822 



Mr. W. J. Sell and Prof. W. J. Lewis. [Feb. 14 ? 



menstrua, rendered it advisable to make some preliminary analytical 

 determinations on the different samples of crude well-washed sub- 

 stance. From the results obtained it was evident that the salt was 

 either a chlorochromate of chromium urea, or a compound of the 

 dichromate and chloride, a conclusion which at once harmonises with 

 its genesis, and suggests the trial of dilute hydrochloric acid as a 

 possible vehicle for its purification by crystallisation. The purification 

 by dilute hydrochloric acid containing one volume of strong acid to 

 nine of water, was successful, the numbers obtained on analysis being 

 substantially the same as those obtained from the crude well- washed 

 product of the reaction. The analytical results were satisfied by 

 either of the formula 



(1.) 





(2.) 



The latter, however, is regarded as very improbable. 



It is difficult to believe that a chlorochromate in fine powder can 

 withstand the action of water for weeks without appreciable change. 

 The fact also that the hydrochloric acid used in its recrystallisation 

 may be replaced by metallic chlorides, such as those of sodium or 

 potassium, is against the second formula. Moreover, the decomposi- 

 tion effected when the salt is recrystallised from water, may be cited. 

 A chlorochromate having the formula given in (2) should normally 

 decompose, according to the equation 



whereas the decomposition effected by water is of a totally different 

 character, and may be represented thus : 



These facts may be regarded as conclusive that formula (1) is the 

 more correct representation of this compound, which may be called 



Dichlordichromate of Chromium Urea. 

 The following results were obtained on analysis : 



The samples employed were dried by pressure between bibulous 

 paper. 



