1835.] Chemical Analysis of Gadolinite, $fc. 417 



Infusion of nutgalls : O. 



Gallic acid : . . . O. 



Tincture of nutgalls : White, merely from the alcohol. 



Chromate of potash : A yellow precipitate. 



Bichromate of potash : O. 



Hydriodate of zinc : O. 



Sulphate of potash : No immediate action. 



After some time a copious white powder falls. 

 Oxalate of ammonia : A white powder. 

 Oxalic acid : A white curdy precipitate 



Phosphate of soda : A white precipitate. 

 Tartrate of potash : A white precipitate. 



V. SALTS OF CERIUM. 



1. Sulphated protoxide. — This salt may be obtained by 

 dissolving peroxide of cerium in sulphuric acid, and adding 

 a little muriatic acid. Chlorine is given oft*, and a colour- 

 less solution obtained, which when sufficiently concentrated 

 yields prismatic crystals of an amythystine colour. When 

 alcohol is added to the concentrated solution, the salt falls 

 in fine silvery needles : its taste is agreeably sweet and 

 astringent. Its specific gravity is about 2*5 : 100 parts of 

 water at the temperature of 60°, dissolve 6*47 of the 

 crystallized salt. When heated, it becomes white and 

 opaque, but cannot be rendered anhydrous without losing 

 a little of its acid. After having been once or twice cry- 

 stallized it is quite neutral. 



The analysis of this salt was attended with unexpected 

 difficulty. It was not till after a considerable waste of time 

 and matter, that the varying results were found to arise 

 from the formation of various double salts. When the acid 

 was thrown down by barytes, the sulphate obtained after 

 the most careful washing, contained abundant traces of 

 cerium. When ammonia was employed to throw down 

 the oxide, a subsalt fell, and the acid being driven off 

 from this salt by a red heat, gave an apparent loss, and 

 rendered the results quite unintelligible. 



I. 12*75 grains of the crystallized salt lost by a gentle 

 ignition 1*6 grain ; the residuum dissolved completely in 

 water; the cerium was thrown down by oxalate of ammonia. 

 The oxalate was collected on a filter, well washed with 

 boiling distilled water, dried and ignited : 6*58 grains of 

 peroxide of cerium were obtained . From the residual solu- 



vol. i. 2 E 



