1C8 



ANNUAL OF SCIENTIFIC DISCOVERY. 



the negative. I subjoin a table of the results of numerous ex- 

 periments, conducted in the manner above described: — 



ELECTRO-POSITIVE. ELECTRO-NEGATITB. 



Coffee, Sugar (loaf). 



Tea (black), " 



Cocoa, ** 



Nutmeg, " 



Cloves, " 



Cinnamou, " 



Maco, " 



Vanilla, . . . . t " 



Almonds, " 



Rhubarb (tincture), ** 



Starch, " 



Starch caramel, ** 



Gum caramel, " 



Cane sugar caramel, " 



Milk sugar, ** 



Gum, " 



Almonds, ' Raisins. 



Horseradish, Beetroot. 



Onion, " 



Horseradish, Table salt. 



Mustard, " 



Pepper (white), " 



Mustard, Tartaric Acid. 



Ginger, " " 



Cayenne pepper, ** " 



Pepper (white), *' ** 



Tea (black), " " 



Tobacco, " " 



Quinine (Howard's), ** " 



Gentian root, " ** 



Lemon juice, " " 



Horehound, *' " 



Lavender water, ** " 



Quassia, " ** 



Peppermint, " " 



Raw Potato, Lemon Juice. 



Rind of Lemon, " ** 



Peruvian Bark, " " 



Camphor (Tincture), " ** 



Laudanum, " " 



Arnica (tincture), Dilute Sulphuric Acid. 



Peruvian bark, , " " " 



Quinine (Howard's), " " " 



Iodine (tincture), Turpentine. 



Caustic Potash, " 



Starch, " 



Starch, Iodine (tincture). 



Caustic potoah, Neat's-foot oil. 



•♦It is somewhat difficult to eliminate from these experiments 

 all error arising from difference of temperature, if the galvanom- 

 eter is tolerably sensitive. Care must be taken to bring the pair 

 of solutions operated upon to the same temperature before testing 

 them ; otherwise a thermo-electric current from the hotter to the 



