^6 On the Ufe of Calcareous Sionds 



Analogous to thefe fa6ls, we daily fee the fuperiority of 

 fituation evinced, and ca:tens paribus larger products in iron 

 obtained from a general ufe of calcareous iron ftones than 

 any other. This fuperiority is derived from the congenial 

 mixture of the ore, combined with a large proportion of lime, 

 which facilitates the carbonation of the metal ; and united 

 with a juft portion of fand to conftitute fufibllity, the fame 

 column of blaft will, in the fame time, reduce a much 

 greater quantity of it, affording the iron at the fame time 

 fufficiently carbonated, than of other iron ftonea differently 

 combined. 



On the other hand, where the intention of the manufac- 

 turer is to fabricate a quality of iron pofleffed of every requi- 

 fite for converting into good malleable iron, calcareous iron 

 llones, in quantity, ought to be avoided, and thofe of the 

 argillaceous and filiceous clafles fubftituted. Thofe of 

 rqualifed mixtures of earth, combined with pure argilla-r 

 teous ores, afford the ftrongeft quality of crude iron; capable 

 of being melted to advantage for the conftniftion of heavy 

 pieces of machinery', or ufed for the purpofes of the forge. 

 In the ufe of thefe clafles, however, great ftrength and quan- 

 tity will be freqviently found at variance, when the quality of 

 the metal is wifhed to be prelervcd carbonated : this alfo 

 arifes from the nature of the mixture in the iron ftone; clay 

 in quantity, united with various proportions of lime, forms 

 an alloy, more difficult to fufe than where lime in quantity 

 is united with various proportions of filex. 



Where nature has beftowed mixtures produftive of every 

 quality of crude iron, the proper arrangement of ores would 

 become fimple and eafy; jufl combinations of mixture fuper-f 

 fede the necefiity of changing the quality of the lime flone 

 added for a flux, or of having recourfe to various qualities of it, 

 in order to aflift or correft the. defieiency of the native mix- 

 ture. Wherever the ores are of a Itruclure thus deficient, it 

 then becomes the province of the manufatturer to afcertain 

 the mixture of the individual ores which compofe his fupply, 



and 



