on the Haloid Compounds of Mercury. 445 
Section III.—Of the Action of Ammonia upon Peroxide of Mercury. 
The accurate examination of the action of ammonia upon peroxide of mercury is 
of very great importance, as the compound resulting ; the ammoniuret of mercury is 
one of a very remarkable class of bodies, viz. the fulminating compounds containing 
ammonia; and in addition, the experiments of Guibourt, the only chemist I believe 
who has made analyses of it, would appear to demonstrate in it, a relation between 
the number of atoms of ammonia and oxygen, which must influence the ammoniacal 
theories to a very great extent. These circumstances made me trace out the proper- 
ties of this body with more exactness than should have been otherwise required. 
I have not been able to prepare a substance possessing the external characters of 
the ammoniuret of mercury described by Fourcroy and Thenard. I have varied in 
every manner I could imagine, the method of obtaining it ; but, although I got asub- 
stance constantly the same in its properties and composition, it differed much in 
appearance from that described by the French chemists. They state, that by digesting 
liquid ammonia on red oxide of mercury during eight or ten days, the oxide gra- 
dually covers itself with a yellowish-white powder which generally passes to a very 
fine white. I have never obtained it of a pure white, but always with a tinge of 
yellow, possessing an appearance and affording on analysis, results always the same. 
The constancy of its properties justifies me, I should think, in considering it as pure, 
notwithstanding its not exactly agreeing with their result. Unfortunately they did 
not publish any quantative analysis of their product; the only one known to me is 
that in Guibourt’s thesis. 
In order to prepare ammoniuret of mercury, I precipitated a solution of sublimate 
by potash, and the precipitate having been well washed from all excess of alcali, was 
put into a bottle of water of ammonia and left for some days; its colour became 
much lighter, but never completely white. Other portions of recently precipitated 
peroxide were boiled in water of ammonia for a few minutes, until the colour ceased 
to undergo any change: the reaction was very much accelerated by heat. ‘These dif- 
ferent portions of product had all the same colour, and were indifferently, but with- 
out mixture, used in the following examination without any difference of properties 
becoming observable. 
When this ammonuret is heated it gives off much ammonia, and azote ; a consider- 
able quantity of water collects in the tube, and the matter remaining becomes dark- 
red, like peroxide ; but if it be allowed to cool, it reassumes its whitish colour, and is 
evidently still unaltered ammoniuret. ‘The reaction evidently does not consist in a 
separation of the ammoniuret into ammonia and peroxide; but, from the commence- 
ment to the termination, there are disengaged water, ammonia, azote, oxygen, and 
