BACTERIOLOGICAL, PHY STOLOGICAL, ETC. 87 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. The Identification and Estimation of Lactic Acid in Biological Products. -I. I. K. Phelps and 13. E. Palmer. (J.Amer. Chem. SOC., 1917,39,136-149.)- It is shown that lactic acid may be estimated as guanidine lactate, identified by its melting-point, 160" C., alfter separation by esterification from citric and tartaric acids and by fractional distillation from formic and acetic acids.Lactic acid may be separated from mixtures containing formic, acetic, propionic, butyric, and citric acids, and accurately estimated by weighing as quinine lactate, which is identified by its melting-point, 165" to 166.5" C. (racemic). The separation from citric acid and other acids whose ethyl esters have high boiling-points is effected by esterifica- tion with the vapour of alcohol containing dry hydrogen chloride in solution passed through the mixture suspended in vaseline a t 100" to 110" C., using zinc chloride as a second catalyser ; the ethyl lactate passes quantitatively into the distillate, while the ethyl citrate remains in the flask.By fractional distillation of the distillate through a Hempel fractionating column filled with glass beads the ethyl formate and acetate, together with a large part of the propionate and butyrate, are removed. The residue in the flask containing the ethyl lactate is hydrolysed and converted into quinine salts, and the quinine lactate separated from the propionate and butyrate by the solubility of the la,tter in carbon tetrachloride.Esterification of mixtures containing lactic acid is efEected in a distillation flask of 75 C.C. capacity, with side- neck connected with a condenser. This is charged with the lactic acid mixture, 1 grm. of zinc chloride, 25 C.C. of vaseline, and 10 C.C. of absolute alcohol containing in solution 2.5 grms. of hydrogen chloride per litre. It is kept at 100" to 110" C.by a glycerol bath, and 190 O.C. of similar acid and alcohol are distilled through the mixture from another flas:k, connected with the esterification flask, during a period of one and a half hours. The distillate of esters is fractionated through a 15 cm. Hempel column until the volume of residue is 20 c.c.; 100 C.C. of alcohol are added and distillation continued this is again repeated.The beads in the column are washed with dcohol, and the distillation residue treated with excess of silver88 ABSTRACTS OF CHEMICAL PAPERS carbonate, allowed to stand two hours in the dark, and filtered through asbestos. An excw of barium hydroxide is added to the filtrate, which is heated on the water- bath for one hour until the ethyl lactate is completely hydrolysed.The excess of barium hydroxide is precipitated by a current of carbon dioxide, the solution evapor- ated to dryness, and the residue extracted with 25 C.C. of water and filtered through asbestos. To the filtrate is added a slight excess of a neutral solution of quinine sulphate, calculated from the barium hydroxide uged, and the precipitated barium sulphafe is removed by filtration as soon as possible after cooling in ice. The filtrate contains quinine lactate and any excess of quinine sulphate; it is rinsed with 95 per cent.alcohol into a distilling flask and evaporated t o dryness under diminished pressure, so as to keep the temperature as low as possible. After distillation is com- plete the walls of the flask are washed down %vith 10 C.C. of alcohol, and the latter again removed by distillation under dimin;8hed pressure.This treatment frees the residue as far as possible from moisture, and brings it into a condition suitable for carbon tetrachloride extraction. The residue is warmed with 50 C.C. of the tetra- chloride to remove the quinine propionate and butyrate; the amount of solvent necessary for this depends on the quantity of these salts: as determined by their solubilities in comparison with that of quinine laatate, and the loss of lactic acid increases with the proportions of propionate and butyrate present.The residue is filtered off after standing for eighteen hours, and washed with tetrachloride. The substance on the filter and in the flask, after evaporating the tetrachloride, is treated for one hour with chloroform free from alcohol, which dissolves the quinine lactate, leaving the quinine sulphate.The solution is filtered, the filtrate together with the washings evaporated, and the residue dried under diminished pressure a t 75" C. and weighed. The lactate may be further purified, if necessary, by redissolving in hot ethyl acetate free from alcohol. The evaporation of aqueous solutions of quinine lactate must be conducted at temperatures as low as possible, to avoid the formation of quinotoxine lactate, which is far more soluble in carbon tetrachloride.The estimation of lactic acid as guanidine lactate is carried out by esterification on similar lines, but is only admissible when the ethyl esters can be thoroughly separated by fractional distillation--e.g., ethyl formate and ethyl acetate.The barium lactate solution is treated with slight excess of guanidine sulphate; the barium sulphate is filtered off and washed with water; the solution is evaporated to dryness in an Erlenmeyer flask, and all moisture removed by a current of air. The residue is digested for eighteen hours with 50 C.C. of absolute alcohol in which the guanidine lactate is readily soluble and the sulphate only sparingly.A second extraction is made to insure completeness, and the combined filtrates evaporated, the residue dried under diminished pressure a t 50" C., and weighed. J. F. B. Pyrrole Black. A. Angeli. (Gaxz. Chim. Itcsl., 1916,46,279-282; 283-300.)- On treating a solution of pyrrole in acetic acid, chilled with ice, with hydrogen per- oxide it is oxidised, and yields a crystalline derivative which agrees in composition and properties with succinimide and an amorphous black powder, for which the name of pyrrok b h k is suggested.It has a composition closely resembling that of the melanins of animal pigments (carbon, 60.01 to 58-14; hydrogen, 4437 to 4-31;BACTERIOLOGICAL, PHYSIOLOGICAL, ETC.89 and nitrogen, 15431 to 15.27 per cent.), and also resembles them in being soluble in solutions of alkalis and a,mmonia. It does not dissolve in the ordinary organic solvents, but is sparingly soluble in pyridin. C. A. M. Urinary Test for Trinitrotoluene (T.N.T.) : Illness and the Early Diagnosis of Cases suffering from Trinitrotoluene Absorption. B. Moore. (Medical Press, 1916, 53'7 .)-Trinitrotoluene, like some other toxic substances, becomes bound up in the body in a probably less poisonous form in which it is no longer soluble in the usuad solvents, requiring to be set free again before it can be recognised by chemical tests.In such cases it is not obtainable from urine by ether extraction, unless previously acidified. If a positive reaction is obtained without Etcidification, it may be set down t o contamination from clothing, skin, or hair, in the act of passing the urine, and is an indication that proper precau- tions are not being observed.When patients show a positive reaction they should discontinue work for some days, when, as a rule, the urine becomes normal; if it does not and the symptoms continue, they are specially susceptible, and should not be allowed t o proceed with this class of work at all. A method' is given for testing urine for trinitrotoluene as described by Webster, in which 12-5 C.C. of the urine are mixed with the same volume of 20 per cent. sulphuric acid, and then ex- tracted in a separating funnel with ether. The ethereal extract, after washing with water, is tested for trinitrotoluene by adding 5 per cent. alcoholic potash, a purple coloration, rapidly turning to brown, being a positive indication. H. F. E. H.