58 T. S. Hunt on the Chemistry of Natural Waters. 
In connection with the suggestion made in § 31 as to their 
akan origin at great depths, it would be very desirable to 
ave careful observations as to the temperature of these acid 
springs. When, on the 19th October, 1847, I visited the Tusca- 
rora spring, the water in two of the small pools had a tempera- 
ture of 56° F.; but on plunging the thermometer in the mu 
at the bottom of one of these it rose to 60°°5. Y 
$ 49. It appears from a comparison of the analysis of Croft 
with my own, that the waters of the Tuscarora spring underwent 
a considerable change in composition in the space of two years; 
the proportion of the bases to the acid at the time of the second 
analysis being little more than one-third of that in the analysis 
of Cr This change was indeed to be expected, since waters — 
of this kind must soon remove the soluble constituents from the 
rocks through which they flow, and eventually become like the 
water from Byron, little more than a solution of sulphuric acid. © 
The observations of Eaton at Byron, and my own at Tuscarora, 
show that half-decayed trees are still standing on the soil which 
is now so impregnated with acid waters as to be unfit to support 
vegetation. Reasoning from the changes in composition, it may 
sup that these waters were at first neutral, the whole of 
the acid being saturated by the calcareous rocks through which 
they must rise. It was from this consideration that I was for- 
merly led to ascribe to the action of these waters, the formation 
of some of the masses of gypsum which appear along the outcrop 
of the Onondaga salt-group. (This Journal, [2], vii, 175.) That 
waters like those just mentioned must give rise to sulphate of 
lime by their action on calcareous rocks is evident; and some 
of the deposits of gypsum in this region, as described by g 
observers, would appear to be thus formed. So far, however, as 
my personal observations of the gypsums of western Cana 
have extended, they appear to be in all cases cotemporaneous 
with the shales and dolomites with which they are interstratified, 
and to have no connection with the sulphuric-acid springs which 
are so common throughout that region. (This Journal, [2], xxviii, 
365, and Geology of Canada, 352.) 
§ 50. We have included in a sixth class the various neutral 
waters in which sulphates predominate, sometimes to the 
exclusion of chlorids. bases of these waters are soda, pot- 
ash, lime, and magnesia; which are usually found together, 
though in varying proportions. For the better understanding 
of the relations of these sulphated waters, it may be well to 
recapitulate what has been said about their origin; and to con- 
sider them, from this point of view, under two heads. 
First, — Te = — of neutral sulphates 
reviously existing in a solid form in the earth. Strata enclosin 
cae aad deposits of sulphates of soda and magnesia, steer. 
