828 NOTICES OF THE MEETINGS [May 27, 
zinc-ethyl alone isformed. Ata higher temperature the zinc-ethyl 
disappears and the ethyl is produced. 
It is evident that the formation of the compound molecule of 
hydrogen H H, must be a very different physical event to the 
formation of the single atom of hydrogen H, if such could exist. 
The ordinary hypothesis of the ‘ liberation’ of hydrogen gives us 
no conception of its nature: we need some other explanation. 
It seems to me probable that when zinc acts on. hydrochloric acid 
and water, there are, as in the case of ethyl, two steps in the process ; 
the first, the formation of a zinc-hydrogen, Zn H, the second, the 
action of this zinc-hydrogen on the water with the formation of 
hydrated oxide of zinc, Zn H O, and hydrogen gas H H. There 
are various arguments in favour of this view. First, it explains the 
result, which the other hypothesis does not. Secondly, the analogy of 
ethyl compels us to it. It is not probable that bodies so similar, in 
other respects, are dissimilar inthe mode of their formation. Thirdly, 
there is, at least, one experiment in which we are absolutely able to 
analyse the process of the formation of hydrogen and to prove that 
it does take place in this manner. 
This remarkable experiment is the formation of hydrogen by the 
decomposition of hypophosphorous acid by copper salts.* Hypo- 
phosphorous acid is, like zinc, what is termed a reducing agent. It 
precipitates certain metals from their solutions, and by a process of 
disoxydation decomposes alkalies with the formation of phosphorous 
acid and hydrogen. If this hypophosphorous acid be boiled with 
the copper salt, nothing is perceived but the formation of metallic 
copper and hydrogen gas; but if the solution be gradually heated, 
and the action arrested at a certain point, it can be shewn that this 
formation of hydrogen is preceded by the formation of a combination 
of hydrogen and copper, Cu,H, analogous to zinc-ethyl. The 
part which this bears in the formation of the hydrogen is distinctly 
shewn by the action of acids, hydrochloric acid, H C1, for example, 
upon it. This acid, which does not act upon metallic copper, im- 
mediately decomposes this body, forming protochloride of copper, 
Cu,Cl, and hydrogen HH. 
This hydride of copper has only a very ephemeral existence. It 
is decomposed very nearly at the same temperature at which it is 
produced, and its formation, for this reason, had long been overlooked 
by chemists. We can hence readily comprehend that other combi- 
nations of this class may take place in the case of which the tem- 
perature of formation and of decomposition may either coincide, or 
so closely approximate to each other, that it may ever be impossible 
to isolate the substance produced. This is probably the case in the 
action of zinc. 
[B. C. B.J 
Se ee ene ESE EESENIS SEUSS SERRE 
* See Annales de Chimie, III. Serie, tome XI. p. 250. 
