RICHARDS AND BONNET. 



DISSOLVED CHROMIC SULPHATE. 



9 



Preliminary Series of Catalytic Experiments. 

 Fresh Violet and Boiled Green Solution at 17"^^. 



hence the first few hours of the experiment give the best clue to the com- 

 position of the sohition. 



The inference to be drawn from this result is, then, that the fourth 

 molar green solution contains about as much ironized hydrogen as a 



0.468 



3.0 



^^ = 0.133 normal solution of hydrochloric acid, or every ion of 



hydrogeu corresponds to 3.7 atoms of chromium. This is a much 

 smaller proportion of ionized hydrogen than that found by Recoura and 

 Whitney (1:2); but it must be remembered that both of these experi- 

 menters made their determinations by neutralization, a proceeding which 

 might well displace an existing equilibrium and make the amount of 

 ionized hydrogen seem too large. 



In another series of experiments the conditions were varied. The 

 chromic solution was hydrolyzed for many hours at 50°, instead of by 

 boiling. A temperature of 30° was chosen for the inversion in order that 

 its speed might be greater than before ; this temperature was maintained 

 by means of an Ostwald thermostat. The acid solution which served as 

 a measure of the ionized hydrogen present was much diluted for this 

 comparison, because it had been shown before to be stronger even than 

 the acid in the chromic solution which had been boiled. By two or 

 three preliminary tests it was found that an acid having about the same 

 inverting power as the green solution prepared at 50° was very nearly 

 tenth normal. Below are given the data and results of the series, ar- 

 ranged in the same way as before. The hydrochloric acid whose results 

 are recorded in the fifth and last columns was 0.105 normal. 



