lOo 
immediate effect of immersion in acid was to 
Decrease the tensile strain of unannealed steel 4,0451bs. per 
square inch of section. 
And increase the ultimate elongation of „ ,, D14 per cent. 
The change is thus similar to that which takes place in 
annealed steel as shown in table C. It is, however, 
interesting to observe that 12 hours at a temperature of 
40° — 100° C. not only restores but actually increases its 
original breaking strain and elongation, while a still more 
prolonged submersion of 7 days to the same temperature 
still further increases them. These last experiments also 
show that some considerable time is required to overcome 
the change produced by the acid. 
In conclusion I may say that the numerical results 
arrived at, though based on experiments conducted with 
considerable care, must not be taken as more than approxi- 
mations to the truth, for experimental errors and variations 
arising from the imperfect homogeneity of structure of all 
iron falsify the results and are only lost by multiplying 
experiments almost indefinitely. 
Table A. 
Effect of Hydkochlobic Acid on Annealed Ikon Wire. 
j 
Diametr^ 
Ultim’te 
Breaking j 
Breaking 
Increase! 
m ^ 
.2'5-El 
1 Description. 
1 
inches. 
Elonga- 
tion. 
Increase in 
ditto. 
strain. 
strain per 
sq. inch of 
section. 
in 
ditto. 
o =5 
a 
1 Annealed Iron 
1 i 
lbs. 
lbs. 
lbs. 
j Wire immersed ! 
! in acid 1 hour... ^ 
•150" 
22-4°/„ 
918-4 
51,890 
9 
Same piece as"^ 
above after be- | 
ing 48 hrs. on a | 
hot plate of a j 
•150" 
22-3°/„ 
-0-1% 
922-8 
52,140 
250 
9 
temperature of 
40°-200° C J 
Annealed Iron " 
Wire immersed 
in acid 1 hour... , 
164" 
18-6°/„ 
1105-3 
52,389 
3 
Same piece as"] 
1 
above being 12 
lu’s. on a hot 
plate of a tem- 
1 
•164" 
20-3“/o 
1112-6 
52,733 
344 
3 
perature of 40° 
-200° C 
1 
1 
Average decrease in B. strain after immersion in Acid zr 297 Ihs. per sq. in. 
„ „ ultimate elongation „ „ — 0-8 °/q 
