188&] On Salts of a Base containing Chromium and Urea. 325 



The question naturally arises, " Is the compound last considered 

 the initial chief product of the reaction of chromyl dichloride on urea, 

 or is it produced from this compound by interaction with the water 

 added subsequently ? As at the present time difficulties, which seem 

 insurmountable (see below), attend the direct determination of this 

 question, and as, moreover, it was suspected that the salt above 

 described is the product of the action of water on the chlorochromate 

 of the base, it was determined before proceeding further to attempt 

 the isolation of such compounds. With this object in view an in- 

 vestigation was made of the action of aqueous hydrochloric acid on 

 the compound last considered. As mentioned above, the dichlordi- 

 chromate crystallises out unaltered from a hot solution containing one 

 volume of strong acid to nine of water. If, however, the quantity of 

 acid to water be increased to one in six, a salt crystallises out as the 

 solution cools in brownish-yellow crusts of small crystals. When a 

 much stronger acid than one in six is used, the product is a mixture 

 of the brown-yellow salt and green needles of the chloride. The 

 examination of this brown-yellow compound showed it to be the 

 dichlorfcetrachlorochromate of the base having the composition 



formed from the dichlordichromate by the following change : 



The colour of the new salt presents a striking contrast to that of 

 the preceding compound. With the exception of the acid of the 

 strength from which it has been crystallised, it is either insoluble 

 in, or decomposed by, all the usual solvents. With alcohol 

 the chloride of the base is formed, and the usual products of the 

 action of chromic acid on that reagent. Water effects immediate 

 decomposition, the colour changing to the characteristic dark green of 



