T. Crook—Titaniferous Volcanic Rocks. 159 
the same in all cases; that it was a compound of iron and titanium 
oxides; and he gave it the name fer titané. We need not here 
concern ourselves with the misfortune that befel the use of Cordier’s 
term. It is sufficient for us to note that his fer ¢itané is the same 
thing as our modern titaniferous magnetite (titanomagnetite of 
Lacroix) ; while the fer titané of modern French is the mineral 
ilmenite. 
Memoir No. 2. 
Having examined the sands, Cordier proceeded to work on the 
voleanic rocks themselves, and here again he examined material 
from many different sources. He first attempted to isolate the 
titaniferous magnetite by crushing and magnetic separation; but he 
observed that a considerable amount was always left behind, which 
could not be withdrawn in this way.! For this reason, he resorted to 
the method of leaching the titaniferous magnetite from the crushed 
rock by means of hydrochloric acid. 
A large number of basalts, ashes, and tuffs, from Puy-de-Dome, 
Vesuvius, Etna, Teneriffe, Popayan (South America), and elsewhere, 
were examined in this way, and analysis showed a variation from 0°5 
to 4 per cent. in their titanium oxide content. 
Cordier expressed surprise that titanium should be so widely dis- 
tributed im volcanic rocks, and added that the only specimens which 
were practically free from it were those of certain pumices and glassy 
lavas. He estimated that 95 per cent. of volcanic rocks contained 
titaniferous magnetite in considerable amount, the proportion varying 
from 2 to 18 per cent. Its partial extraction, even when fine-grained 
and imperceptible to the eye, could be accomplished easily by crushing 
and separation with a bar magnet. Volcanic rocks owed their mag- 
netic character exclusively to this mineral, except when hematite 
was present, which was very rarely. Its abundance in these rocks 
fully explained its plentiful occurrence in the sands which were 
derived from them by disintegration. 
It is unnecessary to refer to Cordier’s third and well-known memoir 
of 1815, except to note that in it he continues to use the name fer 
titane for the highly magnetic constituents of volcanic rocks. He 
distinguished this mineral from ilmenite, stating that the latter 
consisted of a combination of titanium and iron oxides in somewhat 
equal proportions, whereas fer titané contained only about 15 per cent. 
of titanium oxide. He was also aware that ilmenite was far less 
magnetic than titaniferous magnetite, and that with proper care it 
remained behind when the latter was extracted by the magnet. He 
found only a small quantity of ilmenite, as such, in the volcanic rocks 
which he examined, 
There are many points arising out of Cordier’s results which it 
might be profitable to discuss, did space permit. One point is 
especially worthy of emphasis, and that is the importance, in this 
1 Cordier appears to have thought that this was due to the extreme fineness of 
some of the particles, and the difficulty of freeing them from the matrix. It is not 
peels however, that some of the grains which thus resisted attraction were 
ilmenite. 
