2d On the Vapours which render Platinum red-hot, [tvLY^ 



Solids, — Camphor, 



Benzoic acid. 



-F/wjJi.— Oil of turpentine, 

 Oil of ether, 



Spirits of camphor, as well as the following 

 essential oils. 



Essential oil of amber, 



anniseed, 



carraway, 



cinnamon, 



cloves, 



juniper, 



lavender, 



origanum, 



nutmeg, 



savine, 



rosemary, 



peppermint. 



Gaseous Mixtures, f Hydrogen C Hydrogen, 



t Oxygen, \Air, 



{Carburetted hydrogen, f Olefiant gas. 



Air, \Aih 



All substances, whether solid, liquid, or gaseous, containing oxy^ 

 gen, hydrogen, and carbon, in their composition (the two former 

 are the only essential, though the latter is one of the constitu- 

 ents of most of the bodies experimented on) provided they are 

 volatile either at the temperature of the atmosphere, or by the 

 application of heat, not sufficient to decompose them, seem to 

 produce this effect. 



The caloric communicated to the platinum wire by heating it 

 in the flame of a spirit-lamp is taken up in decomposing the 

 portion of the vapour which arises from the evaporation of the 

 fluid, or solid substance, experimented on. The decomposition 

 of these substances (at least the vapour, which is identical in 

 chemical composition with the body itselQ being thus effected, 

 oxygen and carburetted hydrogen gases are set at liberty ;* 

 these, by the medium of the metallic coil, whether it be palla- 

 dium, or platinum wire, or foil, again unite, forming in some 

 cases water; in others, acetic acid. 



By this condensation of the gases into a fluid, sufficient heat 

 is evolved, enabhng the wire to decompose successive portions 



♦ It may be necessary here to remark, that ethers, oils, alcohol, &c. are compounds 

 of oxygen, hydrogen, and carbon, united in different proportions ; they are all (cam- 

 phor and benzoic acid included) decomposed at a red heat, affording the above»men- 



tioued ga8«8} and a residue of c^boa. 



