Prof. Daniell's Fifth Letter on Voltaic Combinatiojis. 813 



thickness, a state of very active inflammation was induced. The 

 whole of the face of the author became scorched and inflamed, as if 

 it had been exposed for many hours to a bright midsummer's sun. 

 The rays, when reflected from an imperfect parabolic metallic mir- 

 ror in a lantern, and collected into a focus by a glass lens, readily 

 burned a hole in a paper at a distance of many feet from their source. 

 The heat was quite intolerable to the hand held near the lantern. 

 Paper steeped in nitrate of silver and afterwards dried, was speedily 

 turned brown by this light : and when a piece of fine wire-gauze 

 was held before it, the pattern of the latter appeared in white lines, 

 corresponding to the parts which it protected. The phenomenon 

 of the transfer of the charcoal from one electrode to the other, first 

 observed by Dr. Hare*, was abundantly apparent; taking place from 

 the zincode (or positive pole,) to the platinode, (or negative pole). 

 The arch of flame between the electrodes was attracted or repelled 

 by the poles of a magnet, according as the one or the other pole 

 was held above or below it : and the repulsion was at times so great 

 as to extinguish the flame. When the flame was drawn from the 

 pole of the magnet itself, included in the circuit, it rotated in a 

 beautiful manner. 



The heating power of this battery was so great as to fuse, with 

 the utmost readiness, a bar of platinum, one-eighth of an inch square: 

 and the most infusible metals, such as pure rhodium, iridium, tita- 

 nium, the native alloy of iridium and osmium, and the native ore of 

 platinum, placed in a cavity scooped out of hard carbon, freely 

 melted in considerable quantities. 



In conclusion, the author briefly describes the results of some ex- 

 periments on the evolution of the mixed gases from water in a con- 

 fined space, and consequently under high pressure ; with a view to 

 ascertain, first, in what manner conduction would be carried on, 

 supposing that the tube in which the electrodes were introduced 

 were quite filled with the electrolyte, and there were no space for 

 the accumulation of the gases ; secondly, whether, decomposition 

 having been effected, recombination would take place at any given 

 pressure ; and lastly, whether any reaction on the current-force of 

 the battery would arise from the additional mechanical force which 

 it would have to overcome. These experiments he purposes pur- 

 suing at some future time. 



A paper was also read, entitled, " An experimental inquiry into 

 the influence of nitrogen in promoting vegetable decomposition, and 

 the connexion of this process with the growth of plants." By 

 Robert Rigg, Esq. Communicated by the Rev. J. B. Reade, A.M., 

 F.R.S. 



The author considers it as a general fact, to which there are very 

 few if any exceptions, that vegetable bodies in the state in which 

 they are produced in nature, undergo spontaneous decomposition 

 when kept under circumstances favouring such an action ; and that, 

 from the decomposition of each, compound products peculiar to that 



• This phenomeuon, we believe, was first observed by Prof. Silliman ; 

 see Phil. Mag. First Series, vol. Ixiii.p. 243j Ixv. p. 283.— Edit. 



