446 An Attempt to analyse Cast Iron. 



these variations seldom essentially aflfeci the food proper- 

 ties of manufactured bar iron. The cast iron often ac- 

 quires other differences, derived from foreign combustible 

 substances in the ore, or in the fluxes, which may greatly 

 alter the properties of the bar iron made from it. To dis- 

 cover these, and means for their separation, is a nice and 

 interesting object for the iron works. The quantity of 

 these combustible matters which are metallized along with 

 the iron in the heat of the furnace, and deteriorate its 

 quality, is in most instances so very trifling, that in 

 analysis it easily escapes notice ; and being diffused in a 

 tnass of iron proportionally infinitely greater, it maintains 

 jts hold through all the processes to which the iron is after- 

 wards subjected to render it malleable. 



The surest way for a chemist to discover these substances 

 is, first, to examine the ore and the fluxes employed in 

 making the cast iron, and then in the iron itself to endea- 

 vour to detect such substances as were known to be pre- 

 sent in the ore, and likely to affect the quality of the bar 

 iron made therefrom. 



This mode it is probable would also be the safest for the 

 miner to pursue, in searching for means to separate on the 

 Jarge scale unfriendly substances from the ore, when he 

 wishes to gain goqd iron from inferior ore. 



But before we proceed to investigate the composition of 

 cast irc-n of a bad quality, it is plain that we ought to 

 know the constituent parts of cast iron in general, and the 

 causes which operate to produce iron of different quaiities 

 from the same ore ; namely, the dificrent phoenomena in 

 the furnace, the duration of the smtlliug, the diflferent 

 qualities of the coal or ore made use of, Ike. — I will begin 

 with reciting an analysis of a sjiecimen of good cast iron, 

 containing manganese furnished by Mr. Svcdensljcrna 

 from a blast-furnace in Lekebergslag. 



One of the greatest obstacles we meet with in the ana- 

 lysis of cast iron, is to ascertain the quantity of carbon 

 which it cortains. The difficulty of obtaining an accurate 

 result, is no doubt the reas n why our knowledge of the 

 true composition of cast iron has hitherto remained so de- 

 fective. When we dissolve the cast iron in an acid, tlie 

 carbon in the moment of parting with the iron enters into 

 new combinations, partly with the component parts of the 

 cast iron, partly with hydrogen ; nay, even with the com- 

 ponent parts of the acid ; and therefore the products vary 

 according to the acid employed. 



ff. On the dissolution of cast iron by sulphuric acid, 

 ' ■■ there 



