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XVI. Iron and Steel at Welding Temperatures. 
By T. Wricutson, M.P., Memb. Inst. CE. 
Communicated by Professor Roperts-Austen, C.B., F.R.S. 
Received February 2,—Read February 21, 1895. 
[Puate 17.] 
Ty 1879-80 I drew attention to a method of measuring the changes of volume 
taking place in cast iron while passing through the varying temperatures lying 
between its cold and its molten state. 
If a ball of cast iron at atmospheric temperature be immersed in a vessel of 
molten iron of the same quality, it first sinks. In a few seconds it comes to the 
surface, owing to the heat penetrating and expanding the ball, which, causing 
increased displacement of the fluid metal, produces the increased buoyancy observed. 
The increase of buoyancy does not stop here, as the ball continues to rise above 
the surface of the fluid metal to a considerable height, until it arrives at the melting 
point, when it rapidly melts down and joins the molten iron in the vessel. 
An instrument was designed by me* to measure this change in the volume of iron. 
The principle of the instrument is based on the law of flotation of bodies in liquids, 
by which an increase of buoyancy in a submerged body is equivalent to an increase 
in weight of the displaced fluid. 
The ball of cast iron to be experimented upon is hung by a chain and rods from a 
frame, and lowered over a pulley into a ladle of molten iron. The instrument is 
suspended between the chain and lower rods, and contains a spiral spring similar to 
that used in a Saurer’s balance; this spring is arranged so that the ball and rods 
hang with their full weight upon the spring. 
If the ball be kept well below the surface of the fluid metal it will, in expanding, 
and displacing the fluid, relieve the tension on the spring to an extent equivalent to 
the weight of the displaced metal. 
The spring is placed in a brass frame, on which is also mounted a cylinder, which 
revolves uniformly by clockwork. A pencil attached to the moving end of the 
spring presses against a sheet of paper wound round the cylinder. This vertical 
* ‘Journ. Iron and Steel Inst.,’ vol. 2, 1879, p. 418, 
MDCCCXCV.—A, 4g 3,10,95 
