362 Experiments. om Prussic Acid. [May, 
the tube is covered with a slight coating of charcoal. This decom- 
position is similar to that which sulphureted hydrogen undergoes ; 
for Cluzel has shown that this last is partly converted into hydrogen 
and sulphur by heat. 
it will be recollected that iron at a red heat decomposes hydro- 
cyanic acid, The elastic fluid collected is a mixture of equal 
volumes of azote and hydrogen. The greatest part of the carbon is 
deposited round the iron, and a small part combines with it. Copper 
and arsenic have no action on hydro-cyanie acid. Platinum appears 
to decompose it at a high temperature, but the result is the same as 
is produced by heat alone. | 
The oxides produce on hydro-cyanie acid a variable action de« 
pending on their affinity for oxygen. 
Having placed barytes, recently prepared from its nitrate, in a 
glass tube heated to an obscure red, and made hydro-cyanic vapour 
pass over its surface, the barytes became slightly incandescent. 
it became soft, and then dried. No water was disengaged, but only 
pure hydrogen gas.* 
This experiment shows that barytes decomposes hydro-cyanic 
vapour ina manuer analogous to that in which it decomposes mu- 
riatic acid gas. But we obtain hydrogen in the first case, and water 
in the second, in consequence of the difference in the affinities of 
barium for cyanogen and chlorine. 
Since hydro-cyanie acid in combining with barytes loses its 
hydrogen, the compound is a true cyanuret of barytes ; when placed 
in contact with water, it ought to produce compounds analogous to 
the chlorates, iodates, or sulphites; that is to say, containing an 
acid composed of oxygen and cyanogen, which would be cyanic 
acid, strictly so called. But there is here a peculiar circumstance, 
which modifies a great deal the results; namely, cyanogen is a 
compound, and its elementary affinities appear more energetic than 
its resulting affinities. It is certain, at least, that by dissolving a 
cyanuret in water, we do not form a combination of oxygen and 
cyanogen. Ishal]l soon examine this subject more particularly, 
Instead of barytes, potash prepared by means of alcohol may be 
employed. The experiment may be made in a small curved glass 
tube, and it is more easy than the preceding one. Cyanuret of 
potash is obtained, and hydrogen is disengaged ; but its quantity is 
greater than the hydro-cyanic acid could furnish, because the water 
which the potash contains contributes to the decomposition of a part 
of the cyanogen. 
I likewise formed cyanuret of soda by passing hydro-cyanic vapour 
over dry carbonate of soda in a glass tube heated obscurely red-hot. 
‘The acid of the carbonate is disengaged, and an inflammable gas is 
obtained, which is not pure hydrogen, because both this gas and 
* This experiment may be conveniently made with hydro-cyanie vapour mixed 
with azote or hydrogen in a small bent tube, heated bya spirit of wine Jamp ; 
but the incandescence will not be seen, as the absorption will be less rapid. While 
cold, baryles exercises no sensible action on hydro-cyanic vapour, 
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