14 EXPEEIMENT STATION EECORD. [Vol. 37 



Is described. The distilling constants of the individual volatile fatty acids have 

 been determined and are represented frraphically by straight lines on a logarith- 

 mic chart, while the distilling variables of mixtures are Indicated by curved 

 lines. Tne calculations neces.sary for determining the amounts of the various 

 acids In a mixture are described in detail. 



Some qualitative tests for the identification of various acids in a mixture, 

 together with a simple and convenient apparatus for maintaining a constant 

 volume during the distillation, are described in detail. 



[Examination of lulu kernels and lulu oil (shea butter) fromi Uganda] 

 {Ann. Rpt. Dept. Agr. Uganda, 1916, pp. 59-61). — Analytical data of a sample 

 of lulu kernels and of two samples of butter made from the oil of the kernels 

 are submitted. 



A general method of estimating the general turbidity or opacity of fluid 

 suspensions including bacterial emulsions. G. Dkeyer and A. D. Gakdneb 

 {Biochem. Jour., 10 (1916), No. S. pp. S99-407, fig. i).— A simple and accurate 

 method for measuring the turbidity of two fluids and its special application 

 to the standardization of aggiutinable cultures is described In detail. The 

 procedure is Indicated as being applicable to all chemical and biological inves- 

 tigations which require turbidity measurements. 



The estimation of amino-acid nitrogen in blood, J. C. Bock {Jour. Biol. 

 Chem., 28 {1917), No. 2, pp. S57-S68). — Experimental data submitted Indicate 

 that the use of alcohol as a protein precipitant In the determination of amino 

 nitrogen in blood, as recommended by Van Slyke and Meyer.' is undesirable. 

 A comparative study Indicates that the use of trichloroacetic acid as intro- 

 duced by Greenwald ' is very serviceable, and a slight modification of the 

 procedure Is described. Coagulation of the blood at boiling temperature In a 

 weakly acid solution was found not to Increase the filtrate nitrogen provldet! 

 the traces of protein which escaped coagulation were properly removed. 



Factors connecting the concentration and the optical rotatory power of 

 aqueous solutions of nicotin, A Tingle and A. A. Ferguson {Proc. and Trans. 

 Roy. Soc. Canada, S. ser., 10 {1916), Sect. HI, pp. 19-25). — Experimental data 

 on the Influence of dilution on the rotatory power of aqueous nicotin solutions, 

 the effect of free alkali and alkali salts on the rotatory power of nicotin 

 solutions, effect of evaporation in the presence of sulphuric acid, and the 

 preparation of pure nicotin are reported. 



The results show that for concentrations between 4 per cent and 0.37 per 

 cent the rotatory power of an aqueous solution of nicotin Is strictly pro- 

 portional to Its concentration. Repeated evaporation with sulphuric acid in 

 small excess did not cause any change In the rotatory power of nicotin, nor did 

 the presence of free caustic alkali or salts of the alkaline metals cause any 

 change In the rotatory power of such solutions. The rotatory power of nicotin 

 In water was found to be such that, examined In a 200 mm. tube, 1 gin. of 

 nicotin in 100 cc. of solution would give a negative rotation of 4.5 divisions on 

 the Ventzke sugar scale, or conversely a negative rotation of 1 division would 

 correspond to 0.2198 gm. of nicotin in 100 cc. 



A new method for the determination of nicotin in tobacco, A. Tingle and 

 A. A. Ferguson {Proc. and Tram*. Roy. Soc. Canada. S. ser., 10 {1916). Sect. 

 Ill, pp. 27-Sl). — A polariraetric method which depends on the assumptions that 

 the rotatory power of a solution of nicotin in water Is not changed by the 

 presence of alkalis or salts of alkalis In the solution, that the acid solutions 

 of nicotin sulphate may be evaporated without either loss by vaporization 



«Jour. Biol. Chem., 12 (1912), No. 3. pp. 399-410. 

 •Jour. Biol. Chem., 21 (1915), No. 1. pp. 61-68. 



