NICHOLS. — THE VISIBLE RADIATION FROM CARBON. 



107 



the acetylene flame. A noteworthy fact exhibited by means of these 

 curves is the relatively rapid increase of intensity in the middle of the 

 spectrum. In passing from 930° to 1055° the brightness of wave 

 length .7C p, increases 5.3 times ; that of .70 p, 7.2 times ; that of .60 p, 

 13.5 times, and that of .50 p o>dy 9 times. We have here the beginnings 

 of a process which becomes more marked in its effects as higher temper- 



■ss-^. 



■6o. 



y- 



■JfS-f*. 



IOOO" nOQ a /lOO° /ZOO' 



Figure 19. 



atures are attained. From 1100° upwards it was found much more 

 difficult to obtain satisfactory readings. The carbon rods which I had 

 brought from Paris for this investigation would not stand prolonged 

 heating and it was necessary to replace them frequently. 



