5i Notices respecting New Books. 



Cast Iron : three of these kinds were run by Mr. F. Bramah, 

 from the Pigs of different Furnaces in Shropshire and in 

 Derbyshire ; one was from re-melted old Iron scraps ; another 

 kind consisted of new Pig and old Iron, in equal parts ; and 

 the last pair, of Pig Iron -Jyth alloyed with Copper. 



These experiments and the practical results which Mr. 

 Tredgold draws from them, appear to us highly important ; 

 and so do the seven new Experiments by Mr. Bramah, on 

 the Twisting or Tort ion of Cast Iron, given in Art. 67 a . 



Art. 68 a concludes this Section, with a set of new Rules, 

 for judging of the quality of Cast Iron by the aspect of a 

 newly fractured surface thereof, as to colour and lustre. 

 " The colour of Cast Iron, is various shades of gray, some- 

 times approaching to dull white, sometimes dark iron gray 

 with specks of black gray. The lustre of cast Iron differs 

 in kind, and in degree : it is sometimes metallic, for example 

 like minute particles of fresh cut lead, distributed over the 

 fracture ; and its degree in this case, depends, on the number 

 and size of the bright parts ; but in some kinds, this lustre 

 seems to be given, by facets of crystals, disposed in rays ; I 

 will call this lustre crystalline. 



" In very tough Iron, the colour of the fracture is uniform 

 dark iron gray, with abundance of metallic lustre. If the 

 colour be the same, but with less lustre, the iron will be 

 soft, but more crumbling, and (will) break with less force. 

 If the surface be without lustre, and the colour dark and 

 mottled, the Iron will be found the weakest of the soft kinds 

 of Iron. 



" Again, if the colour be of a lighter gray, with abund- 

 ance of metallic lustre, the iron will be hard and tenacious : 

 such iron is always very stiff. But if there be little metallic 

 lustre, with a light colour, the iron will be hard and brit- 

 tle : it is very much so, when the fracture is dull white; but 

 in the extreme degrees of hardness, the surface of the frac- 

 ture is grayish white, and radiated, with a crystalline lustre. 



" There may be some exceptions to these maxims, but I 

 hope they will, nevertheless, be of great use to those engaged 

 in a business which is every day becoming more important." 

 In previous pages Mr. Tredgold says, 



" The best and most certain test of the quality of a piece 

 of Cast Iron, is, to try its edge with a hammer : if the blow 

 make a slight impression, denoting some degree of malleabi- 

 lity, the iron is of a good quality, provided it be uniform : if 

 fragments fly off, and no sensible indentation be made, the 

 iron will be hard and brittle." 



" The Tables in this work and Rules, are calculated for 



soft 



