5*0 Intelligence and Miscellaneous Articles, 



dually increased, arrived at a maximum, and then decreased, ceasing 

 apparently with the process of fermentation. 



On attempting to investigate the cause of these curious phaeno- 

 mena, I was led to conclude that they were connected with a cata- 

 lytic decomposition undergone by the yeast. The reasons which led 

 me to adopt this explanation were, first, that these phsenomena 

 would not admit of being explained by supposing them to result 

 from a mere ordinary chemical decomposition; secondly, I had 

 noticed that the change in the direction of the current took place 

 on the first appearance of a considerable quantity of yeast on the sur- 

 face ; and, thirdly, supposing the galvanic currents to be caused by 

 a catalytic decomposition, their direction was the same as results in 

 the analogous appearances produced by the contact of spongy pla- 

 tinum, and some metallic oxides, with the peroxide of hydrogen. 



In order to ascertain, if possible, the correctness of this opinion, 

 I placed some tow covered with the solid part of yeast well washed, 

 on the surface of a piece of platinum, the tow being necessary in 

 order to make the yeast remain on the platinum. This was placed 

 in a jar of wort the temperature of which was about QQ° Fahrenheit. 

 I then introduced another piece of platinum into the fluid, and upon 

 connecting these through the galvanometer there was a deflection 

 of 10°, indicating that the positive current entered the galvanometer 

 by the wire which was not in contact with the yeast. T have re- 

 peated this experiment many times, and always with the same re- 

 sult. 



From all that has been observed, I conclude that when yeast comes 

 into contact with saccharine matter in circumstances favourable to 

 fermentation, the yeast assumes a negative electrical state, causing 

 the surrounding fluid to become positive. 



Whilst conducting these experiments I also endeavoured to as- 

 certain the effect of a galvanic current on the process of fermenta- 

 tion, when passing through a fermenting fluid. 



The current used was that resulting from a single pair of plates 

 so arranged that the fluid to be experimented on formed part of the 

 liquid conductor between them without the metals being in imme- 

 diate contact with it. I found the effect to be that the process of 

 fermentation was constantly accelerated by the passage of a gal- 

 vanic current through the fermenting fluid, the sp. gr. always di- 

 minishing more quickly than in a portion of the same fluid, through 

 which no current was passed. This takes place equally if the cur- 

 rent pass from the surface to the lower part of the fluid, or in the 

 reverse direction. 



Electrical currents produced during the process of vegetation. — 

 I have lately ascertained that the decomposition going on at the 

 surface of leaves gives rise to electrical currents. The manner in 

 which I have been able to demonstrate this, is by placing a leaf 

 in water, the stalk remaining out of the fluid. A platinum wire 

 is placed in the stalk of the leaf, another wire being placed in the 

 water on the surface of the leaf. On connecting these wires with 

 the galvanometer, a current passed through it which entered from 

 the wire in connection with the stem. This would tend to show 



