38 ON CAST IRON. 



been expelled, gave 32* cubic inches of carbonic acid gas. 

 An equal quantity of white cart iron afforded 165 cubic inches 

 of the fame air. Four ounce* of the call iron juft taken from 

 the reverberatory furnace, mixed with two ounces of charcoal, 

 yielded 96 inches, or 192 inches to half a pound. 



Hence we may infer, that the proportions of oxigen con- 

 tained in thefe different kinds of caft iron are, 



In iron fuper-refined by the vapour of water - 192 

 Common white call iron - - - - - 165 



Gray call iron - - - - - - 96 



Th'sfuper- To the iron produced in the experiment juft mentioned, I 



refined iron im- - e the ep j tnet fuper-refined f, becaufe I conceive it to have 

 bibed oxigen ? r 



from the de- been formed as follows: — The water in vapour was decom- 



compofed water p f e d, and deflroyed the carburet, asatmofpherie air does in 

 which deftroyed , ,. . . , * > . . ■ - , 



its carburet. tne ordinary refining ; but at the lame lime this water imparted 



to the iron fo large a quantity of oxigen, that in the refinery 

 it was neceflary, not only to feparate the fcoria, but to difoxide 

 the metal like wife. This experiment farther confirms the pro- 

 perty iron poffefles of becoming oxided in different degrees. 



If this experiment afforded nothing practically beneficial, it 

 has at leali thrown fome new light on the properties of caft 

 iron. 



Exp. III. Third Experiment ; the Fire of the Furnace being aJJJJled by the 



AStion of Bellows, 



Bellows applied The fame furnace was ufed, and the place of the retort in 



with the rever- ^e preceding experiment was fupplied by a pair of double 



beratory furnace. , ,, ' , . , . * , r ■ x i „ ,„ r 



bellows mounted with leather, 5 teet (4-r. 8 in.) long, 3 (2 r. 



10 in.) broad, and 4 (3. f. 9 in.) high at the poflenor extremity 

 when open. It was fo placed, that the dream of air was pa- 

 rallel to the flame and to the middle of the furnace, and worked 

 at the rate of eight or ten flrokes in a minute. We were de- 

 firous of feeing how far the air thus allifled would carry the 

 refining ; the furnace being managed and filled as before. 

 The heat was -At the end of half an hour the heat was perceived to be 

 much greater, much greater than in the firfl and fecond experiments. The 

 phenomena of the refining already mentioned appeared in fuc- 



* Probably this is an error of the prefs in the original : as it does 



not agree with the proportion affigned in the next paragraph, one 



of the two muft be wrong. 



f Or furcharged with oxigen. 



ceffion; 



