works, might answer the purpose.--_Chemical News._

* * * * *




CARBONIC ACID AND BISULPHIDE OF CARBON.[1]

[Footnote 1: A paper read before the Royal Society, April 5, 1883.]

By JOHN TYNDALL, F.R.S.


Chemists are ever on the alert to notice analogies and resemblances in
the atomic structure of different bodies. They long ago indicated
points of resemblance between bisulphide of carbon and carbonic acid.
In the case of the latter we have one atom of carbon united to two of
oxygen, and in the case of the former one atom of carbon united to two
of sulphur. Attempts have been made to push the analogy still further
by the discovery of a compound of carbon and sulphur analogous to
carbonic oxide, but hitherto, I believe, without success. I have now
to note a resemblance of some interest to the physicist, and of a more
settled character than any hitherto observed.

When, by means of an electric current, a metal is volatilized and
subjected to spectrum analysis, the "reversal" of the bright band of
the incandescent vapor is commonly observed. This is known to be due
to the absorption of the rays emitted by the vapor by the partially
cooled envelope of its own substance which surrounds it. The effect is