226 Royal Society :— 
This alkaloid was also furnished me by the kindness of Mr. Howard, 
but has not yet been sufficiently purified, or in the quantity necessary 
to give certain results. 
It possesses one very peculiar property. When dissolved in chloro- 
form and evaporated spontaneously on glass, the gummy and uncry- 
stalline residue, mounted in Canada balsam, at once shows a deep 
blue-green, epipolic, or fluorescent appearance. 
Pure cinchonidine does not possess epipolic dispersion and does not 
become green by chlorine-water and ammonia; and when it is dis- 
solved in acetic acid or chloroform and the fluid is exposed on glass 
plates to spontaneous evaporation, beautiful crystals in circular spots 
or drusze develope themselves, which under polarized light exhibit 
black crosses and white or coloured sectors. 
These appearances are not exhibited by pure quinine or true qui- 
nidine (3-quinine), both of which give a gummy, uncrystalline, and 
perfectly transparent residue. 
Pure cinchonidine, thus optically and chemically distinguishable 
from either quinine or quinidine, is still further remarkable for pro- 
ducing with sulphuric acid and iodine an optical doubly absorbent 
compound of intense power, even equal to the sulphate of iodo- 
quinine compound ; these crystals are very similar in form to my 
artificial tourmalines, and have long been mistaken by me for them ; 
even at present I can only distinguish them by the tints in reflected 
light and the complementary body-colour, viz. whilst sulphate of 
iodo-quinine gives a cantharidine-green reflected tint, and a pink, 
ruby-red, reddish-brown or black body-colour when polarized perpen- 
dicular to the axis, according to the thickness of the plate examined, 
the sulphate of iodo-cinchonidine is golden-green by reflected light, 
and gives a sky or indigo-blue or black “ body-colour”’ when polarized 
perpendicular to the axis. I have not yet made sufficient chemical 
analyses of this substance to enable me to decide on its formula, but 
I have obtained 39°307 per cent. iodine and 8-864 per cent. sulphuric 
acid, which sufficiently indicate a chemical difference in constitution 
from the sulphate of iodo-quinine, which, it may be remembered, 
contains 32°609 per cent. iodine and 10°61 per cent. sulphuric acid. 
I hope soon to present these results in more detail when sufficient 
leisure is afforded me for the purpose.—W. B. H. 
January 29.—Major-General Sabine, Treas. and V.P., in the Chair. 
The following communications were read :-— 
«On the Nervous System of Lumbricus terrestris.” By J. Lock- 
hart Clarke, Esq., F.R.S. 
« An Account of the two Methods of Reproduction in Daphnia, 
and of the Structure of the ‘Ephippium.’”’ By John Lubbock, 
Esq., F.G.S. 
“On the Thermo-electricity of Ferruginous Metals, and on the 
Thermal Effects of stretching Solid Bodies.” By J. P. Joule, F.R.S. 
The experiments on the above subjects were made with a thermo- 
multiplier placed in the vacuum of an air-pump. Its sensibility was 
