23 



cimation, and when thus used the mobile forms of ^natter lose 

 exactly the amount that the solid or solidifying matter gains. 



Thus the using up of the aeriform or liquid oxygen must 

 have begun in the formation of the ahiminous silicates of 

 the granitic formations, and must have continued through 

 all the past building up of the earth's crust, through the 

 agency of the water and atmosphere, the succeeding media 

 of the supply of oxygen, wherever oxydation or acidifica- 

 tion have occurred to form chemical compounds, and where 

 these compounds have remained undecomposed, they con- 

 stitute part of the matter once belonging to the air or 

 oceans, but now forming part of the solid crust. 



The part that water performs in these changes is won- 

 derful. Anstead says: "Water enters not only into the 

 composition of every solid and of every liquid of which 

 every living thing is composed, but is present in all mineral 

 matter; even the most solid and compact marble contains 

 a small percentage of water." "Wherever change has 

 taken place at great depths, there water has acted as the 

 chief agent." "Heat and chemical action could do little — 

 they act by and with water, and thus produce their results." 



" Tens of thousands of feet in the earth a slow but inces- 

 sant crystalization goes on, in which water is entangled, 

 and with minerals helps to form a part of the substance of 

 each crystal." "Itself a liquid, it enters into all solids, 

 almost as essential to solidity." 



The large class of minerals known as hydrates, belong- 

 ing to past as well as present formations, contain a certain 

 proportion of "waters of crystallization" as essential to 

 their, formation. 



What they thus gain, the liquid mass of matter must 

 have lost. In alum, 46 parts in 100 are water — in epsom 

 salts, 51 — in gypsum, 21. The opal in its pure state is a 

 hydrate of silica, consisting of from 90 to 95 per cent, 

 silica, and from 5 to 10 water. All crystallization is indeed 

 well known to be defined " as the process, natural or artifi- 



