58 
The pervading idea has been that this acid was pre-eminently 
the mineral acid, and that its study belonged therefore to 
mineralogy, a science in itself so great and complex that it 
has, as yet, scarcely advanced beyond the first stage, namely 
that of provisional classification. 
He believes, however, that his studies have unmistakably 
tended towards the conclusion, which will be startling to 
many, that silicic acid as such, that is, in isolated forms, 
appertains, tn origin at least, altogether to the vegetable kingdom ; 
and that the tendency of chemical investigation and discoy- 
ery is to confirm this conclusion. He presented, to illustrate 
this and other related generalizations, the following diagram, 
which was prepared in substance nearly a year since, and of 
course before the announcement of the discovery by PAUL 
THENARD of the nitrohumic solvents of silicic acid. This 
discovery serves now to illustrate the agencies concerned in 
the second stage of migration, in tne diagram, that which 
involves the transfer by condensing atmospheric waters, of 
the soluble silica of soils of the external continental cutieles 
(so to speak) to the fluviatile systems of drainage. As illus- 
trations of the general neglect that the whole subject has 
received from chemists hitherto, it may be mentioned that 
almost the only analyses of the waters of first-class river 
systems, in which the amount of soluble silica present has 
been determined separately, are those of Sterry Hunt. In 
his analysis of the waters of one of the great rivers of the 
world, the St. Lawrence, he found the relative properties of 
carbonates of lime and silica to be, in 10°000 parts 0,8083 
and 0°37 ; or as 100 to 45°77. A comparison of this result 
with others recently published by Joun Huvnrer, of 
Atlantic deep-sea ooze, from 14,600 feet deep (See Am. 
Chemist for October, 1870, p. 188) is instructive. HuNTER 
found for the’ relative proportions of carbonate of lime and 
silica in this, 100 to 39°10; and this notwithstanding that we 
haye scarce an analysis of oceanic water indicating silica as 
a constituent. 
He finds also that an analysis made by himself very care- 
