440 M. Vauquelin’s Memoir on (June, 
further facilitated by a little potash which is volatilized by the 
action of the heat. 
Observations on the Decomposition of Cyadide of Mercury by 
Muriatic Acid, 
This paragraph contains very interesting observations, which 
are quite new ; not only respecting what takes place during the 
preparation of hydrocyanic acid by the process of Gay-Lussac ; 
but they led Vauquelin to a good method of obtaining this acid 
without any risk and in greater quantity than heretofore from 
the same weight of cyadide of mercury. 
On decomposing,” says M. Vauquelin, “ 10 grammes of 
cyanide of mercury with 20 grammes of muriatic acid in an appa- 
ratus i for condensing and collecting the hydrocyanic acid 
that should be disengaged ; and at a temperature not sufficiently 
high to cause the mixture to boil, I did not observe a single 
trace of hydrocyanic acid. I then made it boil gently for some 
time ; but notwithstanding this elevation of temperature, nothing 
appeared in the receiver which was cooled by a mixture of snow 
and salt. I presumed, as M. Gay-Lussac had announced, that 
this acid had been condensed in the part of the apparatus in 
which the marble was. I, therefore, heated that part; but with- 
out success. After some hours of labour, I obtained only some 
drops of a white liquid, having a very strong smell, which I was 
scarcely able to collect. 
“‘ If (judging from the composition of cyadide of mercury) all 
the hydrocyanic acid had been disengaged in our process, it 
would have amounted to two grammes and a half. 
“The matter remaining in the retort ought to have been 
either calomel or corrosive sublimate, if things had passed as 
had been stated. But the crystals of the salt, which formed on 
the cooling of the liquid, appearing to me different from those of 
corrosive sublimate, I subjected them to the following trials : 
“1, The salt dissolved in water much more rapidly than deu- 
tochloride of mercury, and produced a considerable degree of 
cold. 
‘2. Its solution gives with potash a white precipitate, 
whereas it would have given a yellow precipitate if it had been 
pure corrosive sublimate. ; 
“3. A certain quantity of the salt being triturated with a solu- , 
tion of caustic potash, became white on the spot, and exhaled a 
strong odour of ammonia. ; : 
“These properties show that the salt is not corrosive subli- 
mate, but a combination of muriate of ammonia and muriate of 
mercury, formerly distinguished by the name of sal alembroth. 
They show at the same time that, in the process above described, 
the cyanogen was in part decomposed, and that its azote united 
to the hydrogen of the muriatic acid, or of the water, to form 
