528 



METALLURGY. 



of being attacked. The results of the experi- 

 ments tend to show that it is exceedingly diffi- 

 cult, if not impossible, to obtain by Caron's 

 method zinc-calcium alloys containing more 

 than from 6 to 7 per cent, of the latter metal. 



It has been shown in papers read at the Insti- 

 tution of Civil Engineers that whereas from 

 2'5 to 7'5 per cent, of manganese in steel makes 

 it as brittle as glass, so that it will break under 

 a much less transverse load than iron, from 12 

 to 14 per cent, of manganese in the metal se- 

 cures higb carrying power with great elonga- 

 tion. Thus, a bar of the composition, c;irbon, 

 0'85 per cent. ; silicon, O23 per cent. ; sulphur, 

 O08 per cent. ; phosphorus, 0'09 per cent. ; and 

 manganese, 13'5 per cent., carried a load of 

 57'02 tons to the square inch, and took a per- 

 manent set at 29^ tons, with an elongation of 

 39'8 per cent. This metal is toughened by 

 heating it to a high temperature and plunging 

 it into water at a temperature of 72 Fahr., but 

 it is difficult to machine. 



In the process of R. N. P. Richardson, of 

 Pittsburg, for coating iron or other metallic 

 surface with lead, the sheets, having been 

 pickled and cleaned, are placed in the solution- 

 vat containing various chemicals in dilute hy- 

 drochloric acid. They are then passed through 

 the molten lead, from which they come out 

 the first time with a clean, bright, even, and 

 pure coating of lead. The secret of the pro- 

 cess, according to the author, after the pickling 

 and washing of the sheets, is simply in the so- 

 lution to which the sheet is subjected before 

 its immersion in the molten lead. The solution 

 also forms the flux for the sheet, bone-ash 

 mixed with charcoal being used to prevent the 

 oxidation of the metal. 



Processes. The process of electric welding 

 discovered by Prof. Thomson several years 

 ago has recently been greatly developed. Hav- 

 ing started with the welding together of small 

 wires of iron and copper, the operators are 

 now able to weld bars of a very large size and 

 of almost any shape or metal. The principle 

 of the process is that of forcing through a con- 

 ductor an amount of current that it will not 

 carry without heating. The resistance in con- 

 ductors being greatest at their point of abut- 

 ment or contact, heat is first generated, and 

 this heat increases the resistance at that point 

 so greatly that more heat is developed at a 

 remarkably rapid rate. A great advantage of 

 the method arises out of the localization of the 

 heat at the points or point where it is desired, 

 whereby an enormous amount of energy is 

 saved which is usually wasted in welding with 

 the forge or flame. It is possible by it to weld 

 any metal, including both those that melt at 

 very low temperatures such as lead, zinc, and 

 tin and those that melt at enormously high 

 temperatures, as iridiurn, platinum, etc. Al- 

 most absolutely perfect automatic control of 

 the current is obtained. The time required to 

 weld metals depends upon the power of the 

 apparatus and the skill of the operator. Strong 



and practically perfect welds have been made 

 in one-half-inch round wrought-iron in six sec- 

 onds; in inch round wrought-iron in forty-five 

 seconds. The power required to weld appears 

 to be nearly proportional to the cross-section 

 of the piece. The authors are able, by the 

 same process, to solder, braze, anneal, temper, 

 and do other heating that can not be done 

 economically by present methods. 



A mixture of compressed oxygen, as pre- 

 pared by Erin's cheap process with coal-gas, 

 has been successfully applied by Thomas 

 Fletcher to brazing and welding. With a 

 half inch gas-supply, a joint could be brazed 

 in a two-inch wrought-iron pipe in about a 

 minute, and without heating to redness more 

 than one inch on each side of the joint. A 

 good weld was obtained on an iron wire one 

 eighth of an inch in diameter with a blow-pipe 

 having an air-jet of about one thirty-second of 

 an inch in diameter. The surface of iron heated 

 to welding-heat by this means comes out clean 

 and free from scale. 



Carbon in steel, pig-iron, and other ferro- 

 carbon alloys is usually determined by methods 

 in which the carbon it first separated in a state 

 of proximate purity, and afterward burned in 

 a current of oxygen. To effect the separation, 

 the particular ferro-carbon alloy is treated 

 with some salt, whose base can either be sub- 

 stituted entirely, or which can be reduced to 

 some lower compound by the iron that is pres- 

 ent in the alloy, the carbon not taking any 

 part in the reaction. For this purpose a neutral 

 solution of cupric chloride has hitherto given 

 the most satisfaction; but its use is attended 

 by the inconvenience that the cupreous chloride 

 that is produced is comparatively insoluble, 

 and its precipitation has to be provided against. 

 This inconvenience is entirely obviated in the 

 new mixture proposed by Mr. T. W. Hogg of 

 a solution of ferric chloride and cupric chloride. 

 When these substances are brought together 

 an immediate change takes place, and cupric 

 chloride and ferrous chloride are formed. 



In M. A. Levy's process for depositing thin 

 sheets of metal upon other metals, batteries 

 and dynamos are dispensed with, and a double 

 decomposition is depended upon. In deposit- 

 ing a layer of nickel upon either copper or 

 iron, a solution of salt of the metal is prepared 

 preferably the acidulated chloride and, 

 after the object has been scoured, it is sus- 

 pended in the solution at the extremity of a 

 zinc wire, which partially enters the bath. 

 The zinc is attacked by the salt, and it replaces 

 the nickel in the chemical constitution of the 

 solution, whereby the object is covered with 

 a layer of nickel. In copper-plating cast-iron, 

 an alkaline bath is employed in place of the 

 acidulated one. 



A process for tempering spring wire and 

 ribbon, by introducing a current of electricity 

 as the heating power, has been invented by 

 Mr. Frederick Sedgwick, of Chicago. The 

 greatest difficulties met with in tempering a 



