EXPERIMENTS ON MAGNETISM. 185 



into one the fouth polar end of a magnetic wire, into a fecond the north pole 

 the nortli polar end of a fimilar wire, and into the third theend „the^^ and the 

 of an equal wire not magnetic : the fouth pole will firil begin end of a fimp'e 

 to depofit oxide, the unraagnetic iron a little after, and the ^^'^^^j"^jp|jj^'^' 

 rortii pole laft. This experiment requires contiderable care, firft depofits ox- 

 The furface of the water muft be covered with very frefli oil '''V"V'',^^ 



J north pole laft. 



of almonds, to exclude all accefs of air. Care muft be taken This expeii- 

 too, that one of the bottles is not more expofed to the fun '^^Jl^JJ;'!"^''^' 

 than the others, becaufe light accelerates oxidation. Ritter cautions, 

 convinced himfeif of this by direfl experiments : expofing two Air muft be ex- 



. r . • f .u 1 • 1 eluded J 



iron wires in water to the fun, but covering one or the phials ^^^ j- j^. ^^^^ 

 ■with black paper, when that in the phial left uncovered was ierates oxida- 

 oxided much the more quickly. 



If infufion of litmus be fubftituted inftead of the water in If infufion of 

 the three phials in the preceding experiment, the relative oxi- ^ ^^ rdati^ve oxi- 

 dations will be the fiime ; but they will be attended with a dations will be 

 change of colour, tliewing, that an acid is produced P'""?'^''- an\ '■T-^ ' ^"' 

 tional to each oxidation; fo that the fouth pole not only un- portion to each 

 dergoes the greyteft oxidation, but llkewife reddens the infu- '^''' ^^P''°^""'^» 

 fion of litmus moft *. The a61ion that takes place in this ex- change of co- 

 periment is very feeble, and frequently requires a weekor'"";- 

 more to produce a diftin<5t efF £t ; and indeed to accelerate it very ilow 

 fo much as this, it is necetfary to add, previoufly to the infu- a"d to accelerate 

 fion, as much acetic acid gis will incline it to red, without ^f^g^^?^ ^P?^''°'* 

 completely changing its colour. The infufion reddened in fliould be added 

 this experiment refumes its blue colour on expofure to the air; ^, infufion, 



' ' The infufion 



but we muft not hence conclude, that the acid produced by thus reddened 

 the adion of the magnet is very volatile, for infufion of litmus becomes blue 

 reddened by phofphoric acid, or any other, exhibits the famcfy^g to tj^g aj^. 

 phenomenon. hut it is the 



The following experiment exhibits fome things peculiar, ^g^gj ^j^|^ 3^^' 

 and therefore I (liall give it more at large. It has not been other acid, 

 repeated, but the harmony of its refults is in favour of its ac- ^P"""^"'^* 

 curacy. Sixteen magnetic wires, of equal fize and power, 

 were placed in fix vefTels, all equally full of a mixiure of one 

 part nitric acid and thirty-fix parts water, in the following 



* Ritter has remarked, that the oxidation of zinc, and fevjeral Ritter and Jager 

 other metals, in pure water, produces an acid. Mr. Jager, a ce- '^.^''^ found, that 

 , , , , V - r <- 1 , 1 ,• .w- • . fhe oxidation of 



lebrated phyiician ot Stuttgard, made the lanle difcovery, without fgyg,.ai j^^t^lg ;^ 



knowing any thing of Ritter's. pure water pro- 



duces an acid. 



manner ; 



\ 



