of Albertite and allied minerals. 367 
___ It only becomes necessary, therefore, to subject pyroschists 
like the Albert shales, rich in bituminous matter, to metamor- 
phic action through the agency of aqueous vapor, and the dis- 
tillation of the volatile matter at the lowest possible tempera- 
ture becomes a necessity. As time always enters as an element 
into the operations of nature in sufficient quantity, all the con- 
ditions would be present requisite to the production of the 
most copious and dense distillate which such materials were 
capable of furnishing. It is impossible to conceive of the 
this secondary action, Masses of melted bitumen, have formed 
the nucleus around which quartz or calcite began to crystallize, 
* Travels, i, 198; iii, 113, Bohn’s ed. 
+ This Jour. (II), xlv, 38. 
¢ Vanuxem; T. 8. Hunt, Geol. Surv. Canada, 1866, p. 262. 
