinct layer. I f at the line of contact a violet colour above a green layer is produced, carbohydrates are present. Urine is diluted with 9 volumes of water and one drop proceeded with as above. If the violet colour is not produced, the urine is considered normal; if the colour is produced, the urine may be considered abnormal because it yields a quantity of furfurol which is also obtained from a glucose solution containing at least 0.5 per cent.By means of these two tests carbohydrates were detected in all urines examined : albumen perfectly free from carbohydrates heated with concentrated acids formed furfurol which was recognised in the distillates, estab- lishing for the first time by chemical reactions a close relationship between the albumi- noids and the carbohydrates. I n testing urine for carbohydrates, if albumen be present in larger quantities it must first be removed, small quantities do not introduce appre- ciable errors, owing to the small quantity of urine taken.Fehling’s solution under the most favourable conditions failed to detect less than 0.00012 gm. glucose in aqueous solution ; testing urine by the three tests the bodies other than carbohydrates decrease the delicacy of Fehling’s test to a greater degree than the first two tests. W. H, D.THE ANALYST. 217 DELICATE TESTS FOR AROMATIC AMINES. A. THL. Chem. Zeitung, 76.-The oxidation of aromatic amines yields complicated condensation products, which are nearly all splendid dyes. The author tried manganic dioxide, but in presence of mineral acids no striking result was obtained. Very interesting results were, however, got by using hydrated manganic dioxide, in conjunction with acetic, oxalic or tartaric acids.Toluidin oxalate gives with the manganic dioxide a red colour, changing to green on heating, but turning red again on boiling. A t the same time a black colouring matter precipitates, which dissolves in spirit with a rod colour. Xylidin acetate similarly treated gives a splendid reddish-violet, which gradually darkens. Dimethylanilin oxalate, diethylanilin acetate, in fact all aromatic amines, give the most splendid display of colours. These colours may also be prepared by making the amine salts with manganic dioxide to a paste, and heating until the mass looks yellowish-red. The colouring matters may then be extracted with water or spirit. If a thread of wool is boiled in a very weak solution of toluidin or xylidin oxalate with addition of some manganic dioxide, it becomes black, but after washing, it will look of a nice dark-brown colour.Cotton wool is not dyed under the circumstances. If the solution of toluidin oxalate is first boiled for some time with manganic:dioxide, and then allowed to settle, it will colour a piece of wool beautiful reddish-violet. The other amines will also colour the wool in various shades. The colours seem to stand pretty well the action of light and soap. L. DE K. CONVENIENT PREPARATION OF CHLORINE FOR ANALYSES. L.L. DE KONINCK. Zeitschre f. angew Chemie, No. 18.-The author for several years advocated the use of a K.ipp’s apparatus, which after being charged with manganic dioxide and hydrochloric acid had to be heated on a water bath.Owing to the many breakages, the author has now con- structed an apparatus by means of which the chlorine may be prepared in the cold. Hydrochloric acid is evolved in the author’s apparatus (see Zeitschr. f. angew Chemie, page 353) and passed through CL tower, containing granulated manganic dioxide, when the usual reaction takes place, and chlorine is liberated. The gas is then dried by means of calcium chloride or sulphuric acid. For the preparation of small quantities, the author used a Peligot’s tube (a U-tube with three bulbs), one side of which is filled with lumps of manganese of the size of a pea, and the other with calcium chloride. For large quantities the author prefers R. Muencke’s drying cylinder. L. DE K. DETECTION OF MERCURY IN URINE. DR.HIELBIG. Phama. Zeit. BussZ.-The author adds to 100 C.C. of urine 10 C.C. of diluted hydrochloric acid (1 Go 2) and 2 to 3 grains of recent copper scrapings, and evaporates in a porcelain dish to about 5 c.c., stirring occasionally. The mercury, if present, will precipitate upon the copper, which is taken out, rinsed with water, boiling alcohol and ether, allowing it to dry at ordinary temperature The copper is then heated in a glass tube of 5 mm. diameter for ~ 2 cr 3 minutes; the mercury sublimes, After cooling, the copper is shaken out, a few frag- ments of iodine introduced, and the tube heated gently, when the vapours of iodine will combine with the mercury forming the biniodide. Experience has shown that the above218 THE ANALYST. proportions are the best.microscope is an aid t o the detection of very minute quantities. The test is very sensitive. Examination of the tube by the W. H. D. TESTING ,!!nIBER VARNISH. W. SONNE. Zeitschr. f. ungew Chemie, ATo. Is.-Com- mercial amber varnish is made by dissolving amber or colophony-amber in linseed oil, varnish, and turps. In many cases it is made without the expensive amber, and an analyst is sometimes asked his opinion, whether a sample is genuine, viz., really made with amber. The best way is to try for succinic acid, although even a genuine article only contains small quantities of this substance, as a large quantity volatilises during the heating of the varnish. The detection is, however, difli- cult, owing to the nature of the article. Neither boiling with hydrochloric acid, nor treatment with alcoholic potash, extracts any succinic acid.The author's plan is to treat the sample with nitric acid of 1.20 specific gravity." He proceeds as follows :- 20 grms. of the varnish are put into a flask of about 300 c. c. capacity, and heated on a sand bath with 50 C.C. of the nitric acid. When action sats in, the flask must be some- what cooled to prevent a too fierce oxidation, when it may be again gently heated for about fifteen minutes. The acid, which holds all succinic acid in solution, is now poured off and the insoluble resinous mass washed with water. The acid is evaporated in the water bath, a little water being from time to time added. When the acid has been completely 'expelled, the remaining syrup is dissolved in about 10 C.C. of water, and this solution shaken with 100 C.C. of ether. After distilling off the ether, the residue is put in a watch glass and put under a dessicator, After about twelve hours, crystals of succinic acid separate out and the amount gradually increases. The mother liquor being removed by means of blotting paper, the crystals may now be tried by the usual tests for succinic acid. It is thus possible to answer within twenty-four hours the question whether a, sample of amber varnish is really deserving of the name. L. DE K.

ISSN:0003-2654    

DOI:10.1039/AN8881300216

出版商:RSC    

年代:1888

数据来源: RSC

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218 THE ANALYST. MONTHLY RECORD OF ANALYTICaL RESEARCI-IES INTO FOOD. FUSEL OIL IN SPIRITS.-~. S E L L . - ~ & ~ S C ~ . f. angezu Chemie, No. 20.-Among the best processes known is the method of Rose, an elaborate abstract of which will be found in the AnaZyst, vol xi. It is, however, necessary to strictly adhere to the various pre- cautions, otherwise the results will be faulty. The author also studied the influence of ethereal oils, and found them not to se~ioasly interfere with the accuracy of the process. They may (if present in larger quantity) be practically got rid of by rectifying the spirit with caustic potash. 200 C.C. of the sample are made strongly alkaline with caustic potash and put into a retort containing a few lumps of pumice-stone (to prevent bumping) and the retort is then connected with a Liebig's condenser.The receiver consists of a narrow graduated cylinder, and 4 6 t h ~ of the brandy are distilled off. The distillate is now made up to * Note by abstractor. May not some succinic acid bc actually produced by oxir'ation of fatty matter?-L. DE R.THE ANALYSE. zi 9 original volume. not be exactly 30 by volume, it is ready for the treatment with chloroform. After diluting or strengthening, if the percentage of alcohol shoul d L. DE K. __ ~ . . - - BORACIC ACID AS A PRESERVATIVE. EMMERICH. Chm. Zeiturzg, No. 76.-Boracic acid only acts when present in large quantity. It prevents the growth and multiplica- tion of germs, but does not kill them even in a 1 per cent. solution. Experiments with milk gave very unsatisfactory results, as an addition of 4 per cent.boracic acid only preserved the milk for four days. Horseflesh may be preserved for six weeks by the use of 3 per cent. of the acid. Boracic acid is supposed to be harmless, but recent investi- gators, including the author, prove it to be dangerous, as it strongly acts upon the mucous membrane of the large intestine. A dose of 4 grms. killed a large rabbit; 2 grms. made a dog very sick. The acid is much used in Sweden for preserving fish and milk, but cases of poison- ing have already occurred in that country. Long continued use of the acid is not favourable to good health, and at all events its addition to milk should be prohibited. ,IA. DE K. MONTHLY RECORD OF ANALYTICAL RESEARCHES INTO DRUGEI. DISTINGUISHING CITRIC FROM TARTARIC AND MALIC ACIDS. PROFESSOR MEAU . Zeit. fur. Anal. Chrnie.-The author heats the acid with 0.7 per cent. of glycerin until vapours of acrolein are evolved ; the mass is then taken up by a little ammonia, the greater part of which is afterwards expelled by heating. A few drops of nitric acid (the fuming acid diluted with five parts of water) are then added. Under this treat- ment citric acid yields a green compound, which turns blue on heating. Tartaric and malic acids do not produce the same coloration. W. H. D.

ISSN:0003-2654    

DOI:10.1039/AN8881300218

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年代:1888

数据来源: RSC

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THE ANALYSE. 21 9 REVIEWS. BOILER WATERS. THIS is a record of the author’s work on the waters available for locomotive purposes along the whole length of the Chicago, Burlington, and Quincy Railway. Two hundred and fourteen samples have been analysed, classified, and recorded. The author divides the total solids as follows :-(a) The incrusting solids in grains per gallon representing the sum of the following, viz., carbonates of lime and magnesia-sulphates of the same bases, silica, alumina and oxide, (or carbonate) of iron. The author admits that magnesium sulphate may not be universally viewed as a true ‘ I scale former,” but he prefers to include it as such for various reasons, and thus get truly comparable results in all the waters. (b) The non-incrusting solids in grains per gallon which are obtained by deduct- ing the incrusting solids from the total residue, and are also termed the corroding or dudge-producing solids. They are manifestly alkaline salts, together with any organic matters present. BY WALTER LEE BROWN.Chicago : Shepard and Co. The author adopts the following scale of comparative rating :- Less than 8 grains of incrztstifig solids per gallon, considered as Very good. 8 to 15 ,, 78 99 Good, 15 to 20 3 9 9 9 9 ) Fair, 20 to 30 92 ?) $9 Poor. 30 to 40 ,? 77 ?, Bad. OV6r 40 $2 9 , 72 Very bad.220 THE ANALYST. These are practically the standards adopted by the American Association of Railway Chemists, except in the case of the first degree of ‘( very good.” The Association also determined that the best practical form of report was to state the incrusting solids in Ibs.per 1,000 gallons. It would be well if English analysts were to agree upon similar forms and standards, which are decidedly more comprehensible to steam users in general. There is only one original process given in the book, and here we fear that we British chemists will not go along with our American confrere. ’ It is true he concludes it by the statement that (‘ the above process is not claimed to give the utmost scientific accuracy, but it is much better than any ‘ hardness ’ method.” We have not space to give the details, but will only remark that a process providing for the separation of lime and magnesia in pure aqueous solution, by ammonia and ammonium oxalate, without any previous addition of ammonium chloride, acd finally requiring the addition of one quarter to the amount found (to compensate for the want of solubility of calcium sul- phtlte, is in our opinion very far short of scientific accuracy indeed. THE ANALYST’S LABORATORY COMPANION. BY ALFRED E. JOHNSON. London: J. an6 THIS is a table book of 90 pages, including all the usual tables required by analysts, with a set of 7 figure logarithms from 1 to 1,000. The printing is clear and distinct, and the book, so far as can be seen from a perusal, seems to be very free from printer’s errors. There are a few original tables given, which will be found useful in the estima- tion of carbohydrates with the polariscope, and in the estimation of chicory in coffee, etc. There is also a very good table for calculation of phosphates specially worked out for A. Churchill. agricultural analysts, -.

ISSN:0003-2654    

DOI:10.1039/AN8881300219

出版商:RSC    

年代:1888

数据来源: RSC