AGRICULTURAL CHEMISTRY AGROTECHNY. 307 



phenolphthalelu ; the liberated acid is titrated witli deciuormal alliali solution 

 until the pink color returns." 



The results of comparative tests between this and the Kjeldahl method are 

 given. 



Volumetric determination of potassium by the cobalti-nitrite method, 

 O. M. Shedd {Jour. Indus, and Engin. Chem., 2 (1910), No. 9, pp. 379-384). — 

 After studying the various factors which influence the ultimate results of this 

 method, the author states that the Drushel modification of the cobalti-nitrite 

 method (E. S. R., 20, p. 307) is very accurate if "properly handled, but an in- 

 experienced worker not knowing its weak points may not have this opinion with 

 his first use of it." Briefiy stated, the outline of the method which has given 

 the best and most uniform results in this work is as follows : 



" The solution containing the potassium salt, after the preliminary work has 

 been done to get it at this stage, is evaporated in a 500 cc. casserole to a small 

 volume of about 5 cc, slightly acidified with acetic acid and 15 cc. fresh nitrite 

 reagent added. The larger amount of nitrite reagent makes possible a better 

 filtration and a good excess of reagent after the evaporation is made. The solu- 

 tion is evaporated on the water bath for about 45 to 60 minutes, or until the 

 contents become a thick sirup while hot and pasty on cooling. Continued heat- 

 ing is to be avoided, and this is important to obtain good results. After the 

 filtration is made and the casserole washed, the Gooch crucible and contents 

 can be put in the same casserole and treated with permanganate, as prescribed 

 in the method." 



See also previous notes (E. S. R., 22, p. 510; 23, p. 509). 



Quantitative chemical analysis of animal tissue. — V, Estimation of chlorin, 

 W. Koch (Abs. in Science, n. set:, 32 (1910), JS/o. 823, p. //77). — The estimation 

 of chlorin and aqueous extracts of lipoid-like substances or in the ash is some- 

 times difficult and often yields inaccurate results. This is particularly so with 

 the ash, because the chlorids are often displaced by the sulphates or phosphates 

 during the burning of the organic combinations. 



"In connection with the methods previously outlined (E. S. R., 22, p. 411) 

 it was found that the chlorids all pass into the fraction 2 or the alcohol soluble 

 fraction. By precipitating the lipoids in this fraction without chloroform 

 and with nitric instead of hydrochloric acid a solution is obtained in which 

 the chlorids can be titrated direct by Volhard's method. The estimation of 

 chlorin can be thus combined with that of any other tissue constituent described 

 in these methods. Some results obtained on the brain are given." 



The estimation of iodin in organic compounds and its separation from 

 other halogens, A. F. Seeker and W. E. Mathewson ( U. S. Dept. Agr., Bur. 

 Chem. Circ. 65, pp. 5). — As accurate results could not be obtained with the 

 Carius method for estimating the iodin in erythrosin, the authors elaborated a 

 satisfactory method which is based on treating the erythrosin with potassium 

 permanganate and nitric acid. This decomposes the organic matter, volatilizes 

 the chlorin and bromin, and leaves the iodin as iodic acid. 



Quantitative determination of ergot in flour, R. Bernhakt (Ztschr. Ricch u. 

 Geschmackst., 2 (1910), No. 11, pp. 122, 123; abs. in Jour. Soc. Chem. Indus., 29 

 (1910), No. 12, p. 778; Analyst, 35 (1910), No. 1,13, p. 557).— "The amount of 

 ergot in fiour can be determined as follows : Two hundred gm. of flour are boiled 

 with dilute hydrochloric acid (not less than 2 per cent) till all the starch is 

 converted into sugar. The solid matter is filtered off through silk, and washed. 

 The filter while still moist is dipped, first into dilute, then into 98 per cent 

 alcohol. The residue is extracted with acetone and carbon tetrachlorid to 

 remove the fat. It is then shaken with strong, freshly prepared ammoniacal 

 81088°— No. 4—11 2 



