426 On some Unknown Combinations of [Dec. 



fine and firm crystals, which, if I may be allowed a comparison, 

 are similar to a tree loaded with fruit. These crystals, which consist 

 of prisms and cubes, have a peculiar appearance. Chromate of 

 yttria is very soluble in water. 



7« Chromate of Strontian. 



This salt is insoluble. When carbonate of strontian is thrown 

 into chromic acid, a yellowish powder is formed, which is this salt : 

 probably it would be most easily procured by double decomposition. 



8. Chromate of Barytes. 



Carbonate of barytes is not dissolved by chromic acid ; but the 

 earth combines with the acid, and forms a light yellow insoluble 

 powder, which lies at the bottom of the vessel. This salt is best 

 obtained by mixing together muriate of barytes and chromic acid. 



9. Chromate of Nickel. 



Chromic acid dissolves the carbonate of nickel in considerable 

 quantity ; hut after some hours a pulverulent precipitate falls from 

 the clear solution, which is again soluble in an excess of acid. This 

 precipitate is probably a chromate of nickel. The acid solution 

 gives, by slow evaporation, fern-leaved crystals in the state of elip- 

 tical plates, truncated on both sides, which towards the beginning 

 and end of the leaf stalks become smaller, in order to preserve the 

 resemblance. When these crystals are exposed to a high tempera- 

 ture, the acid is decomposed, and a black mass formed, which is 

 insoluble in water, and consists of oxide of chromium and oxide of 

 nickel. 



10. Chromate of Cerium. 



Carbonate of cerium is dissolved in great abundance by chromic 

 acid. The solution has a yellow colour, and an astringent taste ; 

 after some time the chromate of cerium falls to the bottom as a 

 yellow powder. The remaining solution deposites some small 

 reddish transparent crystals, which make their appearance in the 

 nihist of an incrystallizable mass. 



11. Chromate of Tellurium. 



Tellurium likewise is dissolved by the acid : of all the chromates, 

 this salt appears least disposed to crystallize. It deposites some soft 

 round grains, but the greatest part goes into the state of a syrupy 

 mass. 



12. Chromate of Uranium. 



Carbonate of uranium is readily dissolved with effervescence by 

 chromic acid. The solution is coloured yellow, has an astringent 

 taste, and the salt is easily dissolved in water. It shoots into a 

 dendritical mass containing small cubic crystals. They have an 

 aurora colour. This salt melts in a weak red heat, and after 

 cooling appears of a dark brown colour. This compound docs not 



