10 THE CANADIAN NATURALIST. [Feb. 



The trap which underlies this sandstone is amygdaloidal, but 

 becomes more compact at a distance from the sandstone. In the 

 ad it which is being driven across the strata on the Quincy pro- 

 perty, and which, so far as it has yet gone, is in the trap underlying 

 the conglomerate, the rock much resembles the one first described 

 as occurring on the road passing the Quincy mine. The grains of 

 delessite are however smaller, seldom exceeding one tenth of an 

 inch in diameter. An occasional crystal of feldspar is also obser- 

 vable in the fine grained mass of the rock. This mineral is in 

 places reddish-grey, and in others greenish-grey, fuses readily to a 

 colourless blebby glass and colours the blow-pipe flame strongly 

 yellow. The sp. gr. of the rock is 2 . 89, and the colour of the 

 powder light greenish-grey, but somewhat darker than that of the 

 rock first described. It changes like that to a light brown on 

 ignition, losing at the same time 2 . 77 p. c. On being treated 

 with nitric acid and caustic potash the following substances are 

 removed from it : 



Silica 12.41 per cent. 



Alumina 5.96 " 



Peroxide of iron 15.85 " 



Lime 3.77 " 



Magnesia 1.84 " 



39 . 83 per cent. 

 These substances, together with the water lost on ignition, cal- 

 culated in the same manner as in the case of the rock first 

 described, for 100 parts give 



Silica 29.52 



Alumina 14.00 



Protoxide of iron 33.47 



Lime 8.80 



Magnesia 4.29 



Water 9.92 



100.00 

 The residue from this treatment, which amounts to 57.17 per 

 cent, of the original rock, on being digested in hydrochloric acid 

 lost 6 . 7 p. c. additional, consisting of 



Alumina 2.38 



Peroxide of iron 2.45 



