310 EXPERIMENT STATION RECORD. [Vol.40 



saturating the flasks containing the reagents with carbon dioxid. The liber- 

 ated iodin is then titrated with N/70 arsenions acid. 



Determination of residual nitrogen in blood serum. Fischer (Hoppc-Sey- 

 lcr'8 Ztschr. Physiol. Chew., 102 {1918), Xo. 5-6, pp. 266-274).— An examina- 

 tion of different methods of precipitating the proteins in blood serum prelimi- 

 nary to the determination of the nonprotein nitrogen is reported, the results of 

 which indicate that precipitation with uranium acetate in the cold is preferable 

 to precipitation with an acetic acid solution of either sodium chlorid or sodium 

 acetate at boiling temperature. The details of the method are as follows: 



Ten cc. of blood serum is mixed in a 50 cc. cylinder with 10 cc. of a 1.6 per 

 cent uranium acetate solution and made up with water to 50 cc. The mixture 

 is shaken well, allowed to stand for 5 minutes, and then filtered. A mixture of 

 25 cc. of the clear filtrate and 10 cc. of Kjeldahl sulphuric acid solution is made 

 in a Kjeldahl llask and the nitrogen determined according to the usual methods. 



The colorimetric determination of blood sugar by the reduction of picric 

 acid, C. Salomon (Biochem. Ztschr., 90 (1918), No. 1-2. pp. 89-52). — Thia is 

 a resume* and critical review of the original method of Lewis and Benedict for 

 the determination of blood sugar by reduction of picric acid and subsequent 

 modifications of the method (B. S. B., 39, p. 112). A bibliography of 20 titles 

 is appended. 



Chemical analysis of bacteriological bouillons. I'. C. Coob and E. LeFevbe 

 (Amer. Jour. Pub. lh"ith. 8 (1918), No. 8, pp. 587 589). Chemical analyses of 

 standard bouillons prepared from fresh beef, meat extract, and fresh liver are 

 reported from the Bureau of Chemistry of the U. S. Department of Agriculture. 

 The bouillons wen- prepared by the cold Infusion method. Five hundred gm. of 

 finely ground beef or liver was infused in 1,000 CC of water for 24 hours, and 

 the fluid obtained alter pressure and filtration was made Dp to 1,000 CC The 



meat extracf bouillons wen- prepared from .'! !_ r m. of Liebig's l f extract and 10 



gm. of Witte'S peptone, made up to a volume of 1,000 CC. with water. Three 

 samples of each series were analyzed for total solids, ash, l' : <>,, total nitrogen, 

 purin nitrogen, protein nitrogen, creatin, and creatinin. 



The liver bouillon was found to contain a higher percentage of all these con- 

 stituents than the meal extract of beef bouillon, with the exception of creatin 

 and creatinin, while the beef bouillon contained more of all constituents than 

 the beef extract, with the exception of protein, which was present in practically 

 equal amounts. These results are though! to afford an explanation of the higher 

 bacterial counts frequently found on beef bouillon media than on beef extract 

 media and of the failure of certain organisms to grow on the latter. 



A study of the extent of loss of peptone resulting from the addition of Witte's 

 peptone to beef juice prior to coagulation and filtration showed that on an aver- 

 age 12 per cent of the peptone is held by the coagulum and therefore wasted, 

 indicating that the economical procedure is to add the peptone to the filtrate 

 after coagulation. 



A new and novel method of determining the amount of methyl alcohol in 

 mixtures of ethyl and methyl alcohol. W. G. Ton. is (Amer. Jour, l'hnrm.. .'"' 

 (1918), X". .'). pp. 686 -6)n i. - -The method described depends upon the fact that 

 when methyl and ethyl alcohols are mixed and treated with metallic sodium the 

 yield of hydrogen is proportional to the amounts of the two alcohols in the 

 mixture. The fad thai commercial samples containing higher alcohols yield gas 

 in a different ratio as their molecular weight varies is considered not to affect 

 the application of the method in determining the minimum of methyl alcohol. 

 The determination is conducted simultaneously with that of a previously pre- 

 pared standard denatured alcohol, the hydrogen being collected over gasoline. 



