58 THE CANADIAN NATURALIST. [Vol. vi. 



are massive and horizontal, is, according to Prof. Worthen, from 

 thirt^^-five to forty feet, and they occupy a position about mid- 

 way in the Niagara formation, which has in this region a thick- 

 ness of from 200 to 250 feet. As exposed in the quarry, the 

 whole rock seems pretty uniformly saturated with petroleum, 

 which exudes from the natural joints and the fractured surfaces, 

 and covers small pools of water in the depressions of the quarry. 

 I selected numerous specimens of the rocks from different points 

 and at various levels, with a view of getting an average sample, 

 although it was evident that they had already lost a portion of 

 their original content of petroleum. After lying for more than 

 a year in my laboratory they were submitted to chemical examin- 

 ation. The rock, though porous and discoloured by petroleum, is, 

 when freed from this substance, a nearly white, granular, crys- 

 talline and very pure dolomite, yielding 54*6 p. c. of carbonate of 

 lime. 



Two separate portions, each made up of fragments obtained by 

 breaking up some pounds of the specimens above mentioned, and 

 supposed to represent an average of the rock exposed in the 

 quarry, were reduced to coarse powder in an iron mortar. Of 

 these two portions, respectively, 100 and 138 grammes were 

 taken, and were dissolved in warm dilute hydrochloric acid. The 

 tarry residue which remained in each case, was carefully collected 

 and treated with ether, in which it was readily soluble with the 

 exception of a small residue. This, in one of the samples, was 

 found equal to -40 p. c, of which -13 was volatilized by heat 

 with the production of a combustible vapour having a fatty odour ; 

 the remainder was silicious. The brown etherial solutions were 

 evaporated, and the residuum freed from water and dried at 

 lOO'^C, weighed in the two experiments equal to 1-570 and 1-505 

 per cent, of the rock, or a mean of 1-537. It was a viscid red- 

 dish-brown oil, which, though deprived of its more volatile por- 

 tions, still retained somewhat of the odour of petroleum which is 

 so marked in the rock. Its specific gravity as determined by 

 that of a mixture of alcohol and water, in which the globules of 

 the petroleum remained suspended, was -935 at 16'*'C. Estimat- 

 ing the density of the somewhat porous dolomite at 2-600, we 

 have the equation -935 : 2-600 : : 1-1537 : 4-26; so that the 

 volume of the petroleum obtained equalled 4-26 per cent of the 

 rock. This result is evidently too low for two reasons ; first, 

 because the rock had already lost a part of its oil, while in the 



