358 Dresser — Geology of Brome Mountain. 



Such a rock would stand nearly on the line between the per- 

 salanes and the dosalanes, the ratio of the salic to the femic 

 minerals being 85-33 : 12*40. 



The average composition of the Brome and Shefford lacco- 

 lite, as indicated under XYIII, would therefore give a rock 

 which would be classed thus : 



Class I, Persalane 



Order 5, Canadare 



Rang 3, (alkalicalcic) 



Subrang 4, (dosodic) 



This agrees with the mean of Brome, and differs but slightly 

 from that of Shefford which stands very near the dividing line 

 between Classes I and II, while they quite agree in the subor- 

 dinate part of their classification as to Order, Rang and 

 Sub-Rang. 



The genera] mean of the two hills, as well as that of Brome, 

 thus falls in a part of the scheme of the Quantitative Classifi- 

 cation that has not yet been occupied. Being hypothetical 

 rocks, however, they do not warrant the introduction of a new 

 name, nor is it necessary, since their position can be otherwise 

 definitely indicated by means of this admirable system of classi- 

 fication. 



