1918.] 



AGRICULTURAL CHEMISTRY AGROTECHNY. 



505 



0.3 to 0.35 per cent of cresylic acid to the plasma previou.s to the heating of 

 the plasma-ammonium- sulphate mixtures. The mixtures should he neither 

 heated beyond 60° C. nor allowed to remain at this temperature for more than 

 two or three minutes. Experimental data are given to show that the addition 

 of cresylic acid increases the concentration of the sera and the percentage 

 removal of the serum proteins. 



See al.so previous notes (E. S. R., 37, pp. 376, 877). 



A note on the use of indicators for the colorimetric determination of the 

 hydrogen ion concentration of sera, Annie Homek {Biochem. Jour., 11 {1911), 

 No. 3-4, pp. 283-291). — Results of investigations on the accuracy of the deter- 

 mination of the hydrogen ion concentration of sera by the colorimetric method 

 of Clark and Lubs (E. S. R., 37, p. 506) with the use of certain indicators are 

 reported. 



The author suggests that " in view of the personal error involved in the 

 determination of color reactions with sera it is advisable that each worker using 

 the colorimetric method should ascertain the degree of approximation of his 

 own values to the true values determined by the electrical method." 



The preparation of plant nucleic acids, G. Clarke and S. B. Schryver 

 {Biochem. Jour., 11 {1917), No. 3-Jf, pp. 319-324).— Methods are reported for 

 the preparation of protein-free nucleic acid from plant tissues without peptic 

 digestion by first bofling the material used with alcohol and then extracting 

 with warm 10 per cent sodium chlorid solution. The nucleic acid is precipi- 

 tated from the extract on the addition of hydrochloric acid. 



Starch-containing material, such as wheat embryos obtained in the modern 

 milling processes, should be fermented with diastase before extracting with 

 sodium chlorid solution to avoid difRculties in filtering. Analyses are included 

 of nucleic acid obtained by this method from yeast and from wheat embryos. 

 The results agree closely with the formula C3SH50O29N15P4 suggested by Levene 

 for plant nucleic acid (E. S. R., 22. p. 115). 



The proteins of cow's milk, T. B. Osborne, A, J. Wakeman, et al. {Jour. 

 Biol. Chem., 33 {1918), No. 1, pp. 7-/7). — A study of the proteins remaining in 

 milk after the removal of casein is reported. The methods of separation and 

 purification of the constituents are given in detail. Analyses of the purified 

 lactalbumin and lactoglobulin gave the following composition : 



Composition of purified lactalbumin and lactoglobulin. 



Special investigation of the phosphorus in the lactoglobulin showed its simi- 

 larity to that of the vitellin of hens' eggs and suggested to the authors that 

 lactoglobulin is a similar lecithalbumin or mixture of proteins. That only a 

 trace of phosphorus was found in lactalbumin would indicate that the phos- 

 phatids previously obtained from the coagulated protein of milk (E. S. R., 

 33, p. 660) are not associated with the purified lactalbumin but with the 

 globulin. 



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