196 JOURNAL OF THE PLYMOUTH INSTITUTION. 
MINERAL RESOURCES OF DEVON AND CORNWALL. 
EARTHY MINERALS. 
BYR wOXL ADP), 
(Read November 26th, 1874.) 

For the convenience- of systematically reviewing the mineral re- 
sources of Devon and Cornwall, we shall do well to use, to some 
extent, the classification commonly adopted in works on Mineralogy. 
At present all substances are known to be resolvable into about sixty- 
seven elementary forms, known as simple substances or elements. 
Very few of these are ever found in Nature in the elementary form, 
but in a form disguised by combination with other substances, which 
possess few, if any, properties in common with their constituents. 
These simple substances, when combined with each other, are said 
to be mineralized. 
On reviewing the list of elements, we shall find but very few 
that are not to be found in the two counties in some form or other. 
I am not aware of the discovery as yet in Devon and Cornwall of 
Platinum, Osmium, Palladium, Rhodium, Rubidium, Tellurium, 
or Thallium. Mercury is as yet doubtful. The recent discovery of 
it at Exeter is not as yet admitted as proof of its natural occurrence. 
So that out of the sixty-four elementary bodies, about fifty-four are 
of more or less common occurrence in the two counties. 
Commencing first with the consideration of the most common 
minerals, I may possibly excite some surprise by beginning with 
Water. Its claim to our attention consists in its being the most 
abundant and most useful mineral. It has been regarded as a metal 
—Hydrogen mineralized by combination with Oxygen. Referring 
to Chapman’s ‘ Mineralogy,” page 11, we find it thus described : 
‘“‘ Water, Oxide of Hydrogen. Sp. gr. 1:00. When pure, tasteless 
and inodorous. C.P. (7.e. constituent parts), O. 88°94, H. 11-06.” 
Its localities are air and earth, sea and sky. It is absolutely essen- 
tial to our existence, constituting more than 0°9 of our system. 
