MICROCHEMISTRY. 145 
phuric acid, which in concentrated solution throws out 
Fic. 54.—CRYSTALS OF Czstum Atum. (After Lehmann.) 
phate. From dilute acid solutions slender monoclinic 
prisms of the compound (CaSO4+ 2H20) crystallize out 
Fic. 55.—CRysTaLs oF CaLciuM SULPHATE. (After Lehmann.) 
(Fig. 55), showing numerous double twins, as at C, 
and in presence of strong acids, masses of minute needle- 
like crystals, as at A. 
