ON METALLIC PHOSPHURETS. 369 



tcmains : 2, to emit a beautiful phosphorescent light in the 

 dark, when thrown on a hot iron, and leave a metallic pel- 

 licle as a residuum. 



Their specific characters are easily determined, first by 

 the metal left after the action of the fire, and secondly by 

 that found in solution in the nitric acid. 



Their formation may be explained in the following way. Their forma- 

 The spirit of wine impregnated with phosphorus quits it, *'*^" ^^^ ^"^^ * 

 as soon as it is mixed with the solution of either of the four 

 metals mentioned above, and unites with the acid, producing ^ 

 ether. The metallic oxide, being set free, gives up its 

 oxigen, either to the hidrogen of the alcohol, or to a small 

 portion of the phosphorus, the greater part of which seizes 

 on the metal in its pure state. This explanation results from 

 the pro"ducts of the two liquids, the phosphuret that falls 

 down, and the ether that remains in the liquid, the fragrant 

 smell of which is perceptible the moment after the operatioQ 

 is effected. 



§ 3. A very singular phenomena exhibited in this experi- Singular agita- 

 ment is the agitation, which the metallic particles display. ]|q"ij* ^^^^ 

 If, for instance, a few drops of phosphuretted alcohol be 

 dropped into a solution of gold contained in a shallowish 

 vessel, immediately we perceive currents take place through- 

 out the whole of the liquid, and particles of the revived 

 metal attracted in all directions. Sometimes they dart with 

 impetuosity toward the sides of the vessel ; sometimes a cen- 

 trifugal force appears to whirl them round a common centre; 

 and these commotions are always carried on with such 

 velocity, that the eye can scarcely follow them. This ex- Prismatic 

 hibition is frequently rendered more pleasing by the fine ^'^^""'^*- 

 prismatic colours displayed on the brilliant particles in 

 motion. No doubt this decomposition of the light must be 

 ascribed to a very thin stratum of some heterogeneous sub- 

 stance adhering to the metal, as in those coloured rings 

 which Newton observed between convex lenses. I satisfied The agitation 

 myself by a very simple experiment, that these movements ''^.'"§'-®^^*I"*" 

 were owing to the evaporation of the alcohol ; for they 

 ceased as often as I placed the vessel before a window, 

 where the temperature was that day at [32^F.] ; and the 

 moment I took it thence, and brought it near a gentle fire, 

 jthe commotions began anew with great rapidity. 



' Vot. XXV.—SuppLEMENT. 2B § 4. The 



