82 REPORT— 1840. 
oxygen going to the positive, where it produces secondary effects of oxi- 
dation*; and that the galvanic agency was greatly increased by dissolving 
minute quantities of potash in the alcohol, so small a quantity as ;g2gqth 
part having a marked effect, by increasing the conducting power of the 
liquid. As it had been objected that the water of the hydrate of 
potash employed might contribute to the result, the author has since 
employed potassium instead of hydrate of potash, with precisely the 
same effects. It is known, that when potassium is dissolved by alcohol, 
it is oxidated with evolution of hydrogen, so that in this way we pro- 
duce the same consequences as if we added anhydrous potash. B 
adding small quantities of potassium, such as ;35 or 34,, to absolute 
alcohol (sp. gr. *7918, at 66° F.), and then submitting the liquid to 
voltaic action, hydrogen was given off at the negative pole; and when 
the effect ceased, it was renewed by re-charging the battery, and again 
adding a similar small quantity of potassium ; and the usual secondary 
effects of oxidation were produced at the positive pole. In instituting 
a comparison between the quantity of hydrogen thus given off, and 
that evolved by the same electric current from acidulated water, it is 
necessary that a powerful current should be employed, and a some- 
what larger quantity of potassium dissolved; because otherwise, from 
the inferior conducting power of the liquid, and from a little of the 
hydrogen entering into the constitution of the secondary products, 
the quantity of hydrogen evolved from the alcohol is somewhat less 
than that from the acidulated water; and the comparison is best insti- 
tuted during the early stages of the action, because the conducting 
power of the liquid diminishes as the potash gets saturated by the 
secondary products, and the electric energy declines also. The author 
still regards these experiments as affording the only direct proof which 
we yet have of the existence of water, as such, in absolute alcohol. 
On Resins. By Professor JounstToN. 
In this paper the author drew attention to the following facts, appa- 
rently established by a table of analytical results, which he exhibited, 
and has had printed. Ist. That the resins differ from each other in 
the quantity of oxygen they contain. 2nd. That in those in which the 
atoms of oxygen are the same, the hydrogen may vary, and that this is 
another cause of difference in the properties of the resins. 3rd. That 
in all the resins hitherto carefully analysed, the number of atoms of 
carbon is constant. 4th. That the resins, as a natural family, may be 
represented by a general formula containing two variables. 5th. That 
the known resins divide themselves into two groups, possessing unlike 
chemical and physical properties; that of one of these groups colo- 
phony may be considered as the type, and that it is represented by 
Cyy Hy +x Oy; that gamboge, or dragon’s blood, may be considered 
as the type of the other group, which is represented by Cy) Ha, + x O,- 
* Transactions of the Royal Society of Edinburgh, vol. xiii. 
