The end of the lower tube rested on a fireclay ladle nozzle, and was properly jointed with fireclay; through this nozzle the steam or air was supplied to the inside of the refractory tubes. In each experiment the ore and fuel were raised to the temperature "of from 1,800 to 2,200 deg. Fahr." by means of an external fire of anthracite. Great care was taken to prevent the contact of the solid carbonaceous fuel with the ore. In each experiment in which steam was used, the latter was supplied at a temperature equivalent to 35 lb. to the square inch.
The air for producing the carbon monoxide (CO) gas was used at the temperature of the atmosphere. As near as possible, the same conditions were obtained in each experiment, and the equivalent weight of air was sent through the carbon to generate the same weight of CO as that generated when steam was used for the production of water gas.
First Experiment, Steam (per se).--Both tubes, A and B, were filled with ore broken to the size of nuts. The tube, A, was heated to about 2,000 deg. Fahr., the upper one to about 1,500 deg.
NOTE.--In this experiment, part of the steam was dissociated in passing through the turned-up end of the steam supply pipe, which became very hot, and the steam would form with the iron the magnetic oxide (Fe3O4). The reduction would doubtless be due to this dissociation. The pieces of ore found on lowest end of the tube, A, were dark colored and semi-fused; part of one of these pieces was crushed fine, and tested; see column I. The remainder of these black pieces was mixed with the rest of the ore contained in tube, A, and ground and tested; see column II. The ore in upper tube was all broken up together and tested; see column III. When finely crushed, the color of No. I. was bluish black; No. II., a shade darker red; No. III., a little darker than the natural color of the ore. The analyses gave:
-----------------------------+---------+---------+---------
| I. | II. | III.
+---------+---------+---------
|per cent.|per cent.|per cent.
Ferric oxide (Fe_{2}O_{3}). | 68.55 | 76.47 | 84.81
Ferrous oxide (FeO). | 16.20 | 9.50 | 1.50
+---------+---------+---------
Total. | 84.75 | 85.97 | 86.31
+---------+---------+---------
Calculated: | | |
Ferric oxide (Fe_{2}O_{3}). | 32.55 | 55.36 | 81.47
Magnetic oxide (Fe_{3}O_{4}).| 52.20 | 30.61 | 4.84
Ferrous oxide (FeO). | | |
+---------+---------+---------
Total. | 84.75 | 85.97 | 86.31
+---------+---------+---------
Percentage of total
oxygen reduced. | 6.93 | 4.02 | 1.07
Metallic iron. | 60.59 | 60.92 | 60.54
-----------------------------+---------+---------+---------
Second Experiment, Water Gas.--The tube, A, was filled with small pieces of anthracite, and heated until all the volatile matter had been expelled. The tube, B, was then placed in tube, A, the joint being made with fireclay, and to prevent the steam from carrying small particles of solid carbon into ore in the upper tube, the anthracite was divided from the ore by means of a piece of fine wire gauze. The steam at a pressure of about 35 lb. to the square inch was passed through the anthracite. The tube, A, was heated to white heat, the tube, B, at its lower end to bright red, the top to cherry red.
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Experiment. | 1st. | 2d. | 3d. |
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Number. | I. | II. | III.| I. | II. | III.| IV. | I. | II. | III.|
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Total Iron. |60.59|60.92|60.54|65.24|61.71|61.93|57.23|59.73|57.93|55.54|
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Iron occurring as
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
FeO. |12.60| 7.39| 1.17|46.98|18.59| 4.03| 0.84|29.45| 2.69| 1.12
Fe_{2}O_{3} |47.99|53.33|59.37|18.26|43.12|57.90|56.39|30.28|55.24|54.42
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Per cent. of Oxides. |
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
FeO. |16.20| 9.50| 1.50|60.40|23.90| 5.18| 1.08|37.86| 3.46| 1.44
Fe_{2}O_{3}. |68.55|76.47|84.81|26.08|61.60|82.71|80.55|43.26|78.91|77.74
Total. |84.75|85.97|86.31|86.48|85.50|87.89|81.63|81.12|82.37|79.18
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Oxygen in Ore.
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Before experiment.|25.97|26.10|26.05|27.96|26.45|26.54|24.52|25.60|24.81|23.80
After experiment. |24.16|25.05|25.77|21.24|23.79|25.96|24.40|21.39|24.44|23.64
Difference. | 1.81| 1.05| 0.28| 6.72| 2.66| 0.58| 0.12| 4.21| 0.37| 0.16
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Per cent. of oxygen reduced.
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
oxygen reduced. | 6.93| 4.02| 1.07|24.03|10.02| 2.18| 0.49|16.44| 1.49| 0.42
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
Degree of Oxidation of the Ore after the Experiment.
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
FeO. | ... | ... | ... |84.66| ... | ... | ... |18.40| ... | ... |
Fe_{3}O_{4}. |52.20|30.61| 4.84|37.82|77.01|28.12| 3.88|62.72|11.14| 4.64|
Fe_{2}O_{3}. |32.55|55.36|81.47| ... | 8.49|59.77|77.75| ... |71.23|74.54|
Total. |84.75|85.97|85.97|85.97|85.97|85.97|85.97|85.97|85.97|85.97|
------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
------------------+-----------------+-----------------------+-----------------+
The ore having | | | |
been exposed to | Steam. | Water gas. | Carbon monoxide.|
------------------+-----------------+-----------------------+-----------------+
Four Samples were Tested.--I. The bottom layer, 1¼ in. thick; the color of ore quite black, with small particles of reduced spongy metallic iron. II. Layer above I., 4¼ in. thick; the color was also black, but showed a little purple tint. III. Layer above II., 5 in. thick; purple red color. IV. Layer above III., ore a red color. The analyses gave:
-----------------------------+---------+---------+---------+---------
| I. | II. | III. | IV.
+---------+---------+---------+---------
|per cent.|per cent.|per cent.|per cent.
Ferric oxide (Fe_{2}O_{3}). | 26.08 | 61.60 | 82.71 | 80.55
Ferrous oxide (FeO). | 60.40 | 23.90 | 5.18 | 1.08
+---------+---------+---------+---------
Total. | 86.48 | 85.50 | 87.89 | 81.63
+---------+---------+---------+---------
Calculated: | | | |
Ferric oxide (Fe_{2}O_{3}). | ... | 8.49 | 59.77 | 77.75
Magnetic oxide (Fe_{3}O_{4}).| 37.82 | 77.01 | 28.12 | 3.88
Ferrous oxide (FeO). | 48.66 | | |
+---------+---------+---------+---------
Total. | 86.48 | 85.41 | 87.89 | 81.63
+---------+---------+---------+---------
Percentage of total
oxygen reduced. | 24.03 | 10.02 | 2.26 | 0.49
Metallic iron. | 65.24 | 61.71 | 61.93 | 57.23
-----------------------------+---------+---------+---------+---------