te ot ee eee ee ee Se ee 
Crystalline form and Chemical constitution. 93 
the principle which has been explained, if it is sustained, as we 
believe, by the facts. A few only are briefly touched upon. 
1. It follows that the hexagonal state of the elements may be 
one corresponding to 8R, or 8nR; that while zinc in the isometric 
state if such exists (about which there is doubt) is Zn; in the 
hexagonal it may be Zn®, the same state in which it exists in 
hexagonal oxyd of zinc. So also Pd, As, Sb, may represent the 
isometric state of the elements palladium, arsenic, antimony ; 
but Pds, As?, Sb3, the hexagonal; and so for other cases. 
. The oxyd of copper, CuO, which may also be written 
€u0?, is dimorphous, it occurring both in isometric and ortho- 
thombic forms; and the orthorhombic form is closely isomorph- 
ous with TiO? in brookite—J: J and J: ¢ in the oxyd of copper 
being respectively 99° 39’ and 126° 29’, and in brookite 99 
and 126° 15’. ‘This relation to TiO? shows that the ortho- 
thombic state of the cupric oxyd should have the formula 
€u0?, or that of a deutoxyd, and the isometric alone that of 
CuO. And it indicates further that the element copper may 
exist theoretically, if not actually, in two corresponding poly- 
the above compounds. For convenience these states may be 
designated by using the Greek letters as follows: 
F RO R203 RO? ROS ROS 
malas 1 RO R30 RyO RO R40 
States of R Rg Ry Ry Ri 
Basic element oR BR yR oR BR 
#RO:2 ; 3(@RO)=RO?; and so on: in other wo the one 
molecule R202 corresponds to three of BRO; — 3(8RO) there 
ste soneag! 
Amis stated above, that if a - = pre -ng 
if oxyd of tin had an isometric as well as a te nal form, the 
fr in the crystalline state should be SnjO, and only the latter 
