Chemistry and Physics. = 
ins t 
tains the greater, diagonal of the rhombic base. The researches of 
have been made in this country by Silliman and by Blake—Comptes 
Rendus, xxxiii, 447, 684, and Ann. de Chimie et de Physique, xxxiii, 
force. Ist. In all other rections the parallelopiped exerts a doubly 
i re most vivid when 
ness, and reciprocally proportional to the breadth of the mass. 3d. 
hich produce the same differ- 
Is 
sysiem cannot be considered as bodies optically homogeneous or isO- 
tropic. 2d. That the axes of elasticity of the ether do not always coin- 
ient to make known the direction and magnitude of the mechani- 
pressures existing in the interior of crystals naturally doubly re- 
fractiog.—Comptes. Rendus, xxxiii 
pre . Their density was 
4°26; the | mineral. Glucina 
was obtained in well defined crystals, large enough to admit of mea 
urement. ‘These crystals were six-sit prisms: inat a six- 
