342 THE’ GEYSERS OF CALIFORNIA. 
sulphydric acid escapes with violent ebullition. It must 
be supposed that in these acidulated solutions, the iron 
exists as a ferrous salt, since sulphydric acid has this re- 
ducing power. 
In one spring, which is very nearly neutral, the iron 
has been incompletely precipitated and is suspended, in 
the agitated water, with other insoluble sulphides. 
Another spring is strongly acidulated, and contains 
only the merest trace of the sulphydric acid, which every- 
where fills the atmosphere. The rationale of the reac- 
tions observed at the Geysers is not obscure, but so far 
as the writer is aware, no careful analyses of the waters 
and sinter have been made upon the spot. The scrupu- 
lous care with which the geological survey of California 
is being conducted, warrants the conclusion that trust- 
worthy examinations will be published in due time. 
The writer is unwilling to conclude this imperfect 
sketch of one of the wonders of California, without bear- 
ing his personal testimony to the value of the labors of 
Professors Whitney and Brewer, and the hard-working 
corps. 
The first volume upon geology has been read and ques- 
tioned in the presence of the Coast Range and Sierra, 
from Point Concepcion to the Oregon line, and it has, at 
all times, proved a reliable guide. 
„Norte. — See, also, a very interesting article by Professor F. Shep- 
herd, in “‘Silliman’s Journal” for September, 1851, when the springs 
were far less easily accessible than now. 
