SIR HUMPHREY DAVY 187 



the alkali, and this substance soon penetrated through the body of 

 the tube. 



Soda, when acted upon in the same manner as potash, exhibited an 

 analogous result ; but the decomposition demanded greater intensity 

 of action in the batteries, or the alkali was required to be in much 

 thinner and smaller pieces. With the battery of 100 of 6 inches in 

 full activity I obtained good results from pieces of potash weighing 

 from 40 to 70 grains, and of a thickness which made the distance of 

 the electrified metallic surfaces nearly a quarter of an inch; but 

 with a similar power it was impossible to produce the effects of de- 

 composition on pieces of soda of more than 15 or 20 grains in weight, 

 and that only when the distance between the wires was about 1-8 or 

 i-io of an inch. 



The substance produced from potash remained fluid at the tem- 

 perature of the atmosphere at the time of its production ; that from 

 soda, which was fluid in the degree of heat of the alkali during its 

 formation, became solid on cooling, and appeared having the lustre 

 of silver. 



When the power of 250 was used, with a very high charge for the 

 decomposition of soda, the globules often burnt at the moment of 

 their formation, and sometimes violently exploded and separated into 

 smaller globules, which flew with great velocity through the air in 

 a state of vivid combustion, producing a beautiful effect of continued 

 jets of fire. 



THEORY OF THE DECOMPOSITION OF THE FIXED ALKALIES,* 

 THEIR COMPOSITION AND PRODUCTION 



As in all decompositions of compound substances which I had pre- 

 viously examined, at the same time that combustible bases were de- 

 veloped at the negative surface in the electrical circuit, oxygen was 

 produced, and evolved or carried into combination at the positive sur- 

 face, it was reasonable to conclude that this substance was generated 

 in a similar manner by the electrical action upon the alkalies ; and a 

 number of experiments made above mercury, with the apparatus for 

 excluding external air, proved that this was the case. 



When solid potash, or soda in its conducting state, was included 



