British Association for the Advancement of Science. 23 
The constant constituents were iron, carbon, silicon, and alu- 
minium; and manganese was a pretty frequent ingredient. The 
average propestions were 
3% atoms of iron and manganese 
1 do. of carbon, silicon, and aluminium. 
The atomic proportions of the carbon, silicon, and aluminium, 
were 4, 1, 1, so that cold blast cast iron may be considered as 
composed of 21 atoms iron and manganese, 
The following table exhibits the composition of hot blast cast 
iron, No. 1:— 
Clyde, | Carron. 
—_—_ 
|Carron. | Clyde. |_Clyde. 
. ..  |97.096/95.422/96.09 94.966 94.34 95.58 
0.332) 0.336) 0.41) 0.160 3.120 0.87 
2.460, 2.400) 2.48 1.560 1.416 
0.280) 1.820 1.49 1.322 0.520. 1.086 
0.385, 0.488) 0.26 1.374 0.599, 0.422 
para Peep 0.792 % 
These constituents are in the proportion of 
64 atoms iron and manganese, 
do. carbon, silicon, me aluminium, 
Carbon, &c._ 
In the cold blast * we have 34 Sd + 1 atom. 
In the hot blast 64 atoms + 1 atom. 
Thus, it appears, that hot blast iron contains only about half 
the foreign matter that exists in cold blast iron. 
Cast steel made from the best Dannemora i iron, had a specific 
gravity of 7.8125. Its constituents were 
Tron, - - - - - ~ ‘99.288 
Manganese, - - - - = 0.190 
Carbon, - - - - - - 0.388 
99.866 
or it a sontpined. _ $85.7 atoms iron, 
1 atom carbon. 
In “ape to questions, Dr. Thomson stated, that he had made 
no experiments on the comparative composition of bar iron from 
