NATURAL PHILOSOPHY. 1G7 



minal of the galvcanometer ; a powerful deflection of the needle 

 indicates the presence of an electric current and shows its direc- 

 tion to be from the alkali to the acid, the platinum serving 

 merely as a conductor. It occurred to me, when })erforming 

 this experiment, that an electro-motive combination miii^ht just as 

 well be made of two vegetable substances, with platinum for con- 

 ductor, provided only they were of a nature to act cliemically 

 upon one another, — an alkaloid and an organic acid, for in- 

 stance. It also seemed to me not unlikely that, wherever two 

 flavors are habitually conjoined in our cookery and eating,* the 

 reason why they mutually improve each other is because a cer- 

 tain amount of electric action is set up between the sul)stances 

 employed to produce them. The rationale of the right blending 

 of flavors might be found partly, no doubt, in chemistry, but 

 partly, also, in galvanism. 



*' Pursuing this idea, I tried pairs of eatables which generally 

 go together, such as pepper and salt, coftee and sugar, almonds 

 and raisins, and the like, and found that a voltaic current more 

 or less strong was excited in ever}^ instance which I tested. Bit- 

 ters and sweets, pungents and salts, or bitters and acids, gener- 

 ally appear to furnish true voltaic couples, doubtless in conse- 

 quence of the mutual action of some alkaloid salt and an acid or 

 its equivalent. As others may like to repeat or extend the experi- 

 ments, 1 will describe shortly my mode of procedure : Cut two 

 pieces of platinum foil about Ave inches by two and a half inches, 

 and a number of pieces of filter-paper a trifle larger. Well- 

 washed linen is sometimes more convenient than filter-paper. 

 Have a small wooden board near the mercury-cups of the gal- 

 vanometer, and lot a short copper or platinum wire, dipping into 

 one of the cups, rest on the board. The substances to be tried 

 must be brought to a state of solution, the stronger the better, by 

 infusion, decoction, or otherwise. Suppose coffee and^sugar are 

 to be operated upon ; solutions of both having beeii prepared, dip 

 into each a slip of filter-paper ; place one slip on one of the pieces of 

 platinum foil, and the other on the second piece. Next lay the 

 first slip and its foil on the board, with the metal touching ihe cop- 

 per wire before mentioned. Lay the second slip with its platinum 

 upwards, so that the coffee and sugar come into even contact 

 with slight pressure, and immediately connect this upper slip, 

 through a bit of copper wire, insulated from the touch, with the 

 other terminal of the galvanometer. Deflection occurs instanta- 

 neously, and may be increased to a considerable vibration by 

 breaking and making circuit at the right swing of the needle. 

 After a few distinct vibrations, it is well to turn over the whole 

 pile of slips just as they are, and connect opposite ends with the 

 galvanometer, so as to reverse the current. This is desirable for 

 the sake of confirming your previous observation, and of correct- 

 ing any slio'ht disturbino^ cause arising: from the wire and mer- 

 cury connectors, temperature of the hand, etc. It will be found 

 that coftee and sugar have the same electrical relation to each 

 other as zinc and platinum. Coflee, in fiict, is the positive, sugar 



