BY R. GRKIG SMITH. 117 



attribute the difference between this result and the former one 

 chiefly to the lime having become carbonated during the six 

 months' storage in the sample bottle. 



The fluid in one of the culture flasks was filtered, and the 

 dissolved silica found to be 15 mgrm. The sand in the bottle 

 was washed away by a stream of water, and the grains adhering 

 to the bottom scraped oif. After everything excepting the incrus. 

 tation of carbonate on the wall had been removed, standard 

 acid was run in and allowed to decompose the carbonate. The 

 carbon dioxide was removed and the residual acidity determined. 

 The difference was found to be equal to 22 mgrms. calcium oxide. 

 The small amount of silica in solution in the culture flasks corrobo- 

 rates the conclusion that was arrived at from the observation of 

 the incrustation. 



