940 IRON 



which is drawn off from time to timo through the openings in tho front plate. Fresh 

 ore and coal are continually added, until at the end of 2 or 3 hours a sufficiently largo 

 loup is formed. This is then lifted before the tuyere to get a good welding heat, and 

 shingled to a bloom under the hammer, the reheating of which is usually effected in 

 the same fire. 



In the larger sized furnaces a loup of 300 Ibs. is produced every 3 hours, making 

 the produce per day of 24 hours, 2,400 Ibs. of blooms ; in some cases it is said 1,500 

 Ibs., or even more, are produced in 12 hours. 



The essential difference between the Catalan and the American forge consists in the 

 method of charging. In tho former tho greater part of the charge of ore, in compara- 

 tively large lumps, is placed at tho commencement of tho operation on the sloping 

 wall of the hearth opposite tho tuyere, only the small ore, or grcillade, being added 

 subsequently. In the American or German method, on the contrary, the whole of tho 

 ore is reduced to a fine state of division, and is added by small proportions : a plan 

 which dispenses with tho charging of the furnace after each operation, and permits of 

 a continuous system of working. 



In order further to economise the waste heat, the plan is usually adopted in the 

 Franche-Comt6 fire, of passing the flame and gases from two hearths into a chamber, 

 which serves for the reheating of the blooms when it is required to draw them out 

 into bars ; a set of small blast-pipes, placed just above the forge, serves to heat a 

 portion of air, which is led into the chamber to burn any carbonic oxide gas that may 

 have escaped. The gases from tho reheating chamber are afterwards employed to 

 heat the principal blast of the forgo in the usual manner. 



At Ausable, in the State of New York, the ores employed are dressed so as to yiold 

 about 60 per cent, of iron 2 tons being required to make 1 ton of blooms ; while at 

 the New Russia forges, where a nearly pure magnetite is smelted, 3 tons of 

 dressed ore are stated to yield 2 tons of blooms. The loss at this rate would not be 

 more than 5 per cent, on the theoretical contents of the ore : a result which could 

 scarcely be obtained by any other method. 



At Moisie in Quebec, where titaniferous black sand is treated, the results 

 obtained are not so favourable, owing to the more refractory character of the ore. 

 The tuyere is laid nearly horizontal, as it was found that the strong inclination 

 used with coarser ores could not be advantageously used with the fine sands. A less 

 dense blast is also used, the average working pressure being about 1 Ib. to the square 

 inch. Each hearth yields eight loups, or about 15 cwts. in the day of 24 hours ; tho 

 consumption of charcoal being at the rate of 466 bushels to the ton of blooms. This 

 charcoal is chiefly produced from small and light wood, such as spruce, fir, and birch, 

 the weight being only 15 Ibs. to the bushel, about 62 cwts. being consumed to make 

 a ton of iron. 



This very unfavourable result is due to the imperfectly cleaned state in which the ore 

 is smelted ; the quartz, but more especially the titanic acid, using up a largo portion 

 of the protoxide of iron, in order to form a slag. The amount of titanic acid in the 

 slags is in some cases as high as 34 per cent, and the iron from 40 to 52 per cent. 

 By the use of magnetic machines for separating the ore before treating it in the furnace, 

 it would be possible to remove the non-magnetic and more highly titaniferous part, 

 which is practically worthless, leaving a comparatively pure magnetite, which could 

 be more advantageously smelted. 



The quality of the iron produced in the bloomary fire at Moisie is said to be very 

 superior, as the result of experiments made upon it in England shows that it possesses 

 a tensile strength equal, or superior, to that of the best Yorkshire iron, and works 

 easily both cold and hot. This excellence is to be attributed to tho almost perfect 

 freedom of the magnetic sand from sulphur and phosphorus. A sample taken from 

 a bloom when examined gave only '0094 per cent, of sulphur and '00184 per cent, of 

 phosphorus, and no trace of titanium could be found. 



The Fourneaux apiece of tho French, or Stuck-Ofen of tho Germans, resoml ' 

 514, COPPEE. The tuyere (not shown there), having a dip towards the bottom of the 

 hearth where the smelted matter collects. When the operation is finished, that is at 

 least once in every 24 hours, one of tho sides of tho hearth must be demolished, to 

 take out the pasty mass of iron, more or less pure. This furnace holds a middle 

 place in the treatment of iron, between tho Catalan forge and tho cast-iron Floss-Ofen, 

 or high blast-furnaces. Tho Stuck-Ofen are from 10 to 15 feet high, and about 3 feet 

 in diameter at the hearth. Most usually there is only one aperture for tho tuyero and 

 for working ; with a small one for tho escape of the slag ; on which account, the 

 bellows are removed to mnko way for tho lifting out of tho lump of metal, which is 

 done through an opening left on a level with tho sole, temporarily closed with bricks 

 and potter's clay, while the furnace- is in action. 



