322 THE PETROLEUM SPRINGS OF WESTERN CANADA. 
tain, judging from the similarity of the products in both cases, that 
the petroleum has been generated by a process analogous to that which 
takes place in the destructive distillation of wood-coal or peat in close 
vessels, where, owing to the limited or total absence of oxygen, the 
combination of hydrogen and carbon in the form of hydrocarbons is 
effected. Nature appears to have the power of performing, by means 
of long time and very moderate temperature, processes which the 
chemist and manufacturer perform rapidly and by the application of 
great heat. 
As bearing directly upon the chemical composition and nature of 
petroleum and its products, and illustrating the difference between the 
Canadian and Pennsylvania crude oils, and those derived from the 
Collingwood shales, I shall conclude by inserting (by the kind permis- 
sion of the writer), the following letter with which I have been favored 
by Professor Croft : 
University Con.eGe, Toronto, Novy. 22nd, 1860. 
DeEag Sir, 
In reply to your letter of the 20th inst., requesting information as to 
the chemical nature of the Enniskillen, Pennsylvania and Collingwood oils, 1 am 
sorry that I cannot supply you with any very accurate details, not having exam- 
ined these oils with a view to ascertaining their chemical composition, to any very 
great extent. 
The first two being natural products, are of course quite different from the 
Collingwood shale oil, which does not apparently exist in a free state in the 
shale, but is obtained by and formed during the destructive distillation of the 
animal and vegetable substances contained therein. From the rock consisting 
almost entirely of fossil trilobites, the oil might perhaps be said to be of an 
animal origin, unless the rocks were subsequently impregnated with vegetable 
products. 
Hence the Collingwood oil will be found to assimilate in its characters to the 
oil obtained by the slow distillation of coal, and more especially to that from the 
Boghead Coal; and will undoubtedly be found to contain a number of those 
curious chemical compounds which have been so ably investigated by Greville 
Williams, in his researches on the “ Products of the Distillation of Boghead 
Coal.” These substances are of a basic character and rank with the volatile 
vegetable alkaloids, having the general formula, C? H™N. 
The petroleums or rock oils are essentially different, having been produced by 
a slow process continued through countless ages, and thus substances of a different 
chemical nature have been produced, although, perhaps, the material acted on has 
been nearly, if not quite, the same. 
T am not aware of any means by which we can distinguish the products gene- 
