Paper, 'Physical properties of nickel steel' by J [John] Hopkinson Hopkinson writes: 'Mr Riley of the Steel Company of Scotland has kindly sent me samples of wire drawn from the material concerning the magnetic properties of which I recently made a communication to the Royal Society [see PP/15/4]. As already stated, this material contains 25 per cent, of nickel and about 74 per cent, of iron, and over a range of temperature from something below freezing to 580º C. it can exist in two states, magnetic and non-magnetic. The wire as sent to me was magnetisable as tested by means of a magnet in the ordinary way. On heating it to a dull redness it became non-magnetisable whether it was cooled slowly or exceedingly rapidly by plunging it into water.' Annotations in pencil and ink throughout. Subject: Metallurgy Received 16 January 1890. Read 23 January 1890. A version of this paper was published in volume 47 of the Proceedings of the Royal Society as 'Physical properties of nickel steel'. 1890