99' W. Sturgeon, Esq., on the 



even by the aid of powerful magnetic forces, and leave us in 

 uncertainty regarding their purity when examined by this 

 test alone. 



58. Lead and iron do not easily unite into a perfect alloy, 

 excepting when the ferruginous metal is in very small pro- 

 portions ; but when thus combined, the iron loses a great 

 part of its natural magnetic qualities. 



59. Silver and copper unite very sparingly with iron ; but 

 whether the magnetic powers of the latter are affected by 

 its union with those metals or not, is not yet known. 



60. In order to ascertain the exact quantity of pure metal- 

 lic iron that would render a neutral half-crown* apparently 

 magnetic, to the same extent as another half-crown was 

 absolutely magnetic, I attached to the former, by means of 

 softened gum, new iron filings, and after many trials ascer- 

 tained that the requisite quantity of filings amounted to about 

 a ten-thousandth part of the mass ; and, on changing the pure 

 iron for the peroxide of iron, a 480th part of the mass was 

 required to render it equally magnetic with the standard 

 half-crown. Now, as more than two-thirds of this oxide is 

 iron, it follows that, in this state, the iron loses a consider- 

 able portion of its magnetic powers ; and that the proportion 

 of iron required in this case to produce the standard degree 

 of magnetism to the mass, was little short of a 700th part. 



61. Now, if any iron existed in the standard magnetic 

 half-crown, uncombined with the other metals, it must have 

 been in a state of peroxide,t and that more than an 800th 

 part of the half-crown must have consisted of iron, if its 

 magnetism were due to the presence of that metal. 



62. Again, the magnetic action of this half-crown was con- 

 siderably more feeble than that of the alloy which has been 

 chemically examined ; and in which, if iron were present at 



* This piece of coin was not entirely devoid of magnetic action, but it ap- 

 proached nearer to a state of neutrality than any other I then had. Its action 

 was very feeble indeed. 



t It is possible that the iron, if any, might be in the state of a carburet ; 

 but, even in this condition, much of its magnetic powers would be neutralized. 



