its extraction was comparatively easy, with small charges 
of dynamite. When as more frequently happens, the 
deposits are found under a heavy overload of other material, 
regular mining tunnels are run and dynamite charges used 
to break the rock and other material so that it may be 
carried to the surface. In size, the ore bodies vary from 
pockets containing a few pounds to deposits yielding as 
much as 1800 tons in very exceptional cases. 
As there are often no indications leading to a deposit 
of ore, prospecting is done by drilling in what seem likely 
spots with jack hammers and with diamond drills. When 
‘here is not more than twenty-five feet of earth and other 
material over any ore, the jack hammer driven by com- 
pressed air is the cheapest method of working. To operate 
“hese hammers, portable gasoline compressors are used. 
The extremely irregular nature of the ore bodies makes 
it difficult to follow a definite plan of mining. To meet 
these conditions, use is made of the diamond drill. As 
these drills bring®to the surface specimens of the material 
through which the boring is made, the Standard Chemical 
Company has definite knowledge of about what ore may 
be found beneath any given area of the extensive claims 
to which it has title. 
This detailed and expensive study of this region has 
proved of great value to the Government in connection 
with a thought that it might have been necessary to make 
the radium ore lands a Government monopoly. 
At the Concentration Mill in the wilds of Colorado, 
five hundred tons of ore are reduced to a powdered form 
and sacked. 
These sacks, weighing about 70 pounds, are transported 
by wagon, and where possible, by motor truck, the sixty- 
five miles to Placerville, Colorado. There, a narrow gauge 
railroad takes it to the transcontinental railroad at Salida. 
Colorado. 
From Salida, it travels the two thousand three hundred 
miles to Canonsburg, Pa., just outside of Pittsburgh. 
where the Company maintains its refining plant. 
At the mill in Colorado, and in the operations per- 
taining to it, some three hundred men are kept busy.