636 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 



8. Two dr. of pure honey, that had not been clarified, or exposed to heat were 

 dissolved in 2 oz. of water ; and, after the admission of some mackerel-light and 

 shaking the phial, the solution was fully impregnated with light, which was visible 

 the next evening. — Exper. Q. Two dr. of purified or refined sugar being dissolved 

 in 2 oz. of water, and mixed with the shining matter of a herring, the fluid ac- 

 quired a great degree of lucidness. The same effect took place when the experi- 

 riment was made with soft brown sugar. 



Obser. These experiments enable us to take light, and diffuse it through water 

 so as to render the whole liquid most brilliantly luminous, or in other words to 

 impregnate water with light. By these means, the light is so extended in its sur- 

 face, and combined in such a manner, as to become exceedingly convenient and 

 useful for various other experiments. 



Section 5. When spontaneous Light is extinguished by some Bodies or Substances 

 it is not lost, but may be again revived in its former Splendour, and that by the 

 most simple Means. 



Exper. 1. June 1, 1795, the following experiments were made, to know what was 

 the best proportion of Epsom salt to water, in order to produce the most luminous 

 liquid. Some shining matter was taken from a mackerel, and mixed with a solu- 

 tion of 7 dr. of the salt in 1 oz. of water; and its light was immediately extin- 

 guished. The same effect ensued, but in a less degree, with a solution of 6 and 

 one of 5 dr. In a solution of 2 dr., in the same quantity of water, the liquid was 

 luminous ; but much more so when only I dr. of salt was used. Observing the 

 extinction of light to take place, as above, in the more saturated solutions, while 

 the diluted solutions were luminous, it occurred to endeavour to discover what 

 became of the extinguished light, in the former case, and whether it might not 

 be revived by dilution. For this purpose, I took the solution of 7 dr. of salt in 

 1 oz. of water, in which the lucid matter from a mackerel had been extinguished, 

 and diluted it with 6 oz. of cold pump water; when, to my great astonishment, 

 light in a moment burst out of darkness, and the whole liquid became beautifully 

 luminous ! This revived light remained above 48 hours, that is, as long as other 

 light in general does, which has never been extinguished. Hence, it had lost 

 nothing of its vivid luminous powers by its extinction. — Exper. 2. The last expe- 

 riment was then reversed. A solution of 1 dr. of Epsom salt in 1 oz. of water, 

 was brilliantly illuminated with mackerel light. Then, 6 dr. of the salt were put 

 into this luminous liquid ; and after shaking the phial very well for a little time, to 

 promote the solution of the salt, the light was totally extinguished. But the same 

 light was again recovered by the addition of 6 oz. of water. In this manner the 

 light may be frequently extinguished, and as often revived. In one instance, the 

 same light, by a repetition of this method, was made to undergo 1 extinctions. — 

 Exper. 3. A good quantity of herring-light being mixed with a solution of 4 dr. 

 of common salt, in 2 oz. of water, was immediately extinguished. Then 14 oz. 

 of cold pump water were added ; when the whole liquid was at once finely illumi- 



