178 SttGAR OF GRAPES. 



Pissertation on With rrgard to the objections which may start against my 

 t.I.e nature and . . ^ i t • «' • , . i i . 



i^ffects of heat, f^pmion of the electric fluifl, two at least have occurred : the 



l^iht and com- first is, that if the galvanic influervce were nothing more than 

 ijugtion. . '^ ® 



the combined matters of heat and light, every case of com- 

 bustion would be an electrical experiment. To this I may- 

 answer, that from, substances in combustion the light and heat 

 go of}' in the sensible form ; but it is very different in the gal- 

 vanic light and heat, the essence of it consists in this, that it 

 is not in its sensible form ; as soon as it affects the eye, or the 

 thermometer, it is no more electric matter, but common light 

 and heat ; by how much light and heat is given out from an 

 electrified substance, by so much is that electric matter 

 diminished in quantity. Galvanism is produced by an action 

 very similar to combustion ; a substance is oxidated as is the 

 case with combustion, but the heat being insufficient, and the 

 substance present varying somewhat from those producing 

 real conjbustion, heat and light are given out in that peculiarly 

 subtile form which characterizes the electric fluid. A sup- 

 porter of combustion in both cases acts on a combustible 

 substance, the former of which in both cases gives out light, 

 and the latter heat, «}id these moving in different directions 

 through the apparatus, at the place of contact, appear in the 

 form of sparks.-^ Hence it may appear that galvanic troughs 

 may be much improved, for the action appears to be propor- 

 tionately great, accoi'ding to the surface of the o.xidable metal 

 which is presented to the oxidizer. 



J. ARNOLD. 

 i5% 4.tk, 1805. 



XI. 



On the Si'gar of Grapes, Bij Prqfesso?;, Proust,- 



SugJjrof IVJlY assistant, after several days occupfitior. in drying ^rape 



grapes. suf'ar which had been drained of its molasses, has siuccceded 



* Journal de Ph5"sique, Ixi. p. 399. 



