from the RIFER DEE. 259 



red oxide, when raifed to the ftate of white oxide, increafes ex- 

 actly one-third of its weight. It was the knowledge of thefe 

 facts, that led me to the preceding numbers. And I think they 

 may be ufed, till fome more direct experiment lead us to pre- 

 cife conclufions. 



Red oxide being the only ftate in which this metal has yet 

 occurred feparate, we may conclude that it combines, in this 

 ftate, with metallic oxides, and that the titanium in iron-fand, 

 is moft probably in this ftate. But white oxide, diminifhed by 

 one-fourth, gives us the equivalent quantity of red oxide. On 

 that fuppofition, the titanium prefent, before the analyfis, in 

 the 100 grains of ore, weighed 9.5 grains. 



The appearance of the arfenic furprifed me a good deal, as 

 it was altogether unexpected. I am difpofed to afcribe it to 

 fome particles of arfenic pyrites which might have been acci- 

 dentally prefent. This conjecture will appear the more pro- 

 bable, when we reflect, that arfenic pyrites very frequently ac- 

 companies iron-fand. Before the microfcope, the iron-fand ap- 

 pears to contain fome white mining particles, which, probably, 

 are arfenic pyrites. 



The fmall quantity of filica and alumina, I afcribe, without 

 heiitation, to grains of quartz and felfpar, which had adhered 

 to the iron-fand, and been analyfed along with it. Some fuch 

 grains were actually obferved and feparated. But others, pro- 

 bably, efcaped detection. 



12. If thefe fuppofkions be admitted as well founded, the 

 iron-fand was compofed of 



Protoxide of iron, 85.3 



Red oxide of titanium, 9.5 

 Arfenic, *- - 1.0 



Silica and alumina, - 1.5 

 Lofs, - - 2.7 



100.0 

 Vol. VI.— P. II. Kk The 



