On the Air-Furnaces empJojed in Iron Foundries. 245 



plafler and glue, to prevent its re-a6lion ou the colouring parts 

 of the painting. 



The hardneis of this fubftance, and its fufceptibilitv of re- 

 ceiving a polifh, induce nie to believe that it might be em- 

 ployed on ftucco, and for iniitaling it ou walls and ceilings. 



It may be ufed alfo for uniting water-conduit?;, and for ce- 

 menting ftones of all dimenfions, and efpeciallv thofe which 

 are put into wood caiflons for buildinti; under water. 



It appears from different works, thai the antients had con- 

 ceived the idea of employing blood in the compofitlon of their 

 cements and mortar ; but the ufe of it in painting was before 

 unknown. Befides, there was too great a diltance between 

 this ufe of blood and that of ferum freed from the fibrous part 

 and the colouring matter, to admit of anv doubt that the priur- 

 ciple of my difcovery is entirely mv own. 



It follows from what has been here faid, that this new 

 kind of painting may be added to thofe already known, and 

 that it may be called painting iji ferum \ that it is as ealily 

 applied as prepared ; that the elements of it are common, anil 

 of little value; and that it unites in it all the advantages of 

 painting in oil atid in diftemper, without having any of their 

 inconveniences. 



XLIII. On the Kind of Air-Furnaces e7nployed in Iron Foun-, 

 dries fqr cojUng large Pieces oj Ordnance, Shafts for Mills^ 

 Cylinders,' and other heavy Articles, By Mr. David 

 MusHET, of the Calder Iron IFurks*. 



T 



J. HE furnaces about to be defcribed are eniplqyed for 

 snelting pisriron with the flame of pit-coal, Furnaces of 

 this kind are conllructed of various fizes according to cir 

 cumftances. The fmall fizes will run down froqi feven to 

 ten hundred weight, and are ufed in fmall foundries for what 

 the trade call jobbing. 



Fig. I. (Plate IV.) a ground plan of two large air-furnaces, 

 and chimney for melting pig- or call-iron with the flame uf 

 pit-coal. 



The letters ABCD point out the exterior dimenfions of 

 the ftalk or chimney, which is firit erc6led, leaving two open- 

 ings or arches into which the fore-part of the furnaces arc 

 afterwards built. The breadth of the chimney at the parti- 

 cular place which the plan exhibits is 16 feet from A to B, 

 and from A to D or froni B to C 6 feet 6 inches. The plan 

 ^ drawn at that elevation where the flame enters the chimney 



'" Cominunicunl tjy iliu Audiw. 



il3 by 



