a i hs el 
ON STRENGTH AND PROPERTIES OF CAST IRON. 337 
On the relative Strength and other mechanical Properties of 
Cast Iron obtained hy Hot and Cold Blast. By Eaton 
Hopexinson, Esq. 
[With a Plate.) 
From the great abundance of the ores which produce iron; 
from the fortunate circumstance of these ores being frequently 
found in the neighbourhood of coal and limestone, by which 
they are reduced to the metallic state; from the great strength 
of the metal, and the facility with which it can be moulded 
into any form required—its uses in the arts have become very 
extensive. Every discovery, therefore, tending to facilitate 
its production, or to improve its quality, must always be re- 
garded with great interest, whilst distrust and suspicion are 
likely to be felt respecting any process by which that quality 
may be supposed to be impaired. 
The recent and very general introduction of a heated blast 
into the smelting furnaces has consequently, as might be ex- 
pected, given rise to much discussion, and at the same time 
to great difference of opinion. Iron masters in one part of the 
country had come to a conclusion that the new process greatly 
deteriorated the quality of the iron produced, and they rejected 
it accordingly. Gentlemen from other neighbourhoods, on the 
contrary, maintained that no deterioration of the metal resulted 
from the process, which was admitted by all to diminish the 
expense of its production. i 
These very different conclusions, drawn by persons largely 
connected with the manufacture of cast iron, caused the honour 
__ of an application from the British Association for the Advance- 
ment of Science, at its meeting held at Dublin, to my friend 
Mr. Fairbairn and myself, requesting us to make a series of 
experiments tending toward the determination of this matter. 
We intended to commence the inquiry immediately, but there 
_ was found to be great difficulty in obtaining irons suitable for 
the purpose; a matter which will be adverted to in Mr. Fair- 
3 bairn’s report, where a description of the irons used will be 
_ given. 
In the prosecution of this research it was conceived desi- 
rable to subject the metals operated upon to more than one 
_ species of strain, in order to elicit their peculiar properties ; 
_ and accordingly they were generally broken in the following 
_ three modes :— 
_ Ist. By tension, or tearing the metals asunder in the direc- 
tion of their length. 
VOL. vi. 1837. a eal 
