摘要:

APRIL, 1913. Vol. XXXVIII., No, 446 THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE monthly meeting of the Society was held on Wednesday evening, March 5, in the Chemical Society’s Rooms, Burlington House. The President, Mr. L. Archbutt, F.I. C., occupied the chair. The minutes of the previous ordinary meeting were read and confirmed. Certificates of proposal for election to membership in favour of Messrs.A. C. Bescoby, M.A., T. W. F. Clark, F. E. Day, B.Sc., A.I.C., and J. F. Tocher, B.Sc., F.I.C., were read for the second time ; and certificates in favour of Messrs. Henry Francis Everard Hulton, A.I.C., 15, Oakhill Court, Putney, S. W., assistant chemist to Messrs. Watney, Combe, Reid and Co., Ltd. ; Charles Thomas Kingzett, F.I.C., Newlands, Weybridge ; and Alfred J.Parker, 1, Bulwer Street, Herne Bay, Auckland, New Zealand, public analyst for the City of Auckland, N.Z., were read for the first time. Messrs. J. A. Goodson, F.I.C., F. W. Skevingbon, and J. C. White, A.I.C., were elected members of the Society. The following papers were read : The Bacterial Testing of Disinfectants : a, Practical Criticism,” by C. T. Kingzett, F.I.C., and R. C. Woodcock, F.I.C.; “A Quick and Improved Method for the Estimation of Boric Acid in Milk and Cream,” by Frederic W. Richardson, F.I.C., and William Keighley Walton ; The Combined Estimation of Boric Acid and Fat in Cream,” by Frederic W. Richardson, F.I.C. ; “ A Simple All-Glass Extraction Apparatus,” by Clayton Beadle and Henry P. Stevens, M.A., Ph.D., F.I.C. ; and “ The Accurate Determination of Cazbonic Acid in Carbonates,” by Frank Sturdy Sinnatt.

ISSN:0003-2654    

DOI:10.1039/AN9133800135

出版商:RSC    

年代:1913

数据来源: RSC

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136 SINNATT : THE DETERMINATION OF THE DETERMINATION OF CARBON DIOXIDE IN CARBONATES. BY FRANK STURDY SINNATT. (Read at the Meeting, March 5, 1913.) TEE difficulties encountered in the accurate determination of carbon dioxide evolved in the course of chemical reactions, particularly when the evolution of the gas takes place over an extended period, or when the amount of carbon dioxide produced is very small, will, it is hoped, justify the publication of the process described in this paper.The method appears to be applicable to many of the reactions which lead to the evolution of carbon dioxide; but for the purposes of comparison and as a guide to the quantities of reagents necessary, the estimations given in this paper have been carried out upon pure carbonates.Of the many processes for the determination of carbon dioxide in carbonates, the following are in general use : Schrodters’ apparatus, or some modification, may be expected to yield results within 0.3 to 1 per cent. when the weight of substance available is about 1 grm. and the substance is rich in carbon dioxide. An improved form of Scheibler’s apparatus is described by S. H. Collins (J.SOC. Chem. Ind., 1906, 25, 518). This process depends upon the measurement of the volume of carbon dioxide evolved from carbonates by the action of acids. The method suffers from inaccuracies inherent in any process in which it is necessary to measure small volumes of carbon dioxide-viz., the effect of temperature and the impossibility of standardising the volume of gas remaining dissolved in the reaction liquid.This method has a great advantage in that it is very rapid. Hall and Russell (J. Chem. SOC., 1902, 81, 83)-observe that the determination of small quantities of carbonates in such a material as soil is attended with many difficulties, and they state that when the soil contains only 0.5 per cent. of calcium carbonate the whole of the carbon dioxide produced, when acid is added, remains dissolved in the acid used for the decomposition of the carbonate.These authors describe a process whereby the volume of gas evolved by the action of sulphuric acid on a carbonate may be measured with accuracy. The method in general use for the accurate determination of carbonates consists in decomposing the carbonate with acid, and, after purifying the gas evolved, to aspirate it through weighed potash bulbs.This process is inaccurate when the weight of carbon dioxide obtained is very small, unless the precaution of counter- poising the potash bulbs with an empty bulb be adopted. Even with this precaution variations in weight of the potash bulbs are possible from external causes. Methods in which standard barium hydrate solution is placed in wash-bottles are accurate under certain conditions, but the following reaBons have prevented them being more generally adopted : The comparatively slight solubility of barium hydroxide in water, and the necessity of using a large volume of solution, and consequently a The equivalence of six sources of error is given as 1 per cent.CARBON DIOXIDE IN CARBONATES 137 cumbersome wash-bottle ; the fact that carbon dioxide is not absorbed by barium hydroxide solution very rapidly, and hence a slow stream of gas is essential; the prevention of contact with air and the breath of the experimenter during the work ; the difficulty of titrating the barium hydroxide solution accurately when in the wash- bottle at the completion of the absorption.In a paper (ANALYST, 1912, 37, 12) the author described an apparatus by means of which the rate at which a gas flowed into an evacuated vessel could be accurately and easily controlled. I t is found that the carbon dioxide evolved from carbonates may be conveniently estimated by means of this apparatus. The figure shows the complete train of apparatus employed for the determina- tion of carbon dioxide in carbonates.A is the decomposition flask described by Lunge and Marchlewski. B is a wash-bottle containing caustic potash solution. C i s a wash-bottle containing concentrated sulphuric acid. D a calcium chloride tube, E is packed with alternate layers of glass-wool and pure silver sulphate (to absorb hydrochloric acid gas). F is the special apparatus (Zoc.cit.). The flask a! is of the usual type used for filtering. The capacity of the flask was 2.5 litres, but in some of the analyses one of a litre capacity was used. I t is evident that the capacity of the flask limits the volume of air available for aspirating through the apparatus. The flask and the special apparatus should be freed from moisture previous to commencing an estimation.The determinations were carried out in the following manner: The flask and the apparatus are filled with air freed from carbon dioxide. (If the percentage of carbon dioxide in the air be known accurately, a correction may be made for the carbon dioxide remaining in the apparatus and flask after the evacuation.) Taps K , M, and P are closed, 1p and T are opened, and 0 connected to a water-pump, and the whole evacuated.When the apparatus is exhausted, H is closed. A reservoir containing mercury is brought under the end of F, and mercury allowed to flow into the tube until no further quantity will enter. The tap R is then closed. The mercury column in the tube serves as a manometer, and shows the degree of exhaustion in the flask. A weighed quantity of the carbonate is shaken into the flask A , and an excess of hydrochloric acid is brought into the cup.The tube to the wash-bottle B and the ground stopper of A are then replaced. The tap M is now opened, and mercury is allowed to flow slowly from the tube into the reservoir by opening K ; at the same time the hydrochloric acid is run cautiously into the carbonate.When the whole of the acid has been added, the communication between the cup and the bulb A should remain open. The carbon dioxide evolved is aspirated into the flask; air is also drawn in, passing through the wash-bottle B, and carrying the carbon dioxide into the flask. The current of air need not be interfered with from this period until the determination is finished. The carbon dioxide remaining in solution in the liquid in the vessel A is expelled by slowly heating the contents, and then boiling gently for some time.Air is permitted to flow through the apparatus until the pressure has fallen to about 700 mm., when the tap T into the flask is closed and the latter disconnected from F. A measured volume of standard barium hydroxide solution is placed in the tap funnel, and allowed to enter the flask as quickly as possible; owing to the138 SINNATT : THE DETERMINATION OF w n a I1 .contents of the flask being under diminished pressure, no gas is displaced by the barium hydroxide solution. The last traces of barium hydrate solution are washed from theCARBON DIOXIDE IN CARBONATES 139 Carbon Dioxide found. Grm. 0.0559 0.0685 0,0722 0.0140 tap funnel with water.Air free from carbon dioxide is now passed into the flask until the contents are at atmospheric pressure. The estimation is then completed by the usual procedure adopted for Pettenkofer’s process. The time required for a determination was about one hour. The following numbers were obtained in the estimation of carbon dioxide in calcite, pure barium carbonate, and pure sodium carbonate : Carbon Dioxide Present calculated.Grm . 0-0558 0.0691 0.0726 0.0138 CALCITE. ~ ~ ~~ Barium Hydrochloric Hydroxide Acid required for Solution. Titration. Weight of Calcite. ~~ HYdrochloric Acid to Carbon Dioxide. Grm. 0-1310 0.1710 0-0826 0.3490 0.0785 C.C. 50.0 50.0 50.0 50.0 ~ ~ Barium Hydroxide Solution. C.C. 20.6 13.3 11-2 44.8 7- ~ I I Hydrochloric t o Carbon C.C.50.0 50.0 50.0 100.0 50.0 c. c. 31.7 21.8 43.5 42.6 44.8 c. c. 32.1 42 -0 20.3 85.0 19-0 Carbon Dioxide found. Grm. 0.0576 0.0754 0.0364 0.1526 0.0341 Carbon Dioxide calculated. 0.0575 0.0751 0.0363 0.1534 i 0.0345 Hydrochloric acid (approximately decinormal), 1 C.C. = 0~001796 grm. of carbon dioxide. 50.0 C.C. barium hydroxide solution= 63.8 of & hydrochloric acid.CARBON DIOXIDE IN BARIUM CARBONATE ( KAHLBAUM’S). Weight of Barium Carbonate. Grm. 0.2508 0.3102 0,3258 0.0623 C.C. 32.3 39.6 41.7 8.1 Hydrochloric acid, 1 C.C. =0-001732 grm. of carbon dioxide. Barium hydroxide solution, 50.0 C.C. =52.9 C.C. of hydrochloric acid. The apparatus shown in the figure for purifying the carbon dioxide may be simplified if the process described by G.T. Morgan (Proc. Chem. Soc., 1904, 20, 167) is employed. This process consists in using phosphoric acid in place of hydrochloric acid or sulphuric acid to decompose the carbonate; owing to the former acid being non-volatile, it i R necessary to remove moisture alone from the carbon dioxide. This can be effected by interposing a single wash-bottle containing concentrated sulphuric acid between the decomposition flask A and the apparatus F.The following results were obtained :140 THE DETERMINATION OF CARBON DIOXIDE IN CARBONATES Carbon found. Dioxide CARBON DIOXIDE IN SODIUM CARBONATE. Four Deternaiiaations for Each Sepayatc Weight taken. Carbon Dioxide determined by Titration. calculated and Barium Hydrochloric rochloric Sodium Hydroxide Acid required for 1 Solution.1 Titration. 1 H;:.%:''y I I I I I Grni. 1 Grm. 0.0677 1 0.0671 0.0457 1 0.0448 Hydrochloric acid, 1 C.C. =0*001732 pm. of carbon dioxide. Barium hydroxide solution, 50.0 C.C. ~ 6 4 . 7 cc. of Fn hydrochloric acid. It is known that greater accuracy may be obtained by using more dilute solutions of barium hydroxide and standard hydrochloric acid. The limit of accuracy is obviously that attainable by Pettenkofer's process--i.e., with ordinary. precautions 1 C.C. (0*00196 grm.) of carbon dioxide may be estimated in the gas when the capacity of the flask is about 10 litres. The method is being used at present for the determination of carbon dioxide in beer, and it is thought it may prove useful for the estimation of carbon dioxide in such materials as cements, clay, soil, ~ o a p , and in aerated liquids. The apparatus is being applied to the determination of small quantities of carbon, methane, and carbon monoxide. CHEMISTRY DEPARTMENT, SCHOOL OF TECHNOLOGY, MANCHESTER.

ISSN:0003-2654    

DOI:10.1039/AN9133800136

出版商:RSC    

年代:1913

数据来源: RSC

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140 THE DETERMINATION OF CARBON DIOXIDE IN CARBONATES A QUICK AND ACCURATE METHOD FOR THE ESTIMATION OF BORIC ACID IN MILK AND CREAM. BY F. W. RICHARDSON, F.I.C., AND WM. KEIGHLEY WALTON. (Read at the Meeting, March 5, 1913.) THE method of R. T. Thomson when applied to the estimation of boric acid in milk and cream gives results low in proportion to the amount of combustible matter-fat, etc.-in these liquids.The sodium hydroxide does not prevent a serious loss of boric acid when the solids are charred. To three samples of 10 grms. of cream were added respectively 50, 100, and 200 mgrms. of boric acid. By the Thomson process only 21, 60, and 149 mgrms. respectively were found. We attempted to coagulate milk and cream with mercury, lead, and zinc salts before determining the amounts of boric acid in the filtrate, but with unsatisfactoryESTIMATION OF BORIC ACID IN MILK AND CREAM 141 results, We then tried the following method : Five C.C.of a 5 per cent. solution of sulphate of copper are added to 50 C.C. of milk or 10 grms. cream mixed with 40 C.C. of water. The mixtures are well stirred and are heated to boiling for a few seconds, and the filtrates used for the estimation of boric acid, the contents of the filter having been well washed four or five times with boiling water.To the cold filtrate 2 C.C. of a 1 per cent. neutralised solution of phenolphthalein in alcohol are added and & NaOH until a certain blue shade appears. The usual proportion of glycerol, about one-third of the volume, is added, and the titration with Tc NaOH proceeded with until the blue shade again appears.A very little practice enables the right point to be reached. Under these conditions 1 C.C. of & NaOH = 0.0071 grm. of boric acid. Six milks with amounts of boric acid unknown to the analyst gave- H,BO, Per Cent. Present ... 0.045 0012 0.093 Nil. 0.015 0.006 Found ... 0.041 0.014 0.086 - 0.0124 0-005 --- - --- Error ...-0.004 +0.002 -0.007 - - 0.0026 - 0.001 Six creams under similar conditions gave- H,BO, Per Cent. Present ... 0.050 0.020 0.010 Nil. 0.150 0.100 Found ... 0.050 0.0202 0.0096 - 0.161 0-1001 Error . . . - +0.0002 -0*0004 - + 0.011 - ------ The method is rapid and easy of application, and the results are reasonably accurate. If it is desired to remove the copper, about 0.5 grm. of zinc dust may be added to the boiled mixtures of milk or cream and copper sulphate. The filtrate is colourless. We prefer not to remove the copper, as the small excess of copper acts as an indicator and gives a characteristic blue, as opposed to a green shade when the right amount of Fv NaOH has been added.

ISSN:0003-2654    

DOI:10.1039/AN9133800140

出版商:RSC    

年代:1913

数据来源: RSC

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ESTIMATION OF BORIC ACID IN MILK AND CREAM 141 COMBINED ESTIMATION OF BORIC ACID AND FAT IN CREAM. BY F. w. RICHARD~ON, F.I.C. (Read at the Meeting, March 5, 1913.) ACCORDING to the Public Health (Milk and Cream) Regulations, 1912, it is not per- missible to add any preservative substance to cream containing less than 35 per cent. by weight of milk-Eat. This new enactment makes it incumbent upon the analyst to estimate both boric acid and fat in cream.I find that the fat may be easily estimated in the copper coagulum on the filter left in the process above described. The well-drained filter is142 COMBINED ESTIMATION OF BORIC ACID AND FAT IN CREAM placed in the mouth of a wide but short-necked and counterpoised flask-a GO, flask of about 4 ounces capacity.The flask and filter are kept in the water-oven until the moisture is expelled. The filter is placed in a Soxhlet tube secured into the flask into which most of the milk-fat has filtered. After a brief extraction with petroleum ether, it will be found that the whole of the fat has been recovered. I t is necessary to leave the flask containing the fat some three or four hours in the water-oven before weighing; after this period constant weight can easily be obtained.The results are accurate when compared with those given by standard methods. DISCUSSION. Mr. T. MACARA said in the case of butter he had found as much as 30 per cent. of the boric acid to be lost on ignition with soda. I t seemed as though it volatilised in the fat, much in the same manner as it does with methyl alcohol. He had tried tihe use of caustic lime as well as of caustic soda, because the combustion then was freer; but even this did not seem to fix the boric acid completely.He thought that the Gottlieb method was probably the best for estimating the fat in cream, and by a slight modification the estimation of boric acid could be combined with it. Mr. RICHMOND thought that it would be better to titrate at boiling-point.I n the method devised by Mr. Miller and himself some years ago, advantage was taken of the fact that, in the presence of a considerable quantity of phenolphthalein at boiling temperature, boric acid showed no acidity at all, while when a polyhydric alcohol was added the full acidity was developed, and he thought that if in Mr.Richardson s case the temperature were raised to boiling, the accuracy of the method would probably be improved. The method described for fat estimation appeared to be the old Ritthausen method. It was excellent for cream, though not quite so good for milk, especially when the milk had been heated. As a rapid method he would suggest the estimation of the fat by the Gerber method in a mixture of equal weights of cream and water, and the estimation of the boric acid in 8 measured quantity of the same mixture by the method devised by Mr. Miller and himself. Mr. RICHARDSON, in reply, said that they never used a centrifugal method for estimating the fat, being of opinion that the results were not nearly so accurate &S were obtained by the method here described. As to the boric acid results, these were certainly on the average a, little low, but not to so large an extent as 5 per cent. on the total amount of substance found.

ISSN:0003-2654    

DOI:10.1039/AN9133800141

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年代:1913

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A SIMPLE ALL-GLASS EXTRACTION APPARATUS 143 A SIMPLE ALL-GLASS EXTRACTION APPARATUS. BY CLAYTON BEADLE AND HENRY P. STEVENS, M.A., PH.D., F.I.C. (Read at the Meeting, March 5, 1913.) IN spite of the very large number of extraction apparatus which have been devised, we have always felt the need of a simple Soxhlet apparatus composed entirely of glass without mercury traps, ground-glass joints, or stoppers of any material.There are serious objections to any form of apparatus except one made entirely of glass. Mercury is unhealthy on account of the vapours given off; ground glass joints are very apt to stick, and are expensive ; and, of course, rubber or other similar material is unsuitable for use in any part of the apparatus with which the vapours of the solvents come in contact.The apparatus we are about to describe overcomes these difficultiee. It is made entirely of glass, it is eificient, and it is not expensive. It consists essentially of an ordinary Erlenmeyer flask, about 3 inches in diameter at the bottom and 44 inches in height to the bottom of the neck. The neck is made wide and long, 1$ to 1& inches internal diameter and 44 inches long. These dimensions have been found convenient, but can be altered to suit circumstances; and the neck could probably be made much shorter if a more efficient and complex condenser were employed.We prefer to use one of the simplest construction, consisting merely of a glass vessel of test-tube shape, provided at the top with a water inlet and outlet, and of about la to 1; inches external diameter, which is slipped into the neck of the flask and supported by a flange which rests on the rim.The actual extraction-tube consists of a glass thimble with siphon-tube attached, about 3 inches long and 1 to 1% inches external diameter. The thimble hangs by means of a flangeon three or four projections at the bottom of the neck of the flask, made by softening the glass and forcing a sharp-pointed instrument in to a depth of about a inch.The method of working is self- explanatory. It is found that the condenser is sufficient for the complete condensation of the vapours of such volatile solvents as ether and acetone. We have tested the apparatus constantly in practice, and find no loss after extraction for eight hours. The apparatus has the advantage that the substance to be extracted is immersed in the solvent or its vapour at the boiling-point of the liquid.It is therefore more efficiently extracted144 A SIMPLE ALL-GLASS EXTRACTION APPARATUS than in the ordinary siphon Soxhlet apparatus, where the liquid in the extraction-tube is cooled by radiation. In order to facilitate the removal of the extraction-thimble a piece of fine metal wire may be twisted round it just below the flange, leaving two ends on opposite sides 2 or 3 inches long.When the tube is inserted, these will lie against the walls of the neck within easy reach of the fingers, so that by pulling the wires the thimble may be easily withdrawn. The only possible objection which can be raised against this apparatus is the fact that it is more convenient to transfer the contents to a separate flask for the evaporation of the solvent and the weighing of the extracted material.We do not ourselves see any objection to doing this, but, as pointed out, the neck and condenser could probably be shortened, and the total height of flask and neck reduced to about 7 to 8 inches, when it would not be too high to go on to the pan of the ordinary balance. We have now had this apparatus in constant use for some months in our laboratories, particularly for the extraction of rubber and cellulose products, and have found it satisfactory.A simple and light form of clip is all that is necessary to support it in an upright position when standing on a water-bath or wire gauze. The apparatus may be obtained from Messrs.Baird and Tatlock. DISCUSSION. Mr. R. Ross observed that an apparatus of this kind would be very useful for the analysis of samples of spent oxide in gasworks, where a number of deter- minations had to be made at one time. Mr. E. R. BOLTON remarked that the apparatus might be further simplified, if desired, by placing some cotton wool at the bottom of the extraction tube and a disc of filter-paper on the top, thus doing away with the siphon.In the ordinary Soxhlet apparatus the solvent easily became cold, and, moreover, sometimes some of the solvent was retained in the centre by capillarity, and never passed round. Dr. STEVENS said that they should like to try the apparatus without the siphon tube before expressing an opinion as to the desirability of doing away with this.A good deal of evaporation went on, and it was not easy to say how much of the liquid would drop through; some might possibly evaporate again. Used as a siphon apparatus, however, in the ordinary way, the apparatus worked perfectly well. Mr. BEADLE said that when the apparatus was working, the solvent could be seen boiling in the syphon thimble during the whole time, while it was surrounded by its own vapour. A number of pieces of apparatus could be connected together by rubber tubing, and placed upon a thin iron plate heated by small burners, without any water-bath, and any single flask could be removed without disturbing the others.The contents of the flask must, of course, be transferred to another flask for evapora- tion of solvent and weighing, but this entailed very little inconvenience, and, indeed, had certain advantages. In reply to a question put by the PRESIDENT, Mr. Beadle said that, although the solvent in the thimble could be seen to be gently boiling, this did not interfere with the proper siphoning of the liquid.

ISSN:0003-2654    

DOI:10.1039/AN9133800143

出版商:RSC    

年代:1913

数据来源: RSC

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FOOD AND DRUGS ANALYSIS 145 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD AND DRUGS ANALYSIS. Copper in Cocoa and Chocolate. C. Formenti. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 25, 149-154.)-Three samples of cocoa beans (after removal of the shell) yielded from 09020 to 0.034 grm. of copper per kilo. of substance, whilst the shells separated from the beans were found to contain 0.014 to 0.040 grm.of copper per kilo. These results agree with those found by most other observers, although Gautier (in a book published in 1883) has stated that cocoa-shell contains 0.225 grm. of copper per kilo. Various samples of chocolate examined contained quantities of copper varying with the amount of cocoa present and in proportion to the above- mentioned quantities, w.P. s. Estimation of Coumarin in Melilotus. E. Obermayer. (Zeitsch. aml. Chem., 1913, 52, 172-191.)-The method consists essentially in extracting the coumarin with ether, evaporating the extract, and distilling it from calcium chloride solution, and oxidising the distillate with permanganate. Ten grms. of the powdered, air-dry sample are extracted with ether, and the ethereal extract is evaporated in a 500-C.C.flask until the ether has been removed completely. Three hundred C.C. of calcium chloride solution (1 kilo. of the dry salt to 3 litres of water) are then added, and the mixture is distilled as far as possible, a small quantity of pumice-stone being added to the flask to prevent (‘ bumping.” The distillate is diluted to 500 c.c., filtered, and a quantity of the filtrate corresponding with from 0.005 to 0-05 grm.of coumarin is treated with from 25 to 50 C.C. of pure 20 per cent. zinc sulphate solution. After the addition of from 25 to 50 C.C. of TG potassium permanganate solution, the mixture is boiled for ten minutes, then filtered through an asbestos filter, the insoluble residue washed with water, and the excess of permanganate in the filtrate titrated with A- oxalic acid solution after the addition of sulphuric acid.Eaoh 0.01 grm. of coumarin requires 43.365 C.C. of FG permanganate for oxidation. When applied to pure cournarin, the process yields only slightly over 95 per cent. of the quantity present, and the amount found must therefore be multiplied by 1.04835 to obtain the actual quantity of coumarin in the sample.The process may be shortened by acidifying the oxidised and cooled solution and titrating the excess of permmganate without an intermediate filtration, but the results obtained are not as trustworthy as those given by the method first described. w. P. s. Acid-Butyrometric Method for the Estimation of Fat in Cheese and Milk Products. Hammerschmidt. (Mzkchwirtschaftl.Zentralbl., 1912, 41, 757-763 ; through Chem. Zentrakbl., 1913, I., 467.)-The butyrometer tube employed is open at both ends, and the graduated portion shows up to 35 per cent. of fat in 0.5 per cent. divisions. Two and a half grms. of cheese are placed in the tube,146 ABSTRACTS OF CHEMICAL PAPERS together with 9 C.C. of (‘ solvent ” (cf. 0. Wendler below) and 1 C.C.of amyl alcohol, and the mixture is heated to 4OQ C. and shaken until the casein has dissolved. The contents of the tube are then cooled until the fat begins to solidify, when 10 C.C. of sulphuric acid are added, the mixture is shaken thoroughly, and submitted to centri- f ugal action. w. P. s. Estimation of Fat in Cheese by the Acid-Butyrometric Method without the Use of Amy1 Alcohol.W. L. Kooper. (Milchwirtschaftl. Zentralbl., 1912, 41, 753-757 ; through Chem. ZentralbZ., 1913, I., 466-467.)-Two and a half grms. of the cheese are placed in a, butyrometer tube (a form of tube open at both ends is employed; see following abstract), the wide end of the tube is closed with a rubber stopper, and 6.5 C.C. of sulphuric acid of sp. gr. 1.54 are introduced through the other end of the tube, The cheese is then dissolved by immersing the tube in hot water and shaking the contents occasionally.When the casein has dissolved, 6.5 C.C. of sulphuric acid of sp. gr. 1.82 are added, and the mixture is submitted to centrifugal action. w. P. s. Estimation of Fat in Cheese by the ‘‘Neusal” Method. 0. Wendler. (Milchwirtschaftl. Zentralbl., 1912, 41, 763-765 ; through Chem.Zentralbl., 1013, I., 467.)-A new form of butyrometer tube for use in this method is described (cf. Golding, ANALYST, 1911, 36, 203). The graduations on the tube enable the volume of the separated fat to be read within 0.1 per cent. The casein solvent used consists of a solution containing salicylates and thiosulphates, and the fat-clarifying reagent consists of butyl alcohol.For each test 2.5 grms. of cheese, 12 C.C. of solvent, and 1 C.C. of butyl alcohol are employed; solution of the casein is attained by heating the mixture in a water-bath, and the volume of the fat is read off a t 70” C. w. P. s. Estimation of Water in Cheese. C. Mai and E. Rheinberger. (Study Committee Internat. Dairy Federation : Proposal for the Uni$cntion of Analytical Methods for Cheese, No.1913.) The method devised by Hoffmann (Zeitsch. aizgew. Chem,, 1902, 15, 1193) and subsequently recommended with various modifications by others (ANALYST, 1907, 32, 21 ; 1908, 33, 97 ; 1911, 36, 586), has been tested upon cheese. OE the immiscible solvents, toluene, xylene, turpentine oil, and petroleum oil, only the last was found suitable, Special experiments proved that the water distilled quantitatively with the petroleum oil, and that none was lost through emulsification ; but it was found essential to collect the condensed water in a receiver, the outlet of which was closed by means of a second (reflux) condenser.From 8 to 12 grms. of the cheese are placed in a 300 C.C. Erlenmeyer flask with a mark at 200 C.C.Petro- leum oil is added up to this mark, a few fragments of pumice introduced, and the flask connected with the condenser and heated on a sand-bath over a fairly small flame until the graduated receiver contains about 75 c.c., and the lower aqueous layer no longer increases (thirty to forty-five minutes). The distillation is then stopped, and the receiver disconnected and immersed in water at 1 5 O C.for thirtyFOOD AND DRUGS ANALYSIS 147 minutes, after which the volume of the aqueous layer is read, and calculated into the percentage in the sample. As a rule, though not invariably, the method gives slightly higher results than those calculated from the loss on drying, but the results of duplicate estimations agree well. Special precautions must be taken to obtain average samples for the estimation.C. A. M. Rapid and Accurate Gravimetrie Method for determining Milk-Fat in Evaporated Milk and Milk Powders. E. P. Harding and G. Parkin. (J. Ind. and Eng. Chem., 1913, 5, 131-134.)-The method is a modification of one devised by L. Nye and one of the authors for determining fat in cereals, the principle being the breaking-down of the milk emulsion by dissolving all the proteins in acetic acid (25 per cent.by volume), the solution of the fat in a mixture of alcohol and carbon tetrachloride, and its extraction with petroleum ether (b.-pt. between 50" and 70" C.). With evaporated milks either the material itself or a 40 per cent. emulsion can be used, the latter giving less chance of error in sampling.Forty grms. of the well- mixed sample are transferred to a flask, diluted to 100 c.c., well shaken, and 4 C.C. pipetted into a Nessler jar, or a quantity equivalent to 1-6 grms. of the original sample is weighed out. Eight C.C. of the 25 per cent. acetic acid are added, and the whole is warmed to about 50' C. As soon as the proteins are dissolved 12.5 C.C. of carbon tetrachloride are added, and the flask is stoppered and vigorously shaken for two minutes, after which 25 C.C.of alcohol are added and the mixture again well shaken. Twenty-five C.C. of petroleum ether are next added, and after more shaking another 15 c.c., followed by further shaking. The flask is now allowed to stand for two minutes for the layers to separate ; if, as rarely happens, an emulsion is formed, a few drops of alcohol will cause it to break. The upper layer is blown off by means of a wash-bottle fitting and filtered into a tared weighing-bottle, and three successive washings of ether and carbon tetrachloride are also blown off in the same manner.The fat is dried for an hour at 100' C. and weighed. On an average 0.4 per cent. more fat is obtained from a milk containing about 8 per cent.than by the Rose-Gottlieb method (as described in Circular 66 Dept. of Agric.), and 0.16 per cent. more than is obtained by using Hortvet's modification of the Rose-Gottlieb method, in which one- half the arnount of sample is used and one additional blow-off is made. Good results are also obtained in the analysis of ice-cream. H. F. E. H. Oil from the Seeds of '' Ximenia Americana." F.Schroder. (Arbeiten a26s dem Kaiserl. Gesundheitsamte, 1912, 43, 454-474.)--Ximenia Americana, L., a tree belonging to the OZacucecz is indigenous to tropical parts of America, Asia, and Africa, and is met with in the wild state in German East Africa, where its fruit is eaten by the natives. The seeds of the fruit contain kernels which, in the case of the samples examined, yielded from 65.05 to 67.34 per cent.of a light yel1o.w oil. No hydro- cyanic acid was present, but about 1 per cent. of a rubber-like substance could be precipitated with acetone from the ethereal extracts of the oil. To this body mas attributed the remarkably viscid character of the oil. The oil became partially solid at 8" C., and completely solid at - 4O C.I t gave the following values :148 ABSTRACTS OF CHEMICAL PAPERS Specific gravity at 15" C. ... ... Acid value ... ... ... Saponification value ... ... Iodine value ... ... ... Hehner value . . . ... ... Polenske value ... ... Unsaponifiable matter, per cent. ... Viscosity at 50" C. (Engler) Refractive index at 40" C. (AbbB) ... Neutralisation value of fatty acids .. . Mean molecular weight of fatty acids ... ... Oil Expressed. ~ 0.9205 10.5 173.6 81.3 94.8 0.14 0.46 1.4680 8-5 180.7 310.8 Oil Extracted with Ether. 0.9220 11-76 173.2 85.05 93.9 0.12 0.55 1.4687 11.3 180.2 304.6 Oil Extracted with Acetone. 0.9210 12.0 177.0 80.3 94.8 0.21 0-46 1.4677 6.6 184.4 304.6 The fatty acids melted at 49.5" C. to 50" C., solidified at 44.4" C., and had an iodine value of 71-01, They consisted of about 75 per cent.of liquid acids, and 25 per cent. of solid acids, including about 10 per cent. of arachidic acid. The oil had a, pungent taste, and was unsuitable for food. C. A. M. Estimation of Soluble Nitrogenous Substances as a Criterion of the Quality of Flour. E. Rousseaux and M. Sirot. (Ann. FuZsificut., 1913, 6,78-84.) -In flour derived from fully-ripened grain, the nitrogenous substances are chiefly in an insoluble condition, whilst in that from unripe grain there will be a much larger proportion of soluble nitrogenous substances.Hence the ratio between the total nitrogen and the soluble nitrogen affords a criterion of the condition of the flour. The soluble nitrogen is estimated by shaking 10 grms.of the flour with about 150 C.C. of water until thoroughly mixed, and then placing the flask for two to five minutes on the boiling water-bath, with frequent agitation. Its contents are next cooled, made up to 200 c.c., thoroughly shaken and filtered, and the nitrogen estimated in 50 C.C. of the filtrate. The ratio between the total nitrogen and soluble nitrogen ranged from 5.30 : 1 to 6.02 : 1 in the case of twenty typical samples of good flour of all grades, the average being 5.72 : 1.I n the case of seven samples of inferior flour, the ratio varied from 1.15 : 1 t o 2.60 : 1. Flour kept under bad conditions also showed a low ratio. Thus, a flour with a ratio of 5.69 : 1 was kept for three months under conditions that promoted germination, and then showed a ratio of 3.78 : 1.Should the ratio be less than 5-20 : 1, as in the case of old flour, it will be found in practice that difficulties will be experienced in baking bread from that flour. C. A. M. Estimation of Glyceryl Acetate in Essential Oils. S. G. Hall and A. J. Harvey. (J. SOC. Chem. Ind., 1913, 32, 61-62.)-Schimmel's method is reported on favourably by Salaman and Seaber (J.Soc. Chem. Ind., 1912,31, l052), and dependsupon the solubility of glyceryl acetate in 5 per cent. alcohol and its consequent elimination from the oil on washing, 2 per cent of glyceryl acetate being detectable. The authorsFOOD AND DRUGS ANALYSIS 149 consider a better method is the following, which depends upon the separation and estimation of the glycerol as such.Not less than 10 grms. of the oil to be examined are mixed with about 50 C.C. of alcohol (sp. gr. 0*830), and saponified with $ alcoholic potash ; the solution is then digested on the water-bath for an hour, neutralised with hydrochloric acid, and evaporated to dryness in the water-bath to remove the alcohol. About 20 C.C. of water are added, and the oily portion extracted with ether, the aqueous solution being run into a flask, The ether extract is again washed with about 10 C.C.of water, which is then added to that already in the flask, and the whole evaporated to a syrup, which now contains the glycerol originally present as glyceryl acetate. This can be estimated in the usual way by the triacetin process ; 1 C.C. f caustic soda = 0.01535 glycerol, or 0,03641 glyceryl acetate.Results obtained with Bergamot and lavender oils are appended. H. F. E. H. Composition of Russian Honey. E. J. Sarin. (Zeitsch. Untersuuch. Nahr. Genussm., 1913, 25,131-139.)-Results of analyses of seventy-two samples of Russian honey are reported, the data obtained being as follows : ... ... ... Water ... ... Sucrose ... ... ... ... ... Invert sugar ... ...... ... Ash ... ... ... ... ... ... Non-sugars ... ... 1.. ... Acidity (as formic acid) ... ... ... Proteins ... ... ... ... ... Tannin precipitate (Lund’s test) ... ... Polarisation 10 per cent. solution : Before inversion ... ... ... After inversion ... ... ... ... ... Minimum. Per Cent. 14.80 0 65.64 0.03 2.20 0.03 0.10 0.5 C.C. - 0*8l0 Maximum. Per Cent. 21.79 5.49 79-20 1-02 14.98 0.20 1.56 7.5 C.C.+ 3-82’ + 3.02” I - 0.82” ~~ Average. Per Cent. 16-39 1.90 74.91 0.18 5.96 0.11 0.44 2.0 C.C. The samples yielded negative reactions with Ley’s, Fiehe’s, Jagerschmid’s, Brown’s, and Armani-Barboni’s tests, except in the case of three samples which gave a positive reaction with Ley’s test. Five of the samples examined were obtained from bees which had been fed with sugar ; these samples could not be distinguished from the others.w. P. s. Estimation of Iron in 66Extraetum Ferri Pomati.” K. Kropat. .(Arch. Pharm., 1913, 251, 90-93.)-0ne grm. of the extract is weighed in a stoppered Erlenmeyer flask and gently heated with 30 C.C. of dilute sulphurio acid until dis- solved. After cooling, an addition of 1 grm. of very finely-powdered potassium per- manganate is made, and the flask shaken for a couple of minutes and heated for two to three minutes on the steam-bath, after which it is allowed to cool, with frequent shaking, until manganese peroxide particles can no longer be seen in the light yellow solution.The sides of the flask are then washed down with not more than150 ABSTRACTS OF CHEMICAL PAPERS 10 C.C.of water, 2 ems. of potassium iodide introduced, and the flask tightly stop- pered and allowed to stand for an hour, after which its contents are diluted with 100 C.C. of water and titrated with Fv sodium thiosulphate. At least 9 C.C. (= 5 per cent. of iron) should be required. C. A. M. Estimation of Morphine in Opium and Opium Preparations. G. Guerin. (J. Pharm. Chim., 1913, 7, 162-163.)-Opium.-A quantity of 7.5 grms.of the powdered opium, dried previously at 60" C., is mixed with 3 grms. of calcium hydroxide and 30 C.O. of water in a mortar; the mixture is then transferred to a , 125 C.C. flask, and the mortar and pestle are rinsed with water, using 45 C.C. of the latter. The contents of the flask are shaken gently at intervals during two hours and then filtered.Fifty-two C.C. of the filtrate are placed in a flask, 5 C.C. of pure acetone are added, and 1 grm. of ammonium chloride is dissolved in the mixture. After the lapse of twenty-four hours, the crystals which form are collected on a counterpoised filter, washed with water saturated with morphine until the wash- water is colourless and free from chlorides, and then four times with acetone satur- ated with morphine, 15 C.C.of acetone being used each time. The filter and its contents are dried at 100" C. and weighed. Extract of Opium.-Three grms. of the extract are dissolved in 75 C.C. of water, the solution is treated with 3 grms. of calcium hydroxide, and, after the lapse of three hours, the mixture is filtered. Sixty-five grms. of the filtrate (equivalent to 2.5 grms.of extract) are then subjected to the process described above. Tinctwe of 0pizcm.-Seventy-five grms. of the tincture are evaporated to dryness, the residue is treated with 75 C.C. of water, and the liquid is mixed with 3 grms. of calcium hydroxide. The mixture is shaken for two hours, then filtered, and the morphine is estimated as described in 52 C.C.(50 grms. of tincture) of the filtrate. w. P. s. Analysis of Peru Balsam. H. R. Jensen. (Pharm. J., 1913,90,210-211.)- Artificial products closely resembling Peru balsam are now manufactured ; they consist of a perfumed mixture of synthetic esters with resinous and fatty matters, and, on analysis, yield results which are generally within the range of figures given by genuine balsams.I t was found, however, that the cinnamein extracted from the artificial balsam differed from that of the natural balsam as regards its iodine value and optical properties. The iodine value of the artificial cinnamein was 1.5, and the refractive index at 15" C., 1.565; the cinnamein from natural balsam had an iodine value of 25.5 and a refractive index of 1.575. Further difference was noticed when the cinnameins were fractionally distilled under reduced pressure (15 mm.).The first fraction (10 per cent. of the total) of the natural cinnamein had a sp. gr. of 1.044, a refractive index of 1.5355, and a specific rotary power of + 5 O , whilst the artificial cinnrtmein (first fraction) had a sp. gr. of 1.09, a refractive index of 1.555, and was optically inactive. The fourth fraction of the natural cinnamein distillate still exhibited a slight optical rotation.w. P. s.FOOD AND DRUGS ANALYSIS 1.5 I Detection:of Saponin. L. Rosenthaler. (Zeitsch. Urztersz~ch. Nahr. Genz~ssm., 1913, 25, 154-158.)-The test proposed by C. Sormani (cj. ANALYST, 1912, 37, 350) fails occasionally owing to the fact that certain saponins are devoid of hemolytic action, and the author therefore describes a test which is stated to be capable of giving a positive reaction with saponins derived from any source.The test depends not on the separation of the saponin, but on reactions of the product obtained from it by hydrolysis. The product is not the substance produced by theoretically complete hydrolysis-namely, sapogenin or endosapogenin-but an intermediate product, in which the sapogenin is still combined with a quantity of sugar ; this intermediate product is termed prosapogenin.It yields an orange-red coloration with concentrated sulphuric acid, the colour changing slowly to red, and then (after a few hours) to violet. When shaken with sodium carbonate solution prosapogenin yields a persistent froth.The liquid to be tested for the presence of saponin is treated with hydrochloric acid, so that about 2.5 per cent. of the acid is present in the mixture, and the latter is then heated on a water-bath until hydrolysis is apparently complete-that is, until the mixture ceases to give a froth whenxshaken. If a precipitate forms when the acid is added, the mixture must be filtered before hydrolysis.The mixture, while still warm, is shaken with about one-half its volume of ethyl acet&te, the ethyl acetate is separated, washed with small quantities of water until free from hydrochloric acid, decolorised with animal charcoal, and evaporated. In the case of beer, the sample is heated with an equal volume of 95 per cent. alcohol until a flocculent precipitate forms, filtered, and the filtrate submitted to hydrolysis after the alcohol has been removed.Or, the beer may be evaporated, the residue extracted with hot 70 per cent. alcohol, and the filtered alcoholic extract then The residue is then tested as described, hydrolysed and tested. w. P. s. Detection and Differentiation of Poisonous and Non- Poisonous Saponins by Haemolysis. J. Halberkahn.(Deutsch. Mineralwasserfabrikanten-Zeit., 1912, Nos. 25-30; through Chem. ZentraZbZ., 1913, I., 852.)-The use of saponins in the manufacture of mineral waters should be restricted to those which have been deprived of their poisonous constituents. This may be effected by means of cholesterin, treatment with hot barium hydroxide solution, or saponification of the acetyl compound with barium hydroxide or caustic alkalis.The toxicity of saponins can be determined, and poisonous saponins distinguished from non-poisonous, by haernolysis. For the isolation of saponins the method of Brunner as elaborated by Ruhle (ANALYST, 1908, 33, 408) is alone valid. Concentration of mineral waters without previous neutralisation must be avoided, and the author prefers to eliminate heating, although it may be justified in the case of liquids containing dextrin (Brunner and Ruhle, Zoc.cit.), which must, however, be neutral during concentra- tion. The extraction with phenol is carried out in two stages, with 10 and with 5 C.C. The aqueous liquid which always accompanies the phenol extract is removed either by treating with 15 C.C. of absolute alcohol and drying with freshly-ignited sodium sulphate, or by means of a centrifugal; the extract is then treated with water and ether in a separating funnel, into which it is rinsed with a mixture of equal volumes of phenol and absolute alcohol. The aqueous layer is evaporated at 60° C.,152 ABSTRACTS OF CHEMICAL PAPERS and dried in a vacuum desiccator without heating. A disadvantage of the method is that water-soluble coal-tar colours find their way into the phenol extract, and interfere, particularly the red ones, with the haemolytic test. Animal charcoal cannot be used, 8s it removes the saponins also. Poisonous and non-poisonous saponins show much the same behaviour to haemolysis, whether extracted by the Brunner method from mineral waters, or obtained from other sources, so that this method is without effect on them. Solutions from saponin deprived of its poisonous constituents and solutions containing no saponin give residues showing no hEmolysis. Glycyrrhizin has no haemolytic action, and cannot be confused with poisonous saponins. 0. E. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800145

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

152 ABSTRACTS OF CHEMICAL PAPERS BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Occurrence of Formaldehyde in the Juices of Plants. F. Angelic0 and G. Catalano. (Gaxx. Chim. Ital., 1913, 43, 38-43.)--The plant Atractylis gummifera contains an active glucosidal principle, atractiline, which gives a specific reaction with formaldehyde, and will detect as little as 3 drops of 40 per cent. formalin solution in a litre of water.By means of this reagent the presence of formaldehyde in the juices of the green leaves of numerous plants has been estab- lished, the results being checked by tests applied to the distillates from the juices. On treating the glucoside, atractiline, with 2 or 3 drops of concentrated sulphuric acid, a yellow coloration is produced at the point of contact, and on now adding a drop of a liquid containing a trace of formaldehyde a violet coloration, appearing bright blue in reflected light, is produced.This reaction is not obtained with other aldehydes. The formation of formaldehyde in the cells of the green plant appears to be connected with the phenomena of the chlorophyll function. Thus formaldehyde was found in the juices of the leaves of eleven plants (including Lupinus albus, L.gorgonia, Zea nzazs, etc.) that had been exposed normally to the light during their growth, but it was absent from the juices of the leaves of the same plants after being kept for twenty-four hours in the dark. No formaldehyde was found in the juices or distillates of several species of fungi, such as Psalliota campestris. C.A. M. Respiratory Quotients of Green Plants. L. Maquenne and E. Demoussy. (Comptes rend., 1913, 156, 278-283.)-The authors find that the respiratory quotient of plants (see ANALYST, 1913, 108) always exceeds unity when the plants are examined in the spring or early summer. Out of some thirty-sight different plants investigated, Aspidistra was the only exception to this rule, the respiratory quotient being 0.94. Later in the season (autumn) the value of the quotient decreases, and it may be concluded that the respiratory quotient of green leaves is greater than unity during their period of active vegetation, and that degeneracy is indicated when the quotient is less than unity.It was also found that the percentage quantity of nitrogen in the atmosphere increased slightly in cases where the respiratory quotient was low, whilst it diminished when the plants yielded quotients above unity.w. P. s. Detection of Adulteration by the Serum Precipitation Method. A. Vila. (Ann. Palszjcat., 1913,6,84-89.)-A method is described of obtaining specific anti-seraBACTERIOLOGICAL, PHYSIOLOGICAL, ETC . 153 by treating rabbits with the blood-plasma instead of the serum from the animal in question.By the use of the rabbit 8erum thus prepared it is possible to detect with certainty the presence of at least 5 per cent. of, e.g., horseflesh in sausages. C. A. M. Measurement of Tryptic Protein Hydrolysis by Determination of the Tyrosine Liberated. S. J. IVI. Auld and T. D. Mosscrop. (J. Chem. Soc., 1913, 103, 281-284.)-The method employed is based, with modifications, on that described by Brown, Millar, and others (Trans.Guiness Research Lab., 1903, Part I.), and consists of the estimation by absorption of bromine of the tyrosine formed during tryptic digestion. As described (Zoc. cit.), the end-point of the reaction was indicated by the persistence of the yellow colour of bromine, but the author points out that in ordinary protein digests yielding coloured solutions this is impossible ; nor is the use of starch and potassium iodide permissible, since hydrochloric acid will of itself liberate sufficient iodine from the iodide to colour starch.I t was found that good results were obtained when methyl violet or gentian violet were used, as outside indicators dissolved in 70 per cent.alcohol, at the rate of 1 per cent. About 10 drops of this solution are added to 10 C.C. of 5 per cent. hydro- chloric acid, and dotted over a white tile. The addition of sodium bromate or traces of free bromine causes a change from olive-green (the colour of the dye-stuff in acid solution) to a deep bluish-violet. The change is sharp, but the colour fades after a few minutes.Dibromotyrosine only is apparently formed, and the absorption at first is very rapid, but falls off considerably towards the end of the reaction, as experiments cited show. The solution to be titrated is made of not more than 5 per cent. acidity with hydrochloric acid; a lower concentration than 2 per cent. turns the indicator blue, while more than 5 per cent. turns it yellow. To the acid solution is added 15 to 20 C.C.of 20 per cent. sodium bromide, and the liquid is then titrated with & sodium bromate. Towards the end of the reaction at least thirty seconds should elapse between successive additions of the bromate, and the solution should be well shaken in a stoppered bottle. I n two of the test liquids there were present, in addition to tyrosine, leucine, aspmagin, and ammonium chloride.Experiments carried out with edestin digested in dilute sodium carbonate solution with trypsin, and co'rrected for the bromine absorbed by the protein, confirmed Brown and Millar's (J. Chem. Soc., 1906, 89, 145) contention that the method can be used for determining tyrosine in presence of proteins and other early cleavage products, and also that practically a11 the tyrosine is liberated in the first stages of tryptic digestion. Results quoted show a plus error varying from 0-4 to 2.3 per cent.H. F. E. H. Method for the Estimation of Mercury in Urine and Animal Tissues. H. Buchtala. (Zeitsch. phys.ioZ. Chem., 1913, 83, 249-303.)-The mercury is separated electrolytically from the liquid obtained after the destruction of the organic matter by treatment with hydrochloric acid and potassium chlorate.I n the case of urine, 1 litre of the sample is heated with 10 per cent. of its volume of concentrated hydrochloric acid, and small quantities of potassium chlorate are added154 ABSTRACTS OF CHEMICAL PAPERS from time to time until the mixture on evaporation yields a light yellow liquid measuring a few C.C.This residual liquid is diluted, filtered, and transferred to a beaker of about 400 C.C. capacity; a porous cell filled with dilute ammonium oxalate solution is placed in the solution in the beaker, and the anode (a carbon rod) is immersed in the ammonium oxalate solution. The cathode consists of a piece of gold foil, 2.5 mm. by 3.5 mm., and 0.015 mm. in thickness, and is suspended in the solution contained in the beaker by means of a platinum wire.Using a current of 1 ampere and 5 volts, the mercury which may be present will be deposited completely on the cathode in from four to six hours. The cathode is now removed, washed with dilute hydrochloric acid to remove traces of iron, then with water, alcohol, and ether, dried in the air, and weighed.The mercury may be volatilised from the gold foil by heating the latter in a tube, and the sublimate obtained can be identified as mercury by treatment with iodine vapour. Experimental proof is given that the method is trustworthy. The author also gives the results of an investigation as to the rate, etc., of the elimination of mercury from the body after courses of treatments with mercury compounds, and appends a comprehensive list of the literature dealing with the subject.w. P. s. Nitroprusside Reaction of Urine. V. Arnold. (Zeitsch. physiol. Chem., 1913,83,304-314.)-The colour reaction described previously by the author (ANALYST, 1907, 32, 94) is yielded by the urine of persons in normal health who have recently consumed food-especially flesh foods-but not of persons suffering from high fever. w.P. s. Colorimetric Method for the Estimation of Uric Acid in Urine. 0. Folin and A. B. Macallum, jun. (J. biol. Chem., 1913, 13, 363; through Chem. Zentralbl., 1913, I., 852.)-The residue obtained by evaporating 2 to 5 C.C. of urine with 1 drop of saturated oxalic acid solution is twice extracted for five minutes in the cold with 10 to 15 C.C. of a mixture of 2 parts ether and 1 part methyl alcohol, and dissolved in 5 to 10 C.C. of water containing 1 drop of saturated sodium carbonate solution. To the solution is added 2 C.C. of the uric acid reagent of Folin and Macallum (ANALYST, 1912, 37, 355) and 20 C.C. saturated sodium carbonate solution, and the blue liquid resulting is diluted to 100 C.C. in a measuring flask. It is then compared with a standard solution containing 0.001 grm. uric acid, lithium carbonate, 2 C.C. of the uric acid reagent, and 20 C.C. of sodium carbonate solution. 0. E. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800152

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

154 ABSTRACTS OF CHEMICAL PAPERS ORGANIC ANALYSIS. Quantitative Study of Some Aldehyde Reactions. B. G. Feinberg. (Amer. Chem. J., 1913,49,87-116.)-Methods of estimation based on the combination of aldehydes with bisulphite and titration of the excess of the latter with iodine suffer from the drawback that the compound produced is readily broken up again into its components by dilute acids and alkalis.The end-point of the iodine titration is uncertain, owing to the continuous liberation of fresh bisulphite from this cause; the instability of the compounds is increased by the presence of a hydroxyl groupORGANIC ANALYSIS 155 in proximity to the aldehyde group. Formaldehyde may be titrated in this way with an accuracy of 98 to 99 per cent. Approximate results (93 to 95 per cent.) may be obtained with vanillin and benzaldehyde, but with salicylic, p-hydroxy- benzoic and anisic aldehydes the method is useless.A 1 per cent. solution of the aldehyde is treated with 10 to 25 C.C. of a 3 per cent. solution of sodium bisulphite, and the excess of the latter is titrated back with iodine, after 15 to 25 minutes, until the blue colour with starch persists for an instant.The best results are obtained with an excess of bisulphite equivalent to 25 to 50 C.C. of .& iodine. In the methods based on the use of neutral sulphite, the latter is supposed to combine with the aldehyde, liberating sodium hydroxide. This did not occur in the cases studied, but a reaction took place on the addition of acid, owing to the formation of bisulphite.With benzaldehyde, this method may be used, giving satisfactory results (98 to 99 per cent.), provided a fairly large quantity of aldehyde be taken. Example : About 1 grm. of benzaldehyde is weighed out into a stoppered flask with 10 C.C. of alcohol and about 10 C.C. of water, to wash down the sides of the flask. Six drops of a 1 per cent. solution of phenolphthalein are added, and the solution is neutralised with FG alkali.Then 50 C.C. of a 20 per cent. solution of sodium sulphite, neutralised to phenolphthalein, are added, and the mixture is titrated not too rapidly with The titration is controlled by a blank containing 35 C.C. of the sulphite solution ( i e . , the amount calculated to be left unabsorbed), and the quantity of acid required to neutralise this is deducted from the acid used in the main titration.The same method applied to formaldehyde, but without the use of alcohol, also gave satisfactory results. Anisic aldehyde presented some difficulty about the end-point, more phenolphthalein having to be added during the titration, and the results were low (94 per cent.). Salicylic aldehyde, p-hydroxy- benzaldehyde, and vanillin gave coloured solutions which could not be titrated.Among the precipitating reagents, p-bromphenylhydrazine gives good results with p-hydroxybenzaldehyde, vanillin, and anisic aldehyde : Twenty-five C.C. of a 1 per cent. solution of the aldehyde in water, aqueous rtlcohol, or aqueous acetic acid are mixed with 75 C.C. of a solution of the hydrazine in hot water, equivalent to two to three times the amount theoretically required.Precipitation is effected at 50' C. and the precipitate allowed to stand for one to five hours, collected in a Gooch crucible, washed with hot water, and dried at 105" C . This reagent is not satis- factory for formaldehyde, benzaldehyde, and salicylic aldehyde. On the other hand, p-nitrophenylhydrazine is a good general precipitating reagent for aldehydes.I t is particularly suitable for the estimation of vanillin and p-hydroxybenzaldehyde ; with benzaldehyde, salicylic, and anisic aldehydes the results are subject to errors of 2 to 4 per cent. For benzaldehyde, 25 C.C. of a 1 per cent. solution of the aldehyde in 12 per cent. acetic acid are diluted with 50 C.C. of water and 30 C.C.of 30 per cent. acetic acid containing about double the theoretical quantity of p-nitrophenylhydrazine are added. The precipitate is allowed to stand for five hours, collected in a Gooch crucible, washed with 10 per cent. acetic acid, and dried at 1 0 5 O C. For salicylic aldehyde and anisic aldehyde the conditions are essentially the same. For vanillin and p-hydroxybenzaldehyde, it is best to use a solution of p-nitrophenylhydrazine in hydrochloric acid, adding this drop by drop to the aldehyde solution previously sulphuric acid.156 ABSTRACTS OF CHEMICAL PAPERS diluted with 75 C.C.of water, stirring the liquid all the time, and allowing the precipitate to stand for half an hour before filtration. With formaldehyde the precipitation method gives results much too low, and volumetric methods are to be preferred.J. P. B. Quantitative Estimation of Natural in Presence of Artifieial Asphaltum. J. Mareusson. (Zeitsch. angew. Chem., 1913, 26, 91-93.)-The detection of natural asphaltum in the presence of coal-tar pitch is commonly based on the higher proportions of sulphur and mineral matters generally present in the natural products. Such methods, however, are open to the objection that the proportions of these canstituents may readily be increased artificially to lead to erroneous conclusions. The method now described is based on a constitutional difference between the bituminous portions of the two types of material, in that the bitumens of coal-tar pitch, being members of the aromatic group, readily yield sulphonic acids soluble in water, whereas the bitumens of all varieties of natural asphaltum are converted by sulphuric acid into insoluble carbon-like derivatives, richer in sulphur than the original bitumen.With pure Trinidad asphaltum the product of the reaction with sulphuric acid shows a gain in weight of about 8 per cent., and the bitumens of Syrian and Mexican asphaltums show a similar increase; the aqueous extracts of these products are nearly colourless, whereas those from the sulphonation of coal-tar pitch are highly coloured.The author has made experiments to see how far this reaction is valid as a means for quantitative estimation in mixtures, but has found that the accuracy is considerably impaired by the fact that, in presence of coal-tar pitch, the bitumens of the natural asphaltums do not give a quantitative yield of insoluble sulphonation products, so that a substantial correction must be applied t o the results. In carrying out the test, the bituminous constituents of the asphalt mixture must first be isolated.This is effected in the following manner : 10 grms. of the sample are treated with 75 C.C. of ether, saturated cold with strong hydrochloric acid, added in three to four portions with constant stirring.After about ten minutes, 75 C.C. of water are added, and the mixture is heated to drive off the ether. The residue is filtered off, washed and dried, and then exhaustively extracted with boiling chloroform. The bitumen is recovered on driving off the chloroform, dried for a short time at 105' C., and weighed.Three grms. of this bitumen are treated in a thick test-tube with 6 C.C. of concentrated sulphuric acid, and heated in the boiling water- bath for forty-five minutes with frequent stirring. The product of the reaction is cooled and transferred to a conical flask with about 200 C.C. of water. After about an hour the precipitate settles to the bottom, and the liquid is decanted off through a tared hardened filter-paper on a porcelain funnel, at first without suction.The residue is broken up and washed by decantation until it is brought on to the funnel free from acid; some difficulty may be experienced in filtration, so that, where practicable, a Gooch crucible with a layer of asbestos or treatment in the centrifuge may give better results.The product is dried at 105" C., weighed, and the result calculated as per cent. of the original sample. This result gives, of course, only the percentage of natural bitumen in the sample, and the percentage of natural asphaltum can only be inferred indirectly from the general average of bitumen in the typeORGANIC ANALYSIS 157 of asphaltum present. Mixtures prepared from known materials and analysed by the author showed results considerably too low.I t is therefore proposed to add 4 as a correction to the percentages found calculated on the original sample, in which case it is shown that numbers approximating very fairly to the correct values are obtained. I t is to be noted that the method is only applicable to mixtures of asphaltum with coal-tar pitch, and that mineral oil residues behave on sulphonabion ljke natural asphalturn, so that verification by other tests is necessary to confirm the absence of mineral oil products.J. F. B. Detection of Natural Asphaltum and Petroleum Pitch in Residues from the Distillation of Coal-Tar. F. Schwarz. (Chem. Rev. Fett. Ind., 1913, 20, 28-30.)-The distillates from coal-tar consist largely of aromatic hydrocarbons which combine with sulphuric acid to form soluble sulphonic acids, whereas the corre- sponding distillates from natural asphaltum or petroleum pitch yield only a small proportion of soluble derivatives with sulphuric acid.I n the case of mixtures, this test is rendered unreliable by the fact that when a large proportion of asphaltum or pebroleum-pitch compounds is present, products capable of combining with sulphuric acid are formed during the distillation.The following modification of the test effects the separation of the compounds that combine with the sulphuric acid and obviates the drawbacks of distillation : 10 grms. of the sample are heated to 160" to 180' C., and mixed for five minutes with 4 C.C. of strong sulphuric acid, and the mixture kept at 180" C.(by means of an oil-bath) until the excess of sulphuric acid has been removed. The residue is then pulverised with 40 grms. of bone charcoal, and the mixture extracted in a Soxhlet apparatus with petroleum spirit of low boiling- point. The extract is evaporated, and the residue taken up with more petroleum spirit, the solution filtered and evaporated, and the residue weighed.Sometimes sulphur derived from the sulphuric acid is present, and in such cases the residue should be washed (without agitation) with acetone, the solution filtered and evaporated, and the residue weighed. The results thus obtained with eleven samples of coal-tar pitch, seven of natural asphaltum, and twelve of petroleum pitch, were as follows : Substances not attacked by Sulphuric Acid.Per Cent. ... Coal-tar pitch ... ... ... 0-10 to 0.21 (usually 3.0 to 8.0) Petroleum pitch ... ... ... 6.0 to 36.0 (usually 15.0 to 30.0) Natural asphaltum ... ... 1.0 to 16.0 A result greatly exceeding 0.2 per cent. indicates the presence of one of the other products in coal-tar pitch. The addition of 10 per cent. of petroleum pitch to a sample of coal-tar pitch raised the value from 0-21 per cent.to 0.46 per cent. A sample of English "coal-tar pitch" yielded 3.4 per cent. of substances not attacked by sulphuric acid, but this high result was attributed to the original coal having been mixed with shale before the distillation. C . A. M.158 ABSTRACTS OF CHEMICAL PAPERS Method for the Estimation of Galactan.K. Miyake. (J. Coll. Agric. Tokio Univ., 1912, 4, 337-345 ; through Chem. Zentralbl., 1913, I., 465-466.) -The substance is extracted with ether and then heated on a water-bath with 60 C.C. of nitric acid of sp. gr. 1.15, until the volume of the liquid is reduced to 20 C.C. The mixture is then filtered, and the residue is washed with hot water. The filtrate is evaporated to one-third its volume, and placed aside for twenty-four hours ; 10 C.C.of water are then added, and the mixture allowed to stand for a further period of twenty-four hours. The mucic acid which crystallises out is collected on a filter, washed successively with cold water, alcohol, and ether, dried at 100" C., and weighed. The quantity of substance taken for the estimation depends on its galactam-content; when the amount of galactan present is less than 16 per cent., 3 grms.of substance may be taken, and correspondingly less as the galactan-content increases. Should only small quantities of galactan be present, the filtrate must be evaporated to one-fifth its volume and then set aside for several days. The yield of mucic acid is not quite proportional to the amount of galactan, but the average factor 1.33 may be used to convert the weight of mucic acid found into galactan.w. P. s. Estimation of Hydrocarbons of the Acetylene and Olefine Series in Mixtures of Gaseous Hydroearbons. P. Lebeaw and A. Damiens. (Comptes rend., 1913, 156, 557.)-The usual absorbents, ammoniacal cuprous chloride and bromine, axe inconvenient in use, and the substitution of potassium mercuric iodide for the absorption of acetylene hydrocarbons, and of sulphuric acid containing a catalyser (vanadic acid, uranic acid, tungstic acid, molybdic acid) for the absorption of olefines, is suggested.,The potassium mercuric iodide solution, containing 25 grms. mercuric iodide and 30 grms. potassium iodide in 100 C.C. water, is rendered alkaline before use by the introduction of a fragment of potassium hydroxide into the absorption-tube, and is capable of absorbing twenty times its volume of acetylene.I t dissolves ethylene to the same extent as does water, and the gas may be recovered by evacua- tion. The sulphovanadic acid reagent contains 1 grm. vanadic oxide in 100 grms., 97 to 98 per cent. sulphuric acid, and the sulpho-uranic acid reagent 6 grms.of uranyl sulphate in the same quantity of acid. A mixture of 3.50 C.C. methane, 10.14 C.C. ethylene, 8-88 C.C. acetylene, and 4.88 C.C. allylene, gave 13.53 of residual gas after treatment with the potassium mercuric iodide reagent, instead of the theoretical 13.64 ; the difference is due to dissolved ethylene. After treatment with the sulphovanadic acid reagent 3-48 C.C.(instead of 3-50 c.c.) of methane were left. 0. E. M. Hexabromide Number of Fatty Oils and the Estimation of Rape Oil in Raw Linseed Oils. A. Eibner and H. Muggenthaler. (Farbenzeitung, 1912, 18, 131, 175, 235, 356, 411, 466, 523, 582, 641 ; through Claem. Zentralbl., 1913, I., 567.)-The utility of the hexabromide number, the literature of which is discussed exhaustively, for the valuation of linseed oil, depends upon the determination of the linolenic acid, the constituent of most importance in the drying process. This acid gives a hexabromide insoluble in cold ether, while the simultaneously formed tetra- bromide of the isolinolenic acid is dissolved.The following method is based onORGANIC ANALYSIS 159 lengthy series of experiments : (1) Preparation of Pure Linseed Oil Fatty Acids.- Three portions of linseed oil, each of 3-5 grms., are saponified separately in 220 C.C.evaporating basins on the water-bath, with stirring, by means of 45 C.C. of alcoholic potassium hydroxide solution ; the soap is evaporated to dryness, and each portion dissolved in 50 C.C. of warm water, the wash water from one basin being used to dissolve the soap in the next.The united solutions (180 c.c.) are transferred warm to a 1-litre separating funnel bearing marks at 180 and 340 c.c., and, when cool, treated with 20 C.C. 5 N sulphuric acid and 140 C.C. of ether. After agitation and separation, the ethereal solution is allowed to stand all night over 70 grms. dehydrated potassium sulphate, and filtered ; the potassiuld sulphate is washed out several times with dry ether.The ether is distilled off, the last portions being removed by a current of hydrogen purified by bubbling it through an alkaline solution of a lead salt and through concentrated sulphuric acid ; the residue is dried in a vacuum over sulphuric acid. The fatty acids are made up to an approximately 10 per cent.solution with dried ether. (2) Bromination.-In a wide-mouthed conical flask surrounded by a freezing mixture, 20 C.C. of the ethereal solution, containing 1-9 to 2-0 grms. fatty acids, are cooled to - 10' C. ; 1 C.C. of bromine is added, 0.5 C.C. in single drops and the rest two drops at a time, with vigorous shaking at each addition, the whole requiring about thirty minutes.A cork is inserted, and the flask allowed to stand for two hours at -10" C. The brown mother liquor is then poured through a weighed asbestos-packed Daniel tube, the precipitate is shaken up with 5 C.C. of ether a t - loc C. and allowed to settle in the freezing mixture, and the liquid poured off. The precipitate is then shaken up with 5 C.C. of cooled ether and transferred to the filter, and, after the flask and precipitate have been washed three times with 5 C.C.of ether at - 10" C., drained by suction and dried at 80" to 85" C. The hexabromide thus obtained should be white and granular ; its melting-point is 177" C. Average values of the hexabromide number of various raw linseed oils of authenti- cated origin were found to be : Dutch, 51-73 ; River Plate, 51-66 ; East Indian, 50.50 ; Baltic, 57.96.Baltic oil is thus readily distinguished from the others. The hexabromide number is not materially affected by bleaching, which thus does not limit the applica- bility of an oil; it is much lower in linseed oil varnishes, and may be reduced to zero in oxidised oils. Other oils gave : poppy and china-wood, 0.0 ; perilla, 64.12 ; ocumi, 60.98 ; rape, 6-34 ; soya bean, 7.17.Estimation of Rape Oil in Linseed Oil.-The erucic acid test having revealed the presence of rape oil, the hexabromide number shows the amount of adulteration. The addition of 10 per cent. of rape oil lowers it by approximately 4-4, and con- sequently, the origin of the oil being taken into account, the amount of the addition can be calculated.An allowance of 4 per cent. for the permitted contamination of the flax seed with seeds of cruciferous plants is then deducted. 0. E. M. Oxygen Absorption Test for Linseed Oil. H. Mannhardt. (J. Ind. and Erzg. Chem., 1913, 5, 129-131.)-The recent report of a subcommittee of the American Society of Testing Materials is said to be quite misleading, because the four members of the committee disregarded the direction of earlier experimenters to use a film of approximately uniform thickness in all experiments, Glass plates of uniform size160 ABSTRACTS OF CHEMICAL PAPERS were used, but one experimenter used anything from 0.07 to 0.40 grm.oil, another anything from 0.17 grm. to 2.73 grms. It is not surprising, therefore, that the results of the committee's work seem to discredit the oxidation test as untrustworthy.The author has used several forms of the test and found them trustworthy. One method recommended is that in which about a gram of oil is weighed out and mixed with about 10 grms. of finely ground natural silica, contained in a shallow vessel of about 6 cm. diameter. Aluminium plates also serve well for the test, two drops of oil being applied to each side of each of five plates (3 inches by 6 inches) and distributed over it by means of the finger, the whole series being suspended in a frame of aluminium wire, so as to allow of their being weighed on the fine balance.The time required to reach maximum weight is at least as important as the increase of weight itself. The use of 5 C.C. of ether greatly facilitates the mixing.G. C. J. Solidified (Hydrogenised) Oils and the Detection of Araehidie Aeid. H. Kreis and E. Roth. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 25, 81-85.)- Sesame, earthnut, and cottonseed oil which have been solidified by treatment with hydrogen in the presence of a catalyst (cf. ANALYST, 1912, 37, 452) yield a reaction with Bellier's test (nitric acid and resorcinol in benzene solution), whilst solidified whale oil gives an orange coloration with the test.The sesamol present in sesame oil is not affected by hydrogenisation, and solidified sesame oil gives the reactions described by Kreis for ordinary sesame oil (ANALYST, 1903, 28, 364). Arachidic acid may be detected in mixtures of solidified earthnut oil with ordinary or other solidified oils by saponifying 20 grms.of the oil under examination with 40 C.C. of alcoholic potassium hydroxide solution (20 per cent.), adding 60 C.C. of alcohol, and acidifying the mixture with 50 per cent. acetic acid; the mixture is then treated at a boiling temperature with 1.5 grms. of lead acetate dissolved in alcohol, and after the lapseof about twelve hours the precipitated lead soap is separated, and decomposed by heating with hydrochloric acid.The fatty acids thus obtained are crystallised three times from alcohol (90 per cent.), and the melting-point of the resulting crystals is deter- mined. Should the oil contain not less than 5 per cent. of earthnut oil the melting- point will lie above 70" C. w. P. s. Lemon-Grass Oils from India.(BUZZ. Imp. Inst., 1912, 10, 546-548.)-Four samples of lemon-grass oil from Assam gave the following analytical results : 1. 2. 3. 4. Specific gravity at 15"/15O C. ... 0.9039 0.9035 0.8973 0.9109 Optical rotation in 100 mm. tube at 20" c. ... ... . . . - 0'30' - 0'40' - 0'80' - Citral (by sodium bisulphite method) per cent. ... ... 72.2 81.5 78.0 73.7 None of the oils dissolved to a clear solution, even in 10 or more volumes of 70 per cent.alcohol. In the case of No. 2, which was described as " Coohin " oil, the incomplete solubility was attributed to the presence of other grasses in the lemon grass distilled. C. A. M.ORGANIC ANALYSIS 161 Tests on the Opacity and Hiding Power of Pigments. G. W. Thompson. (J. Ind. and Eng. Chenz., 1913, 5,120-123.)-Hiding power is defined as the power of a paint to obscure optically a surface painted with it, opacity as the obstruction to the direct transmission of visible light afforded by any substance, comparison being made with sections of equal thickness.Opacity refers to tests made under standard con- ditions, whilst hiding power refers to tests made of paints as they are used.The distinction becomes clearer when considered with reference to a paint, the opacity of which is measured with a standard thickness of paint; whilst in the case of hiding power, the thickness of the paint will vary according to the spreading rate at which the paint is applied. Arguments are brought forward in support of the view that, in all comparisons of opacity, the relative vohme of the pigment (not its weight) should be considered, and that a standard of opacity should be based on a definite volume of the pigment placed in a definite volume of the menstruum.Except for zinc oxide and other pigments which need further dilution for testing by the author’s method, he uses a mixture of 1 part by true volume of pigment to three parts of oil. The accuracy of earlier photometric methods (e.g., the photographic method of Hurter and Driffield, J.SOC. Chem. Ind., 1890, 9, 455) depends upon no light being reflected by the object being tested, or on the reflecting power of the object being accurately known. Considering opacity as having to do only with the light which is being transmitted and not at all with the light reflected from the surface of the paint, the author has devised an apparatus, not shown in detail in the paper, by which the opacity of a paint may be determined as follows : Paint is placed between two glass surfaces, the distances between which can be controlled and measured by a micro- meter screw, and the film reduced in thickness by bringing the plates closer together, until the light passing through exactly matches that passing through a standard plate or paper, the opacity of which has been tested on a photometer bench.A less opaque standard is then substituted for the first, and the plates are again brought closer together until a match is obtained. From Bouguer’s logarithmic law that if a, given layer absorbs a certain fraction of transmitted radiation, the next equal layer will absorb the same fraction, it follows that the opacity, as defined, of the paint can be deduced from the thickness of the two films and the known opacity of the standards. The coefficient of opacity is defined as the proportion of light, expressed as decimal fraction of unity, ‘rtbsorbed during transmission through a thickness of 0.01 mm.of paint. G. C. J. Testing Parchment Papers.V. Fortini and A. Ceecherelli. (Chem. Zed., 1913, 37, 237-239.)-The following tests are said to be more conclusive and more easily applied than chemical or microscopical tests for distinguishing between genuine and imitation parchment papers. The first test described consists in determining the tensile strength of the paper before and after half an hour’s immersion in water at 75’ to 80° C.The tensile strength is always reduced by the treatment, but with genuine parchment papers the ratio of the initial to the final value is always less than 2 : 1, whereas with imitation parchment papers it is always greater than 10 : 1. The second test described also depends on the relative indifference of genuine parchment papers to wetting by hot water.It is proposed because apparatus for162 ABSTRACTS OF CHEMICAL PAPERS determining tensile strengths is found in comparatively few laboratories, whereas Vicat's needle is more commonly met with. The paper, before and after treatment with hot water, is stretched in a 10-cm. frame, covered with a disc of metal with a central hole through which the Vicat needle (of 1 cm. diameter) can just pass freely, and the needle is then loaded with shot until the paper breaks.The breaking loads do not measure any property of the paper in absolute units, as the critical load is dependent, among other things, on the diameter of the frame on which the paper is stretched; but, as in the measurements of tensile strength, the ratio of the load required to break genuine parchment paper before and after treatment with hot water is always less than 2 :I, whereas with imitation parchment papers it always exceeds 10 : 1.G. C. J. Estimation of Phenol in Crude Carbolic Acid and Tar Oils. J. M. Weiss. (J. Franklin Inst., 1912, 174, 683; through Chem. Zentralbl., 1913, I., 565.)-The m.-pt. and sp. gr. suffice for the determination of phenol in crude carbolic acid and tar oil; the b.-pt.is unnecessary. Tables showing the phenol content of mixtures of phenol and cresols for m.-pts. from 0' to 23' C. and upwards, and for various densities, are worked out. 0. E. M. Crude Petroleum from the Gold Coast. (Bull. Imp. Inst., 1912, 10, 579- 383.)-Samples of crude petroleum from Bonyere, in the Gold Coast Colony, were black, viscid liquids, which on distillation left from about 14 to 20 per cent.of bituminous pitch. The distillates consisted mainly of lubricating oils, with a small proportion of kerosene. C. A. M. Estimation of Soaps in Lubricating Greases. J. Marcusson. (Chem. Rev. Fett. Ind., 1913, 20, 43-45.)-The volumetric method of estimating the amount of soap in lubricating greases from the results of a titration of the free and combined fatty acids is very difficult in the case of dark-coloured greases, and requires special precautions when rancid fats are present. A method more generally applicable has been based upon the facts that acetone dissolves only a very small amount of the soaps of fatty acids, and that the soaps may then be separated from insoluble inorganic substances (graphite, etc.) by treatment with a mixture of benzene and alcohol.Ten grms. of the sample are digested for several, hours with 100 C.C. of cold acetone (freshly distilled), the mass being repeatedly broken up with a glass rod until in a very fine state of division, The solution is filtered, and theresidue washed with acetone and then boiled with a mixture of benzene and alcohol (9 : 1).The hot solution of soap is filtered and evaporated, and the residue dried at 105" C. until constant in weight. The results thus obtained are occasionally higher than those given by the older volumetric method, probably owing to the presence of considerable quantities of water-soluble fatty acids which escape estimation. Certain very viscous oils do not dissolve readily in acetone, and in such cases the last traces of fatty oil may be removed from the insoluble residue by washing it with a mixture of acetone and petroleum spirit boiling at 50° C.(3 : 1). Alkali soapa may be separated from calcium or aluminium soaps by boiling the mixed soaps with 50 per cent. alcohol.ORGANIC ANALYSIS 163 For a quantitative estimation this is best done prior to the separation of the inorganic constituents.The pitch-like distillation residues introduced into certaiD inferior greases are partially soluble in acetone, and soluble in benzene-alcohol, so that the method is not applicable in such cases. These greases, however, are not often met with. As a rule, only an insignificant amount of soap is dissolved by the acetone, and no correction is usually required.Calcium resinate, however, is fairly soluble, and when it is present the amount dissolved by the acetone may be found by estimating the ash and calculating the corresponding amount of resin acids of mean molecular weight 300. The substances soluble in the acetone may include petroleum oil, resin oil, tar oil, fatty oils, and glycerol, the last of which generally separates as a viscous layer below the oils.C. A. M. Contribution to Methods of Determining Nitrogen in Humus. C. B. Lipman and H. F. Pressey. ( J . Ind, and Eng. Chem., 1913, 5, 143-144.)- Importance attaches to the nitrogen determination in humus, since it is this, and not the total soil nitrogen, which can be depended upon to yield through nitrification an available supply of nitrogen to plants.The author finds that the method of Hibbard (J. Ind. and Eng. Chem., 1910, 2, 463) is more satisfactory than any of the other modifications of the Kjeldahl method, in all cases but one yielding the highest nitrogen figure. Other advantages claimed are freedom from bumping, and rapidity and ease of manipulation. The material is first freed from ammoniacal nitrogen by boiling with magnesium oxide, and is then digested with 30 C.C.of strong sulphuric acid until fumes of sulphur trioxide are evolved. Twelve grms. of a mixture con- sisting of 10 grms. potassium sulphate, 1 grm. ferrous sulphate, and 0.5 grm. copper sulphate, are then added, and digestion continued until completed. The other methods tested included Wilfarth’s, Gunning-Attenberg, and the salicylic acid, this last proving next best to Hibbard’s.H. F. E. H. Comparison of Some Qualitative and Quantitative Methods for Car- bonates in Soils. E. W. Gaither. ( J . Ind. and Eng. Chem., 1913, 5, 138-143.)- The method devised by Marr (ANALYST, 1910, 35, 77) was investigated, and his results confirmed by the author, who used the double titration method of Brown and Escombe (J.Agric. Sci., 1906, 1, 322). Over a hundred soils were tested, and the results compared with their litmus-paper reactions and with the Veitch qualitative test, in which 10 grms. of the soil are extracted in the cold with 100 C.C. of water, allowed to settle, and 50 C.C. pipetted off; phenolphthaleln is then added, and the solu- tion is boiled down to about 15 c.c., the degree of colour (if any) being recorded as slightly alkaline, etc. For the litmus-paper test, strips of red and blue azolitmin paper were either placed direct on the moistened soil or with filter-paper intervening, and left covered up over night.It is shown that the official method of boiling the soil with mineral acids at looo C. decomposes organic matter and liberates carbonic acid, which was not present a6 a carbonate, but that the method used by Marr (Zoc.cit.) of boiling the soil under reduced pressure at 50’ C. with very dilute mineral acid is quite satisfactory. The litmus-paper test is the best qualitative test for native carbonates in soils from humid164 ABSTRACTS OF CHEMICAL PAPERS regions. Some soils will, however, give alkaline aqueous solutions not due to the presence of carbonates, but to the hydrolysis of certain minerals in such soils.Although the reddening of blue litmus-paper by soils may be due to the absorption of the base from the hydrolysed litmus salt, the presence of native carbonates may either prevent this selective absorption or cause an interchange of bases to take place. If a native carbonate, capable of being decomposed by weak mineral acid at low temperatures, is preeent in a soil, it is indicated by the bluing of red litmus- paper; but if there are no alkalies or basic materials capable of giving alkaline solutions, their absence will be indicated by the reddening of blue litmus-paper.H. F. E. H. Analysis of Spirit Varnishes. Part I. : Investigation of the Solvent.H. Wolff. (Farbenzeitung, 1912, 18, 856, 910, 950; through Chem. Zentralbl., 1913, I., 853.)-The sample is heated on the water-bath, under a reflux condenser, with ten times its volume of water, until the resin forms a coherent mass. When cold, the liquid is poured off and the cake of resin boiled up twice with a small quantity of water. The combined aqueous liquid is distilled until a volume equal to that of the varnish taken is obtained, and the distillate is shaken vigorously with salt solution ; if homogeneous, the liquid contains only ethyl alcohol, methyl alcohol and alcohol ; ether, benzine, benzene, amyl alcohol, ethyl and amyl acetate, and turpen- tine separate in an upper layer.From the distillation flask a volume equal to that of half the sample is distilled, added to the salt-containing portion (see above), the combined solutions distilled up to 100" C., and the distillate made equal in volume to the varnish taken.Acetone is tested for by the sodium nitroprusside reaction, and estimated by adding 10 C.C. of 10 per cent. sodium hydroxide solution and 50 C.C. & iodine to 1 C.C. of the distillate, acidulating after three minutes with dilute sulphuric acid, and titrating back the iodine (1 C.C.iodine solution is equivalent to 0.967 mgrm. acetone). For the estimation of the methyl alcohol, 1 to 5 C.C. of the alcohol are dropped into a cooled mixture of 20 C.C. 10 per cent. potassium dichromate solution and 10 C.C. concentrated sulphuric acid, allowed to stand in a closed flask for one to two hours, a volume equal to that of the alcohol taken distilled off, and the distillate heated in a sealed tube with 1 grm.dimethyl aniline and 1 C.C. of 1 in 5 sulphuric acid for thirty minutes in the water-bath. When cool, the liquid is rendered alkaline with sodium hydroxide, heated with water until the smell of dimethylaniline is removed, shaken with lead peroxide, acidulated with acetic acid, filtered, allowed to stand for five minutes, and the tint estimated colorirnetrically.Comparative experi- ments with mixtures of alcohol and methyl alcohol should be carried out. The layer above the salt solution is treated as follows: 1 C.C. is allowed to stand twenty- four hours with 25 C.C. 4 alcoholic potassium hydroxide, and is titrated back. If more than 0.2 to 0.4 C.C.of potassium hydroxide is neutralised, 1 C.C. represents about 5 vols. per cent. acetic ester, or 7.5 per cent. amyl acetate. The presence of amyl acetate or amyl alcohol in any quantity is revealed by the smell. An aliquot portion of the liquid is slowly poured, with cooling, into double the volume of sulphuric acid (sp. gr. 1-80>. If no separation occurs, benzine, benzene, and any con- siderable quantity of turpentine are absent (turpentine colours the acid dark brown) ;ORGANIC ANALYSIS 165 165' to 170" C.170" to 175" C. 175" to lsoo C. i"glI." 2 ;i:: 2 Per Rota- Per Rota- Per Rota- Cent. tion. Cent. tion. Cent. tion. Per Cent. 43 -5'25' 40 +2"0' 8.0 +S05' 3.0 - 56 - 4"40' 33 +3'0' 4.5 -. 1.5 - 157" to 15s' C. 158* to 1600 C .1603 t o 1703 C. 74 +37'10' 16 $36'15' 7 +34"0' - - . 6 2 O to 1630 C. 1630" to 16j'C. lG5' t o l G 9 O C. 25 -1"50' 57 -4'40' I1 - 10'40' - - if the liquid separates completely, it contains benzine, or benzene or its homologues. To test for esters, an aliquot part of the liquid is saponified by allowing it to stand with concentrated alcoholic potassium hydroxide, diluted to five times its volume with water, and half distilled off.The distillate is salted out with sodium chloride, and the upper layer poured into sulphuric acid (sp. gr. 1.80). If there is no separation on salting out the distillate, the original liquid was exclusively acetic ester. Separation of a layer mostly soluble in water shows the presence of ether or amyl alcohol, while solubility in sulphuric acid reveals arnyl alcohol, ether, or turpentine, benzine, and benzene.If nothing goes into solution, benzine or benzene is indicated; if everything, amyl acetate, originally present as such or as amyl acetate. Examples of the method, and hints for the detection of solvents containing chlorine, are given. 0. E. M. Residue and Loss. Per Cent. 6 5 3 7 (rotation - 7"30') Turpentine Oils from India.(BzdZ. Imp. Inst., 1912, 10, 539-546.)-The bulk of the turpentine oil produced in India is derived from Pinus longifolia, but oil could also be obtained from other species of Indian pines, including P. Khasya and P. excelsa. The oil from the last, after redistillation tc remove the yellow colour, is equal in quality to the best French and American oils.The following results were obtained with samples of these diff'erant oils : P. longifolia : Crude ... Refined ... P. excelsa ... P. Khasp ... 0,868 +0'20' 0.866 -0'40' 0.862 +36'40' 0.870 - 4'50' C. A. M. Estimation of Water in Petroleum and its Products. J. C. Allen and W. A. Jacobs. Dept. of the Interior, Bureau Jf Mines, U.S.A., 1912, l-ll.)-An outline is given of the different methods of estimating water in petroleum products, together with a critical discussion of the accuracy of each method.Estimation of the water by ascertaining the loss on heating gives approximate results, and is only applicable to heavy oils and greases. The method of diluting the oil with a solvent and allowing the water to separate by gravity is also approximate, and can only be used with thin oils; whilst the use of centrifugal force in this method increases the rapidity of the separation and gives somewhat more accurate results.The calcium carbide method, in which the amount of water is calculated from the volume of acetylene evolved, is convenient to UBB, (Techn.IPaper 25.166 ABSTRACTS OF CHEMICAL PAPERS and in the case of petroleum products gives results that are accurate within about 3 per cent. of the real values, Graefe's method (Petrooleum, 1906, I, 818) of shaking the oil with finely-cut sodium, and measuring the volume of hydrogen evolved, gives more accurate results than the carbide method, since hydrogen is not appreoiably soluble in petroleum products. Comparison of the sample with standard mixtures of oil and water gives only roughly approximate results; and the same criticism applies to the method in which the sample is shaken with standard acid, and the decrease in acidity of the aqueous layer estimated. The electrical process of Cottrell and Wright (US. Pat. 987114 of 1911), in which a current is passed through the emulsified oil, and the separated water drained off through a cheesecloth info the lower end of the tube, will rapidly reduce the amount of water down to 0.5 to 1 per cent. with little heating. The residual quantity can then be eliminated by one of the other methods. Distillation of the oil with an immiscible solvent such as benzene or toluene, and measurement of the volume of water separating from the distillate (cf. ANALYST, 1907, 32, 21), is accurate to within about 0.033 grm. of water per 100 C.C. of benzene and oil in the distillate. The method of direct distillation of the water is also fairly accurate. The distillation of 200 C.C. of the sample should be carried out at temperatures between 90° and 150° C. at the rate of about 1 drop per second, and the water removed from the receivers by means of a micro-pipette and weighed, the residual traces in the condenser tube being absorbed by means of a tared pellet of cotton wool. When much water is present, a slow current of carbon dioxide passed through the oil will prevent bumping and overheating. The method gives results accurate to within about 0.003 grm. of water in the distillate, provided that the water is cooled to about 2' C. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9133800154

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

166 ABSTRACTS OF CHEMICAL PAPERS INORGANIC ANALYSIS. Iodic Acid Method of Estimating Bromine in Halogen Salts. F. A. Gooch and P. L. Blumenthal. (Zeitsch. anorg. Chem., 1913,80,36-42.)-Bugarski’s method for the separate estimation of bromide and chloride when occurring together (ANALYST, 1896, 21, 79) always underestimates bromide and overestimates chloride. The error, which varies from almost nil to 3 per cent., according to the exact experimental conditions, is shown to be due in all probability to the formation of iodine chloride and bromide. G.C. J. Estimation of the Carbonates and Hydroxides of Potassium and Sodium when together in Solution. W. A. Bradbury and F. Owen. (Chem. News, 1913, 107, 85-86.)-1n order to determine the composition of a 4 L boiler fluid ” containing the hydroxides and carbonates of sodium and potassium, an attempt was made to separate the hydroxides from the carbonates by extraction with absolute alcohol, but this was found impracticable owing either to carbonation of the hydroxides during evaporation of the original solution ; or, if this were obviated by concentrating out of contact with air, the residue in the flask after alcoholic extraction was found to contain much hydroxide along with the carbonate. I t is unnecessary to effect a, separation such a8 that attempted, since it is possible to obtain the desired resultsINORGANIC ANALYSIS 167 by calculating from three values : (1) The acid equivalent to the carbonates present ; (2) the acid equivalent to the hydroxides ; and (3) the total weight of mixed sulphates left after evaporating to dryness a portion of the solution rendered just neutral to methyl-orange by titration with standard sulphuric acid. The values (1) and (2) are obtained in the usual way by titration first with phenolphthalein, and then with methyl-orange.Having obtained these three vdues, the total acid required is cal- culated to its equivalent of potassium sulphate, and from this is subtracted the weight of the mixed sulphates ; the difference is due to the sodium sulphate.The weights of potassium and sodium sulphate present in a given volume of the neutral- ised solution can therefore be calculated. As the whole of the acid is calculated to potassium sulphate, and since the acid was, in fact, neutralised by carbonates and hydroxides, it is evident that the proportion of the total sulphate due to carbonates and hydroxide is equivalent to the amount of acid used for each respectively ; there- fore the proportion of the above obtained difference due to the carbonates and hydroxides respectively is also proportional to the amount of acid used for each. A worked example of a particular case is appended, which makes the above reasoning clear.H. F. E. H. Detection of Traces of Copper. W. B. Pritz, A. Guillanden, and J. R. Withrow. (J. Amer. Chem. Xoc., 1913, 35, 168-173.)-For determining whether all the copper has been deposited from a solution submitted to electrolysis, the following test is recommended : One C.C. of the electrolyte is transferred by means of a pipette to a colourless, thin glass tube, about 3 to 5 mm.in diameter and 15 cm. long, and with the side walls coated with black paper. The solution is made alkaline with ammonia, then acid with acetic acid, and two drops of 2 per cent. potassium ferro- cyanide are then added, The test will just detect 0.1 mgrm. of copper in 100 C.C. of electrolyte. Other modifications of the ferrocyanide test differ greatly in sensitive- ness, and, in particular, attention is called to the fact that the sensitiveness is approximately inversely proportional to tho ferrocyanide concentration.With a nitric acid electrolyte, the pink colour of copper ferrocyanide rapidly gives place to, or is entirely masked by, a yellowish-green colour, but this interfering colour does not appear in solutions containing a negligible amount of copper (< 0.1 mgrm.per 100 c.c.). In presence of zinc the method fails, and ammonium sulphide must be used, the limiting sensitiveness with freshly prepared solutions being 0.15 mgrm. per 100 C.C. Solutions of ammonium sulphide deteriorate so rapidly on storage that for this purpose they should be freshly prepared each day.A solution a fortnight old will not detect 3 mgrms. of copper in 100 C.C. G. C. J. New Hydrogen Table. L. Vanino and A. Schinner. (Zeitsch. angew. Chem., 1913, 26, 55-56.)-A table is given showing the weight of 1 C.C. of hydrogen in fracttions of a mgrm., at temperatures ranging from 10' to 25' C., and barometrical pressures of 700 to 770 mm. Application of Diphenylearbazide (' ' Diphenylcarbohydrazide ") as Indi- cator in Titration of Iron with Dichromate. 0.L. Barnebey and S. R. Wilson. ( J . Amer. Chem. Soc., 1913, 35, 156-162.)- An investigation of Brandt's proposal C. A. M.168 ABSTRACTS OF CHEMICAL PAPERS (Zeitsch. anal. Chem., 1906, 45, 95) to use diphenylcarbazide as internal indicator in dichromate titrations. The end-point is excellent, but the indicator itself is a reducing agent and a blank titration with some ferric chloride and a measured quantity of indicator, equal to that used in ordinary titrations, is necessary.Iron ores (0.5 grm.) are dissolved in 20-25 C.C. hydrochloric acid with the addition of a small excess of stannous chloride, which is destroyed by means of mercuric chloride, and the ferrous solution is diluted to 500 to 600 C.C.About 20 C.C. of a manganese solution, containing 100 grms. manganese sulphate, 140 C.C. concentrated sulphuric acid, and 50 C.C. of phosphoric acid (sp. gr. 1-7) per litre, is next added, and followed by 10 C.C. of hydrochloric acid, and a measured volume (2 to 3 c.c.) of the indicator, which is made by dissolving 1 grm. of diphenylcarbazide in acetic acid and diluting to 1,000 C.C.The first drop of dichromate produces a pink or red tinge, which becomes deep red as the titration proceeds. The colour gradually changes to lavender as more and more chromic chloride is produced, and finally gives place to the clear green colour of that salt, the end-point, as stated, being quite sharp. Directions are given for preparing diphenylcarbazide.G. C. J. Application of Electric Resistance Furnace to Determination of Oxygen in Iron and Steel. R. H. McMillen. (J. Ind. Eng. Chem., 1913, 5, 123-125.)- With the reservation that the oxides of tungsten and aluminium and some other oxidised constituents of steel are not reduced by Ledebur's method (see also Walker and Patrick, ANALYST, 1912, 37, 586), the following modification of that method is recommended. Its most original feature is the use of a second combustion tube to remove traces of oxygen from the hydrogen employed.The hydrogen generated from pure hydrochloric acid and zinc is passed through scrubbers containing a 25 per cent. alkaline solution of pyrogallol, 50 per cent. caustic potash, stick potash, soda lime, and pumice saturated with concentrated sulphuric acid.It then passes through the first combustion tube, which contains several spirals of platinum gauze, and is maintained at 950" C., and thence through a U-tube containing phosphoric anhydride and glass beads to the second combustion tube, maintained at the same temperature as the first, and containing in a porcelain boat 25 grms. of drillings (through 20 and over 30 meshes to the lineal inch). The water is collected in a U-tube filled with phosphoric anhydride kept open by admixture with glass beads, and a Drexel wash- bottle containing concentrated sulphuric acid serves as guard-tube and completes the chain of apparatus. The combustion tubes used are thick-walled quartz tubes of % inch internal diameter and 24 inches long, the furnace being of the type now common in steel works for determination of carbon (e.g., see Blount and Levy, ANALYST, 1909, 34, 94).G. C. J. Determination of Lithium. W. W. Skinner and W. D. Collins. ( U S . Dept. Agric., Bureau of Chena., Bull. No. 153, September 14, 1912; through J. SOC. Chem. Ind., 1913, 32, 214.)-As a result of an investigation of various methods which have been proposed for the determination of lithium in mineral waters that recommended by Gooch, modified slightly in some of the details of manipulation, wag found to be satisfactory when weighable amounts of the metal are present.TheINORGANIC ANALYSIS 169 method is carried out as follows: The water is acidified with hydrochloric acid, barium chloride is added, and the whole is evaporated to dryness; the residue is dissolved in a small quantity of water and hydrochloric acid, the barium sulphate is removed by filtration, and the filtrate is evaporated.After ignition to remove ammonium salts, the residue is dissolved in water, the magnesium salts are precipitated by the addition of milk of lime (a double precipitation is necessary if the water contains a large quantity of alkalis), and the excess of calcium hydroxide, together with barium salts, is removed by treatment with ammonium carbonate in ammoniacal solution.The filtrate from the calcium precipitate is evaporated, the residue is ignited, and any remaining traces of calcium salts are removed as oxalate. The solution is then evaporated in a weighed platinum basin, the residue is treated with a small quantity of hydrochloric acid, again evaporated to dryness, ignited, and weighed.The rnixed chlorides thus obtained are dissolved in a few C.C. of water, and the solution is transferred to a flask (any insoluble matter is filtered off, ignited, and its weight deducted from that of the mixed chlorides); the solution is now boiled until the salts begin to crystallise out, and about 40 C.C.of amyl alcohol are added. The contents of the flask are next distilled until a thermometer in the neck of the flask indicates 130" to 132' C. (the boiling-point of amyl alcohol), a drop or two of dilute hydrochloric acid being then added, and the distillation continued until the boiling-point of amyl alcohol is again reached. The mixture is cooled slightly and filtered, note being made of the volume of the filtrate, and, after the insoluble portion has been washed with a little anhydrous amyl alcohol, the filtrate is evaporated to dryness.The residue, consisting of lithium chloride with small amounts of potassium and sodium chlorides, is treated with sulphuric acid, ignited, and weighed. The sulphates are then dissolved in water, and treated with ammonium phosphate and ammonia ; if any precipitate forms within about fifteen hours, it is collected and weighed as magnesium pyrophosphate, an equivalent weight of magnesium sulphate being subtracted from the weight of the mixed sulphates.To correct for the solubility of potassium and sodium chlorides in amyl alcohol, there must be subtracted, from the weight of the sulphates, 0.00109 grm.for every 10 C.C. of the amyl alcohol filtrate (exclusive of the amount used for washing). I n many cases the corrections amount to the total weight obtained within the limit of the weighing error of the work, and the amount of lithium present may then be determined by means of the spectroscope. For this purpose the residue of sulphates is dissolved in water and spectroscopic observations are made, until, with increasing dilution of the solution, the lithium line is no longer visible.Knowing the extent of the dilution, the amount of lithium is ascertained by comparison observations with solutions containing known quantities of lithium under the same conditions as to dilution, etc. The limit of visibility of the red line of the lithium spectrum is reached with 0.00002 mgrm.of lithium per C.C. of solution. A preliminary and approximate spectroscopic determination of lithium in the mixed chlorides obtained in water analyses saves much time by indicating whether it is worth while to extract the lithium for weighing. A similar test may be used to determine whether much strontium is present in the calcium precipitate obtained in the usual way.170 ABSTRACTS OF CHEMICAL PAPERS Volumetric Determination of Manganese in Rocks, Slags, Ores, and Spiegels.F. J. Metzger and L. E. Marrs. (J. Ind. and Eizg. ChevrL., 1913, 5, 125-126.)-The method previously described by the authors (ANALYST, 1911, 36,368) has proved particularly useful for the determination of small quantities of manganese in silicate rocks.From 2 to 5 grms. of the material are boiled with 5 to 15 C.C. of dilute (1 : 2) sulphuric acid, to which 5 to 15 C.C. of hydrofluoric acid are subsequently added, and boiling continued until complete decomposition is effected. From 5 to 10 C.C. of dilute (1 : 1) nitric acid and 2 to 3 C.C. of concentrated sulphuric acid are next added, the flame removed, and about 1 grm.of ammonium persulphate is added in small portions. When gas ceases to be evolved, the mixture is evaporated to fuming, cooled, diluted with 50 C.C. water, boiled, again cooled, and transferred to a wax beaker. Ammonium fluoride (5 grms.) and 25 C.C. hydrofluoric acid are next added to the mixture, which should measure about 100 c.c., and the manganese titrated with & permanganate (Mn titer=0*787 Fe titer).Slags are treated in a similar manner, but less substance is taken, or the final solution is made up to known volume, and an aliquot portion taken for titration with TG permanganate. If much manganese is present, the solution obtained on evaporating to fuming with sulphuric acid may contain permanganate. If a pink solution is obtained, the colour should be destroyed by the cautious addition of hydrogen peroxide after the usual process of cooling, dilution, boiling, and re-cooling. The excess of hydrogen peroxide is destroyed by boiling for ten minutes, and the titration completed as usual.Ores (0-5 to 1.0 grm.) are dissolved in the least possible quantity of hydrochloric acid, and the solution evaporated to fuming after addition of 15 C.C.of dilute (1 : 2) sulphuric acid. The solution is then treated with nitric acid and persulphate, and the process completed in the manner already described. Some siliceous ores and slags may need treatment with hydrofluoric acid as described for rocks. Spiegels and ferromanganese (0.2 to 1 grm.) are dissolved in 5 to 10 C.C. dilute (1 : 1) nitric acid, and the solution is treated with persulphate after cooling slightly, and then evaporated with sulphuric acid.Nitric acid up to 2 C.C. of concentrated acid in 150 C.C. has no effect on the titration, but very small amounts of hydrochloric acid interfere. I t is recommended to have not much more than 60 mgrms. of manganese present in the portion taken for titration, and to use & permanganate with spiegels and other relatively high-percentage manganese products. These directions put a limit on the accuracy with which a high-grade ferromanganese can be assayed by the method, but the test numbers given are good. G.C. J. Detection of Nitrate in Presence of Nitrite. W. N. Ivanov. (Chem. ,&it., 1913, 37, 157.)-By the following method 1 parb of nitrate may be detected in presence of 100 parts of nitrite, without risk of the formation of nitric acid by decom- position of nitrous acid.Though less sensitive than the diphenylamine reaction, it has the advantage that only chlorine interferes, ferric salts, even in presence of much nitrite, having no perceptible influence. The reagent is a 0.025 per cent. solution of quadrivalent iridium, made by treating the necessary quantity of IrO, or (NH,), IrC1, with 3 to 5 C.C.of water, then adding 100 C.C. of 98 to 99 per cent. sulphuric acid, and boiling until the solution is colourless. I t is important that the concentrationINORGANIC AWALYSIS 171 of the sulphuric acid in the reagent when bottled for use shall not fall far outside the limits 96 to 96.5 per cent.The test for nitrate is made as follows : Into a stoppered test-tube, with inlet and outlet tubes for the introduction of an indifferent gas, 5 C.C. of the reagent is introduced, a current of carbon dioxide passed through the tube, and the reagent heated to incipient boiling. The flame is then withdrawn, the stopper removed, the solid substance to be tested introduced, and the stopper replaced.I n presence of 0.1 mgrm. of nitric acid an evanescent blue appears, whilst 0-5 mgrm. gives rise to a permanent blue, the depth of which is said to be proportional to the amount of nitric acid present. G. C. J. Estimation of Nitric Oxide. Koehler and Marqueyrol. (BUZZ. SOL Chim., 1913, 13, 69-72.)-The method of Baudisch and Klinger (ANALYST, 1913, 45) is criticised on the ground that it is not available in presence of carbon dioxide.The authors have for many years employed a somewhat similar method, but, in place of the potash used by Baudisch and Klinger, they use a small quantity (0.6 c.c.) of a liquid secondary amine such as monoethylaniline. Monoethylaniline absorbs only its own volume of carbon dioxide at 15' C. and 760 mm.Consequently, if the per- centage and partial pressure of carbon dioxide in the gas mixture is small, the amount of carbon dioxide absorbed is negligibly small and, even when much carbon dioxide is present, a correction can be made which reduces the error to negligible proportions, G. C. J. Notes on Valuation of Ores and Minerals and on Metallurgical Calcula- tions. (Trans.Inst. Min. and Met., 1912, 567-592.)-The paper includes a table of factors for shortening the calculations which must precede any attempt to value an ore. The actual monetary value of the ore depends on a number of considerations beyond the simple chemical relationships set out in the table, for example, presence of undesirable constituents and physical characteristics such as porosity, a desirable property in chemical pyrolusite, or tendency to disintegrate under ordinary conditions of transportation, nearly always a, disadvantage. The paper does not attempt to explain how the actual value of every ore, or even every common ore, is to be arrived at.Its object is rather to point out the factors which may affect the value and to encourage the mining man to study these and attempt an independent valuation of his produce, instead of being content with the highest offer he can get.As examples, the valuation of manganese ores, tin ores, and bauxite are discussed in detail, and the discussion which followed the paper led to the publication of further useful notes on the valuatioii of manganese ores. G. T. Holloway. G. C. J. Estimation of Phosphoric Acid Soluble in Citric Acid in Thomas Slag.W. Simmermacher. (Chem. Zeit., 1913,37,145-146.)-1t is pointed out that, when ferric chloride is added to a phosphoric acid solution containing dissolved silica in order to prevent precipitation of the latter on the addition of ammonium citrate and magnesia mixture, the latter reagents should be added slowly and with constant stirring, otherwise a quantity of ferric hydroxide will be precipitated together with the ammonium magnesium phosphate.The addition of ferrous chloride will not pre-172 ABSTRACTS OF CHEMICAL PAPERS vent the precipitation of silica. I t is recommended that the ammonium citrate solution should be added before the magnesia mixture, but if the two br! added together the mixed reagent must be freshly prepared.Hydrogen peroxide may be used to oxidise any hydrogen sulphide present. w. P. s. New Delicate Reaction for Elementary Oxygen. K. Binder and R. F. Weinland. (Ber., 1913, 46, 255-259.)-When an alkali is added to a mixture of pyrocatechol and a ferric salt, a salt of the complex tribasic acid [Fe(C,H,Q,)..]H, is formed, having an intense dark red colour.When a ferrous salt is employed instead of the ferric, a pale red solution only is obtained which rapidly darkens with ab- sorption of oxygen forming the ferric derivative. The complex ferrous salt is recommended as a delicate reagent for the detection and estimation of oxygen in gases. The reagent must be prepared with special precautions in the ap- paratus in which it is to be em- ployed, in an atmosphere of puri- fied hydrogen, freshly boiled water being used.The apparatus illus- trated consists of a glass cylinder, 2, 21 cm. long and 2.6 cm. in diameter. A dropping funnel, T, of 100 C.C. capacity passes just through the cork, while a, capillary tube, K, with tap C, goes almost down to the bottom of the cylinder. V is a gas-trap containing water.0.4 grm. of purest ferrous ammonium sulphate and 0.5 grm. of pyrocatechol are placed in the dry cylinder. The stem and part of the bulb of the dropping funnel are filled with boiled water, and the rubber stopper carrying the funnel and capillary is inserted in the cylinder. Hydrogen gas, purified from oxygen by passing through two washing bottles containing an alkaline solution of sodium hydrosulphite, is then passed through the cylinder by way of the capillary, taps C and A being open.About 60 C.C. of boiled water and 5 drops of dilute sulphuric acid are placed in the funnel T, and purified hydrogen is passed in through the tube R, reaching nearly to the bottom of the funnel. The passage of hydrogen is continued for about fifteen minutes, the tap D is then closed and the tap C nearly closed.The water is next admitted to the cylinder, but the tap B is closed before the funnel is quite empty. The current of gas through the capillary is increased by opening the tap C again, about 15 C.C. of 15 per cent. potassium hydroxide solution are placed in the funnel andINORGANIC ANALYSIS 173 treated with hydrogen by opening the tap D.After passage of the gas for about forty-five minutes, the alkali is admitted to the reagents in the cylinder and all the taps are closed. The reagent should then be nearly colourless. The capillary tube K is filled above the tap with water freed from air by the passage of hydrogen and then connected with the source of gas to be tested; the latter is passed through the reagent in a slow stream regulated by the tap A, and if oxygen be present the liquid becomes coloured red.If the tap C be provided with a 3-way bore, the introduction of the sample and the displacement of air from the leading tubes may be simplified. The test may be made quantitative by preparing standard solutions of the complex ferric salt, diluting them with weak alkali and matching them colorimetrically with the reagent after the passage of a measured volume of gas.In ordinary gas analysis the ferrous reagent may be used for the absorption of oxygen in the Hernpel pipette. A solution of 14 grms. of ferrous gulphate and 18 grms. of pyrocatechol in 75 C.C. of acidulated water is introduced into the pipette, cooled with ice, and a solution of 33 grms. of potassium hydroxide in 75 C.C.of water is then added. For the quantitative absorption of oxygen from a sample of gas, the gas must be shaken with the reagent in the pipette for five minutes. J. F. B. Estimation of Platinum by Precipitation as Sulphide. R. Gaze. (Apoth. Zed., 1912, 27, 959-960 ; through Chem. Zentralbl., 1913, I., 464.)-Nurmann has shown (ANALYST, 1899, 24, 51) that the addition of mercuric chloride to zinc salts before the precipitation of the zinc as sulphide enables the zinc sulphide to be filtered without difficulty.I n the case of platinum, a similar addition of mercuric chloride is of advantage; the quantity of mercuric chloride added should be from 5 to 10 per cent. of the weight of the platinum, and if it is desired to estimate chlorine in the same portion of the solution as theplatinum, mercuric nitrate may be used in place of the chloride. For the analysis of barium platini-cyanide, a portion of the salt is heated with sulphuric acid and then with aqua regia until the barium sulphate is white in colour ; the excess of aqua regia is then evaporated, the residue is diluted with water, the mixture cooled, and the barium sulphate collected on a filter.The filtrate is then concentrated, mercuric chloride is added, and the platinum is precipitated with hydrogen sulphide. An alternative method consists in igniting the salt over the blow-pipe, moistening the residue with nitric acid, and evaporating to dryness. The platinum is then extracted from this residue with aqua regia and precipitated as described.w. P. s. Purity of the International Radium Standard. E. Haschek and 0. Honigsehmid. (Monatsh., 1913, 34, 351-357.)-Last year the Vienna radium standard was compared actinometrically with the international standard of radium chloride prepared by Mme. Curie. The two preparations agreed within the Iimits of error of the method employed, which is taken as about 1 in 300. Mme.Curie has not described the preparation of the international standard, but it is reasonable to suppose that she adopted the method described by her in 1907 in her communication on the atomic weight of radium. This method-repeated recrystallisation from dilute hydrochloric acid-was adopted by Honigschmid in Vienna. I n 1907 Mme.174 ABSTRACTS OF CHEMICAL PAPERS (hrie recorded the fact that her purest radium bromide contained spectroscopic traces of barium, though certainly not more than 0.06 per cent.As this amount would introduce an error of 6 units in the second decimal place of the atomic weight, the authors subjected the Vienna standard, on which Honigschmid’s value for the atomic weight of 225.95 was based, to stringent tests for barium. The metal could not be detected in the Vienna standard, but it was detected and its amount approxi- mately estimated (spectroscopically) in the mother-liquors from the preparation of the standard.On the assumption that the standard preparation still contains as much barium as remains in the mother-liquors, the standard may contain 0.004 per cent., but not more, barium. The radium bromide used by the same author cannot have contained more than half this amount of barium.Such amounts of barium would only affect an atomic weight determination 2 or 4 units in the third decimal place, and the atomic weight of radium is not known within k0.012 per cent. The authors express the view that the Paris standard is most probably of the same order of purity as the Vienna preparation ; that for actinometric purposes, with existing methods of conducting measurements, both may be regarded as pure, but that, should methods of measurement be so far improved as to justify a correction, then they should be regarded as of only 99.996 per cent.purity. G. C. J. Estimation of Iron in Water. E. Tassilly. (Bull. SOC. Chim., 1913, 13, 34-37.)-The method is based upon the fact that in solutions of ferric thiocyanate aontaining a large excess of potassium thiocyanate the degree of spectroscopic absorption is proportional to the quantity of iron present.One hundred C.C. of the water are boiled with 20 C.C. of hydrochloric acid, 0-5 to 1 grm. of potassium chlorate added, and the boiling continued until chlorine ceases to be evolved. After cooling, 20 C.C.of potassium thiocyanate solution (17 grms. per litre) are added, and the liquid made up to 100 C.C. and examined in Fkry’s spectrophotometer in a 2 C.C. trough, the absorption due to the water being compensated by the use of a second trough containing water. The proportion of iron is then found from the reading by reference to the curves already established by FBry.The effect of nitrateg is negligible, whilst that of sulphates is reduced to a minimum in the presence of hydrochloric acid. C. A. M. Determination of Moisture. G. N. Huntly and J. H. Coste. (J. Soc. Chem. Irzd., 1913, 32, 62-67.)-The Eighth International Congress of Applied Chemistry appointed a sub-committee to deal with the determination of water in coal, and their findings were published in the general report of the International Analysis Com- mittee, and reprinted in the Transactions of the Congress.The present paper is mainly based on this report, but in addition deals with the determination of moisture by all methods likely to be of use in the drying of materials which through oxidation in air, or for other reasons, present difficulties. (A) Direct Methods.-1.Water driven off by ignition, condensed in part of ignition tube and weighed directly (Penfield). Specially suitable for the analysis of rocks, giving accurate results in presence of carbonates or ferrous salts, but cannot be applied to organic substances.INORGANIC ANALYSIS 175 2. Substance heated in a current of dry gas or in a vacuum, water vapour collected in calcium chloride or sulphuric acid and weighed, an accurate and widely applicable method ; but air is not a safe gas to use, as with coal at 100OC.oxidation occurs. The use of inert gases, however, lessens the practical value of the process ; and in the case of coal at any rate, coal-gas, unless carefully purified, would seem to be risky, since it contains gases absorbed by coal.3. Substance mixed with an excess of a volatile, non-miscible liquid such as xylene, distilled, and the water under the hydrocarbon layer measured, with or without corrections for the mutual solubilities of the water and liquid used for its removal. A promising method and deserving of careful comparative study against Nos. 2 or 8 , especially for difficult substances such as oils, butter, tar, and coal.Constam and Allen and Jacoba both describe the results of experiments in which this method is employed for the estimation of water in oils, fats, soaps, resins, coal, and petroleum. The method has the drawback of requiring close attention during the distillation, and is not free from danger of fire. 4. The material directly heated to 130' C. by a, vapour jacket (high pressure steam), the steam given off condensed, and measured.A method applicable for dealing with samples of coals weighing as much as 1 lb. and has the advantage of requiring only a rough balance. It does not require skilled handling, and is eminently suitable for use in a power-station where results are required immediately. Allen and Jacobs distill 200 grms. of petroleum in the ordinary way, and then separate and weigh the water.The last method is exact to within 0-03 per cent. (B) Qasometric Methods.4. The substance is mixed with calcium carbide ; acetylene measured. 6. The substance is mixed with magnesium methyl halide in presence of a suitable dry solvent, and the methane measured. 7. The substance is treated with sodium and the hydrogen measured.The carbide method has been applied to cordite, wool, butter, cocoa, coffee, and coal (see following abstract). Treatment with sodium has been used, as well as treat- ment with calcium carbide, by Allen and Jacobs for the determination of water in petroleum and its products, in which case the method is very accurate, since hydrogen is insoluble in oil ; 2 grms. of finely cut sodium are used for each grm.of water supposed to be present, and the apparatus employed is similar to that for the carbide method. ( C ) Indirect Methods.-8. Determination of the loss of weight by heating to a definite or indefinite temperature. The usual method. Correct results will be obtained if (a) the temperature of the oven and period of drying is sufficient to drive off all the moisture ; (b) no moisture is reabsorbed before weighing; (c) no volatile substance other than water vapour is evolved ; (d) no oxidation takes place ; ( e ) no absorption of carbon dioxide takes place; (f) no internal chemical change is induced which may lead to the formation of water in the substance to be dried.A11 these points are discussed at some length, and the experience of different members of the sub-committee are summarised, considerable space being given to this section owing to the universality of the employment of the ordinary moisture oven.9. Prolonged exposure in a vacuum in presence of strong sulphuric acid, either at176 ABSTRACTS OF CHEMICAL PAPERS ordinary or at higher temperatures. It is important that the vacuum should be at least under 2 mm.(a pump of the Fleuss type will easily get the pressure down to 1 mm.). Before removing the samples from the exhausted desiccator dry air should be admitted, The sulphuric acid should be concentrated (1.84) and have a large effective surface. Figures are given for the loss of weight in a number of coals as found by different observers, and it is probable that by working with a really high vacuum (0.01 mm.), such as can be obtained by a double oil pump working in series, the time required for a vacuum moisture determination might be reduced to one or two hours.The paper concludes with a list of recommendations and conclusions arrived at by the International Reporters, which refer more par- ticularly to coal, but, as this presents most of the difficulties which are found with other substances, most of the conclusions may be considered as of general appli- cation.It is improbable, the authors say, that either the direct or the vacuum method will be adopted to any great extent, notwithstanding their undoubted merits ; more- over, in various statutory rules and regulations (e.g., the Fertilizers and Feeding Stuffs Act, 1906), it is provided that water shall be determined by drying at 100' C.For general work, temperatures below 100" C. are not nearly as satisfactory as those a few degrees above, both on the grounds of speed and accuracy. The Committee recommend that (1) whenever possible, especicllly in the case of very moist coals, the water in the original sample should be determined after it has been subjected to a minimum amount of preliminary mechanical treatment by either of the following methods : (a) A carefully weighed portion of from 100 to 500 grms.of coal is spread out on a metal tray and exposed for at least twenty-four hours to the atmosphere of the sampling-room. The tray containing the coal is then re-weighed and the percentage change of weight calculated.The coal is then coarsely ground (a ball-grinder is best) and a water determination concluded by one of the methods given in Recommendations 2, 3, or 4. ( b ) The xylene method used by Constam (Recommendation 5). (2) For ordinary technical work coal should be dried in an oven with a good air circulation for period not exceeding one hour at a temperature not below 104" nor above 111" C.This temperature can be obtained by the vapour of boiling toluene, by steam at a pressure of 906 to 1,100 mm., or by an electrically heated thermostatic arrangement. An oven, such as described by Siau (ANALYST, 1911, 36, 126) or Coste (ibid., 1512, 37, 385), is suitable. Air-ovens, and all devices in which the temperature of the walls is variable, are strongly condemhed.A pre-heated supply of air is to be desired, and mere heating without a proper air-current is unreliable. (3) When it is suspected that a coal is specially liable to oxidation, or the half-hour and one-hour results differ materially, drying at 104" to 111' C. in a current of nitrogen, or carbon dioxide is to be preferred to drying in an oven through which a current of air is passing.The method of drying in a current of inert gas which must be quite free from oxygen is to be preferred for all exact work. (4) Drying to constant or minimum weight in a vacuum in the presence of sulphuric acid possesses no advantage over the last-mentioned method as it is much slower. Unless the vacuum is very high, it is better to fill the desiccator with carbon dioxide before exhausting.The coal should bc weighed in watch-INORGANIC ANALYSIS 177 glasses, and the loss after 24, 72 and 144 hours should be determined, when the results are practically identical with those by method 3. (5) The xylene method is worthy of serious consideration, though in view of the limited information at the Committee's disposal it cannot be recommended unconditionally. H.F. E. H. Determination of Moisture in Organic Substances. F. H. Campbell. (J. SOC. C h m , Ind., 1913,32,67-70.)-The method involves the use of calcium carbide in a new form of apparatus, and is claimed to be as accurate as the cold vacuum method, and more rapid than any of the recognised methods, while the necessary apparatus is both simple and inexpensive.The necessity for its use only arises when the material gives low results owing to oxidation when heated in air (cj. ANALYST, 1911, 36,112). The principle adopted is that of Rivett (ibid., 1912,37, 51) in which the acetylene evolved is determined gravimetrically by difference, and the factor obtained (1 grm. acetylene = 1.44 grms. water) agrees closely with that found to hold by Rivett (Zoc.cit.). The apparatus consists of a tube about 12 crns. long and 1.5 crns. in diameter bent half-way at an angle of 45", and closed at the lower end. Into the upper open end is fitted another tube holding the carbide and fitted with a stopcock leading to a mashing bottle containing strong sulphuric acid. Calcium carbide is shaken down into the lower tube which contains the material to be tested, and the liberated acetylene escapes through the tube packed with carbide, being thus dried in its passage.Air is finally aspirated through the apparatus, which is heated towards the end of the gas evolution, and the loss of weight is a measure of the acetylene evolved. The results of a large number of comparative determinations are recorded in which roasted coffee, sweetened cocoa, tea, butter, and coals are dried by various methods.The time required for a determination varies from thirty to sixty minutes, and from 1 to 2 grms. of material as a rule are used. H. F. E. H. Determination of Moisture in Foods and other Organie Substances. W. P. Skertchley. (J. sbc. Chem. Ind., 1913, 32, 70.)-A comparison is made of the loss of water from a number of materials when dried: (a) In vacuo for about twenty-four hours, and ( b ) in a water-oven at 100" C. for two hours. The substances generally yielded more moisture when dried in vacuo, especially in the case of farinaceous materials, which, when heated for more than two hours, began' to increase in weight to the extent of a few mgrms. for each period of one hour. Working on a sample of biscuit the moisture apparently fell from 6-92 per cent. in two hours to 6.6 per cent. after six hours when dried in a water-oven at 100" C., whereas the moisture value rose in one case from 7-39 to 7.65 per cent., and in another from 7-13 to 7-48 per cent. when the drying-time was increased from twenty- four hours to forty-eight hours in vucuo. H. F. E. H. Estimation of Water in Vegetables by Hoffmann's Apparatus. St. von Haydin. (Zeitsch. Untersuch. Nahr. Genussm., 1913, 25, 158-160.)-1n this process the substance is heated in a copper flask with ordinary petroleum (parafinurn liquidurn) and oil of turpentine, the distillate being collected in a narrow graduated178 ABSTRACTS OF CHEMICAL PAPERS vessel, and the water measured under the hydrocarbon layer. I t is recommended that 2 grms. of the finely divided vegetable be placed in a wire-gauze cage, which is then immereed in the petroleum in the copper flask ; 20 C.C. of oil of turpentine are added, and the contents of the flask are heated to 180' C. A further quantity of 20 C.C. of oil of turpentine are then added through a tapped funnel, and the tempera- ture raised to 200' C. About five minutes' heating at this temperature is sufficient to remove the last traces of water from the flask, and the whole operation requires only twenty minutes. The results obtained are concordant and agree with the figures found on drying the substance to constant weight in a water-oven. (See also ANALYST, 1907, 32, 21 ; 1908, 33, 97.) w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9133800166

出版商:RSC    

年代:1913

数据来源: RSC

摘要:

178 ABSTRACTS OF CHEMICAL PAPERS APPARATUS, ETC. Multiviscosimeter. I. Kurzmann. (Chenz. Zeit., 1913, 37, 234.)-The multiviscosimeter, which is of the enclosed type, is fitted with a series of interchangeable capillaries, so that; one instrument covers a large range of viscosities. The liquid under examination is measured into a bulb at the bottom, and forced up by air admitted through the stopper above, acting as a 3-way cock, into the capillary pipette, which is supported by the stopper in the axis of the instrument.The air displaced from the pipette reaches the atmosphere through a side U-tube which may contain some of the sample, so that the liquid is pro- tected from alteration by evaporation. When the stopper is turned through 180 degrees the pressure on the two surfaces of the liquid is equalised, and the flow from the pipette takes place under the influence of gravity alone.Results at various temperatures agreed satisfactorily with those obtained with an Ostwald viscosi- meter. The instrument is made by Aloys Schmidts Glasbliiserei, Breslau I. 0. E. M. Portable Pettersson - Palmqvist Apparatus. R. P. Anderson. (J. Arner. Chem. SOL, 1913, 35, 162-168.) - The apparatus described and figured in the paper differs from earlier forms mainly in the dimensions of the gas burette, the principal portion of which is only about three times 8s long as it is broad, the graduated small bore portion lying nearly horizontally.One result of this arrangement is that the whole apparatus can be accommodated in a comparatively small rectangular glass cell, the outside dimen- sions of the case being 11 x 18 x 42 cm., as compared with 24 x 24 x 92 cm., which were the dimensions of the apparatus formerly made by Greiner and Friedrichs.There is also a great saving in weight. Another novel feature is a convoluted copper tube lying wholly within the water-bath, and serving to convey the gas samples or air from dwelling rooms to the burette, and effectually cool it to the temperature of the bath, thus making it possible to draw gas from a hot source, and proceed withAPPARATUS, ETC. 179 its analysis without any delay.The apparatus is made by Greiner and Friedrichs, Stutzerbach in Thuringen. G. C. J: Small Apparatus for Electrochemical Analysis. F. Chancel. (Buzz. XOC. Chirn., 1913, 13, 74-76.)-The cell is a Jena glass test-tube 30 mm.in diameter and 125 mm. high. The anode is a platiniridium wire, 1 mm. in diameter and 50 mm. long, which is sealed through the centre of the bottom of the test-tube SO that its top stands about 40 cm. above the bottom of the tube. The cathode is a cylinder of platinum gauze, 20 mm. in diameter and 30 mm. high, supported by a wire 1 mm.in diameter and 110 to 120 mm. long, and weighing from 6 to 9 grms. With such apparatus, a current of 1.5 amperes and a temperature of 80' to 85' C., 0 3 grm. of copper can be deposited quantitatively from 30 C.C. of solution in forty-five minutes provided only a little nitric acid is present in addition to 2 C.C. of sulphuric acid. An equal weight of nickel can be deposited quantitatively and in the same time from an ammoniacal solution of the sulphate containing ammonium sulpbate with a current of 1 ampere at 75' to 85' C.I n presence of nitric acid the results are equally exact, but the time required for complete deposition is prolonged to several hours. G. C . J. Colorimetric Methods for Water Analysis by the Use of Autenreith- Roenigsberger's Colorimeter.W. Autenreith and A. Funk. (Zeitsch. anal. Chem., 1913,52,137-167.)-Details of processes are given for the estimation of ammonia, nitrous acid, nitric acid, iron, lead, hydrogen sulphide, etc., in water by means of a colorimeter devised by the authors. The comparisons are made by the use of a Helmholz double plate, and the two vessels containing the test solution and the comparison solution respectively have flat sides, and are placed at right angles to one another.The vessel containing the comparison solution is wedge-shaped, and may be moved up or down relative to the other vessel, so that the same depth of colour may be obtained in both vessels. w. P. s. REPORT. Western Australia. The Health Act, 1911 : Food Standards and Regulations.(Published as a Supplement to the Government Gazette, November 1, 1912.)-The Regulations come into operation on May 1, 1913, except that relating to whisky, which comes into force on July 1, 1913, and provide for the proper labelling and description of foods, condiments, wines, oils, drugs, etc., which are sold in Western Australia. '' Standards " are given in almost all cases, the maximum quantity of preservative allowable in foods, etc., is mentioned, and a list is given of the colouring matters which may be employed in certain cases. The methods of analysis and examination which must be followed in ascertaining the composition, quantity, or conformity, or want of conformity, to standard of any food or drug, are given in a Schedule to the Regulations. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9133800178

出版商:RSC    

年代:1913

数据来源: RSC