Sept. lo, 191 7 



Formation of "Black Alkali" 



555 



to titrate out the phenolphthalein color. A standard solution of carbon 

 dioxid was prepared by saturating water containing calcium carbonate in 



£' /O /5 BO BS 30 35 'fO <!5 SO SS CO 

 Fig. 8. — Graph showing the same system as in figure 5, but titrated with carbon-dioxid soiution. 



excess with the carbon-dioxid gas. A fairly stable solution of calcium 

 bicarbonate (or calcium carbonate dissolved in carbon dioxid) was ob- 



30 



^^S 







/O /5 ^O 



30 



Fig. 9. — Graph showing the same system as in figure 6, but titrated with carbon-dioxid solution. 



tained and standardized to contain 360 parts per million of carbon di- 

 oxid. The results of these titrations are shown in Tables XVI, XVII, 



