CLAY MANUFACTURES. 721 
perceptible amount of irony and fluxing materials which tend to flux 
the outside of the ware and give it the dark appearance that runs along 
the arches and exposed parts of the brick kilns, ete. This is usually 
attributed to “sulphur in the fuel”, etc., but its explanation is found in 
the above facts. The only way to obviate this difficulty is to burn terra 
cotta in closed spaces, or to put up a net-work of surfaces which shall 
catch this dust before it touches the ware. If the draft from every fire- 
place were made to pass through a cubic yard or so of bricks closely 
piled, they being both the hottest parts of the kiln, and the most ex- 
posed would probably act as strainers to their respective fires, and would 
eliminate part of the trouble, if not all. 
Nearly all the river works make terra cotta, but at N. U. Walker’s, 
the best ware of this district, and the most of it, is made. Thisis probably 
the largest terra cotta factory in the United States. It has a tempering 
plant for terra cotta alone, a sewer-pipe press for linings and chimneys, 
and has 6 kilns, three of which are very large ones. His daily pro- 
duct would amount to 24 tons of ware, about 20 in flues, ete., and 4 in 
statuary and finer grades of work. The Wassall works, at Columbus, 
make but a small amount, but in the finish and execution of what they 
turn out they take the first rank. 
46 Ge 
