I 4 4 EFFECTS OF HIGH TEMPERATURE. PAKT i. 



bead of tlie metallic salt on a platinum wire was placed 

 between the platinum terminals, from which the spark 

 of a powerful inductive coil could be passed, but in order 

 to have a more intensely hot spark the coating of a Ley- 

 den jar was placed in communication with the terminals 

 of the secondary current respectively. By this addition 

 of static electricity, the intensity of the current was in- 

 creased four-fold, and must have been beyond estima- 

 tion. 



By high temperature the csesium spectrum has been so 

 changed, that for number, colour and distinctness of its 

 lines, it is the most beautiful of those of the alkaline 

 and earthy metals, for besides its characteristic blue 

 lines, it has six red and an orange-red line in the red part 

 of its spectrum, a fine yellow line, and nine green 

 lines, the last coinciding with Fraunhofer's E. The 

 thallium spectrum also acquires more lines when evapo- 

 rated by electricity, for besides the remarkable green 

 line in the green, it acquires a faint one in the orange, 

 two of nearly equal intensity in the green, a third fainter, 

 and a fifth in the blue. 



MM. Pliicker and Hittorf, in recent experiments, 

 proved that many non-metallic bodies, such as nitrogen 

 and sulphur, give two distinctly different spectra 011 

 change of temperature, and that the transition from 

 one spectrum to the other is sudden. The change is 

 particularly striking in sulphur, for at the moment the 

 first spectrum attains its maximum brightness, it dis- 

 appears, and gives place to the second or high tem- 

 perature spectrum, which is one of the richest in 

 brilliant rays known. When the temperature is lowered 

 the first spectrum reappears. These changes M. Pliicker 

 ascribes to the existence of the elements in two allotropic 

 conditions. M. Pliicker has also found that each metal- 

 loid possesses a peculiar and characteristic spectrum : as 

 hydrogen, which has three bright lines, all of which are 



