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30 ANNUAL REPORT 
As in the case of the meta-acid, we can obtain from the ortho-silicic 
acid, by splitting off one molecule of water from two molecules: 
2H ,SiO,—_H,O=H,5i,0,, ortho-disilicic acid, valency six. 
Finally, by the union of one molecule of ortho-silicic acid with one 
molecule of the ortho-disilicic acid, at the same time splitting off three 
molecules of water, we have: 
H,51,0,+ H,SiO,—3H,O=H,Si,Og, tri-silicic‘acid, tetra valent. 
From these five acids all of the natural silicates can be deduced. 
They may then be said to form the foundation of the great system of 
silicates, the basis of the clay, glass and cement industries. But the 
number of compound silicates theoretically possible is very great, and 
we may say that the different silicates correspond to the equation, 
xSiO,+yH,O=2yH-+xSi-+ (2x-+y)O. 
where x and y are whole numbers.* The number of hydrogen atoms 
is always divisible by 2, and the number of oxygen atoms is always equal 
to twice the number of silicon atoms plus half of the number of hydrogen 
atoms. ‘The following table will illustrate this: 
Formula. Name. 
te SHO, Silica, silicon dioxide. 
De lal silos Meta-silicic acid, valence 2. 
2. lel ,SiO),. Ortho silicic acid, valence 4. 
My lalaSiitO., IMieia, chesilieic acid, vallence 2. 
So JelSitOh, Orla chesihiere acicl, vallemes ©, 
6. H,Si,0,,  di-basic tri-silicic acid, valence 2. 
Wo lalySi(Os,  ineisihiene are, wallenee 41, 
S JE.Si,Oh,  ticsilicre acd, wallence &. 
OO. erie St Onn eteura-silicicnacidnmyalences2: 
10; InlsSiOu., tuasilicie acic, wallenee ©. 
Ho nlp SiOhe, weabra-silliens acicl, vallemee TO, 
These hydrous compounds may or may not exist in nature, nor, 
perhaps, are there anhydrous equivalents produced in the arts, yet the 
conception of the growth from the acid to the more and more basic 
compounds must go through the entire scale of silicates and the proper 
ratios between the RO, RO, and the acid constituents must be borne 
strictly in mind. ‘This is illustrated very strikingly by the glasses, and 
the glazes used in the clay industry which for certain purposes are burnt 
to different temperatures, each fusing point being fixed by the chemical 
composition, the ratio of the number of molecules of base to the number 
of molecules of acid, as well as by the character and number of bases 
employed. For each one base or one combination of bases combined 
with silica the fusibility is a function of the base-acid ratio, readily ex- 
pressed by the oxygen ratio, that is, by the ratio between the number of 
oxygen atoms in the basic part of the molecule to the number of oxygen 
atoms in the acid part, as in CaOSiO,(CaSiO,) where the oxygen ratio 
*Dr. Gustav Rauter, Sprechsaal, Vol. 36, p. 462. 
