Absolute Quantity of Electricity in Matter, 435 



particles of matter, and the identity as to quantity, of that be- 

 longing to them with that necessary for their separation, I will 

 describe an experiment of great simplicity but extreme beauty, 

 when viewed in relation to the evolution of an electric current 

 and its decomposing powers. 



863. A dilute sulphuric acid, made by adding about one 

 part by measure of oil of vitriol to thirty parts of water, will 

 act energetically upon a piece of plate zinc in its ordinary and 

 simple state; but, as Mr. Sturgeon has shown*, not at all, or 

 scarcely so, if the surface of the metal has in the first instance 

 been amalgamated ; yet the amalgamated zinc will act power- 

 fully with platina as an electromotor, hydrogen being evolved 

 on the surface of the latter metal, as the zinc is oxidized and 

 dissolved. The amalgamation is best effected by sprinkling 

 a few drops of mercury upon the surface of the zinc, the latter 

 being moistened with the dilute acid, and rubbing with the 

 fingers so as to extend the liquid metal over the whole of the 

 surface. Any mercury in excess forming liquid drops upon 

 the zinc, should be wiped offf. 



864. Two plates of zinc thus amalgamated were dried and 

 accurately weighed; one, which we will call A, weighed 163*1 

 grains; the other, to be called B, weighed 148*5 grains. They 

 were about five inches long, and 0'4 of an inch wide. An 

 earthenware pneumatic trough was filled with dilute sulphuric 

 acid, of the strength just described (863.), and a gas jar, also 

 filled with the acid, inverted in it j. A plate of platina of 

 nearly the same length, but about three times as wide as the 

 zinc plates, was put up into this jar. The zinc plate A was 

 also introduced into the jar, and brought in contact with the 

 platina, and at the same moment the plate B was put into the 

 acid of the trough, but out of contact with other metallic 

 matter. 



865. Strong action immediately occurred in the jar upon 

 the contact of the zinc and platina plates. Hydrogen gas 

 rose from the platina, and was collected in the jar, but no hy- 

 drogen or other gas rose from either zinc plate. In about ten 

 or twelve minutes, sufficient hydrogen having been collected, 

 the experiment was stopped ; during its progress a few small 



* Recent Experimental Researches, &c, 1830, p. 74, &c. 



■j- The experiment may be made with pure zinc, which, as chemists well 

 know, is but slightly acted upon by dilute sulphuric acid in comparison 

 with ordinary zinc, wbich during the action is subject to an infinity of vol- 

 taic actions. See De la Rive on this subject, Bibliotheque Universel/c, 

 1830, p. 391. 



X The acid was left during a night with a small piece of unamalgamated 

 zinc in it, for the purpose of evolving such air as might be inclined to se- 

 parate, and bringing the whole into a constant state. 



3K2 



