336 M. Berzelius on Fluoric Acid. [Nov. 



the same time applied, the fluate thus formed is gradually con- 

 verted into a subfluate. The neutral salts are only sparingly 

 soluble in water. A small quantity of water dissolves them 

 tinaltered ; but an excess decomposes them into salts which are 

 held in solution by the disengaged acid, and insoluble subsalts. 

 The subfuaies of nickel and copper have a pale green colour. 

 The fluate of copper, when decomposed by sulphuric acid, yields 

 116 per cent, of sulphate of copper, and when ignited with ten 

 times its weight of oxide of lead, gives off" 26*3 p. c. of water. 

 Hence it is a neutral fluate of copper combined with four atoms 

 of water. The insoluble salt obtained by boiling the preceding 

 in water yields, by a similar mode of analysis, 158*2 p. c. of sul- 

 phate of copper and 9*3 p. c. of water. It is, therefore, a sub- 

 salt, composed of two atoms of peroxide of copper, one atom of 

 fluoric acid, and two atoms of water.* 



Fluate of oxidule of copper may be formed by treating the 

 hydrate with fluoric acid : it instantly becomes red, and does not 

 dissolve in an excess of the acid. It must be washed with alco- 

 hol. When ignited it assumes a dark cinnabar red colour. 

 When exposed in a moistened state to the air, it at first becomes 

 yellow, in consequence of half the base forming with the acid 

 neutral fluate of oxidule, while the other half forms hydrate of 

 oxidule ; after some time it becomes green, and is wholly con- 

 verted into the subfluate of oxide of copper. This salt is soluble 

 in muriatic acid : the solution is black, and water precipitates 

 the salt in the form of a pale rose red coloured powder. 



Filiates of oxidule and of oxide of cerium correspond in most 

 of their characters with the fluate of yttria. Both occur native. 

 The fluate of oxide of cerium has a yellow colour. 



Fluate of lead is slightly soluble in water, but not in an excess 

 of fluoric acid. It melts in a low heat, and after fusion appears 

 yellow. Ammonia converts it very readily into a subsalt. This 

 subfluate is soluble in water ; when the solution is exposed for 

 some time to the air, it becomes turbid, and a crust is formed 

 upon its surface, composed of carbonate and fluate of lead. If 

 a solution of fluate of soda be mixed with a boiling hot solution 

 of muriate of lead, a double salt precipitates, which is to a small 

 extent dissolved, but is not in the least degree decomposed by 

 washing. This salt is white and pulverulent, and may be fused 

 without losing either acid or water. I found it by analysis to be 

 composed of an atom of fluate of lead and an atom of muriate or 

 chloride of lead. 



Fluate of oxide of chromium maybe prepared by dissolving 



• Berzelius considers the atomic weights of oxygen, fluoric acid, oxide of copper, and 

 water, to be 100, 270-34, 991 -39, and 112-4354. If we represent them by the num- 

 bers 1, 1-3517, 5, and 1*125, the neutral salt will be composed of one atom of acid, one 

 of base, and two of water ; and the subsalt, of one atom of acid, two of base, and one of 

 water. 



