2 8 Mr. Davy’s Experiments on 
powder. The purple fluid is, I find, a solution of a compound 
of tellurium and hydrogene in water ; which in being diffused, 
is acted upon by the oxygene of the common air, dissolved in 
the water, and gradually loses a part of its hydrogene, and 
becomes a solid hydruret of tellurium. The compound of hy- 
drogene and tellurium produced at the negative pole when 
uncombined is gaseous at common temperatures, and when 
muriatic acid, or sulphuric acid are present in the water, it is not 
dissolved, but is given off, and may be collected and examined. 
I acted upon potash by means of a surface of tellurium, 
negatively electrified, by a part of the large Voltaic apparatus 
lately constructed on a new plan in the laboratory of the Royal 
Institution, an account of which, with figures, will be found 
annexed to this paper. 1000 double plates were used. The 
potash was in the common state, as to dryness. There was a 
most violent action, and a solution of the tellurium, with much 
heat, and a metallic mass, not unlike nickel in colour, was 
formed ; which when touched by water, did not inflame nor 
effervesce, but rendered the water of a beautiful purple 
colour, and when thrown into water entirely dissolved, making 
a bright purple tincture. It immediately occurred to me, 
that the whole of the hydrogene, which in common cases 
would have been furnished from the decomposition of the 
water, had in this instance combined with he tellurium, and 
that the telluretted hydrogene, (if the name may be used,) had 
formed with the oxidated potassium, i. e. the potash, a peculiar 
compound, soluble in water ; and this I found to be the case ; 
for on pouring a little diluted muriatic acid into the mixture, 
it effervesced violently, and gave a smell very like that of 
sulphuretted hydrogene ; metallic tellurium was formed where 
