105 
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 „ ,, 1’14 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 Hydrochloric Acid on Annealed Iron Wire. 
Description. 
Diametr 
inches. 
Ultim’te 
Elonga- 
tion. 
Increase in 
ditto. 
Breaking 
strain. 
Breaking 
strain per 
sq. inch of 
section. 
Increase 
in 
ditto. 
No. of tests 
of wh. the 
meau is giren 
Annealed Iron 
lbs. 
lbs. 
lbs. 
Wire immersed ] 
in acidl hour... ^ 
•150" 
22-4“/„ 
918-4 
51,890 
9 
Same piece as" 
above after be- 
ing 48 brs. on a 
hot plate of a 
» 
•150" 
22-3% 
-O'lVo 
922-8 
52,140 
250 
9 
temperature of 
40°-200° C 
Annealed Iron ' 
Wire immersed 
in acid 1 hour... , 
1 
164" 
1105-3 
52,389 
3 
Same piece as" 
above being 12 
hrs. on a hot 
plate of a tem- 
perature of 40° 
-200° C 
> 
•164" 
20-3°/„ 
-t-l-77o 
1112-6 
52,733 
344 
3 
Average decrease in B. strain after immersion in Acid ~ 297 lbs. jicr sq. in. 
„ „ ultimate elongation „ „ “0’8°/o 
