Chemistry. 389 
ed in. it phosphoric acid. Dr Torrey was particularly careful in 
ascertaining that Gibbsite contained neither Phosphoric nor Fluo- 
ric acids, both of which are ingredients in Wav ellite. Nearly all 
the Gibbsite yet found, has been collected at the mine in Rich- 
mond, where it was originally discovered. — New-Yorlc Medical 
and Physical Journal by Drs Francis, Dykeman, and Beck, 
No. I. p. 68. 
14. Cathartine., or the Active Principle of Senna. — MM. Las- 
saigne and Fenuelle, have discovered the active principle of 
Senna^ and which they have called Cathartine, The precipi- 
tate obtained by acetate of lead from a filtered decoction of the 
leaves, was diffused through water, and sulphuretted hydrogen 
passed through it. The liquor filtered was evaporated to dryness^ 
and digested in alcohol, and the alcoholic solution was then eva- 
porated to dryness. It contained acetate of potash, which was 
separated by alcohol acidulated by sulphuric acid. The sulphate 
of potash insoluble in this fluid, being separated by the filter ; the 
excess of sulphuric acid was precipitated by acetate of lead ; then, 
by decomposing this latter salt, by sulphuretted hydrogen, and 
again filtering and evaporating to dryness, the Cathartine^ or 
purgative principle of senna, was obtained. 
The Cathartine does not crystallize ; is of a reddish-yellow co- 
lour, and has a peculiar smell, and a bitter and nauseous taste. 
It is insoluble in ether, but soluble in alcohol and water, in all 
proportions. The extract becomes moist in the air. It operates 
as a purgative when taken in very small doses. 
15. Analysis of the Meteoric Stone of Juvenas In analysing 
this meteorite, M. Vauquelin found in its crust, grains of silex, 
and yellow brilliant points, like sulphuret of iron. It contained 
no nickel, but traces of copper and potash. It contained more 
alumina and lime,^ but much less magnesia than other n^^teorites. 
TJie iron which it contained did not act upon the most delicate 
magnetic needle, and a portion of it was united to chrome. The 
Sileoc amounted to two-ffths of the total weight of the stone. 
16. Soda Alum. — This new salt described by Dr Ure in the 
Journal of Science, has the same form and taste as common 
, * See this Journal, vol, vi. p. 384. 
VOL. VII. NO. 14. OCT. 18SS. c c 
