RICHARDS AND BONNET. — DISSOLVED CHROMIC SULPHATE. 17 



Maximum Basic Condition of Cold Chromic 

 Sulphate Solutions. 



saturated green solution was tested; and it was found that in thirty-six 

 hours the additional depression of the freezing point of sugar was 0.017°, 

 while in eight days it was 0.125°. This rate of reaction corresponds to 

 a concentration of acid of only about ^}>o normal, even supposing that 

 the basic salt itself has no catalytic effect. Conclusions drawn from such 

 an observation must of necessity be doubtful. 



It seems probable, nevertheless, that there may exist in solution a 

 chromium salt at least as basic as 5:4 — a substance far more basic than 

 tliat found by Recoura and Whitney, whose ratio was 5 : 6.25. This 

 probability of course by no means proves that there are not several 

 stages of hydrolysis, each product being indistinguishably green. More- 

 over, the equilibrium in a solution at one concentration may be displaced 

 at another. These considerations disclose an almost endless opportunity 

 for investigation. Since, however, the time at our disposal was not un- 

 limited, another direction was now pursued, in the hope that it might 

 lead more directly to the desired goal. 



Tiik Occlusion ok Chkomio Salts in Bakic Sulphate. 



It is well known that iron is carried down with baric sulphate, when 

 the iron is present in the ferric condition. This circumstance has formed 

 the subject of numerous investigations.* In a recent paperyf it has been 



* Anions the most important of those are Jannasch and Richards, Jour, prnkt. 

 Chem. [2], 39, 321 (1889); Schneider, Zeit. phys. Cliem., 10, 425 (1892); Kuster 

 and Thiol, Zeit. anorg. Cliom., 1^(1899). 



t Richards, Proc. Am. Acad , 35, 377 (1900) ; Zeit. anorg. Chem , 23, 383 (1900) 



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