t02 , Analysis of a Black ^and, 



the state of red ox'ule, it loses one-fourth of its weight j 

 and that red oxide, when raised to the state of while oxide, 

 increases exactly one-third of its weight, It was the know- 

 ledge of these facts, that led me to the preceding numbers. 

 And I think they may be used, till some more direct expe- 

 riment lead us to precise conclusions. 



Red oxide being the only state in which this metal haa 

 yet occurred separate, we may conclude thai it combines, 

 jn this state, with metallic oxides, and that the titanium ia 

 iron-sand is most probably in this state. But while oxide, 

 diminished by one-fourth, gives us the equivalent quantity 

 of red oxide. On that supposition, the titanium present, 

 before the analysis, in the 100 grams of ore, weighed 9*5 

 grains. 



The appearance of the arsenic surprised me a good deal, 

 as it was altogether unexpected. I am disposed to ascribe 

 it to some particles of arsenic pyrites which might have 

 been accidentally present. This conjecture will appear the 

 more probable, when we reflect, that arsenic pyrites very 

 frequently accompanies iron-sand. Before the microscope, 

 the iron-sand appears to contain some white shining par- 

 ticles, which, probably, are arsenic pyrites. 



The small quantity of silica and alumina, I ascribe, 



without hesitation, to grains of quartz and felspar, which 



had adhered to the iron-sand, and been analysed along with 



*it. Some such grains were actually observed and separated.^ 



But others, probably, escaped detection. 



12. If these suppositions be admitted as well founded, 

 the iron-sand was composed of 



Protoxide of iron, 85'3 



Red oxide of titanium, 9*3 

 Arsenic, - ro 



Silica and alumina, 1*5 



Loss, - - 2*7 



100-0 



The loss will not appear excessive, if we consider, that a 

 portion of the arsenic must have been sublimed, before the 

 presence of that metal was suspected. 



Upon the whole, I think we may consider the specimen 

 of iron-sand examined, as composed of nine parts prot- 

 oxide of iron, and one of red oxide of titanium. The pre- 

 sence of titanium in this ore had been already detected by 

 Lampadius, though, as I have not seen his analysis, J 

 cannot say in what proportion, 



II. Iserme^ 



