VARIOUS SOLIDS. 



45 



Phosphorus (P). 

 (Solid film melted between plates of fluorite. / = o.8 mm. (?). Curve b, fig. 28.) 



Phosphorus was examined in order to answer an inquiry whether it 

 could be used for prisms contained in vessels with quartz or fluorite 

 windows. The yellow stick phosphorus was used. It was melted under 

 water (at 44 C), poured on a glass plate, and pressed into a thin sheet 

 by means of a second plate of glass. This thin sheet was then placed 

 between two plates of fluorite and the edges covered with soft wax. As 

 will be noticed in curve b, fig. 28, the transmission curve shows bands due 

 to water which adhered to the phosphorus. The latter melted during the 

 latter part of the examination. The transmission curve includes the 

 fluorite plates, which were not clear, and hence increase the observed 

 absorption. QuARTZ (Si02)> 



(i=3 mm. Curve b, fig. 29.) 



The sample examined was used as a window on the spark-tube in the 



emission spectra of metals in hydrogen, Part VII. The curve shows that 



emission lines, if of appreciable intensity, would be transmitted out to 4 ;. 



100% 



2 3 



Fig. 20 



4-5678 



Glass (a); Quartz (b); Fluorite. 



2/1 



Glass. 

 (Thickness = 0.7 5 mm. Curve a, fig. 29.) 



This sample was examined in connection with prospective work on 

 radiation from incandescent lamps. The transmission is uniform (80 per 

 cent) out to 2 to 2.4 p.. From this it will be seen that the maximum of 

 the energy spectrum of the filament will not be affected by the glass bulb. 



