182 Dr. Hulme's Experiments and Observations 



considerable time for inspection, and often agitated, to stir up the 

 hidden light, yet no remains of any shining property could be 

 perceived. This experiment was frequently repeated, and always 

 with the same result. 



Exper. 14. Four ounces of very luminous liquid, together 

 with a thermometer, were put into a small earthen vessel, glazed 

 white, the better to reflect light. Boiling-hot water was then 

 added, by spoonfuls at a time, and by slow degrees. The first 

 few spoonfuls made it considerably more lucid ; and then, by 

 adding more, the light began to fade, and at length was gradually 

 extinguished. This effect took place, in one instance, when the 

 liquid was heated to g6°; in another, to 98 ; and in a third, 

 to ioo°. Hence, this species of light, when thus united with 

 water, seems to begin to be extinguished at from 96 to 100 

 degrees of heat. This is a very elegant and pleasing method, of 

 knowing how much heat is required to extinguish the light; 

 because it measures it exactly, provided the hot water be added 

 in small quantities, and by slow degrees, as above directed. 

 To prevent the possibility of any light reviving after an ex- 

 periment of this kind, would require a much greater heat than 

 that of 100 . The intention of the present experiments was 

 only to show, that all light may be apparently extinguished, at 

 so low a degree of temperature as from $6° to 100 . 



Exper. 15. A phial of an ounce and a half was filled with 

 some very luminous liquid, but not corked. It was then sus- 

 pended by a string, in a quart of boiling-hot water contained in 

 a white earthen mug, and the light was wholly extinguished 

 in about three or four minutes. After this, the phial was kept in 

 the water some time longer, was then taken out to cool, and well 

 shaken, but the light did not revive. It was examined the next 

 day, and agitated again, but no luminous appearance could be 



