IX.] CHEMISTRY OF NATURAL WATERS. 131 



group ; but in the township of Niagara, not far from Queenston, 

 are two similar waters which issue from the Medina sandstone. 

 One of these is in the southwest part of the township, and fills 

 a small basin in yellow clay, which, at a depth of three or four 

 feet, is underlaid by red and green sandstones. The water, 

 which, like those of Tuscarora and Chippewa, is slightly im- 

 pregnated with sulphuretted hydrogen, is kept in constant 

 agitation from the escape of inflammable gas. It contained in 

 1,000 parts about two parts of free sulphuric acid, and less than 

 one part of neutral sulphates. This water was collected in 

 October, 1849, and at that time another half-dried-up pool in 

 the vicinity contained a still more acid water. Another similar 

 spring occurs near St. David, in the same township. In con- 

 nection with the suggestion made in 31 as to their probable 

 origin at great depths, it would be very desirable to have 

 careful observations as to the temperature of these acid springs. 

 When, on the 19th October, 1847, I visited the Tuscarora 

 spring, the water in two of the small pools had a temperature 

 of 56 F. ; but on plunging the thermometer in the mud at 

 the bottom of one of these it rose to 60.5. 



49. It appears from a comparison of the analysis of Croft 

 with my own that the waters of the Tuscarora spring under- 

 went 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 Croft. This change was indeed to be expected, 

 since waters of this kind must soon remove the soluble constit- 

 uents 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. Seasoning from 

 the changes in composition, it may be supposed that these 

 waters were at first neutral, the whole of the acid being satu- 

 rated by the calcareous rocks through which they must rise. It 

 was from this consideration that I was formerly led to ascribe 



