352 Messrs. Johnson and Blake on Kaolinite and Pholerite. 
The chemical composition of this mineral was first deduced 
by Forchhammer from the analysis of a number of kaolins. It 
is represented by the formula 4Si3Al6H, or by 2Sidl2H,. The 
per cent proportions vary considerably according to the atomic 
weights employed in the calculation. In the table that follows, 
p. 388, are given the percentages reckoned on the atomic weights 
adopted by Gmelin (Handbook, English ed.), by Rammelsberg 
(Handbuch d. Mineralchemie), and by Fresenius (Quantitative 
-Analysis, 4th ed.). 
Of the substances which have come under our notice, having 
/p a + Sp: gr 2 
mineral made by Richard Miiller appeared in Dana’s 9th Sup- 
plement, and is quoted below. 
DesCloizeaux, in the Supplement to his Manuel de Minéralo- 
gie, p. 549, remarks*concerning this mineral as follows: “There 
has been recently discovered in Saxony a pholerite, at first called 
nacrite, which occurs in large macled hexagonal plates. ‘These 
plates are composed of six triangular sectors, whose boundaries, 
though quite vague, nevertheless give indications of composition 
parallel to the faces of a right rhombic prism approximating the 
angles 120° and 60°. They cleave easily in the direction of the 
base of this prism; their interior structure is fibrous, and their 
surface 
ge, for, when viewed by polarized light, dark shades of 
“anch out irregularly from near the center of the thin 
* 
