relating to Air and Water. .283 



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

 1 had before taken it to be, viz, 2. pure calx o'C f.ag^ but either 

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

 ciform fubflance I found, by various experiments, to be the 

 fame thing with the fca/es that fly from iron wh-en it is made 

 red-hot, or the fubflance into which it runs in a verv intenfe 

 heat, in an open fire. 



Concluding from the preceding experiment, that iron, fufli- 

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

 extracted from the mefs of the atmofphere, I then. proceeded to 

 melt it with the beat 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 boiling or throwing out air, whereas it was on the 

 contrary imbibing air; and when it was faturated the fufion 

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

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

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

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

 the effe(5l when .1 meltedy?i'^/in^the fame circumflances, and 

 alfo every kind of iron on which the experiment could be tried. 

 But I havefome reafon to tliink, that with a greater degree of 

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

 fiate of fuiion fomewhat longer, and by that means have im- 

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

 weight. 



There was a peculiar circumflance attending the melting of 



caji iron with a burning lens, w^hich made it impoflible to afcer- 



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



time afforded an amazing fpeclacle ; for the moment that any 



quantity of it was melted, and gathered into^i. round ball, It began 



O 2 t.Q 



