332 EXPERIMENTAL INVESTIGATIONS. 



frequently used the term ; but notwithstanding, or perhaps on 

 account of, its convenience, it has I fear had an injurious effect 

 on scientific perspicuity. 



The following experiments were made to ascertain whe- 

 ther platinum was the only substance by which the effect 

 could be produced. A knob or button of the native alloy of 

 indium and osmium of the size of a small pea was formed by 

 the voltaic battery ; to this was attached by fusion another 

 smaller knob of the same metal one-fourth the size of the 

 former, and to this smaller one was attached a stout platinum 

 wire ; the object of the second knob was both to prevent the 

 fusion of the platinum wire, and also to avoid the possibility 

 of any of the platinum being exposed under the recipient 

 tube or alloyed with the metal to be heated. The preparation 

 of this simple instrument was very troublesome, but when 

 made it answered the purpose well ; the larger button could 

 be fully ignited to an intense glow, while, on account of the 

 narrow neck which united them, the smaller was barely red- 

 hot, and the platinum wire not perceptibly ignited. An ex- 

 periment having been made with this metallic button and 

 prepared water, similar to that previously made with platinum, 

 gas was given off which averaged 0*3 of mixed gas ; the 

 residue was nitrogen mixed with varying small quantities of 

 oxygen. The effect, upon the whole, was decidedly inferior 

 to that of the platinum. Indeed, as platinum is the most 

 dense and unalterable of all known substances, it would be 

 likely, upon any received theory of heat, to produce the 

 greatest effects. 



I tried palladium in the same manner ; the gas yielded 

 was hydrogen with small quantities of oxygen, and the water 

 was stained with the oxide of the metal. 



I now tried silica and other oxides, but the results were 

 not very satisfactory. A spheroid of silica was formed by 

 fusing pulverised silica on to a platinum wire, so as to cover 

 it for the length of 0*4 of an inch ; when this was plunged 

 into the hot water and again fused in the oxyhydrogen blow- 

 pipe, it constantly became frothed with small bubbles of 

 vapour, and after a few experiments generally separated in 

 fissures ; in the experiment which was continued for the 



