77 
The gain in weight by immersion in H 2 S0 4 is greater 
than by immersion in HC1. 
In experiments 1 — 4 the gain per cent is : 
For immersion in HC1 = *010659 
Ditto in IPSO 4 = -025126 
or almost as 2 to 5, more accurately as 1 ; 2*357. 
In experiments 5 — 7 the gain per cent for 
HC1 *02918 
H 2 S0 4 - *03714 
as 1 : 1*284. 
Experiments 9 — 13 show how rapidly steeping in water 
removes what the iron has taken up by immersion in acid ; 
the loss in weight on subsequent heating being only about 
1-1 0th of that in previous experiments where the iron had 
not been immersed in water any length of time. 
III . — Effect on the Breaking Strain and 
Elongation. 
The effect of immersion in acid on the breaking strain 
and elongation of iron wire naturally suggested itself as an • 
interesting subject for inquiry. Accordingly a number of 
pieces of iron wire were immersed in hydrochloric acid for 
one or more hours, and then carefully tested for elongation 
and breaking strain. The pieces were then heated on a hot 
plate for some hours and again tested with the following 
general results. 
1. That immersion in acid diminishes the breaking strain 
of iron wire from \ to 3 per cent, and steel wire about 4*76 
per cent. 
2. That immersion in acid appears in some cases to 
diminish, in others slightly to augment, the elongation of 
iron wire; and to augment the elongation of steel wire about 
30 per cent. 
