and Iron-Slones hj Viifton. l?^ 



pro(3uce in iron equal to 30 per cent, from the raw iron-flone ; 

 fufed earths, now reduced to an opaque brown glafs ftreaked 

 with white, 294 grains : lofs in volatile mixtures 320 grain?, 

 or ■^^.^ per cent. 



The metallic button produced in this operation had a 

 fmooth cryftallifed furface ; and, when in fufion, combined 

 lefs readily with oxygen offered by the contacl of atmo- 

 fpheric air, than did the former two. The frafture was light 

 grey, with a regular diftinft grain ; the mafs of fufed earths 

 were difpofed afier the manner of a cryftall-.f-ition, in radii, 

 {hooting from the circumference of a mioute circle to the 

 extremity of one larger. 



From thefe experiments it is obvious that reguli of crude 

 iron may be obtained from the different clalTe^of iron-ftones, 

 of a refpeftable produce, without any addition whatever; 

 and that the tendency which thefe have to part with their 

 iron is in the exaft ratio of the quantity of lime prcfent. 

 The following ftatcment exhibits the difference betwixt the 

 real and partial afTa)- of the foregoing iron-llones. 



The filiceous iron-ftone, properly afl'ayed, yielded 34.5 

 f>er cent., but by fufion perfe only 2 : ; leaving in the latter 

 method 9.5 mixed with the fcoria. Argillaceous flone, pro- 

 perly afTayed, gave "^^-6, by fufion per fe 28.5 ; leaving 

 7.1 mixed with the fcoria. Calcareous iron-flone, properly 

 allayed, yielded 33.7, by fufion /(er yi' 30 ; which left 3.7 

 mixed with the fcoria. 



One reafon may be advanced why the iron produced from 

 the calcareous flone was fo much more in proportion than 

 the other two clafTes : both the filiceous and argillaceous 

 buttons, when deprived of their fcoria, decompofed atmo- 

 fphcric air fo rapidly as to fufi'er a little, in point of real 

 metal, from the combination of oxygen. It was olherwife, 

 however, when the furface of the calcareous button was cx- 

 pt)lt'd : the affinity of the oxygen to the metal being lefs 



iron. I have for the lad three years maile ufe of this truth with the 

 jjrcdtcft advatitagc in the afT.iyir.g of ores and other cxpeiiaicnts. 



than 



