J. D, Dana on the Crystallization of Brushite, 45 
Art. VI.—On the Crystallization of Brushite; by Jamus D. DAWA. 
(Communicated to the California Academy of Sciences.) 
gure. The prisms are monoclinic, and are often 
tened parallel to the clinodiagonal, as here repre- 
ted 
figure, which may be called r, is quite rough, owing to an oscil- 
latory combination of two hemi-octahedral planes. In many of 
the crystals, only the right one of the two planes J is present, 
and also only the left one of the two planes 1. The prisms fre- 
ccording to measurements with the reflective goniometer— 
ZT: I= 142° 26) Ps @ = FOr 
F:u = 108 47 1:1 156 20 (approximately.) 
The inclination of 1 on 1 could not be accurately measure 
‘©n account of the minuteness of the planes in the crystals in 
Which both planes occur, and the want of perfection in the re- 
pe The angle obtained for 1:72 would give for 1:1 
U 
By measurement with a goniometer attached to a compound 
microscope, the plane angle between the lines of cross cleavage, 
ore/, and the edge I: I (which equals the inclination of O on 
‘A€ Orthodiagonal section or the plane 72) was found to be 117°- 
1174°; and that between edge J: J and edge 1: 1 (which equals 
* 90 12, both unobserved planes), 95° to 954°; whence, O: 1s 
would equal, approximately, 147° 30’. The inclination of the 
ee. plane r on the edge 1: 1 is about 110°, but varies much. _ 
*he results of calculation, taking as data the above-mentioned 
*. 
