1824.] M. Berzelius on Fluoric Acid. 335 



it is completely dissolved, and it dissolves still more rapidly in 

 boiling water. A subfuate may be obtained either by igniting 

 the neutral fluate, or by digesting it in water along with hydrate 

 of alumina. 



Fluate qfzirconia is very soluble in water. The solution when 

 evaporated deposits crystals, which when digested in water are 

 decomposed into an acid salt which passes into solution, and a 

 subsalt which remains undissolved. 



Fluate of Oxidule of Manganese. — A crystalline powder, per- 

 manent in a red heat, and soluble in water, with the assistance 

 of an excess of acid. 



Fluate of Oxide of Manganese. — A solution of the native 

 hydrated oxide in fluoric acid has an intense red colour, and by 

 spontaneous evaporation deposits this salt in transparent prisma- 

 tic crystals, which are dark brown coloured when large, but 

 ruby red when minute. In a minimum of water it dissolves with- 

 out decomposition ; but if the solution be heated or diluted, a 

 subsalt precipitates, and an acid salt remains dissolved. 



Fluate of oxidule of iron may be prepared by dissolving the 

 metal, with the aid of a gentle heat, in fluoric acid ; the salt 

 gradually separates in small crystals, which appear to be rect- 

 angular four-sided tables. When first obtained, it is white, but 

 acquires a yellowish shade on exposure to the air. Water dis- 

 solves it sparingly. Ignited, it gives off" water of crystallization, 

 and a small quantity of acid : after this, it becomes red coloured, 

 and sustains no further decomposition. 



Fluate of oxide of iron is obtained in the form of a crystallized 

 pale flesh coloured powder, by dissolving the hydrated peroxide 

 in fluoric acid, and evaporating. It has a sweet and astringent 

 taste. Water dissolves it slowly, but completely ; the solution 

 is colourless even when concentrated, and ammonia does not 

 develop in it a deep red colour, as happens with solutions of the 

 ordinary salts of oxide of iron. Ammonia added in excess pre- 

 cipitates from this solution a subfluate. 



Fluate of oxide of zinc forms small white opaque crystals, 

 which are difficultly soluble in water, but are copiously dissolved 

 by ammonia. 



Fluate if oxide of cadmium is obtained by evaporating a solu- 

 tion in the state of a white crust, which exhibits no indications 

 of a regular crystallization. 



Finales of the Oxides of Cobalt, Nickel, and Copper. — The 

 colour of the first is rose red ; of the second light green ; of the 

 third light blue ; in other respects their properties are so closely 

 similar that a description of one may be accurately applied to 

 the rest. They may be prepared by mixing the carbonated 

 oxide with fluoric acid : it dissolves with effervescence, and the 

 fluate is soon after precipitated in the form of a heavy powder. 

 If an excess of carbonate be added, and especially if heat be at 



