PRINCIPLES UNDERLYING METAMORPHIC PROCESSES 605 
AH and V, with pressure and temperature; but fortunately the 
variation of V,/AH is small and for the present purpose unim- 
portant. We may therefore consider V,/AH to be independent 
of pressure and temperature; by integration and transformation 
we then obtain the equation 
¢=95.1 QD log = (VII) 
which gives the unequal melting-pressure (¢) at the temperature 
T, in terms of the heat of melting (Q, in calories per gram), the den- 
sity D, and the ordinary melting-point at 1 atm. pressure (7,, in 
absolute measure). At the present time the data requisite for the 
TABLE III 
LOWERING OF MELTING-PorInT oF METALS EFFECTED BY ONE ATM. UNEQUAL PRES- 
SURE; TOGETHER WITH THE COMPUTED MELTING-PRESSURES (IN ATM.) 
AT ORDINARY TEMPERATURES 
MELTING-POINT 
METAL SSS aoe Deere AT; oy 
t ip Q 
loin beara ae 62 335 D5 7, 0.87 0.59 64 
ING Sane ah Sete) 2% 07 370 > te 0.98 29 266 
a Dpreternis, Sick cha oia-s 327 600 esi: Wy) 24 1,760 
Sin sista Bt aoe AD 505 14.1 a2) Ea 2,200 
Bret ne ots Sere oes 270 543 10). 5 9.80 esr 3,000 
(Col Seapets eee 321 594 9 8.64 5302: 3,300 
JeNl stick Seen oa 658 931 42.0 2.60 20 5,100 
[Ej Ate eae Tee 419 692 28.0 Feat 084 6,900 
LN ie eect een eS ee 960 TORS 23.0 10.50 se 14,000 
(Chile eee nen SA eas 1,083 1,350 43.0 8.93 .086 | 24,000 
120s GRE ae Oe 1,550 1,823 30.3 fit g/l II 31,000 
et reerant ate eth et dn 2, 1,755 2,028 2G) 2 Dit 5 0.084 | 46,000 
calculation of @ are available only for a few metals; these calcula- 
tions have been made and the results are presented in Table III; 
the sixth column (headed A7,) gives the melting-point depression" 
produced by 1 atm. excess pressure acting on the solid, the last 
(headed ¢.,) contains the computed pressure (in atmospheres) 
which, acting on the solid alone, would be required to cause the 
substance to melt at 27°. 
i 
CSOD , which is easily derived from 
As calculated by the formula A7,;= 
equation V. 
