FLUORIC ACID, 85 



54'56 silex 

 45*44 acid 



10000 



I have endeavoured to ascertain what quantity of silicated Water con- 

 fluoric acid gas a given quantity of water will condense. In timeg it8 bullt 

 one instance -J^ of a cubic inch of distilled water absorbed 51 of sil. fl. a. 

 cubic inches, barom. 30*5, therm. 60. The gas was added to gas; 

 the water in a jar over mercury, as fast as it was absorbed. 

 The experiment was stopped, when the gas, after having re- 

 mained in contact with the water a whole night, ceased to be 

 diminished. According to this result, the proper correction 

 being made for the additional pressure, water decomposes 

 about 263 times its bulk of silicated fluoric acid gas. 



Dr. Priestley observed, that muriatic acid gas re-produced 

 silicated fluoric gas from the crust of silex formed, when the . 

 latter is condensed by water*. This experiment I have re- 

 peated, and as it appears to show more correctly the quantity 

 of gas water can condense, I shall describe the result. 2*4 

 cubic inches of muriatic gas were added to a drop of water, 

 that had previously absorbed one cubic inch of silicated fluoric 

 gas, in a jar over mercury. There was an immediate absorp- 

 tion equal to T 2 - of a cubic inch. The mixture of silex and 

 subsilicated fluoric acid effervesced, and from an apparent 

 solid became fluid, the whole of the silex gradually disappear- 

 ing. After the first mentioned absorption, there was no far- 

 ther. The gas produced was silicated, as appeared from the 

 crust it deposited when removed to water, and the liquid formed 

 was pure muriatic acid, for decomposed by concentrated 

 sulphuric, it afforded merely muriatic acid gas, without any sili- 

 cated fluoric. The evident conclusion from the preceding result 

 is, that water condenses equal quantities of the muriatic and 

 silicated fluoric acid gases, and consequently that the first or more cor . 

 estimate is too low, and instead of 263 times its bulk, it is r . ectI y 365 

 probably more correct to say that water to be saturated re- 

 quires at least 365 times its volume. Neither will this estimate 

 appear inconsistent with the former results, when the deposi- 



* Vide Priestley on Air, Vol. II. p. 202, 



lion 



