A. A. Hayes—Red Oxide of Zine of New Jersey. 198 
ri 
Then when placed between the eye and some source of light. 
he rays of light enter the mass, and absorption of part takes 
i q reflect Entire 
~ lower power is best; and when both reflected and transmitted 
aylight illuminates the assay, we observe that a splinter of 
the mineral transmits an olive-green or brownish-yellow light, 
“very in slant rays’ At about 20° inclination a splinter in 
partly reflected light becomes crossed by lines of a dark color. 
Artificial light makes the assay more yellow ; a nice adjustment 
of the incident ray allows a red reflection from the lines, now 
ome surfaces of reflection. Ifthe assay be cubical, the rays 
transmitted through the lamina are arrested and dispersed, 
“aig The scales generally lie parallel with the laminz of 
- assay, so that the passing rays are transmitted or slightly 
sturbed, and the red color of the mineral is replaced by that 
Color, which the scales transmit in a colorless medium. If a 
*oncentrated fluid sulphate of the ore be observed, the naked 
*ye takes in the same tint. : 
le tendency of fracture is in the direction of the lamine, 
and in pre aring the assays the better way is to crush the 
Mineral between steel surfaces to the diameter of pin wire, and 
+ ect the more opaque grains. These show the scales as dis- 
unetly as the bars of a window are seen. 
AM. Jour, Scr, —Turrp Serres, Vor. 1V, No. 21 —Sspr., 1872. 
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