680 BERZELIUS ON THE COMPOSITION OF 
sesquichloride of carbon and 1 atom of dithyonic (hyposulphuric) 
acid = CCl? + S20°, This is a strong acid, which can be sepa- 
rated and crystallized ; it may be called sesquichloride of car- 
bon-dithyonic acid, and is evidently a conjugate dithyonic acid 
in which the conjunct is the same as in chloroxalic acid. 
If metallic zinc is placed in a solution of this acid, it is dis- 
solved without any evolution of gas, and two salts of zine are 
obtained dissolved in the fluid. One atomic equivalent of the acid 
dissolves 2 atoms of zinc, and the solution contains 1 atom of 
protochloride of zinc and 1 atom of an oxide of zinc salt, the acid 
of which consists of C?7HCl?+$?0°. An equivalent of chlorine is 
taken up by the zinc, and the hydrogen which was eliminated on 
the formation of an atom of oxide of zinc to saturate the acid has 
taken its place in the conjunct, which now has been converted 
from sesquichloride of carbon into dichloride of formyle without 
leaving its position in the conjunct. This substitution, compared 
with the previous one, has taken place in an inverse order, and 
at the same time a compound radical has formed itself in the 
conjunct which was previously not present. When this or the 
first-named acid, no matter which, is dissolved in water, mixed 
with an equivalent of sulphuric acid, and zinc then added, the 
acid becomes saturated with zinc, without the evolution of hy- 
drogen. According to the nature of the conjugate acid used, 
3 or 4 equivalents of zinc are dissolved, and we obtain in solu- 
tion 1 or 2 equivalents of protochloride of zinc, 1 equivalent of 
sulphate of zinc, and 1 equivalent of a new salt of zinc, in which 
only 1 equivalent of chlorine remains, the acid of which is 
C?H2Cl1+ 870%, z. e. a conjugate acid composed of protochloride 
of elayle united to dithyonic acid. If more than 1 equivalent of 
sulphuric acid is used in the formation of this salt the proto- 
chloride of elayle is not decomposed, but on the solution of the 
zinc in the excess of acid hydrogen is given off. 
What however the affinity exerted by an excess of sulphuric 
acid cannot overcome, -is effected by an electrical current. 
Kolbe has shown that when the potash salt of either of these 
three conjugate dithyonic acids is exposed in a concentrated so- 
lution between amalgamated plates of zinc to the electric cur- 
rent produced by 2 or 3 pairs of Bunsen’s carbo-zine battery, 
by oxidizement of the zinc basic chloride of zinc is formed, and 
that no hydrogen is evolved, until the whole amount of chlorine 
in the acid has been exchanged for hydrogen. Thus we obtain a 
