107 
Table D. 
Comparative Effect of Sulphuric and Hydrochloric Acids on 
Unannealed Charcoal Iron Wire. 
j 
Description. j 
Diame- 
ter 
inch. 
1 
Ulti- 
mate 
Elonga- 
tion. 
Decrease 
in 
ditto. 
Break- 
ing 
Strain. 
1 
Break- 
ing 
Strain 
per sq. 
inch. 
1 
De- 
crease 
in 
ditto, j 
No.of 
tests 
ofwh. 
result 
is a 
mean 
Charcoal Iron before] 
immersion in acid. . . j 
•049" 
2-3% 
lbs. ! 
1 
147-3 i 
lbs. 
78,200 
lbs. 
3 
Ditto after 12 hours! 
in hydrochloric acid| 
and subsequent 5| 
hours in air at a 
temperature of 12°C. 
•047" 
1-17% 
1-13°/^ 
i 
1 
; 122-7 i 
71,930 
6,270 
3 
Last piece after being] 
on hot plate for 5| 
days at a tempera- 
ture of 40 — 140°C ... 
•047" 
3-5% 
_l-2% 
1 i 
j ! 
81-3 
i 47,954 
30,246 
3 
Charcoal Iron after 12! 
hours in sulphuric 
acid and subsequent 
5 hours in air at a 
temperature of 12°C. 
•045" 
1-3% 
1-0% 
i 
^ 98- 
i 
1 
' 61,800 
16,400 
3 
Last piece after being 
on a hot plate for 5 
days at a tempera- 
ture of 40 — 140°C . . . 
•045" 
4-0% 
-1-7% 
1 
i 104-6 
i 
! 
! 
j 65,995 
12,205 
1 
i 
3 
All the above 15 tests were made from one coil. 
Permanent decrease in B. strain after prolong’ed 
immersion in hydrochloric acid=30,2461bs. per sq. in. 
,, sulphuric „ =:12,205 „ „ „ 
increase in ultimate elongation after pro- 
longed immersion in hydrochloric acid=l-2 per cent. 
» « „ sulphuric „ =rl*7 „ 
