a7« Trench National 'InJIilute. 



give in tlie fame indant a lefs mafs of fluid, but pofTeflinjT a 

 great vclocitv, while the large plates will give a greater mafs 

 with a lefs velocity. Shocks which depend on the velocity of 

 the fluid will not be increafed with the fize of the plates; while 

 metallic combuftions which depend on its mafs and its con- 

 tinued prefence, ought with this fize to be doublv augmented. 

 This is a (imple explanation of the experiments of C. Hachetle, 

 Fourcroy, Vauquelin, and Thenard. 



C. Biot has confidered o-alvanifm alfo in regard to its che- 

 ■mical nature; and finding that what lakes place in water 

 brought into communication with the pile has been fuffi- 

 ciently examined, he wasdefirous of feeing what takes place in 

 the pile itfelf, and what itsa-ftion is on thefurrounding bodies. 

 As it is well knmvn that the zmc of the pile foon becomes 

 oxidated when it afts, it was neceflary to difcover whence 

 the oxygen arofe. For this purpofe C. Biot, in company 

 with C. F. Cavier, n>ade experiments, which proved that the 

 atmofpheric air is dccompofed, and gives up its oxygen to the 

 pile ; that this oxygen increafes the galvanic eiTefts, but that 

 it is not abfolntcly neceflary to them ; that thefc efiefts take 

 place even in luicuo, provided the pile is well nioiflened with 

 water; which proves that the water is dccompofed. 



Guyton found that the abforption of the oxvgen of the air 

 by the pde is fo complete, that it mav be employed as an 

 eudiometric mean to meafure the quantity of oxygen con- 

 tained in any given kind of air. 



Biot next emploved this oxidation of the pile as a means 

 of continuing his theory refpccling the progrefs of the fluid. 

 In the cafe when the fluid poflblfes a greater velocity the 

 oxidation ought to be accelerated ; fmall plates therefore be- 

 come fconer oxidated than larueones; a pile ihe two ends 

 of which communicate bv wires is alfo oxidated much 

 iooner, as might be expefted, than that where there is no 

 fuch communication. 



The fame author has difcovered that the galvanic fluid is 

 tranfmittcd^with difficulty through water, but that it eafily 

 glide's over its furface ; an effect produced alfo, according to 

 Prieftley's experiments, by weak elciitncily polielling great 

 velocity. 



C. Ganlhenet, who Is not a member of the Inftitute, has 

 communicated fome interelting experiments on the fame 

 lubjett, in which he Ihows, in particular, that it is poflible 

 to make efl'eclivc galvanic piles without any metallic fub- 

 ftance whatever. Thefe experiments ferve to confirm thofe 

 before made by PfatTand Humboldt when they tried galvanifm, 

 only on animals. 



While 



