195 
Other two bars were cast out of the same ladle and mix- 
ture, but the metal was allowed to cool a little, and stiffen. 
They broke respectively with 22 and 23 cwt. The fractures 
also presented a grain filled with pores or air bulbs, the size 
of a very small pin's head. 
12. February 23rd, 1841. Two bars were cast from four 
parts strong No. 3 pig, Bierley, and one part strong No. 3 
pig, Elsecar, which broke with 29 cwt, each ; the grain of the 
fracture gray, strong, and close. 
The two following experiments exhibit the results of a 
greater number of mixtures. 
13. In August, 1840, two bars were cast from equal parts 
of strong No. 3 pig, Bierley and Elsecar, and one-tenth part 
of Firmstones Staffordshire cylinder metal^ all "cold blast" 
iron; one broke with 31 cwt.^ and the other with 29 cwt. 
Their fractures were close grained, aud of a clear gray 
colour. The weaker bar seemed defective in soundness in 
one of the angles of the square of its section. 
14. February 22nd, 1841. Two bars were cast from a mix- 
ture of seven different metals, mixed in equal parts, namely, 
Bierley^ No. 3, strong and soft ; Elsecar, No. 3, strong and 
soft; Firmstone's Staffordshire cylinder metal; the Sum- 
merlee ;" and the " Level" The bars broke with a weight 
of 20 cwt, 2 qrs. each ; the fractures presenting a grain of a 
dull white colour, with a fibre neither hard nor soft. 
From these experiments it will be seen that the Bierley pig 
iron is the strongest ; the Elsecar is the next in strength ; 
and the Low Moor is the next, when they are respectively 
used alone ; that the pig irons called Summerlee" and 
" Level," fall respectively very much in the scale of strength; 
that by a judicious mixture of pig irons of different makers, 
in their use for castings, a large increase of strength is 
obtainable — an increase equal to 50 per cent, ; and that all 
these metals are considerably deteriorated in strength and 
