242 Decompofit'mt of Water by Ekctridty. 



Cutlibertfon's lafl improved air pump, of the greateft rarefying power. As the open end of 

 the tube was immerfcd in a cup of quickfilver, a little common air was let up into the con. 

 vex part of the curved end of tlie tube, with the view of preventing frafture from the ele£lri> 

 cal difcharges. 



The wire which pafTed through the fealed extremity was fet In contaft with a brafs infu- 

 lated ball ; and this infulated ball was placed at a little diftance from the prime condurior of 

 the electrical machine. The wire of the lower or open extremity, immerfed in quickfilver, 

 communicated by a wire or chain with the exterior coated furface of a Leyden jar, which 

 contained about a fquare foot of coating ; and the ball of the jar was in conta£l with the 

 prime coiidu£lor. 



The ele£lrical machine confifled of two plates of 31 inches in diameter, and fimilar to 

 that of Teyler. It poirelTed the power of caufing the jar to difcharge itfelf 25 times in 

 15 revolutions. When the brafs ball and that of the prime conduftor were in contact, no 

 air or gaz was difengaged from the water by the eleflrical difcharges ; but on gradually in- 

 creafing their diftance from one another, the pofition was found in which gaz was difen- 

 gaged, and which afcended immediately to the top of the tube. By continuing the dif- 

 charges, gaz continued to be difengaged, and afcend, till it reached nearly to the lower 

 extremity of the upper wire ; and then a difcharge occafioned the whole of the gaz to difap- 

 pear, a fmall portion excepted, and its place was confequently fupplied by water. 



The refiduary portion of gaz being let out after each experiment, and the difcharges being 

 continued in the fame water, this refiduary gaz was left in fmaller and fmaller quantity j 

 fo that after four experiments, probably made on the fame day, it did not amount to more 

 than 1.80th of the bulk of gaz which had been produced. If it had been poflible to pafs 

 ele£lric fparks through this very fmall quantity of gaz a fecond time, or oftener, it was 

 fuppofed it would have been diminifhed ftill more. But when the tube had been left for 

 a night only filled with water, the refiduary gaz was in greater quantity than after the lad 

 experiment the preceding day •. 



It was concluded that the gaz produced by the eleftrical difcharges was oxygen and 

 hydrogen gaz, from dfecompounded water : 



1. Becaufe no 'other gaz hitherto known inftantly difappears on paffing through it an, 

 eleflric fpaik. 



2. The gaz obtained muft have been the oxygen and hydrogen of decompounded water, 

 becaufe they were in exadlly thofe proportions in which by combination they reproduce 

 water j the trifling refidue being confidered to be merely a portion of air which had been 

 diflblved in the water. 



3. Liquids which are not compounded of hydrogen and oxygen, as fulphuric and nitric 

 acids, afforded gaz by the cleclric difcharges, but which did not difappear on pafiing 

 through it an ele£tric fpark ; but which did difappear on adding to it nitrous gai over, 

 water. Mr. Schurer alfo aflerts, on the autliority of Mr. Van Trooftwyk, that even liquid 



• In at lead fifty expcrimenu I have never feen the refidue of gai Itfs than i-4oih of the gaz produced, al- 

 though the water had been freed from air by the moft effcftual means. But Mr. Schurer ( Annalts de Chimic, 

 torn. v. p. 176.) teflifies that he faw Mr. Van Trooftwyk make the experiment; and tliat after if was re- 

 peated many times, on the fame parcel of water, ibtre •»«< m refidue lU all. \ have vt ry good gi-ounds for be- 

 lieving, that this is one ot the number of inaccuracies in the account publiOicd of this fubje£t. 



muriatic 



