Microchemical Test for the Oxygen Place in Tissues. 173 



added and shaken for one minute, allowed to settle for one minute, after 

 which it was decanted off ; the solution was then compared with a sample 

 of the original solution by means of the colorimeter. The same volume of the 

 methylene blue solution was used in every case ; the sand was finally dried, 

 heated to volatilise the methylene blue condensed on the surface, and weighed. 

 The following results were obtained. 



The ordinates represent the heights of columns of methylene blue solutions 



ABCDEFGH ! J K 



Sand 



on the same base and containing the same amount of methylene blue, and 

 consequently the relative desaturation of the original solution. 



A. The height of the column of the original methylene blue solution 



with which the various solutions were compared. 



B. Ordinary sand. 



C. Sand previously treated with gum. 



D. „ „ chloroform. 



E. „ ,, formalin. 



F. „ „ rongalit. 



G. „ „ mercuric chloride. 



H. „ „ soap. 



I. „ „ octyl alcohol. 

 J. „ „ caprylic *acid. 

 K. „ „ _p-eymol. 



These results show, as might be expected from theory, that the previous 

 treatment of the sand has a large influence on the amount of methylene blue 

 condensed on the surface. 



o 2 



