680 PHILOSOPHICAL TRANSACTIONS. [aNNOI 76g, 



LXII. Experiments to prove that the Luminousness of the Sea arises from the 

 Putrefaction of its Animal Substances. By John Canton, M. A.^ F. R. S. 

 p. 446. 



Exper. I. Into a gallon of sea-water, in a pan about 14 inches in diameter, 

 Mr. C. put a small fresh whiting, June 14, 1768, in tin; evening ; and took no- 

 tice that neither the whiting, nor the water when agitated, gave any light. A 

 Fahrenheit's thermometer in the cellar, where the pan was placed, stood at 54 

 degrees. The 15th, at night, that part of the fish which was even with the sur- 

 face of the water was luminous, but the water itself was dark. Mr. C. drew 

 the end of a stick through the water, from one side of the pan to the other, and 

 the water appeared luminous behind the stick all the way, but gave light only 

 where it was disturbed. When all the water was stirred, the whole became lu- 

 minous, and appeared like milk ; giving a considerable degree of light to the 

 sides of the pan that contained it ; and continued to do so for some time after it 

 was at rest. The water was most luminous when the fish had been in it about 

 28 hours, but would not give any light by being stirred, after it had been in it 

 3 days. 



Exper. 2. Mr. C. put a gallon of fresh water into one pan, and a gallon of 

 sea-water into another, and also into each pan a fresh herring of about 3 ounces. 

 The next night the whole surface of the sea-water was luminous without being 

 stirred, but much more so when put in motion ; and the upper part of the her- 

 ring, which lay considerably below the surface of the water was very bright. 

 The fresh water was quite dark, as was also the fish that was in it. There were 

 several very bright luminous spots on different parts of the surface of the sea- 

 water ; and the' whole, when viewed by the light of a candle, seemed covered 

 with a greasy scum. The 3d night, the light of the sea-water while at rest was 

 very little, if at all, less than before ; and when stirred, its light was so great, 

 as to discover the time by a watch ; and the fish in it appeared as a dark sub- 

 stance. After this, its light was evidently decreasing, but was not quite gone 

 before the 7 th night. The fresh water, and fish in it, were perfectly dark during 

 the whole time. The thermometer was generally above 60. 



Exper. 3. Into a gallon of fresh water Mr. C. put common or sea-salt, till 

 he found by an hydrometer it was of the same specific gravity with the sea-water. 

 In another gallon of fresh water he dissolved 2lbs. of salt : and into each of 

 these waters he put a small fresh herring. The next evening the whole surface 

 of the artificial sea-water was luminous without being stirred, but gave much 

 more light when it was disturbed. It appeared exactly like the real sea-water in 

 the preceding experiment, and its light lasted about the same time, and went off 

 in the same maimer.* The other water, which was almost as salt as it could be 



