Home » categories » rare book library » Dieulafait. Diamonds and Precious Stones.
This chapter is tagged (labeled) with: 

Ch. 1: Precious Stones Introduction

Ch. 1: Precious Stones Introduction Page of 296 Ch. 1: Precious Stones Introduction Text size:minus plus Restore normal size   Mail page  Print this page
OPTICAL PROPERTIES.
19
melted before the oxyhydrogen blowpipe. The simple silicates, ternary bodies, are fusible at a much lower temperature; and the multiple silicates offer no serious resistance.
The temperature of fusion of precious stones, since it is allied in a remarkable manner with their hardness, serves as a good characteristic for distin­guishing them.
OPTICAL PROPERTIES.
Refraction.—When a luminous ray passes through a homogeneous medium, its course is in a straight line, as shown in Fig. 16, a phenomenon with which everyone is familiar. But when it passes from one medium into another, the case is generally different, and the ray suffers a remarkable modification. It is then more or less diverted from its primitive direction, and has the appearance of being broken, whence the phenomenon has been termed refraction. A stick plunged into water will exemplify this effect.
The extent to which the luminous rays are diverted in traversing transparent bodies varies greatly. This variation is generally connected with differences in the nature and composition of the re­fracting bodies; but it is likewise intimately con­nected, as experiments prove, with the molecular
Ch. 1: Precious Stones Introduction Page of 296 Ch. 1: Precious Stones Introduction
Suggested Illustrations
Other Chapters you may find useful
Other Books on this topic
bullet Tag
This Page