148 REPORT—1890. 
piece. A sample of iron-wire was taken, which was found to behave very 
like soft steelin the greater permanence of the effects it exhibited, and 
except that it could not be hardened or tempered might have been mistaken 
for steel; the wire was suspended vertically and heated by an electric 
current, a weight of 50 grams being hung from the free end. The wire 
was No. 20 B.W.G. (0°9 mm. diam.) and 29 centims. long. On heating it 
expanded from 290 mm. to 293°5 mm., or 1:2 per cent. of its length; then 
it retracted to 293-3 mm., a retraction of 0:07 per cent., s),, of its 
original length; then expanded again till white hot, when its length was 
Fig. 1.—Anomalous contraction of Iron Wire upon cooling from a bright red heat. 
Wire 0:9 mm. diam. 
290 mm. 500mm. . : : 5 - 5 j . Length of wire. 
rr 
Extension 60 grams. 90 grams, 590 grams. . Load on wire. 
in tenths Ae 
of mm, Expt. 1. Expt. 2. Expt. 3. 
Qo ~ *, 
EEE 
Ht TTT f 
AEA al {ie 
"ot aim 4 HH Sei 
Hew i: ete 
“HEA ESET 
HEHIGIBE HEE Elgeds eee 
greater sel iged Stieeeert cae 
Beene eee Eeeceiey 
“LVEUPS ERSIEIS PULSE 
fEIEHIATE CEE 
Tee sIER THE 
EEE HEE HEHEHE Hea 
FEE FIT HT REE EE 
PTT TTT ee i i 
60 ptt | fb ofade 4 Ht 
HEE EEE HAH 
nde EEEEEEEEEEEEEEE CHEE 
Pooh PEE | 
SeSESUOUNACEREERUIEE (| 
+) DEQ SESS Se see Bees 5). 
294mm. On breaking contact and allowing the wire to cool freely, it 
contracted till its length was 295 mm. or 1-034 per cent. of its length; 
then it expanded to 293'4 mm., an expansion of 0°14 per cent., 7}; of its 
length, after which it contracted till it was cold, when a permanent 
elongation of 0°3 mm. remained. These amounts were diminished on the 
second heating, but the permanent elongation, even under the small load 
of 50 grams, was the same each time, namely, 0°3 mm., or a little over 
