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 demonflrated, 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. 



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 Vauqjjelin 

 and Hecht, compared with thofe of Klaproth, have taught 

 us that there are three oxides of titanium, namely, the blue, 

 the red, and the white. From an experiment of Vauquelin 

 and Hecht, 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 



I. Blue, IOQ 



16 



2. Red, 100 



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 



