34 PRISMATIC COLORS OF TERRESTRIAL LIGHT. 



bited on the surfaces of the water they contain, proportional in 

 number to the symbol of intonation, showing the analogy 

 between color, tone, and/orm, and that they seem to define, by 

 such coincidence, their respective dependence as to their produc- 

 tion on elementary constituents perfectly similar in their 

 properties. 



Although the intonations afforded by the ignition of carbu- 

 retted hydrogen gas may be imputable to other causes, it may 

 be right to notice them. 



Mr. Gurney explains, pp. 302-307, the results of his expe- 

 riments on his blow-pipe when using carburetted hydrogen gas, 

 that having first produced by a regular moderate pressure a 

 perfect white light, that by increasing that pressure gradually 

 to a high degree, he was able to shew the light assuming the 

 several prismatic colors in rotation thus: first, near the orifice 

 of a jet 1-1 6th of an inch diameter, first, vivid red, then 

 yellowish red next, yellow very distinct still increasing the 

 pressure a tint of green appeared ; and lastly, a most beautiful 

 and PERMANENT BLUE. On gradually removing the weights 

 from the gasometer, by which the pressure was reduced, the 

 colors passed again inversely through the several changes until 

 the bright white flame appeared as at first. 



Mr. Gurney found the heat of these colored flames respect- 

 ively corresponded with those produced by the prismatic colored 

 rays of solar light. 



On holding a coil of steel wire in the blue violet flame, it as- 

 sumed a bright white heat, and with a. view to extinguish it by 

 mechanical pressure by placing further additional weight on 

 the gasometer, to his surprise, instead of cooling, it instantly 

 assumed a bright appearance, and fused into globules in the 

 most beautiful manner possible. Mr. Gurney, page 306, states, 

 on placing a platina bar in the bright light, at the extreme end 

 of the flame, most distant (10 inches) from the jet, he could 

 not increase its temperature above the red heat, but on moving 

 it gradually towards the jet, its ignition increased brighter in 



