1906.] 



SULPHURIC ACID ON DEPOSITION OF METALS. 



261 



In 2.5 minutes, 0.1250 gram of cadmium was deposited. 



Twenty-two minutes were required to precipitate all of the 

 cadmium in the presence of three cubic centimeters of acid. 



In 5 minutes, 0.2028 gram of cadmium was deposited. 

 " 7.5 " 0.2260 



" ID " 0.2433 



" 15 " 0.247s 



" 20 " 0.2486 



" 22 ." 0.2498 



(Figure 3, Curve 3.) 



When four cubic centimeters of acid were added to the electro- 

 lyte, twenty-seven minutes were necessary for the complete precipi- 

 tation of the cadmium. 



In 5 minutes, 0.2023 gram of cadmium was deposited. 



When five cubic centimeters of acid were present in the solution, 

 at the end of thirty-five minutes there was considerable cadmium 

 undeposited (.003). 



In 5 minutes, 0.1974 gram of cadmium was deposited. 

 "10 " 0.2354 " 

 "20 " 0.2419 " 

 "30 " 0.2454 " 

 "35 " 0.2475 " 



(Figure 3, Curve 5.) 



Iron. 



Sulphuric acid retards the decomposition of iron sulphate to a 

 far greater extent. Even after forty minutes, in the presence of one 

 cubic centimeter of acid, a trace of iron was held in solution. 



