ioo Mr. Davy's Lecture on some new analytical Researches 
9. Some general Observations , with Experiments. 
An experiment has been lately published, which appeared 
so immediately connected with the discussion entered into in 
the second section of this Paper, that I repeated it with much 
earnestness. 
In Mr. Nicholson’s Journal for December, Dr.WooDHousE 
has given an account of a process, in which the action of water 
caused the inflammation of a mixture of four parts of char- 
coal and one of pearlash that had been strongly ignited to- 
gether, and the emission of ammonia from them. I thought 
it possible, that in this case a substance might be formed similar 
to the residuum described in page 50 ; but by cooling the mix- 
ture out of the contact of nitrogene, I found that no ammonia 
was formed ; and this substance evidently owed its existence 
to the absorption of atmospherical air by the charcoal.* 
The experiments that 1 have detailed on the acids, offer some 
new views with respect to the nature of acidity. That a com- 
pound of muriatic acid with oxide of tin or phosphorus should 
* Potash or pearlash is easily decomposed by the combined attractions of charcoal 
and iron ; but it is not decomposable by charcoal, or, when perfectly dry, by iron 
alone. Two combustible bodies seem to be required by their combined affinities for 
the effect; thus in the experiment with the gun barrel, iron and hydrogene are con- 
cerned. I consider Homesrg’s pyrophorus as a triple compound of potassium, 
sulphur, and charcoal ; and in this ancient process, the potash is probably decomposed 
by two affinities. The substance is perfectly imitated by heating together ten parts 
of charcoal, two of potassium, and one of sulphur. 
When I first shewed the production of potassium to Dr. Wollaston in October 
1807, he stated, that this new fact induced him to conceive that the action of pot- 
ash upon platina, was owing to the formation of potassium, and proposed it, as a 
matter of research, whether the alkali might not be decomposed by the joint action 
of platina and charcoal. 
