7ic'w Expe7ime7its ofM. Doebeveiner, 289 



I tried other finely divided metals, such as lead as precipi- 

 tated by zinc, and gold and silver as thrown down by cojiper ; 

 but without success. 



From those experiments I am perhaps warranted in con- 

 cluding, 



1st, That no chemical change takes place in the platinum, 

 and tb.erefore I presume its effect to be mechanical : 



2nd, That a change does take place in the condition of the 

 gases, which change is their union to form water: 



3d, That in case the gases have the temperatin-e of 55°, the 

 platinum requires a temperature of 98° to cause them to unite : 



4th, That as the condensation of the gases is the only 

 change in the substances used, we must infer that the greatly 

 increased heat of the platinum arises from that condensation, 



I have here pointed out the j^roximate cause of the heat of 

 the platinum, but the ultimate I have not been able to dis- 

 cover. It is therefore left as a problem to future inquirers, "Why 

 platinum in a state of minute division should cause the union 

 of oxygen and hydrogen at 100°, whereas their lowest com- 

 bining temperature without it is 700"? 



If the effect of the metal be mechanical, I have no doubt 

 that other substances will be found having the same power, 

 although I have not succeeded in selecting them. 



The phagnomena altogether are singular, and appear inti- 

 mately connected with aphlogistic phaenomena, or at least to 

 stand in the same relation to them as they do to rapid com- 

 bustion : for instance ; 



At 100°, spongy platinum causes oxygen and hydrogen 

 to combine. 



At 700°, they unite without it silently. 



At 800°, explosion attends their combination. 



At red heat (about 1000°), platinum-, silver- or brass-wire 

 causes carbon, hydrogen, and oxygen to combine, forming 

 water, acetic acid, and resin. 



At a white heat, carbon, hydrogen, and oxygen, combine, 

 forming water and carbonic acid. 



William Herapath. 



LX. On some newhj discovered remarkable Properties oj the 

 Protoxide, Oxidized Sidphtret, and Metallic Powder of' Pla- 

 tinum. By Professor Ucebereiner*. 



T HAVE already proved that the })rotoxide of platinnm ob- 

 ■^ tained by Edmund Davy's method, has the property of 



* From Schweigger and Mcinecke's Ncnes Journal f'tir Chemie, S^c. N. R. 

 band viii. [>. .'i21. 



Vol.62. No. 30G. Oct. 1823. O o causin.r 



