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735 ANALYTICAL CHEMISTRY. An a1y t i c a1 C h em i s t r y. Determination of Nitric Acid by Indigo. By R. WARINGTON (Chem. News xxxv,45-47 57-59).-The author first describes the method employed by Boussingault in which the nitrate is boiled with hydrochloric acid and solution of indigo added till a sap-green colour is permanently obtained. Ronssingnult destroys organic matter when present by a preliminary distillation with peroxide of manganese and sulphuric acid. The experiments made by the author with the method introduced by Marx and since improved by Trommsdorff Goppels-rmder Bemmelen and Sutton are next detailed. In this method the 1-eaction is brought about by mixture with oil of vitriol without the iise of artificial heat. The indigo employed was a solution of "indigo-carmine '' (sulphindigotate of sodium) ; the solution of pure nitre con-tained 0.01011 gram in 10 C.C.; the oil of vitriol was distilled acid. 3c2 ABSTRACTS OF CHEMICAL PAPERS. The author found-I. That the maximum amount of indigo is con-slimed only when a sufficiency of indigo is present with the nitrate before the addition of oil of vitriol. The plan adopted by Marx of mixing the nitrate solution with twice its volume of oil of vitriol and then immediately running in the indigo always consumes less indigo than the nitrate is capable of oxidising. The full amount of indigo can only be ascertained by a series of approximating experi- ments in which the oil of vitriol is suddenly added to the previously mixed nitrate and indigo.11. The amount of indigo required de- pends greatly on the proportion of sulphuric acid present and within certain wide limits the amount of indigo is less as the proportion of sulphuric acid is greater. With 10 C.C.of nitre solution 11.3 C.C.of indigo were required when the indigo and nitre were mixed with their own volume of oil of vitriol ; but 8.9 C.C.of indigo were sufficient when two volumes of oil of vitriol were employed. 111. The full amount of indigo is consumed only when the temperature of the mixture remains sufficiently high during the reaction ; lOO" 110" and 120° are given by various writers as the minimum temperature. When the reaction was immediate artificial heat was found nnne-cessary ; but when through dilution of the nitrate small volume of the liquid weakness of the vitriol &c.the reaction was tardy the tem- perature of the flask containing the mixture must be maintained by a paraffin or chloride of calcium bath or the results will be too low. IV. The true tint of final reaction is a dull brown which precedes the commencement of green; the brown tint becomes green when sud- denly diluted with water. If a solution of sublimed indigotine in sulphnric acid is employed the tint passes at once from gold to green without an intermediate brown stage. V. When a nitrate solution is diluted it apparently requires distinctly less indigo per uuit of nitrate if a double volume of oil of vitriol be employed; but if a single volume is used the difference is very slight and in the contrary direction.If two volumcs of sulphuric acid are employed the indigo must therefore be standardised with nitre solutions of several dilutions to ascertain the value of different parts of the scale. TI. The infln- erice of chlorides is slightly to diminish the indigo required. With -03 to *logram of chloride of sodium in 10 C.C.of nitre solution the reducing effect of 100 chloride of sodium was equal to 1.16 nitre. With much chloride the final tint is a bright green. VII. Some kinds of organic matter have a powerful reducing action. Cane-sugar had a greater effect the larger the proportion of sulphuric acid and the more dilute the nitrate ; with a ,',th nitre solution and a double volume of oil of vitriol 100 of sugar had a reducing effect equal to 62.3 nitre.The soluble humic matter of soils was apparently without influence determinations of nitrate in a kitchen garden sail by the mercury method and by the indigo method giving accord- ant results only one volume of sulphuric acid was used in this experiment. R. W. The Quantitative Determination of Boric Acid by Baryta. By PAGL BERG(Zeitschr. Anal. Chem. xvi 25-33).-Boric acid is mmpletely precipitated from its aqueous solution by addition of baryta- ANALYTICAL CHEMISTRY. water in such quantity that to every molecule of B,O from 1$to 2 molecules of BaO are added and provided alcohol is added until the liquid contains 55-60 per cent. of alcohol. After standing 24 hours the precipitate consisting of Ba0.B203+ 4Aq settles in a crystalline condition and may be washed with 75 per cent.alcohol dried over oil of vitriol and weighed. The operations must be carried out in an apparatus which prevents precipitation of barium carbonate by atmospheric carbon dioxide. Boric acid must be separated from sodium borate by addition of hydrobrornic acid to strongly acid reaction before applying the above method of estimation the sodium and barium bromides formed being readiiy soluble in alcohol. Other metallic borates must be converted into sodium borate by boiling with sodium carbonate solution or by fusion with solid sodium carbonate. IC a larger proportion of baryta-water is used in the precipitation crystals of barium hydrate are sepa- rated on addition of alcohol ; they can be removed from the precipitate by waphing with weak alcohol.Alcohol of 60 per cent. dissolves only of its weight of the barium borate precipitate. Analytical results which accompany the paper prove that the method is accurate and that with proper precautions for avoiding exposure to the air no barium carbonate is present in the precipitate. I?. c. Volumetric Estimation of Sulphuric Acid by Barium Chlo- ride Solution in Acid Liquids. By G. BRUGELNANN (Zeitshr. Ad. Clzem. xvi 19-22) .-The author describes a modification of Wildenstein's arrangement (Zeitsch-. i 431-437) for rapidly filtering off a portion of the liquid under titration in order to determine the point of complete precipitation. The liquid to be titrated is contained in a beaker and is heated over a gas flame to the temperature most favourable to the rapid precipitation of barium sulphate.The apparatus for removing filtered samples of liquid from the beaker consists of a small funnel containiug filter-paper and cotton wool and haigiiig in the liquid; this is joined to a longer tube outside so as to form a syphon by means of' a piece of india-rubber tubing which forms the bend of the syphon. This syphon-filter is filled with hot water its longer limb closed by a piece of india-rubber tubing and pinch-clamp and the Punnel suspended in the liquid in the beaker. The arrange- ment proved very useful and yielded very accurate results in deter-minations of sulphur in animal and vegetable substances and in coal gas. F. C. On the Purification of the Barium Sulphate Precipitates ob-tained in Quantitative Analyses.By G. B R u G E L MAN N (Zeitschr. Anal. Chem. xvi 22-24) .-The method recommended by hesenins for the separation of salts carried down from solution and retained by a barium sulphate precipitate is modified as follows. Several drops of rather strong hydrochloric acid are poured upon the ignited precipitate in the crucible and a few C.C. of water added; the lumps are then broken up with a small glass rod and the liquid warmed short of boiling for about two minutes then poured off through a small tilter. This process is repeated until on washing the precipitate with water ABSTRACTS OF CHEMICAL PAPERS. the filtrate on being tested by a few drops of sulphuric acid is found free from barium ; from five to eight repetitions were usnallr sufficient.If larger quantities of hydrochloric acid are employed or the liquid is heated t'o boiling with the precipitate decomposition of the hriuin sulphate may occur. Tlie volumetric process of estimation is alwaTs less troublesome unless only a few estimations are to be made and tiie standard solutions are not at disposal. I?. c. Estimation of Phosphorus and Arsenic by Ammonium Molybdate. By CHAMPION and PELrlET (BUZZ. XOC. Chh [" xxvii ti).-Tlie authors consider that it is better to weigh the phospho- molybdate than to convert it into ammonio-magnesium phosphate and determine the phospl-ioric acid from this. As the concentration of the solutions exercises a great influence on the time reqnired for precipita- tion certain precautions are necessary to ensure a rapid mode of work-ing 100 grams of molybdic acid are dissolved in ammonia (1.50 C.C.ammonia and 80 of water) and the solution added drop by drop to 500 C.C. of pure nitric acid (sp. gr. not given) and 300 of water. A quantity of' the molybdate representing about 50 times the weight of the phosphoric acid in molybdic acid is placed in a basin; it is ren- dered alkaline by ammonia ; and the solution containing the phosphoric acid after being concentrated as much as possible is added ; the mix-ture heated to 70-80" and nitric acid added until a yellow colour is produced. Collect wash and dry the precipitate at 100-110". Arseriic acid may be determined in the same way.C. E. G. Determination of Alkaline Sulphates. By F. J E AN (Co771pt. rend. lxxxiii 973-979).-To the aqueous solution of the substance a slight excess of baryta-water is added and then Seltzer water which precipitates the excess of baryta. The liquid is separated by decanta- tion boiled and filtered with the first precipitate. The precipitate having been washed the filtrate is coloured with litmus and neutra- lised with a standard solution of sulphuric acid. The amount of acid necessary is of course exactly equal to that which was originally coni- bined with the alkalis. This method is of great advantage where sulphates of lime mag- nesia &c. are present. F. D. B. Estimation of Phosphorus in the Form of Ammonio-phos-phomolybdic Salt.By S E RG IU s K ERN (Chenz. News xxxv 1).-The following method for the analyses of irons and steels being a modificatiou of' that of Eggertz is recommended :-1gram of the specimen is dissolved in 20 C.C. of aqua regia and the phosphorus is precipitated by Eggertz's method ; the resulting yellow precipitate separated from the solution is dissolved on the filter in ammonia and in the filtrate obtained ; is slightly acidulated by hydro-chloric acid ; the phosphorus is precipitated in the form of phospho-amrnonio magnesic salt [n/lg(NH,)PO,] by " magnesium rnixt~ti.e,'~ prepared by dissolving 1gram of MgSO and 1gram of NH,C1 in 8 C.C. of water mixed with 4C.C. of ammonia. The precipitation is finished in 15 to 20 hours ; the precipitate is filtered from the solution washed ANALYTlCAL CHEMISTRY.73 with water containing half a per cent. of ammonia and first gent! heated in a platinum crucible till free ammonia and water are eiapo- rated ; the crucible is next ignited for 30 to 40 minutes and the received Mg2P207is weighed. This salt contains 13.51 per cent. of phosphorus. E. W. P. Volumetric Estimation of Arsenic. By P. CHAM PI ON aiitl H. P E L L E T (BUZZ.SOC.Chiwz. [ 21 xxvi 541444).-The aitthors here give the details of a process devised by them for the volnmetric esti- mation of arsenic and based on the following principles :-1st. Trans-formation of the arsenic into sulphide. 2nd. Solution of the snlphicle in ammonia and saturation with acetic acid. 3rd. Xstimation of the arsenic by iodine in presence of starch.The method is applicable to any quantities of arsenic and is sutficiently delicate to be employed in poisoning cases. R. R. A new Method for the Gravimetric or Vohimetric Determi- nation of Phosphorus Arsenic Sulphur Chlorine Bromine and Iodine in Organic Substances and in Vegetable and Animal Compounds as well as for the Determination of Sulphur in Coal Gas. By G. BRUGELMAYN .4d. Chm., (Z~it.schr. xvi 1-21).-The author brings forward two modificatioiis in the methods already described by him in the Zeitsch-. xv 1-27 175-186; Ckelr2. SOC. J. 1876 i 743 by which the processes there employed for determining phosphorus sulphur and chlorine in organic sab-stances become applicable to arsenic biarnine and iodine.Substances which are exptosire when burnt in oxygen also become nianageable by the new method. The advantages claimed are :-1st. That each of the above six elements can be gravimetrically determined in from three to four hours. 2nd. That even when a large weight of substance is employed only small quantities of reagents are necessary and the contents of the tnbc are thus soluble in a small quafitity of liquid. 3rd. That each of the six elements can be determined in separate parts of the same solution and that the combustion of two different substances may be carried out in the same tube. 1. First ~1ocl1$catio.12.-This is applicable to substances which when heated in a current of oxygen evolve easily inflammable vapours ; such are almost all non-volatile organic solids and liquids.In these cases i~ current of air is used at first and the combustion is completed iii R stream of oxygen. A layer of asbestos of at least 15 ceritimeters is requisite. Cacodylic acid and carbothialdine treated by this method underwent quiet and regular combustion. Only in the case of phosphorus com- pounds where the substance is mixed with excess of soda-lime may the asbestos be dispensed with and combustion made at once in oxygen. Liquids which are readily or not very difficultly volatile should be burnt at once in oxygen else the excess of oxygen requisite for their combustion is not obtained. In the case of compounds containing. ABSTRACTS OF CHEMICAL PAPERS. arsenic the soda-lime should be separated from the asbestos by pieces of glass or by an wbestos plug instead of by platinum as platinum is considerably attacked in presence of arsenic.Arsenic-compounds after having been sublimed in the air-stream into the asbestos must be burnt in a carefully maintained excess of oxygen as metallic arsenic is liable to be separated on the soda-lime by the action of carbon. The arsenic is thus obtained in the form of arsenate which is well suited for estimation as uranium arsenate either by a modifica- tion of Rodeker's volumetric method described below or gravimetri-cally by Werther's method (Fres. Qr~ant.And.) the contents of the tube being dissolved in water and hydrochloric or nitric acid. The soda-lime (or lime) must be free from iron and alumina.Second Mod$cutiorz.-This consists in substituting soda-lime for granulated lime it renders the process applicable to the estimation nt' bromine and iodine. A soda-lime which possessed the maximum power of arresting bromine and iodine together with a minimum corrosive action on the glass was made by dissolving 20 grams of sodium hydrate in 60 of water pouring this hot solution upon 80 of powdered .marble lime in a large porcelain crucible stirring at once quickly so as to mix the solution thoroughly with the lime before the latter slakes and becomes too stiff to be easiiy stirred ; the water is then driven away by ignition and the mass granulated. After combustion the contents of the tube are heated with water until disintegrated and the cooled liquid gradually mixed with excess of dilute nitric acid.This solution can be at once precipitated or titrated with silver nitrate solution in the case of chlorine or bromine ; but before determining iodine the free iodine and sodium iodate must he converted into hydriodic acid by addition of sulphurous acid. Volhard's volumetric method by use of silver nitrate and ammonium sulphocyanide (this Zeitscli. xiii 111-175) is very convenient for the estimation of bromine chlorine and iodine. A modification of Wil- denstein's method for volumetric estimation of siilphuric acid is described below it has given good results; it is preferable to the gravimetric method on account of the extreme difficulty of obtaining it pure barium sulphate precipitate for weighing.The new method is inapplicable to determiniiig phosphorus or arsenic in presence of much iron or aluminium but the minute quantities of these metals often present in organic snbstances do not affect the results by the volumetric method. The six elements under consideration may be det'ermined either successively in one portion or in different portions of the same solu-tion and since any one organic substance rasely contains more than one of the. above elements weighed quantities of two different sub-stances containing different elements may be burnt in the same tube and,at the same time and using the same lime or soda-lime three different substances can hardly be simultaneously burnt with advan- tage since this involves using too small a meight of each or too long a lajer of lime.The weight of substance usedvaries from 2 to 6 deci-grams. Soda-limeis on the whole preferable .to lime. Only in the case of phosphorus arsenic or sulphur is hydrochloric acid applicable for the solution of the contents of the tube. If an excess of oxygen ANALYTICAL CHEMISTRY. is maintained daring the combustion of organic compounds and a sufficiency in that of organic tissue &c. and the process is not too rapidly carried on the layer of lime or soda-lime 10 centimeters in length amply suffices for the absorption the last 2 centimeters usually remaining pure. Substances must be prevented from burning with a flame by proper regulation of the stream of air or oxygen. Tables of results obtained by the above methods conclude the paper.F. C. Volumetric Estimation of Arsenic Acid and Phosphoric Acid by Uranium Solution. By G. B RCGE LMANN (Zeitschr. And C'It ern. xvi 22-24).-Bodeker's method (Arm. Chem. Phama. cxvii 195 and E'res. Quant. And.) is modified in such a way as to make it more siinple and trustworthy. After the arsenate has been dissolved in water nitric aoid or hydro-chloric acid sodium hydrate or ammonia is added gradually to de-cidedly alkaline reaction then acetic acid is added until the liquid is strongly acid ; the operations are carried on with the cold liquid to hinder any separation of phosphates or arsenates of barium strontium or calcium. The addition of sodium or ammonium acetate is unne- cessary and since very little of this salt is present potassium ferro- cyanide can be used as an indicator unless the liquid is very dilute and the value of the uranium solution is at.once given by its strength no correction being necessary. The uranium solution should contain about 20 grams of uranium oxide to the litre and must be free from mitneral acids. The liquid to be estimated must not exceed 50 c.c. this volume being secured by division or evaporation. The solution is first mixed in the cold with almost the requisite quanhity of tbe uranium solution and then after each addition it is boiled for several minutes until after two successivc periods of boiling a few drops give a brownish tint to a drop of feebly coloured potassium fesrocyanide solution. The estimations were free from the loss always experienced by Fresenius when large quantities of calcium were in solution ; this error was probably avoided by wcuiiiig the absence of large quantities of sodium acetate and by preventing the separation of calcinm phosphate on boiling by only boiling tlw solution aff,er almost the requisite quantity of uranium solution had been added.Ta secure the latter result when unknown quantities of phosphoric acid were present a preliminary titration was made which gave the volume of uranium solution to within 1c.c. and in the subsequent determination the quantity was carefully determined to 10.1C.C. (corresponding to O*U00&2P and 0.00053 As). F. C. On the Estimation of Sulphur in Coal Gas. Bg G. B K C G E rj-MA K N (Zeitschr.haZ. Chew&. xvi %%).-The author examined the gas supply of Leipzig by his method (Zeitschr. xv 175) for sulphur and on the 12th and 15th .of July found none. He considers that this result is not due to the volume of gas used by him (10 litres) being insufficient since his method deterrnlnes 0.00213 gram of sulphur in 10,000 C.C. of $as wlien only 2,883 C.C. are burnt aud gas in Xngland ABSTRACTS OF CHEMICAL PAPERS. is considered pure if it contains a maximum quantity of 0.0057 gram per 10,000 C.C. F. C. A Delicate Spectroscopical Reaction for Alumina and Mag- nesia. By HERMANN (Deut. Chem. Ges. Ber. ix 1641 W. VOGEL -1G46).-A dilute aqueous solution of pure purpurin shows a weak absorption in the yellow and a stronger in the green between E' and b.This absorption becomes more intense when ammonia is added and disappears on adding dilute acetic acid a faint absorption in the blne alone reuiaining. But when to a very dilute aqueous solution of puts-purin a dilute solution of alum is added the liquid becomes recl aid gives two strong absorption bands between D and E and b and F. This reaction which is also produced by other aluminium salts is best seeii in a very weak alkaline solution ; it is weakened but not destroyed by acetic acid. Magnesium salts give the same bands only that in the yellow is stronger than the other but the least excess of acetic acid destroys the spectrum. The least traces of magnesium and alnminiuni can be detected by this reaction which is not shown by the salts of iron manganese zinc the alkali-metals or those of the alkaline earths ; but it does not appear when salts of iron or zinc are present in excess.The author then describes the methods for separating these salts arid the pocket-spectroscope which he uses and gives drawings of this apparatus and the curves of the different spectra. c. s. Calculation of the Percentage of Chemically Combined Carbon in Analyses of Steels by Eggertz's Colorimetric Method. By SERGTUS KERX(Chem. News xxxv l).-Owing to the want of published tables for calculating the amount of carbon prcserit in steel it is proposed to proceed as follows :-A solution of normal steel (0.1 gram dissolved in 8 C.C. of nitric acid) containing 0.31per cent. of carbon is compared with the colour of a like solution of the specimen.In calculating the percentage of carbon two cases may happen :-1. The specimen solution is darker in colour than the normal solu- tion. 2. The specimen solution is Zighter in colonr than the normal solu- tion. r. The specimen solution is darker. 8 C.C. of the normal solntion contain 0.31 per cent. of carbon hence 1 C.C. of the same solution contains-Oa3' ~-0.0038 per cent,. of carbon. 8 In comparing the specimen solution it was diluted by 1C.C. of nitric acid in order to obtain the tint of the normal solution. The total volume of this solution is therefore 9 C.C. 0.0038 x 9 = 0.0342 per cent. of chemically combined carbon in the specimen analysed. ANALYTICAL CHEMISTRY.743 TI The specimeia soZutioiz is lighter. In this case the normal solution must be diluted to obtain an equal tint with the specimen solution. 8 C.C. of the normal solution were diluted by 2 C.C. of nitric acid. The total volume of the liquor is hence 10 C.C. One C.C. of this solutim contains-0.31= 0.031 per cent. of carbon. 10 The volume of the specimen solution remains always in this case 8 c.c. so that the percentage is very easily found out :-0.031 x 8 = 0.248 per cent. of carbon in the analysed specimen. BF means of' these calculations knowing the per cent. of carbon in the normal steels tables may be very easily calculated. E. W. P. On the Analysis of Illuminating Gas. By M. BERTHEI~OT (CYo~yt.rend. lxxxiii 1'355).-Up to the present time chlorine and fuming sulphuric acid have been the only absorbents used in the de- termination of hydrocarbons ; the author has however found it advantageous to substitute bromine for chlorine and boiled sulphuric acid for the Nordhausen acid.Boiled sulphuric acid (ie. ordinary sulphuric acid concentrated as much as possible by boiling) does not act on benzene and acts on ethylene and acetylene so slowly as to permit of their separitioii from their more highly condensed homologues. It also produces sulphur dioxide with much greater difficulty than Nordhausen acid does. He has found that chlorine has the disadvantage of decomposing water in presence of hydrocarbons and forming carbonic acid. Bro-mine does not act in this m7ay.When the gas contains only traces of the hydrocarbons removable by boiled sulpburic acid fuming nitric acid may be used for the deter- mination of benzene. It is used over water by means of peculiar coil-trivances and may be applied immediately after the removal of carbon dioxide. If however the gas contains much ethylene acetylene or their homologues as is the case with the gases obtained from bog-liead and cannel coal these must be removed before the application of the nitric acid. The following is the method recommended by the author for the analysis of gases rich in hydrocarbons :-1st. Carboiz dioxide mid hJdT(Jge?I sulphicle are removed by solid potash ; or the sulphide niay be removed by cupric sulphate. 2nd. Oxygen is removed hy pyrogallate.3rd. Wuter is estimated by dried calcium chloride. 4th. C(wbon disulphitk is estimated by potash moistened with alcohol ; and the alcohol vapour is removed by dry calcium chloride. 5th. The gas is then agitated ovcr mercury with about one-twentieth its volume of boiled sulphuric acid for about a minnte. This removes homologues of ethylene and acetylene. The gas (transferred to another eudiorneter) is fre9d from any sulphiirous acid that may have been formed by means of slightly moist potash. ABSTRACTS OF CHEMICAL PAPERS. 6th. Ethylene and Acetylene.-The gas is transferred to a dry flask and agitated with a tenth of its volume of sulphuric acid for three-quarters of an hour. 7. Bemene and its Homologz~es.-The residual gas is transferred over water to a eudiometer and fuming nitric acid passed into it with the precautions mentioned in the original paper.The benzene is thus entirely absorbed and its quantity determined. 8th. Carbonic oxide is absorbed by acid cuprous chloride. It is as well to perform the operation twice using each time a volume of the liquid equal to half the volume of gas. 9th. The remaining gas freed from hydrogen chloride and water is then analysed by combustion in the usual way to find the amounts of hydrogen and of marsh-gas and the other paraffins. c. w. w. Estimation of Carbon Disulphide in Alkaline Sulphocar- bonates. By L. FINOT (Am. Ckim. Yhys. [5], and A. BBEKTRBND ix 142-144).-The autliors propose a new method founded upon the instability of zinc sulphocarbonate.Ten grams of the alkdine sulpho- carbonate together with 25-30 C.C. of water and 10 C.C. of a strong solution of zinc sulphate are introduced into a flask of about 100 C.C. capacity fitted up after the manner of a carbonic acid apparatus. On mixing the contents of the flask a yellow precipitate of zinc sulpho- carbonate is produced which decomposes slowly in the cold but very rapidly at a temperature of 50" or 60" according to the equation :-ZnS.CS2 = 2n.S + CS,; Consequently the loss in weight corresponds with the amount of carbon disalphide contained in 10 grams of the alkaline sulphocar- bonate. The sulphocarbonates of copper and mercury undergo a similar decomposition. H. H. B. S. Estimation of Sugar by Standard Solutions.By E. PERROT (C'ompt. 1.eiir.l. Ixxxiii 1044-1045).-A normal solution of copper is prepared by dissolving 39.275 grams of copper sulphate in 1litre of water. A solution of 25 grams of potassium cyanide in 1 litre of water is also prepared and of this 10 C.C. are placed in a flask and about 20 C.C. of ammonia added. The liquid is raised to a tempera-ture of 60' or 70" and the copper solution is added from a burette chop by drop until the blue colour characteristic of copper salts in ammonia appears when the quantity of copper-solution employed is noted. The analysis of' the solution of sugar (which has previously been changed into inverted sugar if necessary) is proceeded with by adding to it an excess of Pehling's liquid tlie reduction being per-formed over the water-bath.The precipitate is collected washed and dissolved in dilute nitric acid to which a few crystals of potassium chlorate are added. The filtered liquid and washiiigs are made up to a definite bulk and the quantity of this required to yield the blue coloration with 10 C.C. of the cyanide of potassinm solution to which 2~ C.C. of ammonia have been added as before which indicate tlie amount of copper precipitated by the sugar. ft. R. ANALTTlCAL CHEMISTRY. Estimation of Tannin. By J. LOWENT HAT (Zw‘tschr. Anu7. Chem. xvi 33-48).-The author describes the results of his experi- ence in the estimation of tannin and considers that his improvements give determinations satisfactory for technical if not for strictly scien- tific purposes.The estimations of tannin from different sources (e.f/. sumach and nutgalls) are not comparable but only those from sumach inter se and from galls ider se. 13am?ner’s method is used the extract being first titrated after adding indigo-solution so as to ascertain its potassium-permanganate value; the tannin is then precipitated from andher portion of the extract and the permamganate-value of the filtrate ascertained ; the permanganate-value of the tannin is obtained by the difference of these results. For the precipitation of the tannin a solution of glue in water is made and saturated with common salC it conhains 25 grams of‘ glue to the litre. After thoroughly mixing bhis with the tannin extract a small quantity of dilute hydrochloric or sulphuric acid is added to assist the separation of the tannin A vessel with narrow opening should not be used as the precipitate coagulates into a mass.Of the tannin-extmct to be titrated suficient is taken to require 0.06 to 0.08 gram of permanganate 10 grams of sumach are exkracted with boil- ing water and after cooling the liquid is made up to 2 litres ; to 100 C.C.of this solution 100 C.C. of the glue-salution are added and to this mixture are further added 50 C.C. of water containing 5 C.C. of HC1 (1.12 sp. gr.) or 2 to 2.5 grams of H2S‘04. The slight reducing action of the glae-solution upon the permanganate may be safely neglected the error- due to this cause is less when Hanimer’s powdered-skin (hautpulver) is employed this error almost vanishes if + of the glue- solution directed to be added is replaced by saturated solution of common salt.Tbe presence of ivndigo solution is necessary not only as an indicator but it also prevents the oxidising action of the perman- ganate extending to any substances in the extract less readily oddis- able than the indigo is itself. The only requisite for making this method quite accurate is the separation of pure tannin and the deter- minahion of its permanganate-value this would ensure the accurate c:~lculstion of the quantity of tannin from the difference of perman-gxnate-values. The fieparation of tannin from its lead-compound by addition oi insufficient axalic acid yielded much purer taniiin than the separation by sulphuretted hydrogen.The sample in which tannin is ho be estimated is never dried before being weighed as it is sold in the undlried state. Oser’s recommencla-tion to add acid during the titragion of Che indigo solution has been accepted by the author. The determination of glue by precipitation with an exmssof tannin which excess is afterwards titrated is inexact. Since the quantity of tannin combining with a certain quantity of glue iucreases with the quantihy of tannin present the author intends to examine the effect of using sodium chloride solution in plwe of water. Hydrochloric acid is preferred to sulphuric for acidifjTing. The state-ments of Wagner that gall-tannin combined with glue putrifies and that in turkey-red dye-works sumach is never used without galls are not confirmed by the author’s experience.F. c. i46 ABSTRACTS OF CHEMICAL PAPERS. Volumetric Estimation of Phenol. By W. F. KOPP E sc H AA JZ (Zeeitsclw. AYLaZ. Chem. 1876 233-243).-The amount of phenol in creasote oil is usually determined by agitating with a known volume of an alkaline hydrate solution and reading off the volume of hydro-carbons which is gradually deposited. The practical objections to this process are so great that Koppeschaar was led to look for a new process. Landolt has shown excess of bromine water gives a distinct precipitate with very dilute solutions of phenol owing to the forma- tion of the insoluble tribromophenol according to the reaction- C6H5,0H+6Br = C6H2Br,,0H+3HBr. This method of estimating phenol is fairly accurate two test-ey-periments quoted by Landolt giving 98.6 and 99.1 per cent.instead of the theoretical 100.0. As employed by Landoh however this pro-cess is in pract,ice open to serious objections owing td the difficulty in collecting washing and drying the very bulky precipitate of tri-bromophenol. Koppeschaar devised therefore a plan for applying the basis of Landolt's process to a system of volumetric analyses. The principle of the new method is as follows:-To a known amount of phenol in aqueous sohition B known volume of standardised bromine water is added in excess of that necessary to convert the phenol ii;to tribromophenol ; and the excess of bromine employed is determiued in the usual manner by the aid of potassium iodide and sodium thiosulphate Na2S203.The estimation of the percentage of phenol by this method is made in the following manner. Four solutions are prepared namely a so-lution of starch ; a solution of potassium iodide containing 125 grams per litre ; a standard solution of sodium thiosalphate of such strengtli that 1C.C. answers to 1C.C. of a solution of 5 grams of iodine in a litre of water; and a solution of bromine water of such strengtli that 50 c.c. after the addition of 5 C.C. of the potassium iodide solu-tion require from 18 to 20 C.C. of the standard sodium thiosulpliate solution. It is necessary immediately before employing t'he bromine water to est,imate its strength in the above manner and suppose n =the number of C.C.of sodium thiosulphate solution required.Four grams of the creasote containing the phenol are dissolved in water and the solution made up to the volume of 1litre. From this solution 2.5 C.C. are taken and placed in a half-litre flask possessing a closely fitting stopper. The flask is then quickly filled up to the half-litre mark with the standardised bromine water closed and well shaken for some time. After standing a quarter of an honr the contents of the flask are emptied into a beaker containing 10 C.C. of the solution of potas-sium iodide and the flask twice rinsed into the beaker. The iodine set free by the excess of bromine is then determined in the usual manner with the standard solution of sodium thiosulphate with the aid of the starch solution as an indicator. Let b =the number of C.C.of the sodium thiosulphate solution employed. Then the percentage of phenol in the oil examined will be given by the simple equation- Per cent. of phenol =0.61753 (9.5 a -b). Koppeschaar quotes numerous test experiments which show that ASALTTICAL CI-IEMISTIZP 74% the method is fairly accurate the extreme estimations varying al)out 1+per cent. on either side of the theoretical number and with a ten-dency to give a result which is a fractional part of a per cent. too high. The majority of the determinations were within half a per cent. of the mean. Though the results obtained in this manner are accurate the employment of bromine water as a standard solution was a disadvnn-tage of moment. This led Koppeschaar to try the result obtained by using a solution of a mixture of sodium bromide and bromate which on the addition of hydrochloric acid yields free bromine according to the reaction- 5NaBr + NaBr03 + 6HC1 = 6Br + 3H,O + 6EaC1.Direct experiment showed when this mixture was treated witli phenol and excebs of 11)-drocbloric acid added the results were iden- tical with those obtained by the use of bromine water. In employing a solution of a mixture of sodium bromide and bro-mate instead of bromine water the analysis is effected as follows. A solution of five equivalents of sodium bromide and one equivalent of sodium bromate is made of such a streiigth that 50 C.C. mixed with 10 C.C. of the potassium iodide solution and after decompositioii with 5 C.C. of concentrated hydrochloric acid diluted with 100 C.C.of water requires from 86 to 95 C.C. of the sodium thiosulphate standard solu- tion. Let a = the number of C.C. of the standard solution of sodium thiosulphate required. 25 C.C. of the solution of phenol to be exxmined (prepared in the same manner as before) is then placed in a quarter-litre flask with a tightly fitting stopper and 100 C.C. of the stm- dardised solution of the mixed sodiuni bromide and bromate is addcd. 5 C.C. of concentrated hydrochloric acid is then quickly run in the stopper inserted and the flask well shaken for some time. After standing for a quarter of an hour the flask is opened and 10 C.C. of the potassium iodide solution is added the stopper replaced and the whole agitated and then left to itself for a short time.The contents and washings of the flask are transferred to a beaker and the iodine estimated as before with standard sodium thiosulphate. Let b = the number of C.C. of the solution of sodium thiosulphate employed. Then the percentage of phenol in the creasote oil examined is found froin the simple expression- Percentage of phenol = 0.61753 (Za -b). Test experiments are quoted which show the accuracy of the results obtained by this method four experiments giving 99.2 99.5 993 539.5 instead of the theoretical 100. When the sodium salts are re-placed by the potassium salts the different' results were found to be &lightly more divergent. Of ten experiments none were more than three-fifths of a per cent. from the mean or 1per cent.from the theo- retical number. E. N. Detection of Rosolic Acid in presence of Fuchsine. By P. and R. BIDAUX GUYOT (Cowpt. rend. lxxxiii 982-984).-When a solution containing rosolic acid is treated with ammonia a charac- ABSTRACTS OF CHENICAL PAPERS. t,eristic rose tint is observed but if instead of ammonia a9 acid be added the original claret colour of the rosolic acid disappears giving place to a yellowish hue. These reactions being directly contrary to those characteristic of fuchsine the presence of rosolia acid in wine is likely to cause much embarrassment to the analyst in testing for the former sub-stat) ce. The fact that ether does not take up rosolic acid from an ammonia- cal sol’tntion reriders it easy to separahe the two bodies.The wine to be tested is treated with ammonia and then shaken up with ether whereby the whole of the fuchaine is removed from the aqueous layer but none a€ the rosolie acid. On separating the eeher the presence of fuchsine may be tested by the addition of acetic acid which produces a rose colonr or by putting into the ether a piece of gun-cotton which fixes the colouring matter and with which the tests for fuchsine may be made. The aqueous layer on the other hand loses bhe red coiour due to the rosolic acid on the addition of acetic acid. If hhe liquid containing the two substances be rendered acid with acetic acid instead of alkaline with ammonia the ether takes up both the fnchsine and the rosolic acid and if to this ether a few drops of ammonia be added the ether is completely decolorised while the ammonia sepasates the rosolic acid by which it is coloured rose.F. D. B. New Tests for Anthracene. By J. B‘ENNETT (flhenz NWC xxxiv 279).-One gram of anthracene is heated in a flask to which is fastened an upright condenser wit,h 45 C.C. of glacial acetic acid ; 21 C.C.of an oxidising mixture (I00 grams chromic acid dissolved in 50 C.C. glacial acetic acid and 50 C.C. water) is then added and the whole boiled. The quinone thus separated is washed and dried and t,hen treated with sulphurie acid (sy. gr. 1.84) until it becomes a crys- talline mass. It is then diluted with water washed on a weighed filter wibh a 1per cent. boiling solution of potash washed ayain with water and finally dried and weighed.From the weight of quinone thus obtained the ash after ignition is to be subtracted and the amounti of pure anthracene calculated from the remainder. Another rnet.hod is to heat the above mixtures together for tmo hours leave the whole to itself for twelve hours then dilute with water filter wash the precipitated anthraquinone with potash and finally with hot water. The anhhraquinone is then dried and dissolved in ten times its weight of concentrated sulphurio acid and heated until it becomes crystalline. The rest of the process is described above. Anthra-qninone is ealculated into pure anthraceiie by multiplying the anthra- quinone by 0.856. E. W. P. Testing of Quinine Salts for Strychnine and Morphine.By H. HAGER (Chenz. C’entr. 1876 90).-The test which the author proposes as a shont and very suitable one for detecting the presence of these poisons in quinine salts i.s as follows:-For the valuatioii of quinines it is generally the custom to dissolve a few decigrams in con- AX’ALTTICAL CHEMISTRY. 74 9 centrated sulphuric acid and to confirm the presence or absence of sdicin or other bitter principles. Tn order to apply this solution simultaneously for detecting strychnine and morphine it is necessary to use about 0.3 gram taken from various parts of the bulk sample and to dissolve it in about 6 C.C. of pure concentrated sulphuric acid in a test-tube shsking the latter moderately. A few C.C. of the colourless or slightly yellowish solution are then poured over small crystals of bichromate of potassium.In the case of pure so-lutions the liquid remains unaltered for a minute after which the crystals begin to dissolve whereas when strychnine is present blue streaks immediately spread out from the crystals through the liquid aiid afterwards assume a violet then a red and finally a green colour. The remainder of the quinine solution is treated with four to five drops of nitrate of silver and agitated gently. If morphine is present an immediate reddish-brown coloration sets in and the so-lution when warmed assumes a deep reddish-brown colour. It scarcely needs mentioning that substances other thau morphine will produce a similar reaction ; this reaction however is sufficient proof for reject-ing the parcel.With the hydroehloride of quinine a separation of white chloride of silver is formed simultaneously but if morphine is present the reddish-brown coloration is nevertheless visible D. B. Some Reactions of Vegetable Poisons. By 0. PAPE(Arch. 7’hnrrn. [31 viii 233-2.34) .-The transient cvlours produced by sul-phuric acid and alkaloids can be rendered more permanent by addition of wheat-starch. Digitalin mixed with ten times its weight of starch and a few drops of sulphuric acid turns blackish-brown ; on addition of a few drops of nitric acid and some water a deep green colour is produced ; with cane-sugar itl shows the same reaction but the colour- ing matter easily dissolves in the water. Bot’h amorphous and crys- talline digitnlin give substantially the same reaction with starch ;with sugar sulphuric acid turns it yellow then orange and finally brown.On addition of water the colour disappears. If hydrochloric acid be substituted for nitric acid a green colour is also produced. Veratrine with ten times its weigh&of starch and a few drops of sulphuric acid t,iirns brownish-yellow and finally brownish-red and on additioh of nitric acid turns yellow. Morphine gives no colour with sulphuric acid alone but on addition of nitric acid it gives a fine orange colour. The starch may be advantageously used in testing for codeine narco- tine narceine and brucine but not for strychnine. TV. R. Detection of Fuchsine and other Colouring Matters. By A. BI? CHAMP (Compt. Tend. lxxxiv 131-133).-The author gives a process for detecting fuchsine and other aniline-colours wben frail- dulently employed First in caramel-colouring -precipitate by addi- tion of lead salt suspend the precipitate in water pass sulphuretted hydrogen and boil the precipitate with alcohol.which will extract all the fuchsine. Secondly in wine to 25 C.C. add strong baryta-water to pale green colour ; warm gently ; filter and wash with weak baryta- water. Acidify a portion of the filtrate with acetic ad when if VOL. XXXf. 3D ABSTRACTS OF CHEMICAL PAPERS. fuchsine be present the liquid bewmes rose-red and will dye silk. The remainder is to be agitated with twice its volume of ether and the separated ether on the addition of a drop of dilute acetic acid will show a vivid coloration if fuchfiine be present.R.Ro. Detection of Fuchsine in Wines. By G. M. FORDOS (COW@. rend. lxxxiii 980-981).-Ten C.C. of the wine are shaken with 1C.C. of pure ammonia 5 to 10 C.C. of chloroform are then added the whole well shaken and the chloroform after separation by a tap-funnel heated in a porcelain dish with a piece of white silk immersed in it; when the chloroform is nearly evaporated a little water is added and the heating continued. All the fuchsine is thus fixed in the silk which becomes more or less rose-coloured if fuchsine is present. This tnethod permits of the detection of extremely small quantities of fuchsine especially if the wine be concentrated and a very small piece of silk be used. Quantitative results might be obtained by means of a series of pieces of silk coloured more or less deeply with which the piece coloured by the wine under examination might be compared.F. D. B. Fuchsine in Wines. By J. FORDOS (Ompt. rend. lxxxiii 1045 1047) .-The modifications which the author here makes of his former process are intended to render it sufficiently easy of execution for industrial purposes. To 10 C.C. of the wine to be tested for fuchsine 1C.C. of ammonia and 10 C.C.of chloroform are added. The test- tube is to be several times inverted but not shaken and the chloro- form drawn off by means of a tap-funnel ; a little water is added to it and then it is saturated with acetic acid. The fuchsine now separates from the chloroform and its aqueous solution floats on that liquid.Another modification is to use only 5 C.C. of chloroform and when this has settled to the bottom of the tube to drop in a crystal of citric acid. The ammonia being saturated the fuchsine appears on the crystal It.R. Dilution of Wines. Influence of Plastering Fining Brandy-ing &c. on the Weight of the Dry Extract. By A. GAUTIER (Pull. Suc. Chim. [el xxvii 7-17).-When skilfully done it is gene- rally very difficult to detect the addition of water to wine naturally rich in alcohol for the purposes of fraudulent adulteration. Generally the expert founds his judgment on the low percentage of dry extract and of glyaerin hut grave sources of error may creep in if care be not taken. In the detsrmination of the extract it is usual to evaporate the wine at lOO" and then dry the residue on the air-bath; but inaccurate results are obtained in this way owing to loss of glycerin &c.and to the alteration of the tannin and nitrogenous matters. These sources of error however are entirely avoided by evaporating to dryness and drying in a vacuum for several days at the ordinary temperature ; no alteration taking place after 96 hours at 25-:3%". As might be ex-pect,ed the results thus obtained are always higher than those obtained by the ordinary method. The influence of plastering on wine is to raise the amount of extract' by about 3 0 to 3-8grams per litre the ANALYTICAL CHEMISTRY. “Vins du Midi” being raised from 18.2 grams extract per litre to 21.5 to 23.8 grams.The effect of fining on the weight of the dry extract is to diminish it whether gelatin or white of eggs be employed since the tannin becomes precipitated ; and brandying has the same effect not only because it increases the volume of the wine witliout adding any solid material but also because it precipitates after a time certain substances dissolved in the mine especially the acid potassic tartrate. The stoppage of the fermentation by means of sul-phurous acid alcohol or salicylic acid retains a portion of the glucose and so increases the amount of extract. In order to ascertain whether a wine has been diluted it is necessary to determine the amount of ext,ract and compare it with wines of the same vintage and same year having special regard to the amount of tannin and glycerin and also whether the wine has been plastered which is easily ascertained by its giving a precipitate with barium chloride and by the ash being neutral if it has not been mixed with unplastered wines.If the proportion of glycerin is small whilst the extract is uormnl it is probable that the wine has been diluted with washings of the marc from which the wine was made as this would introduce appreciable quantities of colouring matter cream of tartar and tannin. C. E. G. Identification of Foreign Colouring Matters in Red Wine. By HIL GN R (Chem C‘entr. 1876 619).-The colouring matters em- ployed for adulterating red German wines are generally the bil berry mallow kermes and fuchsine solution. The reactions obtained accord- ing to the following table are sufficient to detect their presence :-Hydrogen Concentra-Copper sul- Amy1 alcohol.(Zn + HC1). Ammonia,. ted potash phate. solut,ion. -~-___---~-Mallow ... Decolorised Green gra-Brown Deep blue Dissolves on after short dually shaking a rccl time changing to colouring mat-yellow ter which at the junction of the layers ap- pears violet. Kermes Decolorised Changes im- Changes Coloured No colouring (Phyto-after 12 mediately to immedi-dark brown matter dis-lacca) hours yellow ately to changing to solvod. yellow green Bilberry .. Sloa-ly de-Violet All colouring colorised matter dis-after 12 solved. hours Fuchsine . . Immediately All colouring decolorised ised matter dis-solved. Pure red Decolorised At first no Small amount of wine gradually action then red colouring gradually matter dis-changes to solved.brown E. W. P. ABSTRACTS OF CHEMICAL PAPERS. Determination of the Residue of Wine. By L. MAGNIER de la SOu RCE (Bull. Xoc. Chim [el xxvi 488-490).-The residue ob-tained by evaporating wine at 100" in the ordinary way does not exhibit a constant weight even after prolonged heating. By effecting Ohe evaporation in a vacuum the changes induced by the higher tem-perature are avoided and the results become comparable as the diffeyences of the weighings are then much smaller. Several days are however required to obtain nearly constant weights. R. R. Detection of Mineral Acids in Vinegar. By STROHL (Ah. Plmrm.[5] 4 342-346).-Calcium oxalate is insoluble in acetic acid but is dissolved by mineral acids. + C.C. ammonium oxalate solu-tion and $ C.C.calcium chloride solution each containing + equivalent in 1000 C.C.of water are added to 50 C.C.of the vinegar under examination if the turbidity which is at first produced does not dis-appear the liquid contains less than-2.85 gram ordinary hydrochloric acid of 1.174 sp. gr. per litre or 4.40 nitric 1-33 9 7 9 71 or 1.70 7 sulphuric , 1.843 , 9 $1. M. P. M. Composition of Coffees. By 0. LEVESIE (Arch.Phann. [5],4 294-298).-The author sought to determine whether the analysis of a sample of coffee would enable one to determine the quality and re-lative price. So far as his determinations extend there appears to be 110 connection between the comuiercial quality and chemical composi-tion.The following numbers are given :--i 4 d :e 4i 3 s 4 % u G -4pr Finest Jaiiiaica plan-tation. . . . . . . . . . . . 25 .3 1 -43 14 -76 33.8 3 -8 1 *S7 Finest green Mocha . 22 *6 0 -64 21 -79 29 .9 4.1 2.13 -Ceylon plantation . . . 23 *8 1 -53 14 .S7 36 '0 4.0 Washed ltio.. . . . . . . 27 -4 1.14 15 -95 32 *5 4.6 --Costa Rim .. . . . . . . 20 -6 1.18 21.12 33 *0 4-9 Malabar . . . . . . . . . . 25 *8 0 -88 18 -80 31 '9 4'3 -East Indian . . . . . . . . 24 *4 1 -01 17 *OO 36 -4 -M. M. P. M. Testing Roasted Coffee for Chicory. By A. FRANZ (Ad. Pharnz. [5] 4,298-302).-An infusion of pure coflee when treated with copper acetate and filtered yields a greenish-yellow filtrate an infusion of coffee containing chicory yields wlien similarly treated a dark red brown filtrate.The liquid should be examined immediately after filtration as the colour changes on standiug. Ten per cent. of chicory may be readily detected. If 0.3 C.C.copper acetate solution ANALYTICAL CHEMISTRY. of 2.5-2.6 per cent. be added to 2 C.C. of coffee extract prepared by treating the coffee with 10 parts of water the results are very satisfac- tory. M. M. P. M. Detection of Foreign Mineral Substances in Flour. By H. VOHL(Deut. Chenz. Ges. Ber. ix 1660-1664).-Large quantities of flour are imported from Holland into the Rhine provinces and Westphalia adulterated with gypsum heavy spar China-clay chalk arid powdered quartz.A simple and expeditious method of detecting these bodies consists in deflagrating a mixture of the flour with pure saltpetre in a platinum or iron crucible. If a quantitative exami- nation is to be made potassium and sodium carbonates should also be added and the mixture should be moistened and dried again before iynition. In either case the mass obtained is free from carbon anti when cool of a more or less faint green colour owing to the presence of a minute quantity of manganese. In the case of pure flour this mass is almost entirely soluble in water. Addition of hydrochloric acid liberates carbonic and nitrous acids. Tf a precipitate is formed on neutralisation which re-dissolves in excess of acid silica or a sili- cate is present.If addition of barium chloride to the acid solution produces more than an opalescent turbidity earthy sulphates have been added. Turbidity produced by addition of ammonia in excess to the acidified solution points to admixture with aluminium compoui ids. If a precipitate is left on solution of the mass in water and it is dis- solved by dilute hydrochloric acid chloride of ammonium and ammonia will throw down from this solution a brownish precipitate of phos-phates and. after a time crystals of ammonio-magnesium phosphate will be deposited on the sides of the vessel. If the hydrochloric acid solution of the precipitate gives a precipi- tate with calcium sulphate heavy spar has been added. If in the filtrate from the phosphates oxalate of ammonia gives a white pre- cipitate the specimen is adulterated with gypsum chalk &c.G. T.A. Some Reactions of Hsmaglobin and its Derivatives. By C. HGSSON (J. Phann. Chinz. [4],xxii 326-329).-By the action of iodine on hzemaglobin the latter is resolved into haematin and glo-bulin. This fact may be proved both by comparing the absorption- spectrum after the addition of the iodine with that of pure haematin and by observing the reaction itself under the microscope. In the latter case not only is the actual precipitation of the hzmatin visible but crystals of the iodide may be obtained by gently warming the substance on the microscope slip with a drop of glacial acetic acid. These crystals belong to the rhombohedral system and are generally arranged in a star-like manner often resembling the form of a Maltese cross.By treating blood with sodium borate and glacial acetic acid haernatoldin results. The crystals of this substance though appa- rently belonging to the oblique rhombohedral type assume in the ruicioscopic field such varied and multiple forms of arrangement that any description of their appearance would be valueless ; it is how-3~2 ABSTRACTS OF CHEMlCAL PAPERS. ever noticeable that closely surrounding the crystals granulations of a peculiar reddish colour always occur which seem to result from the precipitation of the iron of the hzmatin at the moment of its conversion into Jmmatoidin. With sodium sulphydrate colourless or straw-yellow needle-shaped crystals may Rometimes be obtained.Ammonium sulphydrate how-ever gives no crystals but communicates sometimes to old blood- stains the well-known colour produced by a sulphocyanate and a ferric salt. Potassium cyanide or ferrocyanide and mercury cyanide also produce crystalline compounds though the reactions are not effected so easily as those previously mentioned. They succeed best with blood which has been kept for some time in which owing to partial putrefaction the globulin of the haemaglobin is destroyed. In such case acetic acid alone without the addition of any other reagent will give a fine crystallisation of haemstin acetate ; and gene- rally the crystals of the other compounds of this substance are found to be larger in size and more regularly arranged. Respecting the foregoing communication M.H6nocque remarks (ibid. 329-531) that the iodine reaction of M. Husson for the detection of blood-stains is preferable to the method devised by Teichmann in which crystals were obtained by the action of sodium chloride and acetic acid since the new process combined much greater precision in working with greater certainty of success. He is of opinion that the microchemical micrographical and spectroscopic methods of research should be used simultaneously for no one pro-cess can at present be relied upon as infallible and in investigations of this nature it is especially necessary to accumulate proof. He alludes briefly to the recent discussion between Richardson and Woor-ward in which it has been distinctly pointed out that the measure-ment of the red corpuscles does rmt serve to distinguish human blood from the blood of the domestic mammifera and suggests therefore that the action of iodine upon the blood of these animals phould be tried in order to see whether the haematin-derivatives so obtained present any characters which may tend to differentiate them from the corresponding compounds obtained from human blood.J. W. Testing Aqueous Liquids for Blood. By V. SCHWARTZ (Arch. Pharm. [5] 4 302-323) .-The author made use of Teichmann’s test viz. production of hzmin crystals the spectrum reaction and the guiacum test as carried out by Liman ; he also determined the best precipitant for blood dissolved in aqueous liquids. In applying the hzrnin test the author allowed the acetic acid to evaporate spontaneously he then obtained better results than by heating the slide before placing it under the microscope.The guiacum test was carried out exactly as described by Hunefeld the author agrees with Leman in saying that if this test leads to negative results we may conclude that blood is absent but that positive results do not cer- tainly indicate the presence of blood. Zinc acetate is generally the best precipitant for blood. One part of blood in 6,000 of water could be precipitated and the bzmin crystals obtained 1 in 15,000 could ANALYTICAL CHEMISTRY. he detected by the spectroscope after precipitation. In water con- taining 17 per cent. of common salt blood could be detected by the hEmin test (after precipitation by means of zinc acetate) only when present in the proportion of 1to 750.One part of blood was detected in Fi,OOO parts of soapy water by the spectroscopic and the haemin tests after precipitation with tannin solution. With zinc acetate blood could only be detected when the proportion was 1 to 750 of soapy water. Small quantities of blood could not be satisfactorily detected by these tests when dissolved in urine. One C.C. of blood was dissolved in 1,500 cb.c. of water (the water used was from a river). The blood could be detected after preci- pitation by zinc acetate by the hemin or spectroscopic test after 8 days but by the hemin test only after 10 days. The precipitate with zinc acetate was carefully washed with distilled water.Small quantities of blood were detected in linen by treating with potassium iodide solution precipitating with zinc acetate and trent- ing the precipitate with salt and acetic acid. This process may be applied to the detection of blood-stains which have been already partially removed by washing and rubbing. M. M. P. M. Analysis of Soap. (Chem. News xxxv 2).-The soap to be analysed should be a slice cut through the bar at right angles to its length (60-80 grams dissolved in distilled water and the volume made up to 1,000 C.C.;of this 50 C.C.are employed for each operation). The total alkali is determined by adding standard acid to 50 C.C.of solution diluted to 200 c.c. and coloured faintly with eosin the dis- appearance of colour marks the point of neutrality.To determine uncombined alkali 50 C.C. are added to 300 C.C.of saturated sodium chloride solution and the whole diluted to 400 C.C. the neutral alkaline salts are precipitated from which the co,mbi?Led and urtcombiwed alkali may be calculated. When 50 C.C. of solution of soap are decomposed by acid and the whole shaken up with carbon disulphide the disulphide evaporated off and the residue dried at loo” the whole quantity of fatty acids is obtained. These con- sisting principally of oleic acid are separated by this process as hydrates and their weight must be multiplied by 0.97 to obtain the amount of anhydrous acid. When “olein” soaps of commerce are to be analysed 50 C.C. of the ljolution are decomposed in a flask with a long neck graduated in c.c.so that on the addition of acid the whole of the separated acid may rise up into the neck and the volume read off this volume multi- plied by spec. gr. (0.9) gives its weight. If the soap be pure 50 C.C. of solution are evaporated to dryness on the water-bath and finally dried in a weighed dish; from the weight of anhydrous soap the quantity of water is calculated. If the soap be cut into thin shavings and these weighed and dried the amount of water found falls short of the true amount by 1or 2 per cent. Should mineral impurities and unsaponified fat be present they may be detected by dissolving the anhydrous soap in alcohol and filtering through a hot funnel the mineral irnpiirjties remaining on the filter the alcoholic filtrate is evaporated mith successive additions of ABSTRACTS OF CHEMICAL PAPERS.distilled water. The unsaponified fat or resin remains undissolved in the alcohol. E. W. P.

ISSN:0368-1769    

DOI:10.1039/JS8773100735

出版商:RSC    

年代:1877

数据来源: RSC

摘要:

ABSTRACTS OF CHEMICAL PAPERS. Technic a1 Chemistry. Photography. Investigations on Iron-developers. By R ofr-TIER aild WALDACK (Cl~em.Centr. 1876 90).-These investiptions were carried out with the view of ascertaining which are the sub-stances most suitable for the composition of iron-developers and what are tJhe conditions under which they give the most favourable results. All the experiments were made on the wet collodion process and in each experiment two negatives were prepared under the same condi- tions and treated with different developers. In order to obtain two equally latent images a stereoscopic apparatus with a glass plate of 1'3by 1.1 cm. was employed the objects taken being the same in each case. After exposure to light in the camera a strip of glass was placed in the middle of the layer and first one half of the plate de- veloped then the other half.In another experiment the glass was scratched along the middle by a diamond and after preparation and exposure broken in half. The following observations were made :-1. Il/jluence uf a Commitrated Iron Solution.-It was found t)hat while u dilu+,e solution developed slowly a thin transparent violet image concentrat'ed solutions gave at once dark dense pictures. A weak solution penetrates through the layer of the collodion producing a precipitate of silver throughout the whole of its thickness while a coricelztrated so1ut;ion yields an image only on the surface of the layer. The stronger the solutions the stronger are the negatives. The manner in which the development takes place apart from the concentration of the solution influences the consistency of the precipitate to some extent different results being obtained accordingly as the developer is left at rest on the glass or moved up and down it.2. Injluence of Acids.-In the above-mentioned experiments solutions of ferrous sulphate without addition of acid were used. It is known that the development of images is retarded by acids different acids showing different results. Organic acids in general produce black precipitates excepting acetic acid which gives a very clean negative and is of great value to the photographer. Glacial acetic acid com- mercial acetic acid and wood-vinegar all give the same results. Sul-phurous acid yields a worthless picture whilst the action of sulphuric acid is as advantageous as that of acetic acid.The greater the quantity of acid used with the developers the less quickly is the pliotoyraph developed and the weaker is the negative obtained. 3. hijluence o,f Various Iron Salts.-With salts other than ferrous sulphate difI'erent results are obtained. With regard to the fineness aud strength of the images obtained the ibllowing order is given:-1. Fw~ousnitrate develops weak images. 2. Ferrous sdphate. No difference is perceived in the results of this preparation either obtained TECHNICAL CHEMISTRY. from the metal or from its ores by the action of sulphuric acid. 3. A mixture of equivalents of ferrous sulphats and cupric sulpphate acts in the same manner as ferrous sulphate alone.4. AvrL??zorLio-fe,*rou.sszslphate. 'this salt has a more advantageous action than ferrous sulphate less time being required for exposure. 5. Fewous acetate is to be pre- f'erred to the former as it requires still less time of exposuie to the light. 4. Otservafionsregayding the Use of Feryous Acetate.-By adding a small quantity of ferrous acetate to the ordinary iron-developer its sensitiveness is increased very considerably intense negatives of har- monious tone being obtained. With too large a quantity of the ace- tate however a confused photograph is obtained. Indeed the extraordinary sensitiveness of this salt which enables it to produce negatives of great intensitly renders its action on the other hand too rapid for the development of powerful pictures.D. B. Preparation of Soluble Glass from Fossil Meal. By F. C AP r-TA I NE (Dir?y2.yolyt. J. ccxxii 363-366).-The use of fossil meal for the preparation of soluble glass was proposed twenty years ago (Dingl. yolyt. J. 1857 143 p. 210 and 237) but has not yet been adopted to any great extent soluble glass being prepared in England where flint is cheap and abunciant by boiling flint in caustic lyes and on tlie Continent by first preparing a glass by fusing sand soda sulphate and coal and then dissolving it in water under pressure. When flint is boiled with caustic lye of 1.25 to 1.3 sp. gr. for six to eight hours at a pressure of 4+ to 6 atmospheres,it yields a strongly alkaline glass the proportion of alkali to the silicic acid being about I 2.Fossil meal on the contrary when boiled for three to four hours with lyes of 1.2 sp.gr. at a pressure of 3 atmospheres gives a much more neutral product the quantity of silicic acid in which is three times that of the a!kali. It is of course necessary to calcine the meal before treating it with caustic alkali but as it is necessary to remove all traces of undecomposed organic impurities the calcination process is rather long and troublesome. As the meal is now however brought into commerce in a calcined state and at proportionately lower prices the author was induced to undertake a series of evper -ments on a large scale. He used caustic soda solutions of 1.22 to 1.24 sp. gr. An agittktor was filled to about 60 per cent.of its volume with this solution and calcined fossil meal added using 1 part by weight of sodie hydrate to 2.8 parts by weight of pure fossil meal. The mixtIure nas then agitated for three hours at a pressure of 3 atmo-spheres and the operation i.e. complete solution of silicic acid fiinished when a portion from the agitator settled very quickly. f? loo concentrated solutions of sp. gr. 1.3 for example gzve UP-satisfactory results the clarifying process being retarded while the specific gravity of the product was too high. To obtain potash glass the boiling must be continued for 1-2 hours longer and 10-1.5 p.c. more meal used. D. B. Use of Soluble-glass in the Textile-industry. Ry H. GROTHE ((%em. C'et~tr-. 1876 92-93).-'l'his paper was worked out by the i58 ABSTRACTS OF CHEMICAL PAPERS.?uthor based on van Baerle's accounts regarding the prospects and practical uses which this substance at the present time affords to com- merce. 1. Soluble Glass used in the Textile industry ad in fhe Pqer Manu--fi~ctzc~e.a. FOYdorvzestic washing purposes.-The action of this coni- position depends upon its rapid and energetic solution of the sweat and fat through which particles of dirt adhere to materials. It sm~estherefore not exactly for washing but for loosening the dirt by the energetic dissolving action of the soda. A hot solution of the composition also takes up sweat fat and tannin from the skin of tilt hmds when the cloths are rubbed in it. Although the material is freed from sweat and fatty ingredients its fibre and colour is not attacked.This composition is used in the following manner The articles without previous soaking are placed in a lukewarni solution of the composition (a tub holding from 6 to 10 pails requires 1lb. of composition) covered with a cloth or lid and kept in this solntion over-night. The next morning the whole is stirred up with a stick and the dirty liquor run of€. The articles (linen or cotton either coloured or white) are then treated with a hot solution of 1to 2 lbs. of composition stirred up taken out separately steeped in a tub of lukewarm water and if they show signs of dry dirt (fat or sweat no longer present) they are washed or brushed with common fat-soap. Linen or cotton if free from albuminous substances (blood pus nasal mucus) may at once be treated with a very hot solut-ion of com-position.Woollen and silk articles may be treated in a similav manner using a warm solution for the former and a lukewarm solu- tion for the latter. Woollen articles do not shrink after this treat-ment. Coloured woollen or silk articles are washed with lukewarm water ; white woollen or silk materials with cold water after having been previously pressed. Materials treated with soluble glass are always without smell much cleaner and never yellow in colour. b. For bleaclLing.-The use of soluble glass as a bleacher will become of great importance in the future. The author's experiments made ill large bleach-works lead him to ihe conclusion as destined to superseclo soda in bleaching operations.Substances like jute (Calcutta hemp) which hitherto could not be bleached without injuring their fibres are bleached successfully by the followiny method Jute materials are placed in a hot solution of soluble glass at 70-80" R. for 15 to 20 minutes (using 100lbs. of water for 6-8lbs. of soltible glass) arid stirred up with a stick; they are then washed in hot water (not boiling) afterwards in cold water bleached in a weak chlorine-bath and lastly in an acid bath. Jute thus bleached will doubtless be available not2 only as a fine white pulp tor the paper manufacture but also for the manufacture of fine white spun-goods. Instead of boiling hemp aid cotton-yarns for 6 to 8 hours in a concentrated soda solu-tion they need merely be moved about in a very hot bath of soluble glass for.10to 15 minutes ; 100 kilos. of linen-yarn require 12-15 kilos. soluble glass the cost of which is 30 per cent. less than the 10 kilos. of' 90" B. calcined soda solution generally used. All the baths may be uscd for three operations. c. For jirzishing linen or cotton goods in place of Chinu-clay.-Soluble TECHXICAL CHEMISTRY. glass is preferable for this purpose to China-clay as it is whiter in velour and can be formed by chemical reaction in the finest fibres of textures. In order to obtain the precipitate a piece of linen or cotton is passed through a hot solution of alum and then through a hot solu-tion of soluble glass to which a small amount of glycerin is added.After this the material is passed through a weak starch-bath and then tlirough warm cylinders. d. For i?~i;vregnating.-Packina cloth jute-mats &c. may be ren- dered fire-proof and materials used for covering waggons tents &c. may be made waterproof by impregnating them with a solution of soluble glass. D. 13. Extraction of Sulphur. (CYhem. Centr. 1876 p. 34).-Native sulphur is usually associated with gypsum. When sulphur and gypsum are heated together to 130° the gypsum is dehydrated; at. 440' or so the anhydrite is reduced to calcium sulphide by the action of the sulphur. CaSOa + 2s = 2S02+ CaS. In the ordinary process of sulphur distillation this reaction doubt- less takes place. Chalk exerts a more prejudicial action than gypsum.M. M. P. M. Extraction of the so-called Soluble Phosphoric Acid from Superphosphates. By E. EEL E N M E Y E R (Dezit. Chem. Ges. Ber. ix 1835-184O).-The author remarks that one partl of acid phosphate of calcium is soluble in two parts of water and that the same salt is decomposed by a small proportion of water into free phosphoric acid and insoluble diphosphate of calcium. This renders Marker's process (Zeifschr.f. Anal. Clzem. 12 s. 275) for the extraction of phosphoric acid applicable with accuracy only to those superphcwphates which contain enough free phosphoric acid to prevent the above decomposition. The same applies also to the method of digestion hitherto used for the same bodies. C. L. F. Dephosphorisation of Iron Ores (Jacobi's Method).By A. GAUTI ER (Chmt. Cedr. 1876 1691.-Jacobi published this method in 1870 and since that time he has used it at the Adslbert iouridry at Kladno. Gautier inspected these works and gave the following accounts The ores which are worked up at Kladrio contain after being roasted 1&p.c. of phosphorus. The roasted ore is placed in large tanks the sides of which consist of wooden boards. They hold 10,000 cwts. Iron pyrites is roasted in furnaces with horizontal bottom similar to those used in the manufacture of sulphuric acid ; the sulphurous acid is condensed with water in separate apparatus and then passed into the lixiviating vessels. This solution is left in contact with the ore for 24 hours afher which the vessel is emptied arid the liquid run through an iron worm where it is heated to 80 or 90°C.The excess of sulphurous acid escapes yielding about 30 per cent. of the originally prepared quantity. The liynid is transferred to another vessel where it deposits impure phosphate of alumina in the form of a white 760 ABSTRACTS OF CHEMICAL PAPERS. powder. The average composition of the roasted ore before and after dephosphorising is as follotvs :-Before. After. Iron ...... 43 p.c. 46 p.c. Alumina .. 14-18 6-8 Silicic acid . 14-16 20-22 1 Phosphorus. 19 During the working. samples were drawn which gave the following percentages of phosphorus :- Ore. Raw iron. Puddled iron. Raw ore .............. 1.1-1-2 1.7-2-1 0.8-0.9 Ore treated with sulphur- ous acid............ 0.2-0.3 0.5-0.6 0.1-0.2 Ore washed with water. . 0*5-0-6 1-0-1*1 - Dephosphorisation takes place to a considerable extent when the ore is lixiviated merely with water. Since the ore is siliceous snl- phuric acid and sulphates are formed which dissolve the phosphates in presence of water. The object of this very sinipfe lixiviating pro-cess is to produce a carboniferous raw iron (foundry-pig) ;the sulphur facilitates the solution of carbon and rendem the formation of a grey pig difficult. D. B. Flooring Slabs. (Chem. Cent?. 1876 93).-For several years flooring-slabs have been used in Berlin N-hich although they do not possess the gre3t hardness of the well known “Mettlach flags,” are nevertheless very suitable for flooring purposes on account of their durability aid their pleasing colours.These slabs are obtained from various establishments on the Rhine and in Lorraine and if well finished show either a fine straw-yellow or a deep black colour. Seger thought it advisable to ascertain whether the material had been dyed black by additions of metallic bodies or whether in its yeparation the “steaniing ” method had been employed. He there- fore analysed a yellow and also a black specimen with the following results :-Alkalis SiOa. A120,. Fe203. FeO. MnO. CaO. MgO. C. andloss. Yellow 51.84 19.71 2.34 -traces 23.35 0.60 -2.16-1WOOp.c. Black 52.87 1995 -1.97 traces 22.88 0.45 0.38 1*61=100*00 , These numbers show that the black colour is not produced by addition of colouring matters since in both cases the composition is ))early the same. The black colonr therefore -must have been ob- t,ained by steaming and judging from the small amount of iron the 1)resence of carbon and the regularity of the black coloration it seems highly probable that the blackening was carried out in moulds sur-younded by powdered fuel. D. B.

ISSN:0368-1769    

DOI:10.1039/JS8773100756

出版商:RSC    

年代:1877

数据来源: RSC