'^r elating to Air and Water, 283 



This calx of irdn, I then concluded, was by no means what 

 .1 had before taken it to be, 'vlz, o. pure calx ox flag ^ but either 

 the calx, or the iron itfelf, fltturated with pure air. This cal=- 

 ciform fubftance I found, by various experimejits, to be the- 

 fame thing with x\\Qfcales that fly from iron when it h made 

 red-hot, or the fubftanee into which it -runs in a very intenfe 

 heat, in an open fire. 



Concludinp^ from the preceding experiment, that iron, fuffi- 

 ciently heated, was capable of faturating itfelf with pure air, 

 extrai^ed from the mafs of the atmofphere, I then proceeded to 

 melt it with the heat of a burning lens in the open air ; and I 

 prefently found, that perfect iron was eafily fufed in this way, 

 and continued in this fufion a certain time, exhibiting the ap- 

 pearance of bGiling o\' throwing out air, whereas it was on the 

 contrary imbibing air; and when it was lliturated the fufion 

 ceafed, and the heat of my lens could not make any farther 

 impreflion upon it. When this was the cafe, I always found 

 that it had gained weight in the proportion of 7! to 24, which 

 is very nearly one-third of its original weight. The fame was 

 the etfe^l when J melted j/?^^/ in the fame circumflances, and 

 alfo ^v^x-'j kind of iron on which the experim.ent could be tried. 

 But I haveiome reafon to think, that w^ith agreater degree of 

 heat than I could apply, the iron might have been kept in a 

 flate of fufion fomev/hat longer, and by that means have im- 

 bibed more air, even more than one-third of its original 

 weight. 



There was a peculiar circumftance attending the melting of 

 cafi iron with a burning lens, which made it impoffible to afcer* 

 tain the addition that was made to its weight, and at the fame 

 time afforded an amazing fpe^lacle ; for the moment that any 

 quantity of it Vv^as melted, and gathered into a round ball, it begnn 



O o 2 to 



