s6S Sir H. Davy on the Substances produced 



the phenomena can at present be given without involving sup- 

 positions. 



It is not easy to devise simple experiments to ascertain 

 which of these hypotheses is true, yet, in admitting strict ana- 

 logical reasoning, it is easy to shew which is most conformable 

 to the general series of chemical facts. 



Those acids which are known by direct experiments of de- 

 composition by heat, to consist of oxygen, bases, and water, 

 such as the strongest sulphuric and nitric acids and hydro- 

 phosphorous acid, when they are acted on by ammonia, afford 

 moisture: this is easily proved, by causing them to absorb 

 ammoniacal gas in glass retorts, and gently heating the mix- 

 ture, when water immediately appears. On this view, it oc- 

 curred to me, if the liquid fluoric acid was a compound of 

 water, and inflammable bases, and oxygen, that water ought 

 to be produced when it was made to combine with ammonia. 

 It was not possible to make the experiment in glass vessels, 

 as the acid acts with great violence on glass, producing silicated 

 fluoric acid gas. I had recourse, therefore, to an apparatus 

 made of platina. A small tray of platina was filled with pure 

 liquid fluoric acid, and introduced into a tube of platina con- 

 nected by proper stop-cocks with a mercurial gazometer, filled 

 with ammonia ; the end of the platina tube was closed by a 

 brass stopper, and a communication made between the am- 

 monia and the fluoric acid ; the ammonia was gradually ab- 

 sorbed, producing heat ; and white fumes sometimes rose into 

 the gas-holder, so that it was necessary from time to time to 

 cut off the communication; ammoniacal gas was supplied till 

 no more absorption took place. When the tube was quite 

 cool, the stopper was removed, and the result examined ; the 



