468 Procecdings Columbia Biochemical Association [April-July 



the urines, to the filtrates f rom aluminium hydroxid mixtures, and to 

 the diffusates through parchment and collodion bags. It was found 

 that removal of the colloidal substances from the urine favored the 

 production of the blue color typical of the reaction produced by 

 amino acids with ninhydrin. A positive ninhydrin reaction on 

 urine from which the colloidal substances have been removed is of 

 no value for the diagnosis of pregnancy, for such positive reactions 

 are obtained in normal, and a large series of pathological cases, as 

 well as in cases of pregnancy. Furthermore, in some cases of preg- 

 nancy the reaction is either very faint or absent altogether. 



130. Note on the solubility of urea in ether, and of uric acid 

 in alcohol and in ether. Ross A. Gortner. (Biochem. Lab. of 

 the Station for Exp. Evolution, Carnegie Inst, of Washington.) In 

 stating the solubilities of urea in ether and of uric acid in alcohol 

 and in ether, Beilstein, and all other authorities I have examined, 

 unite in the Statement that no Solution occurs. Thierf elder^ ^ states 

 that urea is " unlöslich " in ether and uric acid is " gar nicht löslich in 

 alkohol oder aether" (p. 170). These Statements are true regard- 

 ing any appreciable solubility in 100 cc. of the solvent, but when the 

 solubility is tested in a Soxhlet apparatus the weight of the sub- 

 stance dissolved is appreciably large. 



The ether used in the foUowing experiments was Kahlbaum's 

 " ueber Natrium distillert," the alcohol was Squibb's " absolute," the 

 urea and uric acid were of Kahlbaum's best grades. Both the 

 alcohol and the ether were from freshly opened Containers and 

 during the extractions the contents of the apparatus were protected 

 from atmospheric moisture. 



Solubility of urea in ether. 0.3255 gm. of urea was extracted 

 in a Soxhlet app. with anhydrous ether for 48 hr. Within a few 

 hours after the extraction was started, needle shaped crystals began 

 to separate in the flask and at the end of the extraction it was found 

 that 0.0720 gm. of urea had been dissolved. A rough estimation, 

 based on the vol. of the liquid syphoning and on the number of 

 syphonings in an hour, gives the solubility of urea as 0.0004 K^- 

 in 100 cc. of ether. 



Solubility of uric acid in ether. Approximately 0.75 gm. of uric 



11 Thierf eider : Hoppe-Seyler's Handb. d. physiol. u. pathol. ehem. Anal., 

 1909, p. 145 (Berlin). 



