APPENDIX. 351 
The ores are of very different qualities ; no two specimens are 
equally rich ; nor could it he ascertained whether the lumps brought 
to France are exactly like the mass which is wrought by the Negroes ; 
the latter is probably very rich, because the method followed by 
them to extract the iron (which appears to have much analogy 
with what is called the Catalonian method,) must produce scoria 
containing a considerable quantity of metal. 
Two varieties were examined. The first was of a reddish 
brown, shaded with a deep brown, almost black, and some little 
veins of a yellowish white ; it was in pieces of a rounded irregular 
form, rather shining on the outside, but dull in the fracture, and 
containing some roundish cavities. Its dust is of a red brown, 
shaded with yellow ; it is heavy ; it loses water by calcination, and 
assumes a redder and deeper shade. Muriatic acid dissolves it 
without effervescence, leaving a colourless, and by no means 
voluminous residuum, composed of silex and alumine ; the solution 
contains a considerable quantity of alumine, which is never the 
case with those ores called alluvial, in Europe. It was found to 
be composed of 
Tritoxide of iron - . . . 0,772 
Alumine and a little lime - - - 0,082 
Silex - - - - - 0,028 
Water - - - - - 0,114 
Chrome - - - very perceptible traces 
0,996 
No phosphoric acid, and not the least trace of oxide of manganese. 
