J. M. Ordway on Waterglass. 343 
had been carefully dried, water dissolves the alkali out of the 
residue, and leaves the silica, which last, according as the 
strength of the heat has been, is or is not soluble in dilute alka- 
ies. The sesquisilicates also he proved to be decomposable by 
heat, but the monosilicates were ascertained to be unchanged by 
dehydratation. 
Uses—Numerous applications have been proposed for water- 
glass, and for many purposes it has really proved to be of per- 
manent value, but the cases in which there are not material 
drawbacks to its employment, are very few. The properties 
which render it available in the arts, are:— wth 
I. Its adhesiveness in the hydrated state. 2. Its vitrifying 
power in the dry state. 8. Itsalkaline nature. 4. Its capability 
of eating soluble silica. 5. Its peculiar chemical relations as 
a whole, . 
_ 1. Adhesiveness, On account of this most striking character- 
istic of waterglass, its discoverer said that it might justly be called 
“mineral glue,” and to a certain extent the similarity holds good. 
t differs however from glue, and most other cementing sub- 
stances, in continuing to shrink after it has become apparently 
A strong silicate of soda solution forms a good colorless 
cement for glass, porcelain, and stone, but when shut up in such 
Pp : : 
h t solution of waterglass 
ave often made use of a strong cen agg Maer an 
ture undergoes partial fusion in a strong heat, and makes 
Sight, firm rate For brick work that is to be kept moderately 
t, 
heat, is apt tod and lose its binding power. Mr. Joseph 
D, Gould tells sie ths he has found fibrous asbestos wet with a 
Sttong silicate of soda liquor to make a most excellent packing 
for the joints of apparatus ex 
