240 Mr. W. Phillips, on the angles of, &c, 



tive rhomboids of the carbonate of lime, the bitter-spar, and the 

 brown-spar, which had previously been considered to be alike, and 

 conceiving them to be erroneously quoted, as in fact they were, I 

 submitted to the reflecting goniometer some cleavages of the two 

 former, not having a portion of the latter adapted to its use. I 

 afterwards called on my friend Arthur Aikin, Esq. who shewed me 

 an account of the exact admeasurements obtained by Dr. Wollaston, 

 and had the satisfaction of convincing him that those obtained by 

 me perfectly coincided therewith. 



I possess thirty-eight varieties of crystals of quartz, resulting 

 from the combinations of eleven modifications on the primitive 

 rhomboid ; and of the sulphate of barytes I have one hundred and 

 thirteen varieties, the result of eighteen modifications of the primi- 

 tive crystal ; the former are principally foreign, the latter chiefly 

 from the north of England. 



