374 SEVENTH REPORT—1837. 
Coed-Talon Iron, No. 2. 
| Cold Blast. Hot Blast. Cold Beet by 100s, 
Tensile strength .....sesceseseeee | 18855 (2)| 16676 (2)| 1000: 884 
...| 81770 (4)| 82739 (4)| 1000 : 1012 
Compressive do . 
ve) 6955 (4) 6968 (3) | 1000 : 1002 
Specific gravity 
Carron Iron No. 3. 
Tensile strength .......csseseerees 14200 (2)| 17755 (2) | 1000 : 1250 
Compressive ditto..s.c:ceseeseesees 115442 (4)| 133440 (3)| 1000 : 1156 
Specific gravity ....s.csessveeseesees 7135 (1) 7056 (1)| 1000: 989 
Of the three columns of numbers in the table above, the first 
is the strength or other quality in the cold blast iron; the 
second is that in the hot blast; and the third is the ratio of 
these quantities. 
The results in this table contain nearly the whole information 
relative to the question of hot and cold blast iron that the pre- 
ceding research affords ; and before adverting to them it may 
be mentioned that it is usual for the makers of cast-iron to di- 
vide it, when taken from the furnace, into three classes, called 
Nos. 1, 2, 3, differing from each other in the appearance and 
qualities of the material. No. 1 contains the softest and richest 
irons, those which have the largest crystals; No. 3, the 
hardest and densest irons, those with the least crystals; and 
No. 2, irons intermediate between the former two descriptions. 
Beginning with the No.1 iron, of which we have a specimen from 
the Buffery Iron Works, a few miles from Birmingham, we 
find the cold blast iron somewhat surpassing the hot blast in 
all the following particulars—direct tensile strength, compress- 
ive strength, transverse strength, power to resist impact, mo- 
dulus of elasticity or stiffness, specific gravity ; whilst the only 
numerical advantage possessed by the hot blast iron is that it 
bends a little more than the cold blast before it breaks. 
In the irons of the quality No. 2 the case seems in some de- 
gree different ; in these the advantages of the rival kinds seem 
to be more nearly balanced. They are still, however, rather 
in favour of the cold blast. 
Referring to the No. 2 iron, from the Carron Works in 
Scotland, we find the tensile, compressive, and transverse © 
strengths, together with the modulus of elasticity and specific 
gravity, all higher in the cold blast iron than the hot blast, whilst 
the ultimate deflection and power of sustaining impact are 
