TRANSACTIONS OF SECTION B, 451 
furnace already described by one of us.’ CO was admitted and reacted with the 
substance until the pressure had fallen to that of equilibrium. Some CO was 
then pumped out and the equilibrium attained from the other side. 
The upper limit of temperature in some cases was determined by the 
volatility of the metal, the lower limit of temperature is 800°-900° when the 
reaction 
2CO = CO, + C 
begins to take place to some extent. 
Summary- of experimental results :— 
Temperature Pressure 
Vanadium . 5 : : : . 1340° 1-5 mm, 
Tantalum . = c : : ; 3 La10e <0'l mm. 
ULOTTILAI ie Nee TSE os. ate cl (oa! Lao 6°2 mm. 
: - “ 1339° 9:2 mm. 
Tin Pre ce OEE ool so) ete epee OU >760 mm. 
fimo presence OLIO; se tes LOG” 670 mm. 
The values of the equilibrium pressures have also been calculated on the basis 
of the Nernst heat theorem, and the heats of reaction calculated from the 
equilibrium pressures when the heats of reaction were not previously known. 
6. The Dissociation Pressures of some Nitrides. 
By R. E. Suave and G. I. Hiason. 
The dissociation pressures of the nitrides of vanadium, tantalum, and boron 
have been investigated. 
The substance was heated in an unglazed porcelain boat in vacuo, in the 
furnace previously described by one of us.* Nitrogen was admitted and was 
absorbed by the substance to form nitride until the dissociation pressure was 
attained. Some nitrogen was then pumped off and the equilibrium attained from 
the other side. 
Summary of experimental results :— 
‘Temperature Pressure 
Wanadiumi.5, cei). ia\s> tex 203° Not greater than 0-2 mm. 
ye is 1271° Not greater than 1°5 mm. 
Tantalum. . . : ~ ee LLTOS 0-4 mm. 
IB OEOM em, sl. set tee ele ey bat Leeae Not greater than 9-4 mm. 
The results were discussed from the point of view of the Nernst heat theorem. 
7. The Solution of Gases in Metals. By Dr. A. Hour. 
8. A Study of the Degradation or Enhancement of Quality of Com- 
mercial Copper by the Presence of Impurities. By FrEpmrRick 
Jounson, M.Sc. 
In this paper the author surveyed the facts and theories which have been 
brought to light of late years by modern scientific investigation of the influence 
of traces of impurities upon the chemical, physical, and mechanical properties 
of copper. Much of the mystery formerly attaching to defects during manu- 
facture and failures in service has been cleared up, to the benefit alike of the 
manufacturer and the user. Ancient and modern prejudice against the 
presence of impurities such as oxygen and arsenic has been shown to have no 
foundation in fact when certain uses of the copper are considered. 
1 Proceedings of the Royal Society, 1912, vol. 87, A, p. 519. 
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