42 TOWERS AND TANKS FOR WATER-WORKS. 



the flame in a regenerative furnace, and converting the result- 

 ant bath into steel, the operation being so conducted that the 

 final product is entirely fluid." 



As stated, this regenerative furnace steel is classified as 

 acid or basic, depending upon the formation or texture of the 

 lining. 



" In one the hearth is lined with sand, and the slag is sili- 

 cious; in the other the hearth is made of such material that a 

 basic slag can be carried during the operation." 



As is the case with wrought iron, the metalloids as carbon, 

 silicon, sulphur, manganese and phosporus affect the finished 

 product, carbon being the least uncertain and detrimental of 

 the alloys, for structural steel being a carbon steel, its presence 

 should possibly not be limited. Also as with iron, the most 

 important of the metalloids are sulphur and phosphorus, the last 

 being the most to be feared. Regarding the effect of sulphur 

 on steel products, Mr. Campbell says: " Nothing is better 

 established than the fact that sulphur injures the rolling quali- 

 ties of steel, causing it to crack and tear, and lessening its 

 capacity to weld. ... In the making of common steel for 

 simple shapes, a content of .10 per cent, is possible, and may 

 even be exceeded if great care be taken in the heating, but for 

 rails and other shapes having thin flanges it is advantageous to 

 have less than .08 per cent., while every decrease below this 

 point is seen in a reduced number of defective bars." 



Effects of Phosphorus. The effects of phosphorus, the 

 most potent of all the metalloids for evil, is thus given by Mr. 

 Campbell: "Of all the elements commonly found in steel, 

 phosphorus stands pre-eminent as the most undesirable. 

 It is objectionable in the rolling-mill, for it tends to produce 

 coarse crystallization, and hence lowers the temperature to 

 which it is safe to heat the steel, and, for this reason, phos- 

 phoritic metal should be finished at a lower temperature than 

 pure steel in order to prevent the formation of a crystalline 



