on and near the Erie Canal. 1^43 



character is given by the muriate of lime in most cases 

 throughout this district. In the summer of 1819 I examined 

 mo,-:t of the hard-water wells from Albany to Blenheim, and 

 along the banks of the Hudson for more than one hundred 

 miles ; also along the Boston stage road to Connecticut riv- 

 er. In the years 1820 and 1821, Doctors T. R. and L. C. 

 Beck and myself tested most of the hard waters of Albany 

 and Rensselaer counties. In all these cases the wells were 

 sunk uito marly clay, and contained muriate of lime. I have 

 since extended the same examinations from Boston to Lake 

 Erie, and the result was the same. From these and other 

 observations, I believe that this character, " containing mu- 

 riate of lime," might be added to the definition of marly clay, 

 (London clay of Conybeare.) 



8. Sulphate of Iron. 



Having shown that sulphuric acid is produced in great 

 abundance by the decomposition of iron pyrites, it will fol- 

 low, that the presence of iron in Contact with that acid is all 

 that is required for the production of sulphate of iron. It is 

 well known that oxide of iron is almost universally diffused 

 in very small quantities, throughout all the earthy strata. 

 But such minute quantities of sulphate of iron are produced, 

 and it being sufficiently soluble to be even washed away by 

 mists and heavy dews, very little is found in any particular 

 locality. In sheltered places, such as under shelving ledges 

 on the east shore of Cayuga Lake, near Ithaca, in connexion 

 with a thin layer of sulphurous coal, and in a similar situa- 

 tion near the east part of the Helderburg, twelve miles from 

 Albany, it is often found in considerable quantities. I have 

 a large specimen before me, taken from the gneiss rocks of 

 M'Comb's mountains by Mr. Courtland Van Rensselaer. 

 He saw several pounds in a kind of efflorescent state at the 

 same place. 



I shall not enumerate localities of this sort ; inasmuch as 

 it is in every district in small quantities. 



9. Sulphate of Alumine. 



This salt is always present, as far as I have examined, 

 wherever sulphate of iron is found. Being produced like 

 sulphate of iron, by the agency of iron pyrites, no additional 

 circumstance is required but the presence of alumine. Hence 

 a mixture of impure copperas and alum is to be found in nu- 



