224 Royal Society :— 
fraction which gave the nearest result as representing the boiling- 
point of the radical as obtained from the source mentioned. _ 
Propzyle presented itself under the form of a colourless, very mobile 
fluid, having a pleasant odour, and boiling at 68°C. At Ls° it had 
the very low density of 0°6745. Combustion gave results agreeing 
closely with the formula 
C2 H'*=4 vols., 
confirmed by a determination of the density of its vapour by Gay- 
Lussac’s method, which gave 2°96, theory requiring 2°97. Propyle 
had not been previously obtained. 
Butyle from the Torbane-hill mineral distils at 119°, and has a 
density of 0°6945 at 18°; its analysis coincided with the formula 
C'6 H's, 
The vapour-density was found to be 3°88, theory requiring 3°94. 
Amyle distilled at 159°, and had a density of 0°7365 at 18°. On 
analysis, numbers were obtained agreeing perfectly with the formula 
C20 Hee, 
The vapour-density was found to be 4:93; theory requires 4°91. 
Caproyle boiled at 202°; its density at 18° was 0°7568. The 
results of analysis accorded with the expression 
C24 H°, 
which indicates a vapour-density of 5°87, while experiment yielded 
5°83. 
The experiments detailed in the paper appear to demonstrate the 
radical nature of the hydrocarbons, and to negative the assumption 
of their being homologues of marsh-gas. 
The paper concludes with a description of a method, by which, 
where numerous vapour-density determinations are to be made, the 
necessity is avoided of refilling the balloon with water or mercury 
in order to determine the residual air, 
«On the Optical Characters of certain Alkaloids associated with 
Quinine, and of the Sulphates of their lodo-compounds.” By Wil- 
liam Bird Herapath, M.D., in a Letter to Professor Stokes, Sec. B.S. 
You will probably recollect that I sent you some time since a 
small portion of an alkaloid, which at that time was called quinidine 
in Germany, but it has since been distinguished from it and named 
cinchonidine. You then examined it for epipolism or fluorescence, 
and you pronounced the opinion that it possessed this property only 
in a minor degree, and you imagined that this arose from the presence 
of a small per-centage of a-quinine. 
I have since obtained, through the kindness of Mr. J. E. Howard, 
specimens of the perfectly pure alkaloids quinidine and cinchonidine, 
and find that quinidine, which I can now identify as the /3-quinine of 
Von Heijningen, possesses the phenomenon of fluorescence or epi- 
polic dispersion as powerfully as a-quinine; whilst cinchonidine, if per- 
fectly pure, is devoid of it altogether ; and recent experiments have 
shown me that a small per-centage of quinidine was the cause of the 
