542 
COLONEL P. YOEKE’S EESEAECHES ON SILICA. 
the salt had been washed away, gave a result on analysis showing that its silicic acid 
contained at least double the quantity of oxygen contained in the lithia. 
As to the formula SiO, deduced from the lithia compound, I would add, that some 
observations have lately been published by Teoost*, which go to show that lithia in its 
comportment has more analogy with the magnesian class of bases than with the potas- 
sium class. Now, of the known crystallized silicates of bases belonging to the former 
class, whether found in nature or obtained in the processes of the arts, a lai’ge propor- 
tion have a composition in which the oxygen of the base is equal to that of the acid. 
In concluding this paper, I desire to guard myself against di'a'sving any decided 
inference from the experiments I have related, particularly as I hope to be able to 
follow up this communication by further researches, which may afford more definite 
grounds for theory. I venture only to remark at present, that as I cannot but think 
that the quantity of carbonic acid displaced must afford a true measure of the equivalent 
of silicic acid ; so, looking to the results of my experiments, I see at present no alter- 
native but to admit of at least two equivalents (that is to say, of two acids), the value of 
which is determined by circumstances, such as the presence of water, and the natui-e 
of the base to which the silicic acid is presented. 
The existence of different silicic acids has been already suggested by chemists, parti- 
cularly by EBELMENf and by Laurent J. Fremt also considers that his late experiments, 
before quoted, support the same view. 
* Comptes Eendus, November 10, 1856. Chemical G-azette, December 1856. 
t Ann. de Chim. &c. 3 ser. xvi. 162. J Chemical Method, Engl. Trans., p. 127-S. 
