1819.] M. Stromei/er's new Delaih respecting Cadmium. 271 



and infusible in the strongest white heat, and does not lose its 

 oxvgren. When mixed with charcoal, it is reduced with great 

 rapidity before a red heat. It dissolves easily in borax without 

 colouring it, and gives a transparent glass bead. It is insoluble 

 in water ; but in some circumstances forms a colourless hydrate, 

 which speedily attracts carbonic acid from the air, and which 

 easily gives out its water when exposed to heat. 



The fixed alkalies do not dissolve the oxide of cadmium in a 

 sensible degree, but they promote its combination with water. 

 Ammonia, on the contrary, dissolves it easily. It becomes 

 white in the first place, and is changed into a hydrate. On 

 evaporating the ammonia, the oxide precipitates in a very gela- 

 tinous hydrate. 



With the acids, the oxide of cadmium exhibits the properties 

 of a saturating base. It forms salts, which are almost all colour- 

 less, have a sharp metallic taste, are mostly very soluble in water, 

 and crystallizabie, and possess the following characters : 



1. The fixed alkalies precipitate the oxide in the state of a 

 white hydrate. When added in excess, they do not redissolve 

 the precipitate, as is the case with the oxide of zinc. 



2. Ammonia likewise precipitates the oxide white, and doubt- 

 less in the state of hydrate ; but an excess of the alkali 

 immediately redissolves the precipitate. 



3. The alkaline carbonates produce a white precipitate, which 

 is an anhydrous carbonate : zinc in the same circumstances gives 

 a hydrous carbonate. The precipitate formed by the carbonate 

 of ammonia is not soluble in an excess of this solution. Zinc 

 exhibits quite different properties. 



4. Phosphate of soda gives a white pulverulent precipitate. 

 The precipitate formed by the same salt in solutions of zinc is 

 in fine crystalline plates. 



5. Sulphuretted hydrogen and the hydrosulphurets precipitate 

 cadmium yellow or orange. This precipitate resembles orpiment 

 a little in colour, with which it might be confounded without 

 sufficient attention. But it may be distinguished by being more 

 pulverulent, and precipitating more rapidly. It differs particu- 

 larly in its easy solubility in muriatic acid, and in its fixity. 



6. Triple prussiate of potash precipitates solutions of cadmium 

 white. 



7. Nutgalls do not occasion any change. 



8. Zinc, precipitates cadmium in the metallic state in the form 

 of dendritical leaves, which attach themselves to the zinc. 



The following are the salts which Stromeyer has particularly 

 examined. 



Carbonate of cadmium is pulverulent, and insoluble in water. 

 It readily loses its acid when heated. It is composed of 



Acid 100-00 



Oxide 292-88 



