VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 633 



drawn up by the pump. The liquid was contained in a wide-mouthed 3 oz. phial, 

 which was placed in the laboratory. On carefully examining the liquid, on the 2d 

 evening after the process was begun, I could plainly perceive a lucid ring (for the 

 phial was round) floating at the top of the liquid, the part below it being dark; 

 but on shaking the phial, the whole at once became beautifully luminous, and con- 

 tinued in that state. On the 3d evening, the light had again risen to the top; 

 but the lucid ring appeared less vivid, and on shaking the phial as before, the 

 liquid was not so luminous as on the preceding night. — Exper. 2. The same expe- 

 riment was repeated. On the 2d night, the liquid, being agitated, was very lumi- 

 nous; on the 3d, not so lucid; and on the 4th the light was extinguished. — 

 Exper. 3. With sea salt or muriated natron \ dr., and 2 oz. of water. On the 2d 

 night, the liquid, when agitated, was dark ; on the 3d, lucid ; on the 4th, very 

 luminous; on the 5th, it began to lose light; on the 6th, it continued to decrease; 

 and on the 7th it was quite gone. Neither the liquid, nor the herring, had con- 

 tracted any putrid smell. Exper. 4. With sea-water 2oz. -On the 2d night, 

 dark ; on the 3d, 4th, and 5th, luminous ; on the 6th, nearly extinct ; and on 

 the 7th, totally. The piece of herring, when taken out and examined, was re- 

 markably sweet. 



Exper. 5. Roe of herring,* with Epsom salt 2 dr., and water 2oz. On the 2d 

 night, the liquid was pretty luminous ; on the 3d and 4th, still luminous ; and on 

 the 5th its light was extinct — .Exper. 6. With Glauber's salt or vitriolated natron 

 2 dr., to 2 oz. of water. On the 2d night, when the phial was shaken,, as usual in 

 all these experiments, the liquid was pretty luminous ; on the 3d, less so ; and on 

 the 4th the light was scarcely visible. — Exper. 7 . With sea-water 2 oz. On the 

 2d night, dark ; on the 3d, the liquid was moderately luminous ; on the 4th and 

 5th, it had extracted much light ; and on the 7th it was still shining. After this 

 process, both the roe and the sea-water remained perfectly sweet. 



The Flesh of Mackerel. — Exper. 8. With Epsom salt 2 dr., and water 2 oz. 

 On the 2d night, the liquid was finely illuminated ; on the 3d, a similar appear- 

 ance; on the 4th, a diminution of light; on the 5th, it continued lucid in a small 

 degree ; and on the 6th the light was extinguished. 



Roe of Mackerel. — Exper. Q. With Epsom salt 2 dr., and water 2 oz. On the 

 2d night, the liquid, when agitated, was exceedingly bright ; on the 3d, the same ; 

 and on the 4th and 5th, still lucid. 



The Tadpole. — Exper. 10. It occurred to my mind, in 1797, to try what effect 

 a saline menstruum would have on the tadpole. Accordingly, I procured some 

 tadpoles on the 10th of June, and put 6 of them into a solution of 2 dr. of Glau- 

 ber's salt in 2 oz. of water. On the 11th, in the evening, the menstruum was 

 dark; on the 12th, after shaking the phial, I was agreeably surprized to find it 

 impregnated with light ; on the 13th, the light was so abundant as to float on the 

 top of the menstruum ; on the 14th, the same phenomenon appeared ; on the 



* The quantity used in each experiment was about i drams.— Orig. 

 VOL. XVIII. 4 M 



