EFFECT OF GALVANISM IN METALLIC ARBORIZATIOJJS^ ] Q;^ 



iiig. the bulk pf tliese bodies. To prove this, I made a but it h in the 



saturated solution of pure nitrate of silver, crystallized and r^'^'^a'of sil- 



p , 1 • 1- -.1 1 111- 1 • ver by means 



perfectly neutral, in aistilled water ; and with this ftolntion of copper in a 



Ifilled a vpry tWn tube, 108 mill. [4'25 inchefe] long, and 7 ^hin slender 

 miJL [2'75 lines*] in diameter. After satisfjint^ myself, 

 that the solution occasioned no change in blue paper, I let 

 fvkU to the bottom of the tube a small cylinder of well 

 cleaned copper, 14 mill. [5.5 luies] lon«;, and 7 mill. 

 [^^'75 lines] in diameter. Immediately the cylinder was 

 covered with a forest of Diana's trees, and on touching- the 

 correi>ponding part of the tube the heat was very sensible, 

 HMV'ing substituted a zinc instead of a copper cylinder in ^ 



another experiment, the effect was much more considerable ; 

 and. what appeared to me very singular w^s, that, in pro- 

 portion a,s, the bulk of the silver arborization Increased, I 

 ^vas obliged to move m\' fingers towards its extremities, to 

 be able to feel the heat. These experiments appear to me 

 to prove, that the quantity of caloric evolved in the preci- 

 pitation of meta/s by one another is equal to the difference 

 that^exists betw^een , the caloric that was containe'd in the 

 oxide of the metal revived, and that which is absorbed by 

 the oxide ©f the precipitant entering into splp.tiqp. 



;j^^<?^)^.- J^5^Mfy>rem|^insf<^r. m^to.re^ dJffi^Ml'Two objecti. 



ties» that may be objected to the preceding theory, which onstothethe- 

 embraces almost all the chemical effects of galvanic electri- ^^^' 

 city. I proceed to the first* ^.,^,;^ 



fl. It has been observed, that, \vhen the two poles arexhelst 

 immersed in separate glasses filled with water, no gas is 

 evolved, because the communication necessary for the dis- 

 charge of the pile is interrupted. To remove this obstacle, 

 we have only to immerse two fingers of the same hand ia 

 the two glasses, and immediately tl'-e gasses will appear. 

 This observation has been the stumbling block of all theories, ans-vrered, 

 t^i|;,V',ajsi,highly puzzling to explaiii.ist, what l^eeame qf the 

 bidrogen in the glassjn which the zinc pole evolved pure 

 o^igfen ; and Sdly, what on the other l.and became of the 

 qxigen.^ii the glass in which the copper pole equally evolved 

 pure hidrogen. A little sagacity, and a clear idea of the 

 establishment of the electrogalvanic polarity between the 

 ej^a)entary particles of w4ter, ^yill sglye this first difficulty. 



Jit) 



