534 



METALLURGY. 



peared to be the same as that of the good 

 wheel, the well-developed and prominent 

 graphite plates were absent, and were replaced 

 by graphite in irregular and somewhat isolated 

 plates of comparatively large size, without any 

 regular grouping. A weak and almost worth- 

 less pig-iron showed similar characteristics. 

 A high-grade hot-blast charcoal pig-iron ex- 

 hibited a similar structure with that of the 

 good wheel-iron, the only differences being in 

 the size and prominence of the graphite plates. 

 It is generally believed that the presence of 

 graphite in quantity, after a certain limit is 

 passed, renders the metal weak. Mr. Garrison's 

 experiments indicate that the development 

 and distribution in well-defined lines or plates 

 of this substance is at least as important a fac- 

 tor of quality, up to a certain limit, as its total 

 amount. Mr. T. Turner has shown that no 

 general rule can be laid down as to the influ- 

 ence of remelting on the properties of cast- 

 iron ; chemical changes take place during the 

 melting ; the amount of silicon is reduced 

 while that of the sulphur is increased, and the 

 effect of remelting will be dependent upon 

 the proportion of these elements present in 

 the cast-iron; a single melting will be suffi- 

 cient to produce a deterioration in the quality 

 unless the silicon is in excess. Addition of 

 silicon to hard white iron causes it to become 

 soft and gray, and too much silicon makes the 

 iron weak ; by adding silicon in right propor- 

 tion, cast-iron can be made of any desired de- 

 gree of hardness. Mr. Turner has succeeded 

 in making a steel in which the carbon is re- 

 placed by silicon, which can be hardened like 

 steel, is very tough when cold, and is well 

 adapted for tools, but is difficult to work when 

 hot. 



A process of direct melting of wrought-iron 

 into the articles to be made from it, has been 

 introduced into the manufactories of several 

 countries of Europe. It is called the " Mites 

 process," and by it wrought-iron is formed in 

 solid, homogeneous castings, without changing 

 the quality of the metal. It depends upon the 

 addition to the raw materials employed of an 

 exceedingly small percentage of aluminum, 

 which has the effect of causing an immediate 

 and considerable lowering of the melting-point 

 of the wrought-iron. By this means the appar- 

 ently paradoxical result is obtained of effect- 

 ing the necessary superheating of wrought- 

 iron without raising the temperature above 

 the melting-point, and the absorption of the 

 furnace- gases, inevitable in superheating at 

 the excessively high temperature required in 

 the ordinary processes, and the consequent de- 

 terioration of the quality of the metal, are 

 avoided. 



Mr. A. C. Meriten has introduced a new 

 method of protecting iron by exposing the 

 article in a bath at a temperature of from 158 

 to 176 Fahr. to an electric current. The 

 water is decomposed, and oxygen is deposited 

 on the metal, while hydrogen appears at the 



other pole. If the conditions are as they 

 should be, the magnetic oxide, which resists the 

 action of the air, and will protect the metal be- 

 neath it, is formed. 



A property of iron and steel to show a low- 

 ering in tenacity at certain temperatures ap- 

 proaching a blue heat has been remarked by 

 several writers. Prof. Ledebur, of the Frei- 

 burg School of Mines, has cited an instance in 

 which a breakdown could be attributed to the 

 fact that the material was made at this dan- 

 gerous heat. A new pump-rod of Bessemer 

 steel, well tested and having ample suction, 

 broke soon after being put in; and several 

 times afterward during the year. No other 

 cause being shown for the breaking, Prof. 

 Ledebur believes that he is justified in assum- 

 ing that the rods were probably worked at the 

 dangerous blue heat. 



Prof. D. E. Hughes has observed that steel 

 and iron wires are made brittle by being im- 

 mersed for a few minutes in acidulated water. 

 His first experiments were made with water 

 containing one tenth sulphuric acid, but the 

 continued prosecution of his researches showed 

 that the brittleness was no mere accidental re- 

 sult, due to some flaw in the steel and iron 

 wires, but that it is invariable in all kinds of 

 steel as well as of iron ; that it is not depend- 

 ent on any specific proportions of sulphuric 

 acid to the water, nor, in fact, on the use of 

 any particular acid. The effects, however, seem 

 to be confined to steel and iron, as no percepti- 

 ble change was obtained in copper and brass. 

 Tests instituted for the determination of the 

 fact have failed to give any of the signs that 

 indicate a change in the molecular structure of 

 the wires, but the fact that very evident re- 

 sults are produced when the conditions of the 

 experiments are such as to favor the absorp- 

 tion of hydrogen, has induced Prof. Hughes to 

 assign that as the cause of the phenomena no- 

 ticed. 



The uniformity of the quality of open-he? 

 steel was illustrated by Mr. George E. Thi 

 ray, of Pittsburg, before the American Ins 

 tute of Mining Engineers, by a calculation 

 the deviation in two lots of steel. In one " 

 of 73 consecutive heats of steel containing O'li 

 per cent, of carbon, the average deviation in 

 carbon was found to be 0'0068 per cent. Ii 

 another lot of 26 consecutive heats of boil( 

 plate steel containing from 013 to 0'16 

 cent, carbon to suit different requirements, 

 average deviation was 0'0033 per cent. 



Mr. Choubley has confirmed the observath 

 made by Herr Wassum on the influence of < 

 per in steel upon its rolling qualities, whi< 

 were to the effect that 0*862 per cent, of cop- 

 per did not, in the absence of sulphur, produce 

 red-shortness. Noting that Wassum's tests 

 were conducted with steel, low in phosphorus, 

 Choubley made some additional experiment 

 to determine what influence phosphorus ai 

 copper have. The result, with five HOA 

 of slightly different composition, has been 



