M. Miasnikoff on Acetylene. 359 
nated propylene on ethylate of sodium, and has obtained a second 
member of the series, al/ylene, C7 H*. The action is quite ana- 
logous to that in the former case: the gas is passed into an am- 
moniacal solution of copper, with which it forms a voluminous 
flocculent precipitate. This is decomposed, when heated, with 
the formation of a reddish flame; with concentrated acids it dis- 
engages a gas even in the cold. 
Allylene is best obtained from this precipitate by the action 
of dilute aqueous hydrochloric acid, from which, when heat is 
applied, there is given off a colourless gas of a strong and dis- 
agreeable odour, but less so than that of acetylene. It burns 
with a fuliginous flame, and precipitates silver and mercury salts, 
the former grey and the latter white. These compounds are 
analogous to the copper compound, and, like it, are very unstable. 
The property of combining with an ammoniacal oxide of copper 
appears to be characteristic of this group, and will probably lead 
to the discovery of the higher members. 
The formation of allylene may be thus expressed :— 
C? H° NaQO+ C? H® Br= Na Br+ €? H*+€? H°O, 
Ethylate of Brominated Allylene. Alcohol. 
sodium. propylene. 
Miasnikoff*, in some experiments with monobrominated ethyl- 
ene, has also noticed a mode of the formation of acetylene, which 
gives a simple and elegant method of preparing this gas. 
When the vapours of crude monobrominated ethylene, prepared 
in the ordinary way, are passed into an ammoniacal solution of 
nitrate of silver, a precipitate forms, which is at first yellow, but 
which quickly becomes converted into grey; at the same time 
an oil collects at the bottom of the vessel, which is brominated 
ethylene, and which can easily be separ ated by heating to 20°. 
When this bromide further acts upon a fresh portion of ammo- 
niacal solution, it produces no change; but after being passed 
through a boiling concentrated solution of potash, it again 
acquires the property of forming this grey pulverulent deposit. 
By arranging the apparatus so that the vapours of brominated 
ethylene pass more than once through solution of potash, a con- 
siderable quantity of the pulverulent deposit can be formed. 
This powder detonates strongly on the application of heat, 
percussion, or friction, and also by the action of chlorine or of 
gaseous hydrochloric acid. Treated with dilute hydrochloric 
acid, it gives a gas which burns with a fuliginous flame, and 
which reproduces the pulverulent precipitate. The analysis and 
the properties of this gas show that it is acetylene; and the 
analysis of the silver compound gives for it the formula 
C* H? Ag’. 
* Bulletin de la Société Chimique, p. 12. 
