Mr. Playfair’s Account of a 
362 
Gran. Quartz. 
Mic. and Calc. Schist. 
Numbers. 
Specific Gravities- 
Specific Gravities. 
Numbers. 
1 
2.6435 
3.0642 
1 
Q 
2.6437 
to 
(0 
Oo 
00 
Cr» 
2 
3 
2.6296 
3.0476 
3 
4 
2.65367 
2.7293 
4 
5 
2.6460 
2-7935 
5 
6 
2.6269 
2.7307 
6 
7 
2.6274 
2-7499 
7 
8 
2.6109 
2.7728 
8 
9 
2.6296 
2.71845 
9 
10 
2.6576 
2.7206 
10 
11 
2.6656 
2.7087 
1 
12 
2.6452 
2.8890 
2 
13 
2.6387 
2.76057 
3 
Mean 
•••••2.633876 
2.7419 
4 
2.7302 
5 
2.81039.... 
>Mic. 
>Calc. 
