i86 Proceedings Columbia Biochemical Association [Sept. 



grams (two heaping teaspoonsful) of powdered calcium carbonate 

 to the Contents of the porcelain dish (25 c.c. of Benedict's Solution, 

 5-10 grams of anhydrous sodium carbonate, and a small amount of 

 powdered pumice). The titration is then made in the usual manner. 



The snow white calcium carbonate, insoluble and suspended in 

 the alkalin Solution, appears to act like the copper sulfocyanate in 

 that it efTectively obliterates all colors except the blue color of the 

 copper Solution. The end point obtained is sharp, the blue color 

 being visible up to the addition of the last two drops of urine that 

 are necessary for complete reduction. A sufficient amount of cal- 

 cium carbonate (10 grams) must be added, otherwise the precipitate 

 will be gray and the end point less distinct. In order to prevent 

 sudden ebullition of the concentrated Solution, it is advisable to 

 dilute the latter with a little distilled water, Experiments have 

 shown that the addition of the calcium carbonate does not introduce 

 any noticeable error. 



The author demonstrated these facts. 



42. Diffusibility of protein through rubber membranes, with 

 a note on the disintegration of collodion membranes by common 

 ethyl ether and other solvents. William H. Welker. {Puh- 

 lished in füll in this issue of the Biochemical Bulletin, )2* 



43. A further study of the Bardach test for protein. 

 Charles Weisman. {Piihlished in fiill in the June issue of the 

 Biochemical Bulletin ).2^ 



44. A study of the surface tension of dog blood-serum by 

 the drop-weight method.^^ Harold E, Woodward. These ex- 

 periments, about twenty in number, were planned to answer the 

 question whether ordinary variations in the blood supply and nutri- 

 tive condition of an individual affect the surface tension of the 

 blood.^'^ Serum could be handled better than blood and serum from 



** Welker: Biochemical Bulletin, 1912, ii, p. 70. 



** Weisman : Ibid., 1912, i, p. 538. 



^The animals were fed and controlled, and the blood was withdrawn and 

 the serum coUected, by Dr. Gies and Mr. Chris Seifert. The drop-weights were 

 made by the author in the laboratory of physical chemistry under the direction 

 of Prof. J. L. R. Morgan. 



^ These experiments were a logical preliminary to the work described else- 

 where: Woodward, Dissertation, Columbia University, 1912. 



