CLAY MANUFACTURES. 713 
and waiting to refill. The drums are shifted backward and forward by 
a horizontal cylinder to one side. ‘The capacity of a press varies with 
the kind of clay used, the size of pipe made, and many other conditions, 
but in normal working, will not wary far from these figures: 36-inch 
press, making 6-inch pipe, 3,000 feet a day; 12-inch pipe 1,000 feet 
daily ; 15-inch pipe, 800 feet; 18-inch pipe, 650 feet ; 20-inch and 24- 
inch pipe, about 500 feet daily. 
The heat used in sewer-pipe burning is only that necessary to get a 
good salt glaze; about one barrel of salt to a kiln is required. Coal is 
the fuel invariably used. ‘The finished pipe are, after some coating, 
stacked up in piles ready for sale. The fittings which go with the pipe, 
such as curves, elbows, traps, Y’s and T’s, and all the other special shapes 
are made by hand in plaster molds. An outline of the process used at the 
river works has now been given, but it remains to notice the general 
quality and character of the ware, and the defects and their causes. 
The river pipe are made from a homogeneous clay, 7 ¢., the clay, by the 
nature of the preparatory steps, is reduced to a fine, even state of divi- 
sion, and by the character of the tempering plant is made into a per- 
fectly uniform paste. And as it enters the pressing chamber in a com- 
paratively fine state, the force which compresses it does not make the 
lines of demarkation between the particles which composed the mass 
apparent as it would if the clay were not as soft as it is, and as finely 
divided. So when a piece of river pipe is broken its fracture shows an 
even, fine-grained structure, not so fine as stone-ware, but very similar 
and varying from a buff to a grayish-blue. This latter is the best tint 
to get, as it insures the combination of whatever impurity the clay con- 
tains with the free sand, and development of the best qualities of the 
clay. The use of salt makes the color a necessity, as a rule, for the 
combination of iron always begins before the glazing by salt vapor does. 
The strength that these pipe have is far in advance of any other Ohio 
pipe, as the structure, seen on the fracture, would show. The degree of 
heat which the clay will stand without injurious effects is far above the 
glazing heat of the pipe, and the only precaution in the burning to be 
observed is to secure enough heat with no close limit on the side of 
excess. The iron found in these Kittanning clays is present in small 
grains, which, under the action of the salt glaze, make unsightly black 
blisters and holes in the surface, though in no degree injuring the 
utility of the ware; this feature has hitherto much injured its popularity. 
