A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



" 7'(i llic solid groiiml 

 Of Xaiiiru trusts the mind ■J.'hich builds for aye." — Wokdswortii. 



THURSDAY, NOVEMBER 4, 1909. 



MODERX KELDIXG. 

 Welding and Cutting Metals by Aid of Cases or 

 Electricity. By Dr. L. A. Groth. Pp. xvi + 281. 

 (London : .A. Constable and Co., Ltd., 1909.) Price 

 10.S. bd. net. 



'T^HE art of welding iron is very old, probably 

 -L as old as the production of the metal from its 

 ores. Previous to the nineteenth century the art of 

 forging and welding iron reached a high stage of 

 development. Then came the cast-iron period, which 

 for a time usurped the place of the forged metal. 

 But during the last half-century, owing to improved 

 and less costly methods of production and the intro- 

 duction of machines which can make forgings of a 

 size far greater than can be worked by a smith, new 

 methods of welding have become necessary. Welding 

 of the metals has kept pace with the improvements in 

 metallurgy, and a great part of it is now carried out 

 by fusion ; consequently, joins of almost any thick- 

 ness can now be made, whereas hy the method of 

 hand hammering the size and thickness of the joins 

 was very limited. 



The book before us deals with the welding of 

 metals mainh" by the newer methods which have been 

 made possible by the advance in electrical science and 

 by the use of reducing flames of high temperature, 

 such as hydrogen and acetylene. But not only can 

 high-temperature flames be emploved for welding ; 

 they can also, by altering the conditions, be used 

 for cutting thick plates of metal. Whereas, however, 

 the welding is carried out by means of flames contain- 

 ing an excess of a reducing gas, the cutting is done 

 by means of flames rich in oxygen. 



The book commences with a short introduction ex- 

 plaining the nature of a weld. Chapter ii. is headed 

 "Gases and Sources for their Generation." One 

 hardly knows what to make of this chapter; if it is 

 written for the novice it is useless, if written for the 

 chemist unnecessary. We are told, in the first place, 

 " it has been known for ages that matter is capable 

 NO. 2088. vol.. 82] 



of existing in three physical states : the solid state, 

 the liquid state and the gaseous state." 



Further on there is an historical account of the 

 manufacture of calcium carbide and of the prepara- 

 tion of acetylene. It is a pity that this part of the 

 book is not written in a manner to help the welder 

 or cutter, and is not always accurate. What, for 

 example, does this mean ? 



(Hydrogen) " is usually prepared by the action of 

 zinc or iron on a solution of hydrochloric or sulphuric 

 acid. All metals which readily decompose water when 

 heated readily furnish hydrogen on a similar treat- 

 ment. Man)' other acids may be used, hut none cut 

 more readily. In all cases the action consists in the 

 displacement of the hydrogen . . . and if the acid is 

 not one which can enter into reaction with the dis- 

 placed nitrogen, the latter is evolved as a gas." 



Poor novice ! Again, hydrogen was not liquefied 

 by Cailletet on December 30, 1877. 



From chapter iii. and onward the book is interest- 

 ing and instructive. Welding and the different 

 systems employed are described — thus autogenous, or 

 the union of the metals by direct fusion ; under this 

 we get alumino-thermic processes, electric welding, 

 welding with compressed gases. Heterogeneous, in 

 which a foreign metal or alloy is employed, which 

 has a lower melting point than the metals to be 

 joined. 



The welding of aluminium, which is similar to lead 

 burning, is described, and illustrations are given to 

 show that, as a rule, the tensile strength of a welded 

 bar is greatest at the weld, or, at any rate, breaking 

 does not take place at this position. The alumino- 

 thermic process is well described, and two interesting 

 diagrams showing the mending of cracks in the stern 

 frame of a steamer are shown. 



.\ considerable amount of space is devoted to electric 

 welding, which has b6.jn found so useful in the weld- 

 ing of pipes and tubes; very interesting illustrations 

 showing the joining of pipes to form T's and other 

 unions are given. 



Chapter iv. deals with blow-pipes of various design 

 which are used for different purposes. W'e are not 

 particularly impressed with the insertion of advertising 

 letters in chapter v. This chapter deals with the 



b 



