* 
=—_ 
TRANSACTIONS OF SECTION B. 427 
5. The Influence of the Presence of Gas on the Inflammability of Coal 
Dust in Air. By Professor W. M. Tuornton, D.Sc. 
6. Decomposition Products of Indigo in the Val. By H. Enruarpr. 
7. Report on the Study of Hydro-aromatic Substances, 
See Reports, p. 135. 
8. Report on the Transformation of Aromatic Nitroamines. 
See Reports, p. 136. 
9. Report on Dynamic Isomerism.—See Reports, p. 141. 
10. Report on the Study of Plant Enzymes.—See Reports, p. 143. 
FRIDAY, SEPTEMBER 12. 
MerauuurcicaLn Drvision. 
The following Papers were read :— 
1. The Amorphous Phase in Metals. By Dr. W. Rosennaty, F.R.S. 
2. The Volatility of Metals. By Professor T. Turner, M.&c.. 
Considerable attention has been devoted during the past few years to the 
volatility of metals, especially in vacuo or under reduced pressure, and there 
are considerable possibilities of practical applications in this direction in future. 
The boiling-points of metals under various conditions as to pressure and 
atmosphere have been determined by Greenwood and by Kraft, while Berry, 
Groves, Nair, and the author have investigated the behaviour of metals and of 
alloys in vacuo. Distillation in vacuo is specially suitable for volatile and easily 
oxidisable metals such as sodium, potassium, cadmium, and zinc; lead and 
bismuth can also be dealt with by similar means. When alloys are heated to 
suitable temperatures in vacuo, in certain cases quantitative separation can be 
readily effected as with the zinc-copper, zinc-iron, and tin-lead series. In other 
cases, as with the copper-nickel, copper-tin, and copper-iron series, neither metal 
appreciably volatilises. In some instances definite chemical compounds are 
obtained. The rate of volatilisation is very markedly affected by the pressure, 
and to some extent also by the nature of the atmosphere employed. A certain 
definite or critical temperature is required in order to obtain appreciable vola- 
tilisation, and this temperature is raised by gaseous pressure. When this 
critical temperature has been reached the rate is independent of the initial 
pressure or the nature of the gas, but varies directly as the increase of tempera- 
ture. In other words, if the initial rate be R and the rate at any higher tem- 
perature be R’, then R/=R + at. There is an abrupt change in the direction of 
the temperature curve for equal rates of volatilisation when the pressure reaches 
50 mm. of mercury; and at above 80 mm. the curve becomes a straight line. On 
exhausting it is found that the removal of 1 mm. at from say 2 to 1 mm. 
pressure produces approximately seventy times the effect of the removal of 
1 mm. when starting from any pressure above 50 mm. 
