1886.] NEW YORK ACADEMY OF SCIENCES. 5 



with a mere pocket lens, as the whole structure is that peculiar 

 to fused masses. Examination elicited the following facts : 

 The principal distinguishing: characteristic between these and 

 the genuine stones is the presence in them of large numbers of 

 spherical bubbles, rarely pear-shaped, sometimes containing 

 stringy portions showing how the bubbles had moved. These 



Fig. 1. — Spherical cavities in artificial 

 ruby as seen at one time (en- 

 larged 75 diameters). 



Fig. 2.— Spherical and irregular cavities 

 in artificial ruby as seen at one 

 time, evidently from the lower 

 part of the crucible (enlarged 25 

 diameters). 



bubbles all have rounded ends, and present the same appearance 

 as those seen in glass or other fused mixtures. They are nearly 

 always in wavy groups or cloudy masses. When examined indi- 

 vidually they always soem to be filled with gas or air, and often 

 form part of a cloud, the rest having the waviness of a fused 

 mixture. Some few were observed inclosing inner bubbles, 

 appd,rently a double cavity, but empty. In natural rubies, the 

 cavities are always angular or crystalline in outline, and are 

 usually filled with some liquid, or, if they form part of a 

 "feather " as it is called by the jewelers, they are often arranged 

 with the lines of growth. Hence the difference in appearance 



@ 



L-J 



Fig. 3.— Liquid cavities in natural ruby and sapphire (enlarged 100 diameter.) 



between the cavities in the natural gem and those in the fused 

 gem is very great, and can readily be detected by the pocket 

 lens. I have failed to find in any of the artificial stones even a 

 trace of anything like a crystalline or angular cavity. Another 

 distinguishing characteristic is that in many genuine rubies we 

 find a silky structure (called "silk" by the jewelers), which, if 

 examined under the microscope, or under a j%- to y^^ inch objec- 

 tive, we find to be a series of cuneiform or acicular crystals, 

 often iridescent, and arranged parallel with the hexagonal layers 

 of the crystal. When in sufficient number, these acicular and 



