45^ On tie Light from organifed Bodies, 



contained in a white earthen mug, and the light was wholly extinguiflied in about three 

 or four minutes. After this, the phial was kept in the water feme time longer, was then 

 taken out to cool, and well fliaken, but the light did not revive. It was examined the 

 next day, and agitated again, but no luminous appearance could be difcovered ; a proof 

 that all the light had been totally extinguiflied by the power of heat. 



If much Heat be applied to the Bottom of a Tube filed with illuminated Liguid, which has been 

 fame Time at reft, the Light will defend in luminous Streams, from the Top of the Tube to the 

 Bottom, and be gradually extinguijhed. 



Exper. i6. A glafs cylindrical tube, clofed at one end, being y inches long, with a bore 

 of i^i inch, when ufed, was put into a gallipot 3^ inches deep, and 3^ wide, which 

 held about 12 ounces of boiling water, and was placed in another larger veflel, to receive 

 the overflowing water upon the immerfion of the tube. The tube being filled over night 

 with fome very luminous liquid, was placed in the laboratory until the next evening. 

 The 'light had then afcended plentifully to the top of the fluid, (the reft being dark,) and, 

 taking the circular fhape of the tube, formed a very lucid ring. The veflels with the boil- 

 ing-hot water were then carried into the dark laboratory ; and the tube being gently and 

 carefully placed (without fliaking) in the gallipot, the light was, generally in about half a 

 minute, fecn plainly to defcend in ftreams from the top to the bottom; illuminating the 

 whole fluid in its defcent in a beautiful manner, and then was gradually extinguiflied. 

 The extinction of the light began at the top of the tube, and ended at the bottom. 



Exper, 17. The experiment was alfo made with a tube 19 inches high, -i an inch in 

 bore, having feveral curvatures, and fealed hermetically at its lower end. Both ex- 

 tremities were made ftraight for a few inches ; the one to be immerfed in the water, 

 and the other to prevent the liquid running out. The luminous ring being formed as 

 above mentioned, the tube was put into the gallipot of boiling-hot water; and, in afliort 

 time, the light began to defcend from the top, and came waving down, in a pleafing man- 

 ner, to the bottom of the tube in the hot water, and then was by degrees extinguiflied. 

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



The mofl; eligible folutions for this curious experiment, ate thofe made with Epfom 

 fait, Glauber's fait, fea-falt, and fal ammoniac : if either of the two former be ufed, the 

 proper proportion is, one dram of fait to each ounce of water ; if either of the two latter, 

 15 grains to each ounce of water will be fuSicient. 



N. B. The experimentalift, before he views the defcent of the light in the tube, ftiould 

 always remain in the dark for fome little time, in order to get rid of all extraneous light 

 adhering to the organs of vifion, and to accommodate the eye to darkn^fs. . ; 



SECTIOU 



