on the Nature of certain Bodies. 61 
described, and when the upper part of the tube was full of 
gas, I suffered it to pass into the atmosphere ; so as to enable 
me to repeat the process. 
When I operated in this way, there seemed to be no limit 
to the generation of elastic fluid, and in about two hours a 
quantity had been evolved, which amounted to more than five 
times the volume of the sulphur employed. From the cir- 
cumstances of the experiment, the last portion only could be 
examined, and this proved to be sulphuretted hydrogene. 
Towards the end of the process, the sulphur became extremely 
difficult of fusion, and almost opaque, and when cooled and 
broken, was found of a dirty brown colour. 
The experiments upon the union of sulphur and potassium, 
which I laid before the Society last year, prove that these 
bodies act upon each other with great energy, and that sul- 
phuretted hydrogene is evolved in the process, with intense 
heat and light. 
In heating potassium in contact with compound inflammable 
substances, such as resin, wax, camphor, and fixed oils in close 
vessels out of the contact of the air, I found that a violent in- 
flammation was occasioned, that hydrocarbonate was evolved ; 
and that when the compound was not in great excess, a sub- 
stance was formed, spontaneously inflammable at common 
temperatures, the combustible materials of which were char- 
coal and potassium. 
Here was a strong analogy between the action of these 
bodies, and sulphur on potassium. Their physical properties 
likewise resemble those of sulphur ; for they agree in being 
non-conductors, whether fluid or solid, in being transparent 
when fluid, and semi-transparent when solid, and highly 
