I N D E \ 
Page. 
Apparatus for oxidizing sulphides with 
ferric solution, figure showing-.- 22 
Apparatus for washing sulphides in an 
atmosphere of carbon dioxide, fig- 
ure showing 21 
Arsenides, application of method to 20 
Arsenopyrite, influence of presence of- - 32 33 
Bastrop, Tex., composition of specimen 
from 39 
Becker, GeorgeF., letter of transmittal by 9 
Bohemia, composition of specimen from .. 36,37 
Bornite, influence of presence! of 33 
Brown, A. P., cited on action of cupric 
salts on pyrite and marcasite 14,41 
cited on action of potassium perman- 
ganate on pyrite and marcasite. . . 46 
Chalcopyrite, influence of presence of 33 34,35 
Chalcocite, influence of presence of 33,34 
( "obalt, influence of presence of '.V2 
Color of pyrite and marcasite 11 L2 
Colorado, composition of specimens fr< >m 25, 
36,38 
Concentration, influence of 18 
Connecticut, composition of specimens 
from - 25,39 
Copper bearing pyrites, form of copper 
in 34 35 
Cornwall, England, determination of 
marcasite from _' 26,27 
Crystalline form of pyrite and marcasite. 11 
Cumberland. England, composition of 
specimen from 39 
Cupric chloride, experiments with 44 
Cupric salts, action of 41-46 
Cupric sulphate, experiments with. 42 43,44 
Dana, J. D., cited on color and density of 
pyrite and marcasite 1 1 . 1 2 
Density of pyrite and marcasite... 12 L3 
Dimorphous compounds, application of 
method to 20 
Dovei' Cliffs, England, determination of 
marcasite from 26 
Emerson, B.K., acknowledgments to 48 
Emmons, S. P., acknowledgments to 48 
England, composition of specimens from. 26, 39 
Experimental details 20-24 
Ferric solutions, action of 14-20 
Ferric sulphate oxidation method, de- 
scription of 15-16 
Ferrous sulphate, experiments with 44 
Folkstone, England, composition of speci- 
mens from 36 
Franklin, N. J., composition of specimen 
from 39 
Page. 
Galena, influence of presence of 32 
Galena, 111., composition of specimens 
from 36,39 
Gmelin-Kraut, cited on action of hydro- 
gen sulphide on ferric salts 19 
Hazel Green, Wis., determination of mar- 
casite from 26 
Hematite, indication of presence of 32 
Idaho, composition of specimens from 36, 37 
Illinois, composition of specimen from 39 
Impurities, influence of 31 
Julien, A. A., acknowledgments to 35, is 
cited on action of ferric chloride on 
marcasite 15 
cited on density of pyrite and marca- 
site 12 
cited on terms and references pertain- 
ing to pyrite and marcasite 11 
composition of specimens loaned by 39 
hypothesis of 39 W 
quoted on composition of certain spec- 
imens of pyrite-marcasite 39 
quoted on features of marcasite from 
Dover Cliffs, England 26 
quoted on origin and character of 
mixtures of pyrite and marcasite 27 28 
Koninck. L. L. de, cited on action of ferric 
chloride on pyrite 15 
Leadville, Colo., determination of pyrite 
from 25 
Lindgren. Waldemar, quoted ou features 
of specimens of pyrite-marcasite 36,37 
Magnetite, indications of presence of :>:.' 
Marcasite, acl ion of copper sulphate on.. 14 
amount of, oxidized by potassium per- 
manganate 46 
attempted conversion of pyrite to 41 
color of 11 12 
crystalline form of 11 
data obtained for 25 21 
density of 12-13 
oxidation of 13 II 
oxidation coefficient of ... . 27 
Marcasite and pyrite, reasons for different 
1 lehavior of, in experiments made . 1 9 
uncertainty of methods of distin- 
guishing 11-14 
Massachusetts, composition of specimen 
from 39 
Merrill, G. P., acknowledgments to 48 
determination of specimen submitted 
by 37 
Monroe. Conn., composition of specimen 
from 39 
49 
