May, 1904. GEOLOGY OF WESTERN MEXICO—FARRINGTON. — 209 
The extraction of the silver was accomplished at the time of the 
writer's visit, by the lixiviation process as follows: The ore was 
crushed in a Blake crusher, then mixed with from 3 per cent to 6 
per cent of common salt and ground through Cornish rolls. It was 
then roasted in a revolving cylinder. After roasting; the base metals 
were leached out with water, and hyposulphite of soda added to 
dissolve the silver. To this was added, in order to precipitate the 
silver, a solution of calcium sulphide, made by burning together 
quicklime and flowers of sulphur. This precipitated the silver in 
the form of a black sulphide, which was drawn off, again roasted, 
and finally fused in the melting-pot and run into bars, in which 
form it was carried by pack-trains to Durango. 
As previously stated, the region traversed is practically un- 
inhabited. Climatically it is not inhospitable, but topographically 
it opposes tremendous barriers to traffic. How great these bar- 
riers are throughout the extent of the Western Sierra Madre may 
be judged from the fact that of seven railway lines in Mexico, with 
western terminals north of the Isthmus of Tehuantepec, not 
one has yet reached the west coast. These barriers would not of 
themselves probably be so great as to absolutely prevent the con- 
struction of railway iines or other roads if the small size of the area 
to be made available and the lack of good harbors on the coast did 
not considerably limit the inducements to such enterprises. On ac- 
count of the lack of good harbors and productive soil on the coast 
however, the resources to be depended upon for developing the coun- 
try must be almost wholly those of the interior. These resources 
include mineral wealth, of which there is undoubtedly much yet 
unknown, the timber resources afforded by the great forested areas, 
and the extensive areas which could be utilized for grazing. Whether, 
under the conditions, these resources can be developed with profit 
remains to be seen. 
As regards population the region seems to have lacked in an- 
cient times as wellas now. While other parts of Mexico not now in- 
habited, afford evidences of former habitation by man, this is not 
the case with this region, according to Lumholtz,* who searched 
unsuccessfully for any traces of a former population. In the valleys 
to the north and south of the region, however, he found occasional 
villages inhabited by remnants of the northern Aztecs, intermingled 
with Tepehuanes and Coras. These Indians, especially the Tepehuanes, 
he describes as having remarkable powers of endurance. 
FOP Ctt., ps 4615 
