Mr. R. Phillips on Minium, t25 



There appear to me only two ways of accounting for this 

 curious fact. We must either suppose that the electricity 

 having been first arranged in a particular direction is after- 

 wards more easily arranged in trials in the same direction than 

 in the contrary : — or, that in reversing the poles we do not 

 destroy the whole of the magnetism formerly induced, but 

 actually arrange a new series of atoms in an opposite direction ; 

 so that when the magnet has lost all its power, it has done 

 so, simply because we have two equal magnets formed on the 

 same piece of steel, having their poles in opposite directions. 



The magnetism which has been newly induced is more 

 easily destroyed than that which has been induced days or 

 years ago ; since by suddenly destroying the newly induced 

 magnetism, the old, being held by a more^ powerful coercitive 

 force, will regain its force when its temporary antagonist 

 power has been removed. 



As this curious fact appears to me new, and sufficiently in- 

 teresting to be made known, I request you to give it a place in 

 the Philosophical Magazine. 



I am, dear Sir, yours truly, 



University of London, July 18, 1833. WlLLlAM RlTCHlE. 



XXVII. On Minium. By Richard Phillips, F.R S. $c* 



\ FTER the last sitting of this Society, the President men- 

 •£*• tioned to me a paper on Minium, by M. Dumas, con- 

 tained in the 49th volume of the Annates de Chimie et de Phy- 

 sique, dated April 1832.f In this memoir the author shows 

 that minium is a very different compound from what it is usu- 

 ally supposed to be, and consequently that it is not a sesqui- 

 oxide, or as it is sometimes termed, deutoxide of lead. Dr. 

 Dalton also recalled my attention to his having previously an- 

 nounced the same fact in his New System of Chemical Philo- 

 sophy, published in 1827 (vol. ii. p. 39). 



Opinions so different from those commonly entertained, in- 

 duced me to make some experiments on the subject, and an 

 account of them may not be altogether unacceptable to this 

 Society, tending, as they do, to confirm the views of its learned 

 President, and proving their originality. Before I state the 

 opinions of Dr. Dalton, or of M. Dumas, or my own experi- 

 ments, it will be proper to give the generally admitted com- 

 position of the yellow or protoxide, and of the brown or per- 



* Read before the Literary and Philosophical Society of Manchester, 

 early in the present year. 



+ An abstract of M. Dumas' results will be found in Lond. & Edinb. 

 Phil. Mag. vol. ii. p. 402. 



