on the Light emitted from various Bodies. 175 



was at once finely illuminated. On the next evening it ap- 

 peared still very lucid ; and likewise on the succeeding night. 



Exper. 4. The experiment was reversed. Haifa dram of the 

 salt, being dissolved in two ounces of water, had herring-light 

 mixed therewith, so as to be made very luminous. On the addi- 

 tion of two drams more of the salt, the lucidness was instantly 

 destroyed : but the light was again recovered, by pouring eight 

 ounces of cold water upon the extinguished luminous fluid. 

 The revived light was very vivid the next evening. 



Exper. 5. Two ounces of sea water were illuminated with 

 mackerel-light, and then extinguished by adding two drams of 

 common salt. The light was again restored, by diluting the so- 

 lution with eight ounces of cold spring water. 



N. B. If the illuminated liquid be uncommonly brilliant, it 

 may sometimes require more salt to extinguish the light com- 

 pletely, than is here specified ; in that case, the measure of 

 water for dilution, must be always calculated in exact propor- 

 tion to the weight of salt employed. 



SECTION VI. 



Spontaneous Light is rendered more vivid by Motion. 



EXPERIMENTS. 



Exper. 1. A quantity of illuminated liquid was poured into a 

 broad vessel, which was placed in the laboratory. The next 

 evening, on examination, it appeared to be quite dark. But a 

 finger, or rod, being drawn through it, was followed by a lumi- 

 nous line. 



Exper. 2. A phial, containing a pretty large portion of liquid 

 impregnated with light, having been at rest a number of hours, 



