PROCEEDINGS OP THE POLYTECHNIC ASSOCIATION. 551 



cylinder is really a large oven, and evolves on a hollow shaft. 

 It is placed in a covered brick arch, and is heated by the waste 

 heat arising through flues from the puddling furnace. New 

 Jersej'- magnetic ore is that which- is operated on. It is first 

 ground with about 25 per cent, of Cumberland coal, and in this 

 condition it is fed in at regular intervals to the cylinder through 

 an opening in the hollow shaft. During every revolution of the 

 cylinder, 25 pounds of ground ore and coal are dumped eight 

 times into the hopper placed over the shaft at one end, and the ore 

 is then carried slowly to the back end of the cylinder by a screw. 

 A signal bell, operated by the engine, warns the attendant when 

 to dump his bucketful of ore into the hopper. It takes from five 

 to eight hours for the ore to pass through the cylinder to the 

 back end. During this period it is turned over frequently, and 

 exposed in thin layers to the heated surfaces of the cylinder. 

 The object of this roasting operation is the deoxidation of the 

 ore out of contact with the atmosphere. Although the ore is 

 thus treated for several hours, as much roasted ore, at a low red 

 heat, is discharged into the puddling furnace at every revolution 

 of the cylinder as makes a common bloom of wrought iron weigh- 

 ing from 110 to 130 pounds. During every 22^ minutes, 200 

 pounds of mixed roasted ore pass from the revolving cylinder above 

 to the puddling furnace below, and in the same space of time a 

 ball of puddled wrought iron is taken out from the latter, placed 

 under the trip hammer and converted into a bloom. The impu- 

 rities in the ore melt in the puddling furnace, are separated from 

 the iron and flow down into the spue hole in the form of slag. 



Prof. Seely. — I would ask if there is any evidence that the 

 iron is reduced in the cylinder ? 



Mr. Rogers. — We have the apparatus in operation at Newark, 

 and should be pleased to show it to the gentleman. It has been 

 examined by the most scientific men we have, and .it is making 

 good iron. We' claim three advantages for it — that the apparatus 

 can be erected at very low cost, that we make wrought iron at a 

 saving of $10 per ton, and that the iron is of a good quality. 



Prof. Seely. — Have you ever tried the experiment of dispensing 

 with the cylinder— putting your ore and coal directly into the 

 furnace without passing them first through the cylinder ? It is 

 contrary to all the facts with which I ani acquainted, to suppose 

 that the iron can be reduced from its ore in that cylinder. Iron 

 is decomposed by hydrogen at a low red heat, but not by carbon. 



