108 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q7. 



whole of the common or atmospherical air is detached from the water, by merely 

 the impulse of each discharge. Yet I think it probable that, after the discharges 

 have been passed through the same water for a certain time, the whole of the air 

 contained in water will be expelled, and no gaz be produced, but that compounded 

 by means of the electric fire from water ; in which case, supposing the gaz so pro- 

 duced to be at last merely hydrogen and oxygen gaz, it will totally disappear on 

 passing through it an electric spark. But I have never been able to determine this 

 point ; because the tubes were always broken after obtaining a few products, or 

 long before it could reasonably be supposed the whole of the air of the water was 

 expelled from it. 



h. To the gaz obtained in the experiment e was added, over water, an equal bulk 

 of almost pure nitrous gaz. Fumes of nitrous acid appeared, and the gaz examined 

 was reduced almost 4 of its bulk. A small bubble more of nitrous gaz being let up, 

 no farther diminution took place. To this residue was added half its bulk of oxygen 

 gaz, obtained from oxymuriate of pot-ash. This mixture of gazes having stood several 

 days over well burnt lime and boiled quicksilver, an electric spark was passed through 

 the mixture, over quicksilver ; by which its bulk was instantly diminished -i. But 

 no moisture could be perceived on the sides of the tube, or on the quicksilver. The 

 failure of the appearance of moisture was imputed to a bit of lime accidentally left in 

 the tube, which was burst by the explosion and dispersed through the tube ; or else 

 the quantity of water produced was so small, comparatively with the residuary gaz, 

 that the water was dissolved by it in the moment of its composition. For supposing 

 water to have been compounded, it could not amount to the -^-^ part of a grain ; 

 and the residuary gaz was at least 2000 times this bulk. That a quantity of water 

 can be compounded, under the same circumstances as in this experiment, and be 

 apparently dissolved in air, so as to escape observation, even with a lens, was proved 

 by passing an electric spark through a mixture of hydrogen and oxygen gaz, well 

 dried by standing over lime. 



2. With complete or uninterrupted discharges. — The gaz obtained by the first 

 described kind of apparatus, for the uninterrupted discharges, always left a residue 

 of at least -^ of its bulk on passing through it the electric spark ; even when water 

 was used, which had been freed from air by boiling, or the air-pump. This result 

 will not appear surprizing, when it is considered how liable the water in this appa- 

 ratus is to mix and absorb air during the experiment. However, this method would 

 have been extremely valuable if the next other method had not been discovered ; 

 for gaz may be obtained by it with fewer accidents, and much more rapidly, than 

 with the interrupted discharges. The apparatus is also much more easily fitted up, 

 and is more simple. But I think it unnecessary to particularly relate any experi- 

 ments, as they afforded the same results as those already described, and as those 

 following experiments which were made with the apparatus before described, and 

 shown by fig. 15, 16, 17. 



Exper. 1. At O h 40 ra p.m. began to produce discharges with a double plate 24 



