The Microscope. 27 



Artificial Rubies. — Mr, Geo. F. Kunz, in Science, describes 

 some large artificial rubies submitted to him for examination. The 

 whole structure of the artificial stones is that peculiar to fused 

 masses. The principal distinguishing characteristics between these 

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

 spherical bubbles, presenting the same appearance as those seen in 

 glass and other fused mixtures. They are nearly always in wavy 

 groups or cloudy masses. A few enclosed inner bubbles, apparently 

 a double cavity, but empty. In natural rubies the cavities are always 

 angular or crystalline in outline, usually filled with some liquid, and 

 often arranged with the lines of growth. These differences can be 

 easily detected with a pocket lens. In many genuine rubies also is 

 found a silky structure (called "silk" by the jewelers) which, under 

 a 4-10 in. objective, is fou,nd to be a series of cruciform or acicular 

 crystals, often irridescent, and arranged parallel with the hexagonal 

 layers of the crystal. When numerous, they produce the asteria or 

 star effect, if the gem is cut en cabochan form, with the center of 

 the hexagonal prism on the top of the cabochan. The hardness of 

 these stones was about the same as that of the true ruby: 8.8. The 

 specific gravity was 3.93 to 3.95, the true ruby ranging from 3.98 to 

 4.01. With the dichroscope the ordinary image was cardinal red, 

 the extraordinary image salmon red, as in the true ruby of the same 

 color. Under the polariscope annular rings were observed. With 

 the spectroscope the ruby red line, like that in the true gem, is seen, 

 although a little nearer the dark end of the spectrum. The color of 

 the stones was good. K. thinks these artificial rubies were produced 

 by fusing an aluminate of lead in connection with silica in a siliceous 

 crucible, the silica vmiting with the lead to form lead glass, and lib- 

 erating alumina, which crystallizes out in the form of corundum in 

 hexagonal plates with a specific gravity of 4.0 to 4.1, and with the 

 hardness and color of the natural ruby, the latter being produced by 

 the addition of some chromium salt. 



Polarized Light in Examination of the Hair. — Dr. J. Pohl- 

 Pincus, of Berlin, has recently published a paper entitled, " Polar- 

 ized Light as a Means of Recognizing Irritable Conditions of the 

 Nerves of the Scalp." lie has prosecuted his studies in this direc- 

 tion for twenty-five years, and announces, as a result of these inves- 

 tigations, that, by an examination of the hair roots by polarized light, 

 peculiar changes may be observed whenever the patient suffers from 



