32 Mr. Grove on the Decompositioji of Water by Heat. 



and contracted to 0*4 of its original 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 phae- 

 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 cer- 

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

 last two experiments, an attempt was made to ascertain what 

 proportion of water could be decomposed by an ignited pla- 

 tinum wire in aqueous vapour, or, which amounts to a corol- 

 lary from this proposition, what degree of dilution would 

 enable mixed gas to exist without combustion in an atmo- 

 sphere of steam exposed to an ignited platinum wire. The 

 proportion in an experiment in which the globules were so 

 counted, was 1 to 2400 ; the probability is however that dif- 

 ferent temperatures of the platinum wire would give diffei*ent 

 volumes of gas so decomposed, the volume being greater as 

 the wire is more intensely ignited. 



Although there was no known effect of electricity which 

 could produce the phaenomenon exhibited by the last two 

 experiments, and it was in any event new, still, firmly con- 

 vinced that it was an effect of heat, I again determined to 

 attempt its production by heat alone, and without the use of 

 the battery. I procured a tube of silver 9 inches long and 

 0*4 inch diameter; at the extremity of this was a platinum cap 

 to which a smaller tube, also Fig. 9. 



of platinum, was soldered. 

 This platinum tube was 

 closed at the end and sol- 

 dered with gold solder. The 

 apparatus was filled with 

 prepared water ; the water 

 was boiled in the tube to ex- 

 pel the air from the narrow 

 tube and any which might 

 have adhered to the vessel ; 



• I need scarcely point out the distinction, in fact, between this experi- 

 ment and those in which liquid water has been decomposed by the electric 

 spark. See Supplemental Paper. 



