1148 
MR. G. F. RQDWELL ON" THE EFFECTS OF HEAT OH CERTAIN 
at unequal rates till a temperature of 139° C. was attained. Again, the mass 
underwent neither contraction nor expansion during heating through 5° C., and then 
it commenced to expand somewhat rapidly. The most rapid contraction on heating 
took place between 130° and 133° C. Thus, in all, for the temperatures during which 
the mass contracted, the index moved through 15 revolutions of 180° to 0° of arc, and 
these were related to the temperatures in the following manner 
1 
2 
4 
6 
2 
revolution of index took place during heating from 124° to 128° C. 
* „ „ 128°,, 130° C. 
„ „ „ 130° „ 131° C. 
» „ * 131° „ 133° C. 
„ „ „ 133° „ 139° C. 
The details of these contractions are shown in Table B. 
The heating, especially at these temperatures, was excessively slow, and so mode¬ 
rated that a complete observation of the behaviour of the substance in the expansion 
apparatus lasted from three to four hours. Above 144° C. the alloy expanded with a 
coefficient about three times greater than that which it possessed betweed 0° and 
118° C. 
Coefficients of cubical expansion and contraction of the alloy for 1° C. 
Between 
0° 
and 118° C.= + -0000306 
35 
124° 
128° C.= -'0003240 
J5 
128° 
130° 0.= -'-0012990 
v 
130° 
>> 
131° 0.= --0017330 
5? 
131° 
35 
133° C.= --0039000 
J) 
133° 
5? 
139° 0.=-.‘0004329 
M 
144° 
?? 
350° 0.= + -0001150 
Plus has been placed before the coefficients of expansion on heating; minus before 
the coefficients of contraction. The expansion in passing from the solid to the liquid 
condition was determined as before. 
The curve is shown in Table A (p. 1145). 
The coefficient between 144° C. and the fusing point increased rapidly with the 
temperature. 
If we take the volume at 0° C. as unity, we have the following volumes corre¬ 
sponding to the temperatures given ;— 
