502 Intelligence and Miscellaneous Articles. 
transparent crystals of the size of a nut; its density was 3°733. It 
was pulverized in a steel mortar and fused with bisulphate of potash. 
The free mass was completely dissolved in water, which proves the 
absence of silica. The solution contained traces of alumina, and 
was precipitated by excess of ammonia; the oxides thus precipi- 
tated were dissolved in hydrochloric acid, and the solution was de- 
composed in the cold by a solution of potash; the oxide of iron pre- 
cipitated was again dissolved in hydrochloric acid, and then preci- 
pitated by ammonia; the glucina was separated by Gmelin’s process, 
by boiling the solution much diluted; from the solution afterwards 
acidulated by hydrochloric acid, the alumina was precipitated by 
ammonia. ‘The mean of two analyses gave 
Giuema | 92. See ees se O 
Alumina jab. yetiee eee 78°4 
Protoxide of iron ........ 3°9 
100°3 
Chrysoberyl from the Ural.—This mineral contained traces of the 
oxides of copper and lead, which were separated by passing sulphu- 
retted hydrogen into the solution obtained after the action of the 
bisulphate of potash; in other respects the analysis was conducted 
as above, except that the glucina being treated with a mixture of 
carbonate and nitrate of potash, a little oxide of chromium was sepa- 
rated from it; the chromic acid was reduced to the state of prot- 
oxide of chromium by means of hydrochloric acid, and then preci- 
pitated by ammonia. 100 parts yielded— 
Guiveitias pens Sra Sisteiecs<tetnonaet are 18°02 
TABMIN Ars aishowkiere ata iscasis Se 78°92 
Protoxide of iron .......... ache 
Oxide of chromium....... 6652202386 
Oxide of copper andlead .... 0°29 
100°71 
Regarding this mineral as an aluminate of glucina, it would be com-. 
posed of 
Altima? <2). 80h etl eueeek: 80°25 
Glocinars tremens ce tees 19°75 
100: 
Ann. de Chim. et de Phys., Fevrier 1843. 
SOLUTION OF AN EQUATION. BY JAMES COCKLE, B.A. TRINITY 
COLLEGE, CAMBRIDGE. 
To the Editors of the Philosophical Magazine. 
GENTLEMEN, 
I have taken the liberty of sending to you a solution of the equation 
Pde OW A ed OY ei 0 Pag neg eee OUR NREL AB (1.) 
Assume a+ Spat + Sp*rs — b... resi k alee 3 s€2y) 
Subtract (1.) from (2.) and divide by 3 pz: then 
