i 



90 Oil Electricity in Plants^ and on Vegeto-terrestrial Currents. 



effect, if the insertion of the two needles is simultaneous and 

 they are not polar. But on withdrawing one needle and inserting 

 it again in the same place, there is at once a current causing a de- 

 viation of 40 degrees, and the direction shows that the needle 

 restored gives negative electricity. On removing and replacing 

 the other one, the effect is reverse, and this one now gives 

 negative electricity. This succeeds well if the wood is in sap 

 and has been separated but a short time from the trunk. 



In this case, the effect is similar to certain facts mentioned in 

 my earlier work on electro-chemistry. When two plates of pla- 

 tinum in connection with a multiplier, are put into a solution, 

 recently prepared, of protonitrate of iron, on withdrawing one of 



the needles and inserting it again some minutes after, there is a 



current whose direction shows that the plate replaced gives 

 positive electricity. This effect proceeds simply from the fact 

 that the solution of the protonitrate, and the part of this solution 

 which is on the platinum plate while exposed to the air, are not 

 alike in composition : the portion adhering to the plate has passed, 

 during the exposure to the air, to a higher state of oxydation; and 

 comports therefore like an acid with reference to the solution in 

 the vessel. The steps in the process are easily explained. When 

 nitric acid reacts on iron, deutoxyd of nitrogen and nitrous gas 

 are disengaged, and protonitrate and some deutonitrate of iron 

 are formed ; when the solution is exposed to the air, the deutoxyd 

 becomes nitrous acid and the protonitrate deutonitrate. These 

 transformations which take place slowly in the mass of the solu- 

 tion, are effected very promptly in the layer that adheres to the sur- 

 face of tlie platinum. On becoming rapidly saturated with oxygen, 

 the solution reacts upon the solution in the vessel and produces 

 electric effects like those from the action of an acid on an alkali, 

 or from two substances reacting as such. The recently prepared 

 protonitrate is required for these vessels, because of the change 

 to deutonitrate which takes place in the protonitrate after a 

 while on exposure. 



If in the experiment with the sap the effects are the reverse of 

 those with the protonitrate, it is owing to this; — that the sap of 

 the parenchyma loses oxygen on exposure instead of gaining it. 



These facts demonstrate that a very slight difference of chemi- 



cal composition in two liquids of a plant, separated by a perme- 

 able membrane, is sufScient to afford electric effects in the man- 

 ner explained, and these effects vary with changes experienced 

 through the surrounding air or medium. 



These effects should therefore be taken into consideration in 

 experimenting upon the causes which produce electric currents 

 in organized bodies, when one of the liquids is momentarily in 

 contact with the air. 



i 



1 

 ^ 



