320 EXPERIMENTAL INVESTIGATIONS. 



machine of the London Institution ; they had in the steam a 

 beautiful crimson appearance ; on cooling the tube a bubble 

 was perceptible, which detonated by the match. 



As in the previous experi- 

 Flg< 8f ments, a whole day's work did 



not increase the bubble, but 

 when it was transferred another 

 instantly formed ; the gas was 

 similarly collected ; it detonated 

 and contracted to 0*4 of its ori- 

 ginal volume ; the residue was 

 nitrogen with a trace of oxygen. 



This experiment will again surprise by its novelty ; the 

 very means used in every laboratory to combine the mixed 

 gases and form water here decompose water.* From a vast 

 number of experiments which I have made on the voltaic and 

 electric disruptive discharges (which are I believe similar phe- 

 nomena, differing only in quantity and intensity), I believe the 

 decompositions produced by them are the effects of heat alone, 

 and this experiment was therefore to my mind a repetition of 

 the last under different circumstances ; others however may 

 think differently. This experiment also I several times 

 repeated. 



By counting the globules given off, and comparing a certain 

 number of them with the average volume of steam in the last 

 two experiments, an attempt was made to ascertain what pro- 

 portion of water could be decomposed by an ignited platinum 

 wire in aqueous vapour, or, which amounts to a corollary from 

 this proposition, what degree of dilution would enable mixed 

 gas to exist without combustion in an atmosphere of steam 

 exposed to an ignited platinum wire. The proportion in an 

 experiment in which the globules were so counted was I in 

 2,400 ; the probability is however that different temperatures 

 of the platinum wire would give different volumes of gas so 

 decomposed, the volume being greater as the wire is more 

 intensely ignited. 



* I need scarcely point out the distinction, in fact, between this experiment 

 and those in which liquid water has been decomposed by the electric spark. See 

 Supplemental Paper. 



