METALLURGY. 



4G5 



mot;il heated to plasticity through a die by hydraulic 

 - i re. ll ruiisists in placing tin- red-hot rnctal 

 in a cylindrical pressure chamber or container, at 

 (>m> end of which is a die. Upon pressure being 

 applied at the opposite end. rhe plastic metal is 

 forced through the die. issuing from it as rods or 

 hars of the required section and length. The cost' 

 oi' labor per ton involved in the process is small. 

 Samples of sections thus produced, exhibited by Mr. 

 Perry F. Nursey to the Iron and Steel Institute in 

 aluminum, aluminum bronze, delta meral. brass, 

 and other alloys ranged from wire weighing about 

 -ritf of a pound per foot run to heavy rounds, 

 squares, and hexagons weighing 40 pounds and up- 

 ward per foot run. 



Electric smelting processes as generally carried 

 on are discontinuous that is, the furnace is charged 

 with a given amount of material to be reduced or 

 converted, and when the process is complete the 

 furnace is emptied and a new charge inserted. 

 This method of working usually puts the furnace 

 out of operation for a time, so far as actual smelting 

 is concerned, and to that extent entails a loss of 

 time. To effect a desired economy in respect to 

 this point, Mr. J. A. Vincent, of Philadelphia, has 

 devised an electric furnace in which all the opera- 

 tions are continuous. 



The process of M. Tommasi for the desilverization 

 of argentiferous lead depends upon the electrolyza- 

 tion of a solution of very weak electrical resistance. 

 The argentiferous lead itself is taken for the anode, 

 while the cathode is constituted of a turning metal- 

 lic disk, from which the silver is removed by scrap- 

 ers as it is deposited. The silver which is not dis- 

 solved in the bath is precipitated to the bottom of 

 the electrolvzer. The author claims that rhe cost of 

 his process is not more than about one fourth that 

 of the ordinary proc 



In the method of M. A. Demalght for closing 

 cracks or pores in cast iron, the cylinder or vessel is 

 filled with a certain quantity of perchloride of iron. 

 The liquid is then compressed until globules appear 

 on the external surface. The cylinder is thus im- 

 pregnated with perchloride of iron all through its 

 thickness. Any perchloride in the cylinder is then 

 emptied out. and the cylinder is wiped until the 

 polished surface is again made brilliant. It is next 

 filled with ammonia at 2 2 Baume. which is also 

 subjected to compression. The effect of this opera- 

 rion is soon noticeable in the perchloride of iron in 

 the metal becoming transformed under the influ- 

 ence of the ammonia into hydrated oxide of iron, 

 which is at first somewhat frothy and afterward, 

 under the influence of the external pressure, rough 

 and compact. Some hydrochlorate of ammonia 

 also remains, which will soon afterward react upon 

 the iron, converting it eventually into an oxide 

 compound, adding itself to the first. The leaks 

 marked at the beginning of the operation will be 

 entirely stopped up as soon as the ammonia begins 

 to move out externally. The operation occupies 

 about two hours. 



A new process for the production of malleable- 

 iron castings consists in melting in a modified Sie- 

 mens-Martin furnace, using crude petroleum, 20 

 per cent, of pig iron, 78 per cent, of wrought-iron 

 scrap, and. adding to this after it has reached the 

 fluid state. ',' per cent, of a composition which is not 

 named. These proportions may vary either way, 

 according to the quality of metal desired. In other 

 words, by changing the proportions of the pig, 

 scrap, and of the composition, the resulting casting 

 may be made to vary in its physical characteristics. 

 The metal is said to flow very perfectly, and to pro- 

 duce a casting practically free from blowholes. It 

 has a shrinkage of i inch to the foot. A casting of 

 this metal can be forged as wrought iron, welded 

 VOL. xxxvi. 30 A 



without trouble, and under the cutting tool it ex- 

 hibits the characteristics of soft steel. 



In a new method of face-hardening armor, one 

 face of the ingot intended for the armor pi.v 

 carboni/ed direct at i he time of being run into the 

 mold. This i> effected by lining one wall of the 

 mold with the necessary carbonizing material, 

 which must, it is stated, be free from occluded 

 and of great durability, so us to remain stable dur- 

 ing the process of casting. Experience has shown 

 that the amount of cementation obtained varies with 

 the carbonizing material used, about twice as much 

 effect being obtained with charcoal as with coke. 

 On withdrawal from the mold, the cemented sur- 

 face is slightly wrinkled, but this disappears in the 

 after-working of the ingot. The heaviest ingot yet 

 dealt with in this way weighed a ton. and this was 

 reduced from the initial thickness of 16 inches to 4 

 inches by forging and rolling. An examination 

 then showed that for l - 5 inch from the face the 

 metal contained from T78 to 1-5 per cent, carbon, 

 which decreased regularly to between 0'25 and 0-15 

 per cent, at the back of the plate. 



Miscellaneous. In a discussion in the British 

 Iron and Steel Institute having special reference 

 to the Harveyizing process. Prof. Roberts-Austen 

 showed how rapid is the motion of particles of what 

 are called solid bodies. If. for instance, he said, a 

 piece of pyritic ore containing 4 per cent, of copper 

 is heated to a dull redness for some time, the iron 

 pyrites would oxidize, while the copper would travel 

 to the center : silver, on the other hand, passes out- 

 ward. If gold and lead are placed in contact in a 

 vacuum for twelve hours at a heat of 43\ they 

 would unite, against gravity, in the same way as 

 salt and water. These questions are interesting, 

 especially in relation to the Harveyizing process : 

 and the speaker thought it would be worth while 

 for investigators to take the trouble to find out 

 what are the true laws governing the carbonizing 

 of iron. 



The application of higher steam pressure has led 

 to the introduction of iron fittings instead of the 

 old brazed-copper fittings where these pressures are 

 used, and the application of electric welding, or 

 fusing, as some engineers prefer to call it, where 

 joints, such as elbows, T-pieces. etc., are required. 

 In the Benardos system, ordinary low-tension con- 

 tinuous-current dynamos are used ; to the terminals 

 of these a battery of Benardos accumulators is con- 

 nected, into which the current flows continuously. 

 "XVhen the welding circuit is closed, the current flows 

 from the dynamos and accumulators, and large re- 

 sistances are used when necessary. In this way a 

 large discharge is attained, equal to about twice 

 the capacity of the dynamos, and the load factor of 

 the apparatus is high. Special attention is called 

 by Mr. McCarthy in describing this process before 

 the Institution of Mechanical Engineers to the 

 length and size of the electric arc which is used in 

 welding. With a short arc the carbon point is 

 brought down too close to the steel, and the result 

 is inferior work, not only from the presence of the 

 carbon, but because the heat is concentrated upon 

 so small a surface that the strains set up in cooling 

 are considerable. The larger the arc. the sofrer and 

 more defined is the heat, and any slight strain 

 which may be set up can be got rid of by careful 

 annealing! A long arc is therefore indispensable 

 to the proper working of the system. 



Concerning the difference between iron and steel, 

 Mr. James observes that it is possible to have two 

 metals yielding identical results by chemical an- 

 alysis, one of which may be true fibrous wrought 

 iron, and the other what we know as steel. The 

 sole difference would be in the molecular structure, 

 and this difference would be determined by the 



