379 



heated, and not decomposable by mere heat. It had no taste, no' 

 smell ; it did not seem to be soluble in boiling water, nor even in 

 muriatic, nitric, or sulphuric acid ; neither did strong lixivium of 

 caustic potash appear to produce the least effect ; and the only pro- 

 cesses by which it appeared to be affected were combustion, or the 

 action of fused potash. In the latter case it emitted a smell of am- 

 monia ; it appeared to dissolve in the potash, which then gave indi- 

 cation of the acids that had entered into the composition of this sin- 

 gularly intractable substance. 



Amongst the known combustibles, it is observed that charcoal is 

 the only one which does not combine directly with oxymuriatic acid 

 gas ; but Mr. Davy is of opinion that it does in some cases unite by 

 the medium of hydrogen, as in the state of olefiant gas, and in the 

 formation of muriatic ether. The author expresses a hope that new 

 and more correct views of the composition of muriatic salts will faci- 

 litate their decomposition, and explain, in a satisfactory manner, va- 

 rious economical processes, long since practised, for obtaining the 

 acid from common salt by means of aluminous or siliceous sub- 

 stances, the success of which has in general depended on the acci- 

 dental presence of moisture. In this case the alkali forms a glass, 

 and is rendered useless ; but by the substitution of iron filings, and 

 passing steam over the mixture when heated, Mr. Davy has suc- 

 ceeded in separating a portion of soda from common salt. 



Observations upon Luminous Animals. By J. Macartney, Esq. Com- 

 municated by Everard Home, Esq. F.R.S. Read May 17, 1810. 

 [Phil. Trans. 1810, p. 258.] 



Although the property of emitting light, which is possessed by 

 some animals, has appeared interesting to naturalists of all ages, and 

 although many detached memoirs have been written upon the sub- 

 ject, the author observes that the history of these animals is still ex- 

 tremely imperfect ; and he endeavours to supply the defect by enu- 

 merating all the different animals which, to his knowledge, possess 

 that property, and to ascertain, by dissection or otherwise, the parts 

 of their bodies from whence the light issues, and, by experiment, to 

 discover the circumstances necessary or accessory to the emission of 

 light. 



The genera in which individuals certainly luminous are to be 

 found are as many as twelve in number. There is one species of 

 Pholas amongst the mollusca. Among insects are seven genera; 

 Elater, Lampyris, Fulgora, Pausus, Scolopendra, Cancer, and Mono- 

 culus. Among the worms is one, Nereis. And in the class of zoo- 

 phytes, the three genera of Medusa, Pyrosoma, and Pennatula. 



The same property has also been ascribed to various kinds of fish ; 

 but, in the author's estimation, they have probably acquired that re- 

 putation by occasionally evolving light after death. 



It has also been said, that the Lumbricus terrestris, or common 

 earth-worm, has been found to be luminous for several days together ; 



