290 Mr. E. Haeffely's Esoperiments on some of 



tioi), that the cliamagnetic force is not polar, is reduced to de- 

 monstration. "When we remember that against all this no single 

 experimental fact or theoretic argument* which can in any de- 

 gree be considered as conclusive, has ever been brought forward, 

 nor do I believe can be bi-ought forward, the conclusion seems 

 irresistible^ that we have in the agency by which bodies ai'e re- 

 pelled from the poles of a magnet, a force of the same dual 

 character as that by which bodies are attracted ; that, in short, 

 " diamagnetic bodies possess a polarity the same in kind but the 

 opposite in direction to that possessed by magnetic ones." 



XXXV. Experiments on some of the Compounds of Tin with 

 Arsenic. By Ed, Haeffely of Mulhousef, 



[Y pouring an excess of nitric acid into a solution of stan- 

 nate of soda and arseniate of soda, in which the arseniate 

 predominates, and bringing this mixture to a state of ebullition, 

 a white gelatinous precipitate is produced, composed of arsenic 

 acid, peroxide of tin, and water ; when washed and dried at the 

 ordinary tempci-ature, it forms transparent fragments. 



To analyse the above compound, the delicate process described 

 by M. LevolJ was employed, viz. placing within a glass tube 

 heated to redness 100 parts in an anhydrous state, and passing 

 through it a current of hydrogen, when the tin is left in the 

 metallic form, and the arsenic sublimed in the tube. Three 

 analyses gave, — 



Tin ... 45 46-3 45-21 



Arsenic . . 27*2 26-3 



* I ought perhaps to except an argument of Professor W. Thomson's, 

 which professes to prove that an absolnte creation of force, and the setting 

 uj) of a perpetual motion, woukl follow, if diamagnetic polarity were con- 

 ceded. While expressing mj' admiration of the ingenuity of Mr. Thomson's 

 reasoning, it appears to me to labour under the disadvantage of proving 

 too much, his conclusion being equally fatal to polarity of all kinds. The 

 argument, I believe, was first publicly urged against myself at the Belfast 

 Meeting of the British Associ.ation ; but at the Livei-pool Meeting last year 

 Professor Thomson himself admitted " that he had not perfect confidence 

 in the truth of the conclusion, as one of the assumptions on which the 

 reasoning was founded admitted of doubt." — See Athenreum, 1854, p. 1204. 

 Indeed, from many of his published papers, it might be inferred that Mr. 

 Thomson actually assumed what I, in the present memoir, have attempted 

 to prove. 



I refi-ain from alluding to the negative results obtained by Mr. Faraday 

 in repeating M. Weber's experiments ; for though admirably suited to the 

 exhibition of certain effects of ordinary induction, Mr. Faraday himself has 

 shown how imsuitable the apparatus employed would be for the investiga- 

 tion of the question of diamagnetic polarity. See Experimental Researches 

 (2653, 2654), vol. iii. p. 143.— J. T., May 9, 1855. 



t Communicated by the Author. 



+ Annates de Ctiimie et de Pfiysique, 3 ser. vol. xvi. 



