56 JOURNAL OF THE [April^ 



12. True Ruby in matrix of limestone from Burmah. 



13. Artificial Emeralds. 



14. Rainbow Agate. 



15. Zufii Bread. 



16. The new Nachet Grand Petrographical Microscope, with 

 Dr. Koch's Microscope Lamp. 



Exhibits 1-16 all by George F. Kunz. 



17. Macrospore of Siderothrix in Silicified Wood : by A. A. 



JULIEN. 



18. Macrospore germinating in Silicified Wood : by A. A. 



JULIEN. 



19. Crystals of Calcium Oxalate in Silicified Wood : by A. A. 



JULIEN. 



20. The parasitic Wasp, Hyptia sp. : by J. L. Zabriskie. 



Mr. Kunz furnished the following explanation of his exhibits: 



" The researches on the production or synthesis of the ruby 

 have been carried on in the laboratory of the Musee d'Histoire 

 Naturelle of Paris from 1887 to 1890, and to some extent since 

 then. In the first work published by them, M. Fremy and M. 

 Verneil announced that they had obtained rubies approaching a 

 lively red color, made in a crucible of refractory porcelain con- 

 taining a mixture of aluminate of lead and bichromate of potash, 

 the silica of the crucible uniting with the lead of the lead alu- 

 minate and forming a fusible silicate of lead, and the alumina 

 crystallizing as rubies. The crystals formed in quantity and 

 were of a good rose color, but were always lamellar and friable. 



" In a second work published by them, it was announced that 

 they had made transparent rubies that were brilliant, crystallizing 

 as rhombohedrons, the crystals being of a purity equal to that of 

 natural rubies. These were made in a refractory crucible, at a 

 high temperature, containing a mixture of alumina with a little 

 potash, fluoride, or barium, and bichromate of potash. It was 

 found indispensable to pass a current of air through the crucible. 

 The alumina combined with the potash and the air passing 

 through the crucible, causing at a very high temperature the 

 hydrofluoric acid to separate from the barium and form an alka- 

 line fluoride, the rubies remaining in a state of absolute purity 

 in a matrix of alumina. 



" Every time the fluoride or alumina was elevated to a tempera- 



