_ 
Nn 
The exhibit shows tubes of Argon and Helium, ren- 
dered incandescent by the electric spark, so as to exhibit 
the characteristic spectra. 
Also tubes containing large amounts of Helium, and 
the apparatus for preparing Helium from Monazite. 
2. Norman Heptyit SutrocyaniwE. Exhibited by Marston 
T. Bogert, of the Department of Organic Chemistry, 
School of Mines, Columbia University. 
This compound, hitherto unknown, was prepared by 
the exhibitor in January, 1896. Its graphic formula is: 
GH (ena SON: 
Sp Gr. = 0.931 @,. 15° €. 
Bs P= 230-234° C. 
When freshly distilled, it forms a colorless oil, which 
gradually turns yellow when exposed to light and air. 
PHOTOG RAPTLTY. 
=) 
In CHARGE OF CORNELIUS VAN BrRuNT. 
1. AnTI-HALo, for preventing halation, with plate coated and 
plates showing the difference. 
2. META-CARBOL, a new developing material, with bottle of 
developer and negatives. 
3. STIPPLE PLATES, the use of which will prevent retouching. 
These are to be used in contact with the plates during 
exposure in the camera, with prints illustrating the same. 
4. OLMSTED’s LANTERN SLIDE MATS, from which any design 
or size of Mat can be cut without the aid of a ruler. 
5. Wywnne’s Exposure METER, a pocket apparatus for giving 
the correct time of exposure. 
