On the Component Parts of Iron-Jlomsl 1 93 



hinder the abforption to continue, while there remains gas 

 proper for maintaining combuftion. 



If it be common air or vital air mixed with any other gas, 

 you niuft, after cooling, meafure the quantity of water which 

 has entered the retort, and which will exaftly reprefent the 

 bulk abforbed. You niuft not neglecl to confine the re- . 

 maining gas under the fame preffure, by inimerfmg the re- 

 tort in the pneumatic tub, till the internal and external 

 water be oh the fame level, before you clofe the orifice by a 

 ftopper. This operation, very eafy when you have graduated 

 veffels, may be made in common practice by means of a 

 piece of paper cemented along the neck of the retort, and 

 having traced out on it divifions determined by experiment, 

 and which may be covered with varnifh to defend it from the 

 a£f ion of the water. 



C. Chaufiier has cdnftru£ted, for eudioirietric experiments 

 by phofplibrus, an apparatus fomewhat different, compofed of 

 a long tube all of One piece, one end of which is bent and 

 blown into a bulb, and having, 'as at e, a tubulure fhiit with 

 a ftopper after the water has been made to aicend in the in- 

 fide of the tube to two-thirds of its height. This iriftrumerrt 

 would ferve alfo for experiments with the fulphuret of pot- 

 ato ; but I niuft ob'ferve, that the execution of it is not fo 

 eafy as on the firft view might appear. Befides, if the tu- 

 bulure renders it very convenient for trying atmofpheric 

 air, the cafe is not the fame in regard to other gafes which 

 cannot be introduced but by tranfmiffion. 



XVI. On the Component Parts of Iron-Jlones , and how thefe 

 in the manufacturing affect the Quality of Crude Iron, 

 ByMv. David Mushet, of the Clyde Iron Works. Cotn- 

 viunicated by the Author. 



I 



RON-STONES, though commonly denominated orc3 ol^ 

 clay, contain notwithflanding a variety of mixtures, and may 

 with propriety be divided into the following claffes : 



Vol. III. O i, Iron- 



