insects, the creeping glow-worm, the flying glow-worm, the fire-fly, and the great lantern-fly.
The numerous experiments described in this paper were chiefly made on marine animals, particularly herrings and mackerel, which were exposed either in the air, or in water impregnated with different salts, and of different temperatures, in a dark vault to which the Doctor assigns the name of his laboratory.
The results obtained in this investigation are described in nine sections. the summary contents of which are as follows:
l. The quantity of light emitted by putrescent animal substances does not arise from the greater degree of: putrefaction in such substances, as is commonly supposed; but, on the contrary, they begin to shine some time before any apparent signs of putrefaction take place, and the greater the putrescence, the less is the quantity of light emitted.
2. Light is a chemical element, or a constituent principle of some bodies, and particularly of marine fishes; and it may be separated from them by a peculiar process, or be retained, and rendered permanent for some time. The experiments from whence this inference is derived were made with pieces of herrings and mackerel, and with living tadpoles immersed in solutions of Epsom salt, sea salt, Glauber’s salt, and in all which a quantity of light was manifestly imparted to the saline menstruum, which the latter under various circumstances retained for a considerable time. These experiments seem also to evince, that light is not partially but wholly incorporated with every particle of the animal substance; that it is probably the first elementary principle that escapes after the death of fishes; and that as the putrescence was by no means promoted, but rather retarded by this emission of light, it is highly probable that no offensive putrefaction ever takes place at sea after the death of such myriads of animals as must needs daily perish in the vast ocean, which hence continue long a wholesome food to the many kinds of fish that feed upon their congeneries.
3. Some bodies or substances have a power of extinguishing spontaneous light when it is applied to them. These are Water, both pure and impregnated with quick lime, carbonic acid gas, and hepatic gas, fermented liquors, ardent spirits, fixed and volatile alkalies, certain neutral salts, vegetable infusions, pure honey, and the rust of iron, calamine, minium, and manganese dissolved in water.
4. Other bodies or substances have a. power of retaining spontaneous light for some time when it is applied to them. These substances are most of the solutions mentioned in the second article, which, when impregnated with some of the lucific matter scraped from herrings and mackerel, retain the light for some days, especially if assisted with some agitation of the phial containing them. The appearances here exhibited are described as being both beautiful and surprising, as they enable us to take light from one substance and transfer it to another, so as to render the latter most brilliantly luminous; or in other words to impregnate a liquid with light.
