ii. 44 ABSTRACTS OF CHEMICAL PAPERS. Analytical Chemistry. Purification of Filter Paper by Hydrofluoric Acid. A. GAWALOWSKI (Zcitsch. nizcll. Chew. 1915 54 5OS).-Treatment of filter-paper with hydrofluoric acid results in the removal of silica but any calcium and iron salts which may be present are converted into their respective fluorides ; calcium fluoride is insoluble and ferric fluoside is very slightly soluble in water and although the latter may be removed by prolonged washing of the paper care must be taken that the wash-water is free from even traces of ammonium potassium or sodium salts since these convert the ferric fluoxide into a still less soluble double salt. The hydro- fluoric acid solution used t o remove the silica from the paper should be very dilute and the paper should then be washed thor- oughly; otherwise the paper becomes “hardened.” W.P. S. Use of the Colouring Substance of Red Cabbage as a n Indicator. ECKERLIN (Chem. Zentr. 1916 ii 489-490 ; from Mztt. I<. Lumkmnst. Wcuserhygienc 1915 58- 69).-A solution of the indicator is obtained by boiling red cabbage leaves for thirty minutes with three times their weight of water filtering the extract and after cooling neutralisiiig i t with N / 100-potassium hydroxide solution. The indicator is green in alkaline solution and red in acid solution; a t the neutral point in the presence of alkali salts the colour is bright blue although the neutral indicator itself is violet. The indicator solution may be preserved by the addition of 0.2% of chloroform o r 0.9% of phenol and should be stored in the dark (compare A.1913 ii 237 522). w. P. s. Some New Indicators for the Colorimetric Determination of Hydrogen Ion Concentration. HERBERT A. LUBS and WILLIAM MANSFIELD CLARK ( J . Wc~shiizgton Acnd. Sci. 1915 5 609-617).- The authors have pxepared and investigated a number of substances of the methyl-red type with the object of ascertaining their use for the estimation of the hydrogen-ion concentration in bacterial media. Among those newIy prepared were monoethycred [ethyl- amino b enze?ze-o-a.zob e?izoic acid] which gives colour changes over the range P’r 4*25-Pf 6.00; diethyl-red (diethylaminobenzene- o-azobmzoic acid) colour changes over the range Pf 4.50-Pb 6 - 5 0 ; monopropyl-red f o r the range Pf 4.25-Pk 6.25; and dipro&-ANALYTICAL CHEMISTRY.ii. 45 red f o r the range Pf 4*50-P+ 6.50. Of indicators already known the following have been investigated t o ascertain tlie range of concentration over which they may be used monomethyl-red (Pi 4-2-Pi 6.3); a-naphthylamine-red (Pz values of little use f o r the present purpose) ; dimethyl - a - iiaphtliylamine -red (P; 4-50-P$ 6.50) ; and diphenylarnine-red (P ;I 4.25-Pfi 5.50). the symbol PS is defined as log. 1 /CIT w1iei.e C is the concentra- tion of the hydrogen ion. A number of indicators of the sulphone-phtlialein type have been prepared by a new method and investigated. The method consists in tlie action of the phenol in question on the acid chloride of o-sulphobenzoic acid in the presence of zinc chloride. The follow- ing substances were prepared and the range of usefulness deter- mined phenolsulphonephthalein (P$ 6.50-PL 8.50) ; o-cresol- sulphonephthalein (P!r values similar t o those of the phenol com- pound) ; thymolsulphonephthalein (P$ S.O-Pf 9.75) ; a-naphthol- sulphonephthalein (P$ 7.50-Pz 9-00> ; tetrabromophenolsul- phonephthalein (P; 3.50-P f 4.50) ; and bromothymolsul- phonephthalein (Pi 6.00-P-f; 7.25). Full details of the method of application of all the indicators mentioned are given in the paper.J. I?. S. Qualitative Micro-analysis. E. EMICH (Zeitsch. ctizcil. Chevz. 1915 54 489-502).-Directions and methods are given for the preparation of reagents used in micro-chemical tests and for the manipulation of precipitates etc. in capillaries. The presence of nitrogen in 0.002 mg.of urea may be detected by heating this quantlity of the substance with calcium carbonate and allowing the ammonia formed to come into contact with a minute fragment of red litmus paper contained in the capillary in which the mixture is heated; the ammonia may also be identified by means of its reaction with platinum chloride. A quantity of 0.0002 mc. of mercury can be detected by heating a drop of the solution containing the mercury with a piece of copper wire a few mm. in length and 0.1 mm. in diameter then transferring the wire t o a capillary and subliming the mercury ; the sublimed mercury may also be identified by converting it into the iodide. W. P. S. Activation of Chlorate Solutions by Osmium. 111. Separa- tion of Rydrogen and Methane Catalysis of Mixtures of Hydrogen and Oxygen.K. A. HOFMANN and OTTO SCHNEIDER (Ber. 1915 48 1585-1593. Compare A. 1913 ii 62 609).-The behaviour of various noble metals towards oxidisable gases in the presence of chlorate solutions has been studied. Preparations were made by evaporating the salts of the metlals in quantities equiva- lent t o 1 gram of potassium osmate to dryness with formic acid and then adding a solution containing 15 grams of sodium chlorate and 2 grams of sodium hydrogen carbonate to 100 C.C. These mixtures were tested against the gases in a Hempel pipett'e. Towards hydrogen the activity decreased in the order P t Rh Ru Pd Au Os Ir Ag the higheik absorption being only 18 C.C. inii. 46 ABSTRACTS OF CHEMICAL PAPERS. twenty-four hours.Carbon monoxide was even less absorbed the highest rate being 11 C.C. per day and the order Os Rh Au Pt Ru Pd Ir Ag. Methane and ethylene were scarcely absorbed a t all. The addition of an equimolecular quantity of osmium dioxide to these catalysts frequently gave a mixture that was much more active towards hydrogen or carbon monoxide than the two catalysts separately this being particularly so in the case of palladium. It has been the aim of the authors t o improve the rate of absorption of hydrogen so as to apply an activated chlorate solution in the estimation of hydrogen and they have devised an absorbent which is prepared as follows Tubes o r rods of porous earthenware are steepe-d in 5% platinic chloride solution then ignited in a flame so that they are covered with thin films of platinum and packed into a Hempel pipette with the platinised ends uppermost.The pipethe is then filled with a solution containing 35 grams of sodium chlorate 5 grams of sodium hydrogen carbonate 0.05 gram of palladous chloride and 0.02 gram of osmium dioxide in 250 C.C. Such a mixture becomes more active after using it a time or two and can easily be arranged to absorb about 100 C.C. of hydrogen per hour without shaking whilst thel one quantity will oxidise slightly more than 22 litres. The cost of the soluble catalysts is only a few pence. The contact “poisons” are usually removed before i t is neces- sary t o estimate hydrogen in a gaseous mixture but having done this the above absorbent gives excellent results with pure hydro- gen and mixtures of hydrocen and methane with or without nitrogen. Although oxygen alone is not absorbed yet when mixed with hydrogen some of it takes part in the oxidation.This has led t o a study of the catalysis of mixtures of hydrogen and oxygen that is the oxidation of hydrogen under the influence of the above absorbent with the difference that the chlorate was left out’. Hydrogen alone is scarcely absorbed a t all. The speed of the oxidation is influenced by the composition of the gaseous mixture and is greatest not with electrolytic gas but with a mixture containing more hydrogen. Higher concentrations of oxywn have a bad retarding effect’ owinp. no doubt t o an action ~n the catalyst’ but this is overcome by dilutinq with nitrogen o r nitrown and methane. That is mixtures of hydrogen and air soon give the correct absorption calculated f o r the gas which happens not to be in excess.Carbon monoxide is much more slowly oxidised by the above combination of catalvsts than hydrogen but strange t o say i t does not “coison” the mixture for this is just as useful for hvdrogen after being treated with carbon monoxide as before. Neither does a change in the reaction of the solution affect the catalyst much for phosphoric acid may replace the sodium hydrogen carbonate without changing the activity. J. C. W. Estimat;on of Hvgroscopic Moisture in Soils. W. 1). HAIGH (Sci. Proc. Roy. Dublin Soc. 1915 [S.S.] 14 5%-534).-The soilAKALY TICAL CHEMISTRY. ii. 47 is mixed with about three times its weight of calcium carbide and the acetylene evolved measured after a few minutes.The apparatus employed is similar to that described by Masson (T. 1910 97 851). The results obtained by this method were slightly lower than those obtained by heating the soil in zn oven for sixteen hours. M7hen much organic matter is present as in peat for instance the difference between the two methods is greater which seems to be due to the loss of volat,ile substances other than water when the soils are heated. Soil which was heated for several hours a t 180° and then exposed t o the air for several days gave results by the two methods zgreeing within 0.04%. It was found that 0.018 gram of water gives 10.5 C.C. of acetylene; the theoretical amount is 11.2 C.C. N. H. J. M. Estimation of Total Chlorine in Caoutchouc Substitutes.A. HUTIN (Aim. Chim. cmal. 1915 20 241- 242). - From 0.2 to 0.5 gram of the substance is placed in a crucible the latter is about one-half filled with a mixture of sodium carbonate and potassium nitrate and then heated until gases burning with a luminous flame are no longer evolved and the mixture is melted. After cooling the contents of the crucible are dissolved in dilute nitric acid and the chlorine is estimated volumetxically. w. P. s. Estimation of Fluorine. WILLIAM H. A 4 ~ ~ ~ ( J . Anzer. Chem. SOC. 19 15 37 2500-2515).-Practicall;y the whole of the methods hitherto proposed for the estimation of fluorine have been subjected to a critical experimental examination. As the result of a large number of experiments it is shown that the Berzelius-Rose method of fusion of insoluble fluorides will give good results and account for the whole of the fluorine in the mineral if the residue insoluble in water after the first fusion is submitted to a second fusion.I n studying the Offermann method by which the fluoride mixed with silica is converted into silicon tetrafluoride which is decom- posed by water and the solution titrated with alkali it is shown that although the results are always low the best results are to be obtained by using 98.6% sulphuric acid a t 200-220° and employ- in5 powdered quartz. The estimation of soluble fluorides is best effected by precipitation as lesd chlorofluoride. The precipitate in this case is washed by means of a saturated solution of lead chlorofluoride. The only satisfactory method of detecting and estimating fluorine in small quantities is the colorimetric method of Steiger-Merwin.J. F. S. Estimation of Oxygen by Winkler’s Method. G. BRUHNS (Chenz. Zeit. 1915 39 845-848).-Tlie author discusses Winkler’s modified method f o r the estimation of oxygen in waters (A. 1915 ii 277) and suggests further manipulative simplification such as keeping the potassium iodide in the solid form and adding a small crystal immediately before’ acidification and conducting the titra-ti. 48 ABSTRACTS OF CHEMICAL PAPERS. tion in the original bottles after withdrawing a small measured volume t o make room for the thiosulphate solution required for the absorption of the iodine. Also in cases where nitrites o r organic matter is present instead of using carbon dioxide gas f o r converting the manganous hydro'xide into carbonate the addition of about 1.5 grams of solid potassium hydrogen carbonate is recom- mended. The precipitate rapidly settles and the supernatant liquid can be removed and the precipitate washed without removal from the bodtle by decantation followed by upward filtration through a plug of cotton-wool placed in a fairly wide glass tube a t the upper end of which suction can be applied.Three rinsings with wash water are sufficient. G. F. M. Determination of Gases Dissolved in Waters and Effluents. A. A. SWANSON and G. ,4. HULETT (J. Anzc~.. Chcnz. Soc. 1915 37 2490-2500).-A method of determining the amount of gases dissolved in waters is described. This method is applicable in all cases whether the water contains oxidisable material which would effect all tiiximetric methods o r for gases to which chemical methods are not applicable for example nitrogen.The method consists in principle in shaking a known volume of the water in a vacuum until the gas has distributed itself between the vacuum and the liquid and set up an equilibrium. This gas is then withdrawn t o a gas analysis apparatus and analysed in the usual way. From the volumes of t h e water and vacuum and the1 partial pressures of the gas in equilibrium in the vacuum with that in the water the total coiicentration of the gas originally present is calculated. I n the case of oxygen a modification is introduced. A volume of water is shaken with a known volume of hydrogen and the oxygen in the gas phase determined by passing the mixture over heated copper.Apparatus suitable for carrying out the above operations is described in detail in the1 paper. J. F. S. Method for the Estimation of Inorganic Phosphorus in Body Tissues and Fluids. A. COSTANTINO (Chem. Zentr. 1915 ii 287 ; from Arch. Farmacol. sperim. 1915 19 307-316).-The substance or fluid is treated with acid mercuric chloride solution (see this vol. ii 62) excess of mercury is removed as sulphidel the' solution is neutralised and treated with 25 C.C. of 10% barium nitrate solution and 1 2 C.C. of 10% ammonia. After twelve hours the pre- cipit'ate is collected washed with a solution containing 0.1% of barium nitrate and 0.1% of ammonia then dissolved in dilute nitric acid and the phosphoric acid estimated by the molybdic acid method.w. P. s. Estimation of the Citric Acid Soluble Phosphates by the Ferric Citrate Method. N. ZACHARIADES and J. CZAK (Chenz. Zentr. 191 5 ii 724 ; from Zeitsch. landzc. Versiich.c.- Wesen Oes ferr. 1915 18 472-475).-The authors consider Popp's method for the estimation of phosphates in Thomas slag t o be preferable t o the Darmstadb hydrochloric acid method and to give more accurateANALYTICAL CHEMISTRY. ii. 49 results. They point out that addition of hydrogen peroxide for the oxidation of any hydrogen sulphide compounds is usually superfluous and secondly that i t is quite unnecessary to filter off the precipitate a t once; it may without prejudice remain over- night. G. F. M. Purification and Physiological Action of Animal Charcoal.A. G. BARLADEAN (Pharm. Zentr.-h. 1915 5 6 683-687).-Animal charcoal usually contains impurities some of which are soluble in water and some in alkali or acid. Non-carbonised organic material is also frequently present. After recarbonisation and repeated extraction with alkali acid and water animal charcoal still retains salts which are sufficient to double1 o r hreble the growth of the rootlets of germinating wheat corns (Triticum sa"tivum) immersed in distilled water and animal charcoal as compared with those immersed in distilled water alone. H. W. B. Detection of Carbon Monoxide in Blood. KNUD SAND ( J . Pharm. Cham. 1915 [vii] 12 366-368; from Am,. hyg. pub. vied. Zkgnle 19 15 222).-The suspected specimen of blood is compared spectroscopically with normal blood and with blood saturated with carbon monoxide.I n each case 10 C.C. of a 3% dilution of the blood is taken and treated with about fifteen drops of a solution of iodine in potassium iodide which transforms the hzemoglobin into methzemoglobin whilst the carbon monoxide-hzemoglobin remains unchanged. The solutions are then filtered and examined by the spectroscope. The author states that in this way 5% of carbon monoxide in blood can be detected. H. W. B. Apparatus for the Transference of Gases used in Hesse's Method for the Estimation of Atmospheric Carbon Dioxide. EMIL GROZEA (Chenz. Zentr. 1915 ii 297-298; from Bzd. Snc. Ftiinte BzLcurestz 1914 16 156-159).-The air is originally contained in :I holder supplied with a tap above and one below.The gas is displaced from this holder by water entering a t the lower tap and passes through the upper tap into a Hesse flask. This flask is originally filled with water but as the air enters a corresponding amount of water flows out the cork being doubly bored and fitted with tubes f o r this purpose. The carbon dioxide in the transferred air is then estimated by titration with barium hydroxide solution. D. F. T. Estimation of Carbon Dioxide in Carbonates Decomposed by Ammonium Chloride Solutions. A. CAVAZZI (Ann. Chinz. Applicata 191 5 4 137-144).--The carbonates of calcium barium strontium magnesium zinc lead cadmium bismuth copper lithium sodium potassium and probably other metals ar0 gradu- ally decomposed and dissolved by boiling ammonium chloride solution chlorides of the metals being formed and the carbon dioxide liberated as ammonium carbonate (compare A.1915 ii 795). The latter may then be passed into an ammoniacal calciumii. 50 ABSTRACTS OF CHEMICAL PAPERS. chloride solution and the carbon dioxide estimated as calcium carbonate by titration with acid. This method is not affected by the presence in the carbonate of organic matter and avoids the inconveniences caused by such impurities as hydrogen sulphide sulphur dioxide etc. sometinies contained in the gas liberated by acid from complex mixtures like cements. When the carbonate is insoluble in water the mixture containing i t must be very finely powdered in an agate mortar; even with precipitated carbonates this treatment is recommended. The method has been applied t o argillaceous limestone cement soil ash alkali carbonate mixture of the latter with alkali hydroxide white lead bismuth carbonate malachite azurite siderite etc.T. H. P. The Interaction of Perchloric Acid and Potassium Sulphate a8 an Example of Reversible Change. WILLIAM ALFRED DAVIS (T. 1916 107 1678-1681).-Tt is shown t h a t potassium may be accurately estimated by the perchlorate method even in presence of sulphates if the residual solution contains a sufficient excess of perchloric acid. I f the evaporation is continued so as t o expel the greater portion of the perchloric acid the precipitate is con- taminated with hydrated potassium hydrogen sulphate which increases the weight of the precipitate and thus leads to high results. In general practice i t is advisable however t o eliminate the sulphate by evaporating with the addition of baryta igniting very gently and using the aqueous extract for evaposation with per- chloric acid.The treatment with baryta removes not only sulphate but also silica magnesium and phosphates. (KH SO,,H,O) H. M. D. The Estimatinn of Small Quantities of Po+a,ssinrn. A. J. HAMBURGER (Riochem. Zeitach. 1915 71 415-463).-The principle of the method consists in the precipitation of the potassium in the form of the pota-ssiliw sodium colnaltinitrite. C'o(NO2),*3(K / NaNO,),.nH,O which is then centrifuged and the volume of the preciDitate is measured. The cobalt> reagent is prepared by dissolving 50 grams of cobalt nitrite in 100 C.C. of water to which solution 50 C.C. of glacial acetic acid is added.A second solution is made by dis- solving 50 grams of sodium nitrite in 100 c . ~ . of water. Six parts by volume of the solution of the cobalt salt are mixed with ten parts hv volume of the solution of sodium nitrite shortly before use. Five C.C. of the solution containing the Dotassium salt are mixed with 1.5 C.C. of the cobalt solution and the mixture is kept f o r sixteen hours at 3 7 O . It is then introduced into a special form of funnel (of which an ihstration is given) which ends in a Cali- brated capillary tube of 0.04 C.C. capacity etched in 300 parts. each of which corresponds with 0*001 gram of potassium. The precipitate is separated by centrifugalisation into this tube and the volume is then determined. It is necessary t o keep t o the snecified con- ditions of experiment t o obtain satisfactory results which are notANALYTICAL CHEMISTRY.ii. 51 influenced by the presence of relatively large amounts of sodium nor by the presence of calcium magnesium or sulphates. Phos- phoric acid must however be removed and for this purpose a mixture of calcium chloride and hydroxide or magnesia mixture can be best employed. Attention is called to the advantages of this method as compared with others that have been used for the estimation of potassium. S. B. S. Estimation of Potassium in Fertilisers. FERDINAND PILZ (Chem. Zentr. 1915 ii 365 ; from Zeitsch. laizdw. Vers.-Wesen Osterr. 1915 18 77-108).-The author has investigated the per- chlorate method and recommends the following procedure for the estimation of potassium in fertilisers (A) In potaslh fertzlisers (potassium chloride Icainite etc.).-Ten grams of the sample are heated with 200 C.C.of water and 10 C.C. of concentrated hydro- chloric acid ; barium chloride solution is added in quantity sufficient t o precipitate all the sulphate present the mixture is cooled diluted to 500 c.c. and filtered. Twenty-five C.C. of the filtrate are transferred to a glass basin 10 C.C. of perchloric acid (D 1.125) are added and the mixture is heated until hydrochloric acid vapours are no longer given off; after cooling the contents of the basin are treated with 25 C.C. of alcohol containing 0.2% of perchloric acid the precipitate is rubbed down to a fine powder then collected in a Gooch crucible washed with the acid alcohol and dried at 120-130° for thirty minutes.The process must be carried out in an atmosphere free from ammonia vapours. (B) I n mixed f ertilisers (superpihosphates wood-ash etc.).-Ten grams of the sample are dissolved and the sulphate precipitated as described under (A); the solution is then rendered ammoniacal heated treated with ammonium carbonate cooled diluted t o 500 c.c. and filtered. Fifty C.C. of the filtrate are evaporated in a platinum basin the residue is dried and heated to expel ammonium salts then dissolved in water the solution filtered and the potassium precipitated with perchloric acid as described (compare Davis T. 1915 107 678). w. P. s. Determination of the Speciflc Electrical Conductivity in the Testing of Potable Watera.M. FORXAINI (Ann. Chim. Applicnta 1915 4 150-183).-According to Kohlrausch the amount of dissolved salts in an ordinary potable water is given in mg. per litre approximately by the expression 0.75 . x . 106 where x is the specific electrical conductivity of the water (compare Doroschevski and Dvorshantschik A. 1913 ii 1071). The author's investigations in this direction show that the water should be freed from gas by thorough shaking prior to the measure- ment of the conductivity and that care should be taken to avoid the formation on the electrode of gas bubbles which may alter the capacity and thus lead t o appreciable error. I n order to avoid the use of a thermostat the conductivity may be measured a t any temperature between Oo and 25O and the value corresponding with 1 8 O calculated from the formula xls=)it/[1 + 0*023(t - lS)]=xt.w t ;ii. 52 ABSTRACTS OF CHEMICAL PAPERS. a table is given showing the value of mt for each tenth of a degree between Oo and 25.9O. The proportions of organic matter normally present in natural waters have little influence on the conductivity and the silicic acid which varies from 0 to 0.1 gram per litre and may exist in the colloidal condition usually introduces an error of from 0% to 4-5% although in rare cases it may amount to 10%. A number of waters from different parts of Italy have been examined and the results indicate that 0.71 represents more nearly the average value of the coefficient of the above expression than Kohlrausch's value 0.75. Wit'h the former number the approxi- mation of the calculated t o the actual amount of salt present varies between -4.2% and 3.1%.Further it is found that if the saline residue calculated in mg. per litre according to Kohlrausch's ex- pression (factor 0.75) is diminished by the number of mg. corre- sponding with the total hardness determined by Clark's method and expressed in French degrees the resultant number differs from the actual salt content by from - 3.9% to + 2.1%. When the value of xis. 106 is less than 200 calculation of the saline residue from the conductivity gives somewhat untrustworthy results since observational errors become appreciable a t such dilu- tions unless indeed special precautions are taken. Further when xis. lo6 exceeds 700 anomalies become to increase in frequency and magnitude owing to the diminished dissociation of the dissolved salts and the greater complexity of the salt solution; in these cases it is advisable t o dilute the water with doubly distilled or con- ductivity water before measuring the conductivity.A bibliography is appended. Separation and Estimation of Aluminium and Glucinum by the use of Acetyl Chloride in Acetone. H. D. MINNIG (Amer. J. Sci. 1915 [ivl 40. 482-485).-The method of procedure is the same as that described for the separation of aluminium and iron (A. 1915 ii 107) aluminium being precipitated from concentrated solution as the hydrated chloride and weighed as oxide whilst glucinum remains in solution and is precipitated by ammonium hydroxide after diluting with water and warming on a steam-bath to volatilise the acetone.It is essential that the acetyl chloride be free from phosphorus compounds and it is accordingly best prepared from acetic anhydride by saturating with hydrogen chloride and distilling a t looo in a rapid current of the same gas. The insolu- bility of glucinurn chloride in the acetone-acetyl chloride mixture limits the process to the separation of quantities of the two elements which do not exceed the equivalent of 0.15 gram of the oxides and of this amount glucinum should not greatly exceed one- third otherwise there is a danger of inclusion of glucinum chloride in the aluminium precipitate. T. H. P. G. F. M. The Development of Electro-Analysis in America. EDGAR F. SMITH (T~nizs. Amer. Electrochem Soc. 1915 27 23-34).- Historical. A new method for the estimation of cobalt is described.The metal is converted into cobalt ammonium fluoride and electro-ANALYTICAL CHEMISTRY ii. 53 lysed in a platinum dish with 0.8 ampere and 2 volts. The cobalt is precipitated completely on the anode as the dioxide in a hydrated form which is weighed as Co30,. The separation from nickel is complete. The addition of ammonium fluoride is equally successful. C. H. D. The Quantitative Estimation of Nickel with Dimethyl- glyoxims. KARL WAGENMANN (Fermm 1915 12 126-129).- I n place of weighing the dried precipitate of nickel dimethyl- gfyoxime the metal may be deposited electrolytically. The dimethylglyoxime may be added in hot aqueous solution and the cold solution allowed t o remain twenty-four hours before filtration. It is then washed with hot water dissolved in dilute sulphuric acid boiled with a few drops of hydrochloric acid and hydrogen peroxide to destroy the oxinie and neutralised with ammonia.After the addition of an excess of concent’rated ammonia the nickel is deposited on a gauze electrode a t 70-80° in the usual manner for rapid analysis. Manganese if present as in the analysis of special steels may be kept in solution by addition of ammonium chloride. C. H. D. Action of Metallic Magnesium on Tin Antimony and Arsenic Sulphides. C. PERTUSI (Ann. Chinz. aisal. 1915 20 229-233).-When stannic sulphide is suspended in water and mixed with five times its weight of powdered magnesium it is reduced to1 stannous sulphide or metallic tin and hydrogen sulphide is evolved. Arsenic sulphide treated in a similar manner gives a t first a yellow solution from which hydrochloric acid precipitates arsenious sulphide; if the reaction is prolonged the whole of the arsenic may be removed from the solution.The addition of methyl alcohol tends to keep the arsenious sulphide in solution. Antimony sulphide reacts with magnesium in a similar way. The three elements in admixture as their sulphides may be detected as follows. A portion of the mixed sulphides is treated with mag- nesium powder and the mixture filtered as soon as the yellow colour changes to brown; the brown residue is dissolved in hydro- chloric acid and the heated solution treated with mercuric chloride when a grey precipitate indicates the presence of tin. Another portion of the sulphides is shaken for a few minutes with mag- nesium powder and 5 C.C.of methyl alcohol then heated slightly and filtered. The filtrate is acidified with hydrochloric acid; if arsenic is absent a slight precipitate of sulphur is obtained but if arsenic is present a yellow precipitate of arsenious sulphide is formed. A third portion of the precipitate is dissolved in con- centrated hydrochloric acid and a drop of 1% mercuric chloride solution and an excess of potassium hydroxide solution are added; a black turbidity indicates the presence of antimony. WELTON J. CROOK (Chem. LVezus 1915 112 237-238 ; from Chem. Eiujineer 1915 21).-To estimate the soluble acidity of ores a portion of the W. P. S. Testing of Ores for the Cyanide Process.ii. 54 ABSTRACTS OF CHEMICAL PAPERS. finely-ground sample is shaken for one hour with water the mix- ture then filtered and a portion of the filtrate titrated with standard sodium hydroxide solution using phenolphthalein as indicator.The total acidity is estimated by shaking a definite quantity of the sample for six hours with 100 C.C. of the sodium hydroxide solution filtering the mixture and titrating the residual alkalinity with oxalic acid solution. The difference between the total acidity and the soluble acidity gives the “ latent ” acidity of the ore that is the acidity due t o salts sulphides insoluble sub- stances etc. The quantities of the ore taken for the estimations and the strength of the alkali and acid solutions used are such that the results obtained expressed in C.C.of the alkali solution give directly the number of pounds of lime t o be added t o 1 ton of the ore to neutralise its acidity. w. P. s. Differentiation of ‘‘ Benzine ” [Light Petroleum] and Benz- ene. HERM. MIX (KoZZoZd Zeitsch. 1915 17 7-9).-A resin extracted from dragon’s-blood obtained from Sumatra is recom- mended for the differentiation of “ benzine ” and benzene. The resin has a deep red colour and after treatment with hot petroleum (heavy and light) it is inactive towards “benzine ” in the cold but gives a deep coloration when acted on by benzene. The resin has been named dracorubin and in the form of coloured test-papers it may be used for the approximate estimation of benzene in com- mercial samples of “ benzine.” The behaviour of dracorubin tesb papers on treatment with various organic liquids (pure and com- mercial) has been examined in detail.H. M. D. Physico-chemical Studies on Wines Electrolytic Dissocia- tion Constant of Wines. (MLLE.) CLELIA DI MAIO (Ann. Chiin,. AppZzcata 1915 4 245-2265~.-Measurements made on a series of ten wines give the following results I n genuine wines the process of electrolytic dissociation follows with good approximation the law of dilution. The dissociation constant K varies with different wines but the variations lie within narrow limits; a means is thus furnished of determining adulteration with strong mineral acids. With nine wines the mean value of K was found t o bO 0.0184 +0*0016 with a probable error of 9.1%. Besides modifying considerably the value of the dissociation constant the addition to wine of strong mineral acids in greater proportion than 0.05% effects an appreciable alteratio’n in its degree of constancy owing t o the prevalence of strong electrolytes which do not conform to the laws of dilution.Lack of constancy of K may also be observed in wines of low natural acidity which have been treated with meta- bisulpliib. T. H. P. Jaundice Produced by the Absorption of Picric Acid. Analysis of the Blood and Urine under this Condition. POGNAN and B. SAUTON (J. Phawiz. Chim. 1915 [vii] 12 360-352).-The picric acid is first extracted by ether or benzene from the urine or blood and is then recognised by the usual tests. The resultsANALYTICAL CREMISTRY. ii. 55 show that tliere is not the slightest difficulty in distinguishing between pathological jaundice and the condition produced by the absorption of picric acid.Recognition of Picric Acid in Urine in the Presence o r Absence of Biliary Pigments. VILLEDIEU and MANCEAU ( J . Pharm. Chim. 1915 [vii] 12 366 ; from Arch. med. pharm. nzilzt. 1915 64 255).-The method depends on the solubility of barium picrate and the insolubility of biliary pigments in the presence of salts of the alkaline1 earths. To 100 C.C. of urine are added about 20 C.C. of a saturated solution of barium chloride. The mixture is shaken filtered and the precipitate washed with 10-15 C.C. of boiling water. The filtrate and washings are treated with excess of sulphuric acid (about 5 c.c.) and after removal of the precipi- tate extracted twice with 20 C.C.of ether. After evaporation of the ether the residue is dissolved in 2 C.C. of boiling water filtered and tested for picric acid in the following ways (1) 2 drops of the liquid on a microscopic slide1 are mixed with 2 drops of a 10% solution of cocaina hydrochloride; tufts of silken crystals of cocaine picrate are observed under the microscope; (2) 10 drops of the liquid are mixed with 2 o r 3 drops of alkaline potassium cyanide; a dark red colour appears on heating; (3) a piece of wool is dipped into 10 drops of the liquid diluted with water and heated on the water-bath; the wool is dyed yellow and the colour is not removed by washing in water. H. W. B. LEOPOLD KADL- UERGER (Chem. Zeiztr. 1915 ii 493 ; from Oster?-.-ung. Zeztsch Lz~cker-z7zd. 1915 44 261-26.1.Compare A. 1912 i 1020; 1913 I 1386).-'1he author considers that the diphenylamine reaction of l m d o s e takes place in two stages; the diphenylamine is first con- verted by the concentrated sulphuric acid into diphenylbenzidine and this is then oxidised by the laevulose into A'-phenyldi-imine- p-diphenoquinone an indamine. The blue colour reaction of carbohydrates described by Ihl (Chem. Zezt. 1885 9 451) with diphenylamine is probably due to1 the fact that carbohydrates yield laevulose and dextrose when heated a t 68O and that both the H. W. B. The Diphenylamine Reaction of Lze vulose. latter act as oxidising substances. w. P. s. Action of Copper Solutions in Sucrose. Estimation 01 Invert-sugar in the Presence of Sucrose. MILE SAILLARD (C'ompt. rend. 191 5 16 1 59 1-593).-1n estimating invert-sugar in the presence of sucrose by the reduction of alkaline copper solu- tions the results obtained are always too high owing to a portion of the sucrose being attacked and then exerting a reducing action.This attack is more marked the more alkaline is the copper solution and i t varies with the amount of invert-sugar present. The author advises the use of a solution containing 69.26 grams of copper sulpliate per litre and a solution containing 346 grams of Rochelle salt and 130 grams of sodium hydroxide per litre. Ten C.C. of each of these solutions are mixed and heated for twenty-two minutesii. 56 ABSTRACTS OF CHEMICAL PAPERS. with 50 C.C. of the prepared sugar solution a t 62-64O. The blue filtrate from this estimation is similarly heated for a further twenty-two1 minutes and if this second heating precipitates less cuprous oxide than the first the sugar solution contains reducing sugars.Action of Sucroae on the Alkaline Copper Solution. L. MAQUENNE (Cow@. rend. 1915 161 61'7- 623. Compare Saillard preceding abstract).-Working with Barreswill's alkaline copper tartrate solution the author finds that with sucrose the amount of reduction increases rapidly with the1 concentration of the copper and the time of heating for a given concentration of sucrose. The reduction is apparently not due to a preliminary inversion of the sugar but to a direct oxidation of the sugar accompanied or followed possibly by hydrolysis. As the concentration of the suga.r solution increases the amount of cuprous oxide produced a t first increases rapidly to a maximum and then slowly decreases.This maximum effect is reached when the concentration of t4h0 sucrose with respect -to the total volume of solution is about 11%. It is probable that complex copper and potassium sucrates are formed the dissociation of which diminishes in the presence of the excess of sucrose thus seducing the alkalinity and active copper content of the liquid. The presence of inverbsugar acts in the same way as an excess of sucrose causing a diminution in the reduction due t o the sucrose. W. G. A table is given f o r calculating the results. W. G. New Method for the Estimation of Fatty Acids in Soaps. H. F. SLACK (Pharnz. J. 1915 95 696-697).-Fivegrams of the soap are heated with 10 C.C.of glycerol'until the soap has dis- solved; the mixture is theln acidified with 4 c . ~ . of hydrochloric acid (1 3) and the liberated fatty acids are drawn up into a graduated 5 C.C. pipette; hot water is added if necessary to bring the whole of the fatty acid into the pipette. The top of the latter is now closed and the pipette suspended in a water-bath a t 55O. The volume of the fat'ty acids is read a t this temperature; the volume multiplied by the sp. gr. gives the weight. It is necessary for this purpose to know the sp. gr. of the fatty acids of the more common classes of soaps and these numbers should be determined a t 5 5 O . The use of glycerol for dissolving the soap has the advantage that the liberated fatty acids form a perfectly clear layer above the Detection of Lactic Acid in Leathers and aleo in Tanning Lyes and Other Liquids.R. LAUFFMANX (Chem. Zentr. 1915 ii 763- 764 ; from Ledertech. Rzmdschau 1915 14 264-268 287-292).-Lactic acid may be detected by conversion into acet- aldehyde by distillation with le'ad peroxide. I f the solution under examination is very dilute it must first be concentrated by evapora- tion with the addition if sulphate or chloride be present of 10 C.C. of 10% sodium carbonate solution the equivalent quantity of sulphuric acid being again added before the distillation. Twenty- layer of glycerol etc. w. P. s.ANALYTICAL CHEMISTRY. ii. 57 five C.C. of t'he prepared solution are distilled in a 500 C.C. flask with 3 grams of lead peroxide a t such a rate that about 40 drops are collected per minute. I n the distillate which is collected in 5 C.C.fractions the acetaldehyde is detected by adding 10-12 drops of an aqueous diethylamine solution (2 drops in 25 drops of water) and 5-6 drops of a 0.08% solution of sodium nitroprusside. I n presence o l acetaldehyde the blue colour which appears in one t o two minutes persists according t o the amount present for from one to fifteen minutes after the distillation is complete; otherwise it rapidly fades during the distillation. The presence of aceb aldehyde may also be detected by the iodoform reaction. About 8 drops of 10% solut.ion of iodine in potassium iodide and sufficient sodium hydroxide to decolorise is added to the distillate and a distinct cloudiness after some minutes is conclusive of the presence of acetaldehyde ,which may be further confirmed by warming the alkaline solution with a little resorcinol when a carmine-red colora- tion is produced and the odour of iodoform becomes still more apparent.G. F. M. Detection of Free Mineral Acids and Lactic Acid in Leather. R. LAUFFMANN (Chem. Zentr. 1915 ii 765; from Ledertech. Rundschau 191 5 8 292-301).--Dried and undried portions of the leather are dialysed; if the former dialysate is acid mineral acids or oxalic or lactic acids may be present. I f only the latter dialysate is acid the acidity is due to volatile organic acids. I n the former eventuality an extract of 20-30 grams of the leather in 200 C.C. of hot water is tested for sulphate chloride and oxalic acid ions. I f the latter is present the question as t o whether the leather contained free mineral acid cannot be decided.I f absent lactic acid is tested for in an extract of the finely divided leather prepared by prolonged digestion at 60-65O by the author's melthod (preceding abstract). If both oxalic and lactic acid are thus proved absent the sulphate and chlorine ions must have been present as free acid. I n this case the dialysing process can be utilised for their quantitative estimation the aqueous dialysate being titrated with N / 10-alkali hydroxide using Congo-red as indicator. Estimation of ToBal Tartaric Acid Ca,laium Tartrate Potassium Hydrogen Tartrate and Free Tartaric Acid in Wine. RUDOLF KUNZ (Chem. Zenti-. 1915 ii 287-288; from Arch. Chem Mikroscopie 1916 No. 3).-Fifty C.C.of the wine are treated with exactly 3 C.C. of N/2-hydrochloric acid and 2 C.C. of 20% potassium chloride solution and evaporated to 10 C.C. Another portion of 50 C.C. of the wine is evapor- ated a t the same time( without any addition until the residual solution weighs 10 grams. To each of the residual solu- tions are now added 100 C.C. of 96% (by vol.) alcohol; after twelve hours the precipitates are collected washed with alcohol the11 dissolved in hot water and the .solutions titrated with AT/ 10-alkali solution. The quantity of tlie total tartaric acid and of the potassium hydrogen tartrate in the wine is thus G. P. M.ii. 58 ABSTRACTS OF CHEMICAL PAPERS. obtained. The filtrate fromm the potassium hydrogen t a r t r a h estimation (the precipitate also contains the calcium tartrate) is now treated with 2 C.C.of 20% potassium chloride solution; after twelve hours 2 C.C. of iV/lO-hydrochloric acid are added the pre- cipitate is collected washed with alcohol dissolved in hot water and the solution titrated. This result gives the amount of free tartaric acid present and the difference between the quantity of total tartaric acid and the sum of the quantities of free tartaric acid and that present as potassium hydrogen tartrate gives the amount present as calcium tartrate. w. P. s. Source of Error in the Estimation of Tartaric Acid in Wine Lees and Tartars. P. CARLES (Ann. Chim. anal. 1915 22 240- 241).-When the Goldenberg method (A. 1908 ii 237) is employed f o r the estimation of tartaric acid in tartars etc containing calcium carbonate the weighed portion of the substance should be mixed with twice its weight of water and then treated with hydrochloric acid in small quantities a t a time until the mixture no longer evolves carbon dioxide when the acid is added.Eighteen C.C. of hydrochloric acid (D 1-10> are now added and the process carried out as described. Unless the calcium carbonate is first decomposed the ,quantity of hydrochloric acid added subsequently may not be sufficient to dissolve the tartrates. w. P. s. Estimation of Acidity in Potatoes. J. F. HOFFMANN and FR. PRECKEL (Landto. Versmhs-Stat. 191 5 87 237-239).-The expressed potato sap (50 c.c.) is diluted t o 250 C.C. with 95% alcohol frequently sha,ken during an hour and filtered. Of the filtrate 100 C.C.are diluted with 100 C.C. of water vigorously shaken t o expel carbon dioxide and titrated in presence of 1 C.C. of rosolic acid. A titration is also made in a similar vessel in a mixture of alcohol (80 c.c.) and water (120 c.c.) and the result deducted from that obtained with the potato sap. It is of importance t o employ solutions containing the same relative amounts of water and alcohol ; with greater proportions of alcohol the change of colour is retarded. The Salicylates. 11. Methode for the Quantitative Recovery of Salicyl from Urine and other Body Fluids. T. ‘MT. THOBURN and PAUL J. HANZLIK ( J . Biol. Chem. 191.5 23 163-180).-The term “salicyl” is employed to indicate the salicyl group in what- ever form it occurs. To recover salicyl from urine the fluid is distilled in the presence of syrupy phosphoric acid (20 C.C.of 80% acid solution t o 100 C.C. of urine). By this means the conjugated salicylates such as salicyluric acid are hydrolysed and the salicylic acid distils over with the steam. The amount is then estimated colorimetrically in an aliquot part of the distillate by the addition of 2% ferrous ammonium sulphate the colour produced being estimatgd by comparison .with solutions containing varying amounts o f a standard solution o f which 1 C.C. contains 0*0001 gram of salicylic acid. To estimate salicyl in blood tlhe free salicylic acid N. H. J. M.ANALYTICAL CHEMISTRY. ii. 59 is extracted with ether and the amount estimated colorirnetrically. To estimate the conjugated salicyl the proteins are first removed by addition of ten times the volume of alcohol; to an aliquot past of this liquid a few drops of saturated zinc chloride solution are added and the mixture is boiled.The filtrate is then freed from alcohol by boiling and the aqueous solution is hydrolysed by phos- phoric acid and the estJmation completed by the method described above in the case of urine. A method is also suggested for the estimation of salicyl in faxes. S. B. S. Biochemical Reaction of Rancid Fata. J. VINTILESCO and Arm POPESCO. ( J . Phnrnz. Chim. 1915 [viij 12 318-323).-The rancidity of fats and oils is due t o the fixation of oxygen and the authors show that this oxygen may be liberated by the action of peroxydase and detected by the guaiacum reaction. Ten grams of the fat are just melted in a test-tube 5 drops of diluted blood or of 3% haemoglobin solution are added followed by 10 drops of guaiacum tincture and 10 C.C.of water and the mixture is shaken for one minute. I f the fat is rancid the emulsion is coloured blue the intensity of the coloration depending on the degree of rancidity whilst in the case of non-rancid fats o r oils the mixture remains colourless. The blue coloration may be rendered more distinct when deafing with fats which are only slightly rancid by adding an equal volume of 95% alcohol to the mixture after the latter has been shaken. That the acidity of a fat is not a function of the sancidity is shown by the fact that a rancid acid fat after being neutralisea and washed with water and alcohol gives a reaction equal in intensity to that yielded by the fat before neutral- isation.Rancid fats still give the reaction after being heated a t 120° for a few'minutes but not after being heated a t 2 0 0 O . w. P. s. Applied Plant Microchemistry. XI. Microchemical Detec- tion of Baptisin in Baptisia Tinctoria (Roots). 0. TUNMANN (Chem. Zentr. 1915 ii 288-289; from Apoth. Zeit. 1915 30. 272-274).-Pyridine is a better solvent than dilute alcohol f o r the extraction of hapfisin from the powdered soots of Baptisia tinctoria (wild indigo) ; after repeated crystallisations from dilute alcohol the glucoside is obtained as a white crystalline powder m. p. 2 4 4 O . It is soluble in aniline pyridine amyl alcohol and potassium hydroxide solution insoluble in ethyl acetate and tur- pentine and slowly soluble in chloral hydrate solution and acetic acid Baptisin may be detected in sections of tlie r o o t by treating the section with vanadium sulphate; the edge of the section exhibits a violet colorakion which changes t o light blue; cerium sulphate and tungsten sulphate yield reddish-violet colorations.Baptisin sublimes for the greater part without decomposition. I f 5 mg. of the powdered root are heated the first sublimate o'btained consists of colourless o r light yellow needles of the glucoside; the sinhseqnent sublimate consists of white prisms of baptigenin. The glucoside and its derivative give a red coloration with vanadiumii. 60 ABSTRACTS OF CHEMICAL PAPERS. sulphate the colour changing gradually t o violet and brownish- blue. When the sublimate is treated with a drop of sulphuric acid and a crystal of tungstic acid is added the edges of the crystal show a deep violet coloration.If the sublimate is mixed with iodic acid solution dried the residue washed with water and then treate’d with sulphuric acid the crystals become red then violet or black and dissolve whilst the edge of the sulphuric acid exhibits a bluishlgrey colour. . Baptisin is 1;calised in tfie parenchyma. w. P. s. A Frangula Substitute the Barks of Rhamnus Carniolica and Alnus Glutinosa. 0. TUNNANN (Chew. Zentr. 1915 674; from Schweix. Apoth. Zeit. 1915 53 313-318 ; 325-332).-A proposed subst’itute for frangula consists of a mixture of 15% of the bark of Rhamnus c n r n i o l i c a and 75% of the bark of Alnus ylzctinosn. The former bark contains both free and combined hydroxymethylanthraquinonee and might serve as a substitute for frangula but the bark of L4hus glutinosa is worthless.The three Rhccmrms drugs may be distinguisheld by the rays in the cambium layer; in the case of frangula they form one or two very seldom three layers; in R. purshinrLzis they appear in one t o three seldom four layers; in R. cariziolica they are in four six o r even eight layers. A?. car7~ioZica contains 1.84% of free and 3.78 of combined hydroxymethylanthraquinones ; frangula-emodin is also present but not chrysophanic acid. The total anthraquinonw in R. c a r n i o l i c a may be1 estimated as follows Five grams of the dry powder are boiled with 100 grams of dilute sulphuric acid f o r thirty minutes under a reflux apparatus the mixture then filtered and the filtrate extracted twice with chloroform (50 and 20 grams).The cliloro- form solution is shaken for fifteen minutes with two quantities of 50 grams of 5% sodium hydroxide solution the alkaline extract is acidified with hydrochloric acid the precipitated hydroxymethyl- anthra.quinones collected dried a t looo and welighed. IV. P. S. Identification and Estimation of (‘ Saccharin ” [o-Beazoic- sulphinide] in Foodst,uffs. FEDERICO CECCHERELLI (BoZZ. chim. farm. 191 5 54 641-648).-Before a foodstuff is treated with ether in order t o extract any “saccharin” present i t is necessary that alcohol should be completely removed since even a small residuum of alcohol may result in the extraction of other sweet substances such as glycerol lzvulose various glucosides etc.I n some cases tho whole of the alcohol is not expelled by a single evaporation and it is advisable repeatedly t o take up the residue in distilled water and evaporate. The residue obtained after extraction with ether and expulsion of the latter should be purified by treatment with permanganate and should then (1) be pronouncedly sweet ; (2) give the reaction f o r salicylic acid only after fusion with sodium hydroxide a t 2 5 0 O ; (3) contain sulphur in the theoretical proportion; (4) yield 9 silver derivative containing 37% of the metal; (5) give Tarugi and Lenci’s reaction (compare A. 1912 ii 397) after hydrolysis by means of sulphurio acid. T. B. P.ANALYTICAL CHEMISTRY. ii 61 The Microchemical Method for Gasometric Determination of Aliphatic Amino-nitrogen. DONALD D.VAN SLYliE ( J . Biol. Chem. 1915 23 407-409. Compare A. 1910 ii 751; 1911 ii 164 ; 1916 ii 1008 ; 1913 ii lO84).-A niodification of the gas-burette employed for measurement of the nitrogen is described. This is of 3 C.C. capacity graduated into divisions of 0.01 C.C. placed 1 mm. apart. The zero point is placed a few millimetres below the stop- cock. A modification in the manipulation of the author’s micro-method is also described. Readings to 0.001 C.C. are possible. S. B. S. The ‘‘ Ninhydrin ” Reaction. VICTOR JOHN HARUING (Tram. BOY. XOC. Canada 19 15 9 33 -42).-A critical examination of the conditions governing Ruhemann’s test for amino-acids with triketo- hydrindene hydrate (T. 1910 97 2025).The author finds that under accurately defined conditions of concentration and tempera- ture the test can become specific for amino-acids these being the only substances which give the test readily and clearly in very dilute solution. He recommends that in testing for amino-acids not more than 0.1 mg. of nitrogen be present in each C.C. of the liquid to be tested and that 1 C.C. of it should be heated in a boiling water-bath with 1 C.C. of a 1% solution of “ninhydrin” for fifteen minutes. Evaporating the liquid t o be tested t o dryness in a dish with the reagent is unsatisfactory. I n the presence of pyridine ammonium salts and primary amines as well as amino-acids react strongly with triketohydrindene hydrate and theref ore the colori- metric method of Harding and MacLean for estimating the nitro- gen in a-amino-acids present is inapplicable to the analysis of physiological fluids (compare A.1915 ii 382). The blue colora- tion obtained by Halle Loewenstein and Pribram with this reagent and glycerol and allied substances (compare A. 1913 ii 922) is shown to be due t o the presence of traces of nitrogenous impurity. The blue colour obtained with amino-acids is character- ised in three ways namely (1) It gives a broad absorption band in the visible spectrum extending from the red into the green part of the spectrum when viewed in dilute solution; (2) the blue colour changes t o purple when viewed in artificial light; (3) the colour is resistant to mild oxidation the passage of a rapid current of air for five minutes through a standard colour having no effect on the quantity present.The blue colour given by hydrindantin and potassium o r sodium hydroxide differs from this very markedly in that i t gives no absorption band in the visible spectrum; it remains blue when viewed by artificial light and i t is very readily oxidised t o a colourless solution when shaken with air. W. G . New Reaction of isoThiocyanates. G. DEXIGBS ( B d l . SOC. chz7t~. 1915 [iv] 17 380-381).-To a few C.C. of the solution to be tested twice its volume 09 a solution of mercuric sulph‘ate (28 grams per litre) is added the mixture shaken filtered if necewary and heated in a boiling water-bath for one to five minutes according t o the dilution. isoThiocyanates if present to the extent of 0.25 gram per litre will give a crystalline precipitate of dithio-ii.62 ABSTRACTS OF CHEMICAL PAPERS. trimercuric sulphate (compare A. 1915 ii 835 839) which can be examined under a microsco,pe and characterised. W. G. Mercury Ureometer of Simple Gonstruction. HENI~I MARTIN (J. Pharm. Chim. 1915 [vii] 12 352-354).-9 modification of Esbach's ureometer is described f o r the estimation of urea in the blood. The blood is treated with an equal volume of a 20% solution of trichloroacetic acid and the urea in a measured volume of the filtrate decomposed by sodium hypobromib. The nitrogen gas evolved is collected in the modified Esbach's ureometer over mercury. H. W. B. Method for the Extraction of Greatine and Creatinine from Body-tissues and Fluids. A. COSTANTINO (Chem. Zentr.1915 ii. 287 ; from Arch. Farmacol. sperim. 1915 19 254-258),- The fluid or the finely-divided organ is shaken for two hours with 200-250 C.C. of 2% mercuric chloride solution containing 1% of hydrochloric acid; the mixture is then filtered and the excess of mercury is removed as sulphide. An aliquot portion of the solution is heated to expel hydrogen sulphide neutralised with sodium hydroxide and concentrated to about 10 C.C. The solution thus obtained is colourless and free from proteins and serves for the colorimetric estimation of the creatine. w. P. s. The Use of Trichloroacetic Acid as a Protein Precipitant. I. GREENWALD (J. Amer. Chem. Soc. 1915 37 2604-2605).-The author disclaims any right to the discovery of the general use of trichloroacetic acid as a reagent f o r prot'eins (compare Graves and Kober ibicl.2445). D. F. T. Analysis of Proteins by Determination of the Chemical Groups Characteristic of the Different Amino-Acide. A Cor- rection. DONALD D. VAN SLYKE ( J . Bid. Chenz. 1915 23 411)- The formula for determination of histidine and arginine given in the original paper (A. 1911 ii 944) should read Histidine= 1-6670 - 1-225 Arg. as there given. 0 = diamino-acid nitrogen Arg. = arginine nitrogen. - i(0 - 2Arg) = 1.50 - 1-125 Arg instead of 'Histidine N = S. B. S. The Proteins in Caoutchouc and in Caoutchouc Latex. FR. FRANK (Chenz. Zentr. 1915 i 1345 ; from Gummi-Zeit. 1914 29 196-198).-The following method is recommended for the separa- tion of the nilxogenous substances in crude caoutchouc. From 1 to 2 grams of the sample are mixed in a test-tnbe with 30 C.C.of cumene limonene; o r dipentene and the mixture is boiled under a reflux apparatus until a homogeneous solution is obtained. The tube and its contents are then submitted tot centrifugal action (2500-3000 revs. per minute) for one tloc one and a-half hours the clear liquid is decanted the sediment next boiled with xylene and again submitted to centrifugal action and these operations are repeated using light petroleum and ether respectively as theANALYTICAL CHEMISTRY. ii. 63 solvents. The residue is then dried weighed and further ex- amined. It yields distinct reactions with the biuret and xantho- protein tests with Millon's reagent and in most' cases the presence of tyrosine can bel detected. The substance responds to' all the precipitation tests f o r proteins.The cleavage products obtained when the substance is hydrolysed completely are the same as those obtained from the latex and from the serum after coagulation. The presence of the following products may be detected mono- aminomonocarboxylic acids aromatic amino-acids (phenylalanine tyrosine) heterocyclic amino-acids (tryptophan) diarninomono- carboxylic acids monoaminodicarboxylic acids and cystine. It follows that in working up latex the proteins should be separated simultaneously with the caoutchouc in such a way that they do not undergo further decomposition. w. P. s. Estimation of the Ammonia from the Amino-acids and Proteins of Urine by Means of Formaldehyde. M. W. SCHELTEMA (Plaarrn. Weekblad 1915 52 1549-1555).-A historical survey of the application of formaldehyde t o the estima- tion of combined ammonia in urine and an account of the results obtained by the author by this method. A.J. W. Acid Ratio A New Method for Estimating the Proteolytic Strength of Germinated Grain in Technical Analysia. CARL A. NOWAK ( J . Iitd. Eng Chem. 1915 7 858-859).-The method is based on the formaldehyde titration of the amino-groups. Bifty grams of finely-ground malt are shaken for thirty minutes with 150 C.C. of cold water and the mixture then filtered the first por- tions of the filtrate being returned t o the filter. Exactly forty- five minutes after starting the extraction o r fifteen minutes after removing the mixture from the shaking machine 20 C.C. of the filtrate are transferred to a beaker 20 C.C.of water and 0.5 C.C. of 0.5% phenolphthalein solution (in 50% alcohol) are added and the solution is titrated with N / 10 sodium hydroxide solution. This titration gives the natural acidity. To the mixture are now added 10 C.C. of 40% formaldehyde solution (previously mixed with 5% of its volume of 0.5% phenolphthalein solution and then neutralised) and the titration is continued until a distinct pink coloration is obtained. This second titration is a measure of the amino-groups present. The ratio between the amino-acidity and the natural acidity obtained by dividing the number of C.C. of alkali solution representing the amino-acids by the number of C.C. representing the natural acidity is as 1 :1 or greater. This ratio is termed the acid ratio of malt.A really good malt should be high in natural acidity and should show an acid ratio of 1 1.10 which may be expressed as 110; in some malts it may be as high as 130. To obtain comparative figures as t o the proteolytic strength of different malts the remainder of the filtrate is main- tained a t the ordinary temperature for sixteen hours and a second estimation of the acid ratio is then made. Malts showing the greatest increase in the acid ratio are those having the greatestii. 64 ABSTRACTS OF CHEMICAL PAPERS. peptic strength; the increase may timount t o ff0.m 5 to more than 30 units. w. P. s. Analysis of Soils with Strong Hot Hydrochloric Acid. D. J. HISSINK (Bied. Zentr. 1915 44 367-369 ; from liztermt. Mitt. Bode& 1915 5 l).-Whilst the amount of acid per gram of soil and the duratioa of the boiling do not vary much in the method usually employed there seems t o be less uhiformity as regards the strength of the acid and hence the temperature which depends on the density of the acid.The following method is pro- posed. The soil (10 grams) is first treated with water or dilute acetic acid to remove any acid or carbonates. It is then boiled for a few minutes in an open flask with hydrochlotic acid (about 25%) until the temperature l l O o is reached after which it is boiled for two hours in a reflux flask. N. H. J. 31. Method for the Estimation of the Immediate Lime Requirements of Soils. W. H. MACINTYRE (J. Ind. Eng. Chem. 1915 7 864-867).-There is a considerable difference between a soil’s ability to decompose immediately calcium carbonate and its power of continuing the decomposition when the soil and an excess of calcium carbonate remain in moist contact. I n certain lime-treated plots 35% of the accumulated lime after thirty-two years’ treatment was found to be present as silicate. The method described deals with the immediate lime requirement. From 5 t o 10 grams of the soil are mixed with 150 C.C. of calcium carbonate solution (see below) and evaporated to a paste; the latter is then washed into a flask with 60 C.C. of water free from carbon dioxide the carbon dioxide is liberated with phosphoric acid and absorbed in a definite volume of N / 2 sodium hydroxide solution. The amount of sodium carbonate formed is estimated either by the double titration method or by adding barium chloride and titrating the alkali hydroxide after the barium carbonate has settled. The calcium carbonate solution employed is prepared by passing carbon dioxide for four hours into 4 litres of water containing 20 grams of calcium carbonate in suspension then filtering the solution and storing it under pressure of carbon dioxide. The difference between the calcium carbonate content of the 150 C.C. of this solution employed and the residual calcium carbonate found in the actual estimation is a measure of the calcium carbonate decomposed by the soil. w. P. s.