Stoney — On the Interrupted Spectra of Oases. 
107 
presence of ozone are produced in a most striking manner. Cork is 
rapidly bleached and corroded, and an old specimen of the oils, when 
poured upon a solution of starch and iodide of potassium, instantly pro* 
duces blue iodide of starch. Concurrent with the development of 
ozone is a rise in the boiling point of the fluid. A similar action takes 
place when resin spirit is excluded from direct sunlight, but the mole- 
cular condensation is much slower. The action of atmospheric oxygen 
as regards the production of ozone seems much more decided in the 
presence of resin spirit than with turpentine. 
Paper moistened with a solution of iodide of potassium and starch, 
and suspended in a vessel containing resin oils, becomes blued in a 
few hours. After prolonged exposure the oils exhibit a faint acid reac- 
tion. Immediately after washing with a weak solution of carbonate of 
sodium and distilled water, light resin oil does not produce a change, 
but on standing for an hour, or so, it becomes charged again with 
ozone and blues the test-solution. 
Ozone is probably the prime mover in the production of colophonic 
hydrate, described by the author in the Transactions of the Academy. 
Dr. Anderson got some substance which he thought was colophonic 
hydrate in the recent products of the destructive distillation of resin. 
Supposing that it was formed during the process of distillation it would 
not be found in the oils, simply from the fact that this substance (colo- 
phonic hydrate) is very soluble in water — and that as there is an 
aqueous portion of the product of destructive distillation it is there we 
must look for it. The author has examined the aqueous products 
obtained from the distillation of 4j tons of resin in one operation. It 
was perfectly free from colophonic hydrate, which, if it had been 
formed at all, had evidently been destroyed by the action of the acetic 
acid which constitutes about 1 1 per cent, of this fluid. 
I have frequently looked for, but could never discover colophonic 
hydrate in the newly formed hydrocarbons. It simply seems to be 
produced by the action of atmospheric oxygen, which in the first stage 
is converted into ozone. 
XYI. — On the Cause of the Inteeeupted Spectea oe Gases. By 
G. Johj^-stoi^e Stoi^ey, M. A., F. E. S., &c. [Abstract.] 
[Read January 9, 1871.] 
1^ the Philosophical Magazine" for August, 1868, there is a paper 
on the Internal Motions of Gases, f by the author of the present com- 
munication, in which a comparison is instituted between these motions 
and the phenomena of light, from which the conclusion is drawn that 
the lines in the spectra of gases are to be referred to periodic motions 
* Transactions, vol. xxiv., Science, p. 579. 
t In reading that paper, the reader is requested to correct 16^ into \/ 16, at the 
end of paragraph 2. 
