1892.] On certain Ternary Alloys. 375 



two ternary alloys considerably different from one another into a 

 " real " alloy not separating at all, but remaining perfectly homo- 

 geneous at this slightly higher temperature. Leaving out of sight 

 the practical impossibility of maintaining a lead- bath at 600 800 C. 

 at an absolutely constant temperature (within, say, +10) for eight 

 or ten hours together, the lowering of the temperature taking place 

 on removing the clay test-tube from the lead-bath sometimes appears 

 to cause a measurable amount of separation of a different heavier alloy 

 from the lighter one formed in the bath, and vice versa, during the 

 short time that elapses before the compound mass becomes solid. So 

 that, in fine, duplicate experiments with "ideal" mixtures situated 

 near to the limiting point are apt to yield discordant results owing 

 to one or other of these causes, or to the two combined ; and in 

 consequence the direct determination of the exact position of the 

 limiting point is impracticable, although of course its situation can 

 be approximately deduced from the graphical representation of the 

 results on the triangular system. Still nearer approximations can be 

 obtained by the use of other methods kindly suggested by Sir Gr. G. 

 Stokes, and more fully described below. 



The present paper deals with the results of the further experiments 

 made, as above stated, with the mixtures partly described in the 

 previous four Parts* (lead-tin-zinc, bismuth-tin-zinc, lead-silver-zinc, 

 bismuth-silver-zinc, chloroform-acetic acid-water), for the purpose of 

 more completely determining the exact- positions of the critical curves 

 for certain definite temperatures, and the systems of tie-lines and their 

 limiting points pertaining to each curve respectively. In a subse- 

 quent paper the analogous curves will be described, derived from the 

 combinations of lead or bismuth with zinc as A, B, and cadmium or 

 antimony as C, and with various analogous ternary mixtures where 

 aluminium takes the place of zinc. 



Mixtures of Chloroform, Water, and Acetic Acid. 



The experiments described in Part IY were continued, using 

 mixtures containing more chloroform than water (from 2 to 3 parts 

 chloroform to 1 of water), and nearly, but not quite, enough acetic 

 acid to form a homogeneous fluid, the composition required being 

 arrived at by adding enough acetic acid to form a single fluid, and 

 then dropping in a little water or chloroform, or both, until separa- 

 tion ensued. With mixtures represented by points lying close to the 

 limiting point, it was found that comparatively slight variations in 

 temperature produced marked alterations in the composition of the 

 two fluids into which the mixture separated, more especially as 



* Part I, ' Eoy. Soc. Proc.,' yol. 45, p. 461 ; Part II, vol. 48, p. 25 ; Part III, 

 vol. 49, p. 156 ; Part IV, vol. 49, p. 174. 



