on the Haloid Compounds of Mercury. 439 
Q {(@Ch + Hg) + (2 NH? + Hg) +4 H= 
f(2 Ch + Hg) +2Hig +(@2NH? + Hg) +2Ch NH 
There are here equally produced by the two atoms of white powder and two of water, 
two of sal-ammoniac, and one of the yellow powder, of which the composition should be, 
Mercury 85,72 
Chlorine 7,48 
Amidogene 3,42 skies 
Oxygen 3,38 
and it should yield in analysis 3,63 per cent. of ammonia. 
The definite composition of this yellow powder is thus evident, and the decom- 
position by which it is formed perfectly explained. We see that all the results tend 
to show that in these bodies the ammonia is not united with oxide of mercury, but 
rather the metal with amidogene. The perfect demonstration of this principle, how- 
ever, must be sought for in the other metals. 
§3.— Of the products of the Action of Alcalies in Excess on WV hite Precipitate. 
Grouvelle and other chemists have stated that by the action of an excess of alcali 
on a sublimate solution, there is produced the ammoniuret of mercury which was dis- 
covered by Fourcroy and examined by Guibourt, and to which I shall hereafter 
speedily recur ; and even Dumas states, that ‘the same compound (the ammoniuret) 
is obtained by pouring ammonia into a solution of corrosive sublimate, and then adding 
caustic-potash in excess.”” My anxiety to obtain pure ammoniuret of mercury, joined 
to the interest of the preceding investigations, led me to examine the nature of the 
products thus obtained; and the results, as correcting an error very generally fallen 
into, are worthy of being described. 
When corrosive sublimate is decomposed by ammonia, the quantity of alcali in 
excess does not appear to interfere much with the reaction before described. If the 
liquors be cold, there is obtained white precipitate; and if it be boiled, the heavy 
yellowish powder is produced. The liquor retaining in the former, one-half, in the 
latter, three-fourths of the chlorine of the sublimate. Again if white precipitate be 
boiled in water, rendered strongly alcaline by ammonia, we obtain the yellowish 
powder, and half the chlorine and half the ammonia of the precipitate are disengaged. 
Thus, water of ammonia acts on white precipitate only as water itself does, the nature 
of the reaction being the same in both instances. Again when white precipitate 
VOL. XVII. 4H 
