PEGHONPTET., 1895. [3] Trans. R. &.C. 
1.—On some of the Advances in Mineralogical Chemistry. 
By B: JHaRRINGTON, MAT hw: 
(Presidential address before Section III. of the Royal Society of Canada, delivered 
May 15, 1895.) 
The subject of this address was suggested to me by my reading some 
of Klaproth’s remarkable “Analytical Essays towards promoting the Chem- 
ical Knowledge of Mineral Substances,” published early in the present 
century. While struck with the amount of details of patient investigation 
there recorded, the great advance which has been made in recent times, 
both asregards methods of work and interpretation of results, was by con- 
trast brought prominently before me, and it seemed that I could not do 
better than call the attention of this section to a few points in connection 
with modern methods of research in mineralogical chemistry. I advisedly 
say a few points, because the whole field is far too wide to be traversed 
in one short address. Should the mathematical members of the section 
not enjoy the technicalities of the subject, | must remind them that my 
chemical formule are but a slight return for the mathematical hiero- 
glyphies with which I have been tortured in years gone by. 
iveryone will admit the importance of having pure materials for the 
purpose of analysis. If impure minerals are analysed, conclusions with 
regard to constitution, formula, etc., are of comparatively little value. 
Fortunately much attention is devoted to this question at the present time 
and great care used in the selection of material for analysis. In this work 
the microscope lends valuable aid, while the electro-magnet and liquids of 
high density are proving of very great service. The electro-magnet is 
chiefly used in theseparation of certain constituents of rocks, but may also 
be employed in the purification of minerals for analysis. Magnetite can, 
of course, be readily removed from a mixed powder, but so also can 
various iron-bearing species, such as pyroxene, hornblende, olivine, garnet, 
ete. The readiness with which a mineral is attracted by an electro- 
magnet, is not, however, always proportional to the quantity of iron con- 
tained, and, as is well known, many minerals (biotite and chromite for 
example) are less readily attracted than others which contain much less 
iron.! 
The separation of minerals according to specific gravity may be ac- 
complished by various mechanical means, but the methods employed so 
far seem to be susceptible of much improvement. Dafert and Derby have 

! H. Rosenbusch, Mikroskopische Physiographie der petrographisch wichtigen 
Mineralien, 1885, p. 221. 
