1820.] of different inorganic Bodies. 281 



ever beinsc made red-hot ; after which it was redissolved in 

 water, which left a shght trace of sihca undissolved. This solu- 

 tion was mixed with muriate of barytes. The precipitate sepa- 

 rated on a filter and washed, appeared to dissolve in water, 

 though in a very small proportion ; so that the water employed to 

 wash it was always precipitated by sulphuric acid. After having 

 passed through it a quantity of water sufficient in other cases to 

 have washed such a portion of matter, I dissolved a small quan- 

 tity of the precipitate in nitric acid. On pouring in a small 

 quantity of nitrate of silver, muriate of silver was precipitated in 

 abundance. It appears then that the precipitate formed by the 

 addition of fluate of soda to the muriate of barytes is a double 

 salt composed of the two acids united to a single base. I did 

 not examine it more closely ; but satisfied myself with ascertain- 

 ing that it could not be employed for the object which 1 had in 



view 



To obtain pure fluate barytes, I employed a solution of nitrate 

 of barytes, which I poured into a solution of fluate of soda, tak- 

 ing care that the whole quantity of fluoric acid was not precipi- 

 tated. The precipitate being washed, dried, and exposed to the 

 fire, gave out fluoric acid without any trace of the smell of nitrous 

 acid. It was necessary to expose the salt to a red heat repeat- 

 edly before it ceased to lose weight. This circumstance would 

 have deserved a particular examination, if the number of experi- 

 ments necessary for the object which I had in view had not 

 prevented me from touching upon any thing that could give a 

 different direction to my labours. 



Six grammes of this fluate of barytes, long exposed to heat, 

 were decomposed by sulphuric acid, and produced 7*968 grammes 

 of fluate of barytes. According to this experiment, lUL) fluoric 

 acid were united with 697-7 of barytes, the oxygen of which 

 is 71. 



Fluate of Lime. — I made choice of a fine specimen of Derby- 

 shire fluate of hme, forming a large, colourless, transparent 

 crystal, v;hich I considered as sufficiently pure to deserve to be 

 analysed. I reduced it to powder upon a slab of flint, and I 

 levigated the powder with great care, so as to render it perfectly 

 impalpable. 



Ten grammes of this powder, heated some degrees above 212°, 

 were exposed in a platinum crucible to an incipient red heat 

 without any loss of weight. I then exposed it for some lime to 

 a red heat, but still it lost no weight. It follows from this, that 

 when the water, mechanically adiiering to the powder, has evapo- 

 rated the fluate of lime, undergoes no further alteration in the 

 fire. I now mixed the powder with pure sulphuric acid, employ- 

 ing a platinum spoon, whose weight had been determined along 

 with that of the crucible. The first effect of the action of the 

 •ulphuiic acid was, that the mass augmented considerably in 



