822 
The Manufacture of Iron in 
save the small quantity which enters into combination with the 
iron, escapes as carbonic oxide or carbonic acid. In addition to this 
we have the carbonic acid of the flux and tlie nitrogen of the blast, 
which more than double the volume of the gases, so that the 
ammoniacal gas rai’ely exceeds of the total, and is generally 
considerably less even than this. The lowest consumption of raw 
bituminous coal, per ton of iron made, I have ever heard of is a trifle 
above 31 cwt., but it often exceeds the 40 cwt. named. According 
to analysis, the blast-furnace gases using the lesser weight of fuel 
had the following composition : — 
— 
Bj volume 
By weight 
Carbonic acid 
8G1 
13-08= 3-56 carbon 
Carbonic oxide 
28-OG 
27-12 = 11-62 
Marsh-gas .... 
4-.17 
2-41= 0-96 „ 
Hydrogen .... 
5-45 
0-38 
Ammonia .... 
0-13 
0-C8 16-14 
Nitrogen .... 
53-38 
51-59 
Water 
5-34 
Total .... 
100-00 
100-00 
Thus one volume of ammonia was accompanied by 769 volumes, 
or 1,250 parts by weight, of other gases. It is estimated that each 
ton of coal burnt in the furnace is associated with the generation, of 
about 90,000 cubic feet of gas, and that it yields 4-38 lb. of 
ammoniacal gas. In such circumstances, it is quite obvious that 
the condensation of so small a quantity of this gaseous alkali 
becomes a very difticult problem as compared with operations 
where the same quantity has to be extracted from something like 
one-tenth of this enormous volume of gas. 
Nevertheless, at the present time, almost every furnace in 
Scotland now in work is provided with the essential appliances for 
the recovery of ammonia, and for its conversion into sulphate. 
It is not necessary, however, to trouble agricultural readers with 
a technical description of the somewhat complicated plant by means 
of which this remarkable result is obtained. 
Suffice it to say that the ammonia gas is dissolved in water and 
the yield of raw products has averaged 120 gallons of ammoniacal 
liquor (of two degrees of Twaddell’s hydrometer), and 25 gallons of 
tar, per ton of coal used in the furnaces. 
The ammoniacal gas is driven oil from the liquor by means of 
steam in continuous ammonia-stills, lime being introduced into the 
bottom compartment of the stills to remove any fixed ammonia, 
should this be present in sufficient quantity to pay for recovery. 
The steam is obtained by means of blast-furnace gas which has 
passed through the condensing apparatus. The ammoniacal gas 
from the stills is passed into saturators containing sulphuric 
acid, where the sulj^hate of ammonia is deposited, and is then 
