] 64, Dr. Hulme's Experiments and Observatiofis 



was but slightly luminous, and the latter was dark ; on the suc- 

 ceeding evening, they were both dark. 



Exper. 5. Two mackerels were brought from the market at 

 1 P. M. which, to the sight and smell, were perfectly sweet and 

 good. Being then carried into the dark laboratory, and examined, 

 the one was found to be a little luminous, and the other pretty 

 much so, especially about its belly. 



Exper. 6. A fine fresh mackerel, with a bright eye, was pur- 

 chased about noon, and placed as usual in the laboratory, the 

 temperature of which, at that time, was about 54 . At 11 P. M. 

 this beautiful fish was luminous about the head and upper 

 parts ; and the inside of the mouth, which was wide open, shone 

 with most brilliant light. The next evening, the whole body of 

 the fish was very luminous : on the third night, it was less so ; 

 and on the fourth the light was nearly extinguished. 



Exper. 7. In the forenoon, about ten o'clock, a couple of fine- 

 looking mackerels were hung up in the laboratory, at the tem- 

 perature of 56 , and at 10 P. M. they began to shine in various 

 parts, the light seeming to proceed from within outwards. On 

 the second night, they put on a luminous appearance all over 

 their surface : on the third, the light was not so vivid ; and on 

 the fifth it was almost extinct. 



N. B. In experiments of this kind, for the production of light, 

 the fishes should always be gutted, the roes taken out, and the 

 scales, if any, carefully removed. As the roes are likewise very 

 productive of light, they should be preserved. 



OBSERVATIONS. 



Obs. 1. These experiments clearly prove, that light begins to 

 be emitted by marine fishes, before any signs of putrefaction 



