XXXIII. — Electro-Magnetic Experiments and Observations. 

 By Thomas Stewart Traill, M. D. F. R. S. Edin. & 

 William ScoresbYj^ww., Esq. F. R. S. Lond. & Edin. 



(Read May 6. 1822.J 



JL he interesting discoveries of Oersted, and the subsequent 

 researches of Ampere, Arago, Davy, and Von Buch, which 

 promise to throw a clearer light on the mysterious nature of 

 Galvanism and Magnetism, induced us to undertake, and pur- 

 sue conjunctly, a series of Electro-magnetic experiments. In 

 prosecuting our inquiries in this new branch of scientific in- 

 vestigation, we have observed various interesting facts, some 

 of which appeared to us new, while others did not seem to have 

 been detailed so fully as their importance merited. 



Some of our earliest experiments on this subject were per- 

 formed in November 1821, with a cup of platina and slip 

 of rolled zinc, in the manner proposed by M. M. Von Buch *. 

 In order to ascertain the effect produced on the needle, by 

 both sides of the lower portion of the zinc, the whole appara- 

 tus was placed on a piece of plate-glass. With this small ap- 

 paratus the electro-magnetic effect was slight, and its intensity 

 irregular, when the proportion of the acid amounted only to 

 T ^th or even ^th of the liquid employed j but the needle was 



3n2 very 



• Annals ofPkibsophy, vol. ii. p. 282. 



