258 ANALYSIS of a BLACK SAND 
and 37 oxygen. Hence, I think, it follows, that the iron in 
our ore muft have been in the ftate of an oxide, and that it muft 
have contained lefs oxygen than black oxide of iron. A good 
many trials, both on iron-fand, and on fome of the other mag- 
netic ores of iron, induce me to conclude, that the iron in moft 
of them is combined with between 17 and 18 per cent. of oxy- 
gen. This compound, hitherto almoft overlooked, by che- 
raifts, I confider as the real protoxide of iron. THENARD has 
lately demonftrated, the exiftence of an oxide intermediate be- 
tween the black and the red; fo that we are now acquainted 
with four oxides of this metal. But the protoxide, I prefume, 
does riot combine with acids like the others. Analogy leads us 
to prefume the exiftence of a fifth oxide, between the green and 
the red. if a 
As to the titanium, it is impoffible to know what increafe of 
weight it has fuftained, becaufe we are neither acquainted with 
it in the metallic ftate, nor know how much oxygen its differ- 
ent oxides contain. It is highly improbable, that, in iron-fand, 
the titanium is in the metallic ftate, if it be made out that the 
iron is in that of an oxide. The experiments of VAUQUELIN 
and Hecut, compared with thofe of KLaPprotn, have taught 
us that there are three oxides of titanium, namely, the blue, 
the red, and the white. From an experiment of VauQuELIN 
and Hecurt, and from fome of my own, I am difpofed to con- 
fider thefe oxides as compofed of the following proportions of 
metal and oxygen : 
METAL. OXYGEN. 
1. Blue, 100 16 
gamed, 4 * 1G0 33 
3. White, 100 . 49 
I find, that when the white oxide of titanium is reduced to the 
ftate of red oxide, it lofes one-fourth of its weight ; and that 
‘ red 
