210 JAMES SHANKS 



An analogous process, patented by Mr. 

 Shanks, appears to be much more practicable, 

 This process consists in submitting hydro- 

 chloric acid to the action of chromate of 

 calcium, the products being chloride of 

 calcium, chromic chloride, water and chlorine. 



In Mr. Shanks' process the chromic oxide 

 acts as a carrier between the oxygen of the 

 air and the hydrogen of the hydrochloric 

 acid. He does not obtain, however, so much 

 chlorine as the manganic oxide eliminates 

 from the same quantity of hydrochloric acid. 

 For whereas by the action of manganic oxide 

 1 6 equivalents of hydrochloric acid evolve 8 

 of chlorine, Mr. Shanks' process only elimin- 

 ates 6 equivalents from the same quantity of 

 hydrochloric acid. 



It is a question only to be solved by 

 experience on a large scale, whether the 

 cost of roasting the mixture of chromic oxide 

 and lime will not exceed the value of an 

 equivalent quantity of manganese. 



It is also doubtful whether the expense of 

 precipitating by lime and roasting be not 

 greater than the expense involved in the 

 regeneration of peroxide of manganese from 

 residues. 



Taking into consideration all the circum- 



