184 Dr. Hulme's Experiments and Observations 



put into the gallipot of boiling-hot water ; and, in a short time, 

 the light began to descend from the top, and came waving 

 down, in a pleasing manner, to the bottom of the tube in the 

 hot water, and then was by degrees extinguished. The whole 

 length of the tube, including the curvatures, was 26 inches. 



The most eligible solutions for this curious experiment, are 

 those made with Epsom salt, Glauber's salt, sea-salt, and sal 

 ammoniac : if either of the two former be used, the proper 

 proportion is, one dram of salt to each ounce of water; if either 

 of the two latter, 15 grains to each ounce of water will be suf- 

 ficient. 



N. B. The experimentalist, before he views the descent of 

 the light in the tube, should always remain in the dark for 

 some little time, in order to get rid of all extraneous light ad- 

 hering to the organs of vision, and to accommodate the eye to 

 darkness. 



SECTION X. 



The Effects of the human Body, and of the animal Fluids, upon 



spontaneous Light. 



The living Body. 



Exper. 1. On touching the luminous matter of fishes, the 

 light adhered to the fingers and different parts of the hands ; 

 remained very lucid for some little time, and then gradually dis- 

 appeared. But the same kind of matter being applied to pieces 

 of wood stone, and the like, of the same temperature as the 

 laboratory, continued luminous on these substances for many 

 hours. 



