472 



METALS. 



the turn-table), they may be removed in cakes 

 of the size of the boxes, and weighing 200 Ibs. 

 each. Four of these cakes or blooms are put 

 into a reverberatory puddling or heating fur- 

 nace, and raised to a bright-yellow heat. They 

 will not melt at this heat, but become softened 

 so as to be easily broken up with a bar. The 

 four blooms are formed, in the furnace, by the 

 rabble of the workman, as in ordinary pud- 

 dling operations, into eight balls. The balls 

 are brought out, one after another, squeezed in 

 the ordinary squeezers to expel the cinder 

 and superfluous ore, and then rolled into 

 wrought-iron bars, which are now ready for 

 market, or for further reduction into smaller 

 finished forms. 



The chemistry of the operation is as follows : 

 The crude cast iron contains say 5 per cent. 

 of carbon and 2 per cent, of silicon, and more 

 or less sulphur, phosphorus, and other im- 

 purities. The oxygen of the ore or oxide of 

 iron (magnetic oxide is preferred) combines 

 with the carbon and impurities, eliminating 

 them as in the puddling process, and the iron 

 of the ore increases the product. The chemical 

 combination of the ore and the liquid crude 

 iron appears to take place partly at the time 

 of their contact when falling and lying upon 

 the turn-table, and partly when the reheating 

 occurs in the furnace. The proportion of ore 

 mixed is intended to be about 30 per cent.; 

 but, if too much is added, it is readily squeezed 

 out with the slag, and seems to do no harm. 

 The subsequent heating occupies about half an 

 hour. "Puddle bar," the product obtained 

 from the first rolling of the product of the pud- 

 dling-furnace, is never marketable or finished 

 iron. It is usually very ragged and unsound, 

 and requires subsequent piling, reheating, and 

 rerolling, to expel the impurities and to give it 

 soundness and solidity. The new process ap- 

 pears to produce merchantable iron at the first 

 rolling, and, at Pittsburg, from a very inferior 

 pig-iron, made of one-half sulphurous Canada 

 ores, and one-quarter Lake Superior and one- 

 quarter Iron Mountain ores. 



Coating Iron with Copper. A simple pro- 

 cess of coating iron with copper has lately come 

 into use in England. The surfaces of the ob- 

 jects to be coated, having been well cleaned 

 with a brush and with diluted muriatic acid, 

 are steeped in water slightly acidulated. The 

 articles are then placed in a bath composed of 

 25 grammes of oxide of copper, 176 grammes 

 of muriatic acid, half a litre of alcohol, and a 

 quarter of a litre of water. The copper is 

 equally deposited over the surface, the alcohol 

 reducing the rapidity of deposition, and thus 

 giving greater density to the copper film. 

 These coppered objects may be zinc-coated by 

 placing them in a bath composed of 10 

 grammes of chloride of iron, and one litre and 

 a half of alcohol, and in contact with pieces of 

 metallic zinc. A coating of antimony may be 

 imparted by mixing chloride of antimony with 

 alcohol, and adding muriatic acid until the 



mixture becomes clear. In this bath the ob- 

 jects may be left for three-quarters of an hour. 



Purification of Iron. Mr. J. F. Bennett, of 

 Pittsburg, Pa., has discovered a mode of puri- 

 fying iron, especially from sulphur and phos- 

 phorus. After the molten iron has been treat- 

 ed by Bessemer's process for elimination of the 

 carbon, it is further subjected to the action of 

 carbonic acid, which, it is said, becomes de- 

 composed, the carbon remaining with the iron 

 while the oxygen unites with the sulphur to 

 form sulphurous acid gas, which escapes. In 

 like manner the phosphorus unites with the 

 oxygen of another portion of the carbonic acid, 

 to form phosphoric acid, and its carbon re- 

 mains with the iron. Should it be desired to 

 get rid of this carbon, it can be burnt out by 

 the introduction of air, as in the Bessemer pro- 

 cess. There will also be a decomposition of the 

 carbonic acid by the iron with deposition of 

 carbon. "While the blast of carbonic acid is 

 passing through the molten iron, the tempera- 

 ture of the metal will fall somewhat, losing 

 about one-fourth of the additional heat gained 

 by the passage of the atmospheric blast. This 

 is considered to be an advantage, as it is found 

 that, by the atmospheric process, the iron is 

 rendered almost too fluid by extreme heat. If 

 preferred, the carbonic acid may be heated 

 before entering the converter or vessel where 

 the molten iron is acted upon. Carbonic acid 

 gas may also be used with advantage in re- 

 moving sulphur and other impurities from sul- 

 phides of copper, zinc, nickel, and other 

 metals, by passing it as a blast-current through 

 the metals when in a molten state. This pro- 

 cess may be modified by allowing a small por- 

 tion of carbonic acid to enter the blast-cylinder 

 together with the air, thus subjecting the mol- 

 ten crude iron to a combined blast of atmos- 

 pheric air and carbonic acid gas ; by this means 

 the impurities are removed during the decar- 

 bonization. 



Messrs. A. Matthiessen and S. P. Szezepa- 

 nowski have presented to the British Associa- 

 tion further results of the experiments to de- 

 sulphurize iron, a preliminary report of which 

 they made to the same body in 1866. In the 

 endeavor to prepare pure iron, they always 

 found sulphuretted hydrogen on dissolving the 

 metal in dilute hydrochloric acid. The small 

 quantity of sulphur contained in the iron, did 

 not proceed from the hydrogen or from the 

 platinum tube in which the oxide was reduced. 

 The authors say : 



The first series of experiments were made by pre- 

 cipitating the hot, concentrated, clear solution of pro- 

 tosulphate of iron by oxalate of ammonium, washing 

 the precipitate till the wash- waters no longer indi- 

 cated sulphuric acid with chloride of barium, heating 

 the dried oxalate of iron^to redness in a platinum 

 dish, and reducing the oxide thus obtained in a pla- 

 tinum tube. The reduced iron contained sulphur. 

 In all the experiments we describe, sulphur was test- 

 ed in the following manner : The iron was placed 

 in a test-tube with some dilute pure hydrochloric 

 acid, and the gases were allowed to pass through a 

 small tube fitted into a cork in the test-tube, and to 



