298 Analyses of Boohs. [April, 



Article XV. 



Analyses of Books. 



Philosophical Transactions of the Royal Society of London, for 



1823. Part II. 



(.Concluded from p. 229.) 



XXVI. On the Apparent Magnetism of Metallic Titanium. 

 By William Hyde Wollaston, MD. VPRS. 



This brief but interesting communication is as follows : — 



" In an account that I lately gave of the properties of metallic 

 titanium, which is printed in the first part of the volume of the 

 Philosophical Transactions for the present year,* there is an over- 

 sight, which I am desirous of rectifying as soon as may be. I 

 have there stated that the cubic crystals of titanium, when first 

 detached from the iron-slag where they are found, were all 

 attracted by a magnet, but that when they had been freed from 

 all particles of iron adherent to them, they appeared to be no 

 longer acted upon by it. 



" Having since that time been led by the observations of M. 

 Peschier, of Geneva, to examine this question more accurately, 

 I find that, although the crystals are not sufficiently attractile to 

 be wholly supported by the magnet, yet when a crystal is sup- 

 ported by a fine thread, the force of attraction is sufficient to 

 draw it about 20° from the perpendicular, and consequently that 

 the force of attraction is equal to about one-third the weight of 

 the metal. 



" When a piece of soft iron of about the same size was made 

 of a cubic form (weighing half a grain), the attractive force of 

 the iron to the same magnet was found, in successive trials, to 

 lift from eighty to ninety times its weight of a silver chain 

 adapted to this inquiry. 



" By a similar mode of trial, I found that cobalt carried from 

 fifty to sixty times its weight, and that a similar quantity of 

 nickel supported from twenty to thirty times its own weight by 

 the same magnet. 



" From the above comparison of the magnetic forces, it is 

 evident that the presence of about l-250th part of iron as an 

 alloy in the metallic titanium, would be sufficient to account for 

 this power, without regarding titanium itself as a magnetic 

 metal ; and its origin in the midst of iron, gives every reason to 

 suspect that it would be contaminated by some proportion of 

 that metal. 



" It is, however, extremely difficult really to detect the pre- 

 sence of so small a proportion of iron, on account of the high 

 qolour of the precipitates of titanium. For though it may be 



• jlnntls, N. S. v. 67, vi, 222. 



