Bricks made of Anthracke and Clay. 121 



of English coal, or llie coak which is made from it by depriving it of 

 its bitumen : tliis substitute for it was therefore as ingenious as it was 

 successful, and I shall now proceed in describing the mode of using it 

 here, as experience has suggested. 



, The materials for the making of brick at Ncwburgli, Cornwall, antl 



Haverslraw, do not differ materially in any respect except color, 



which in some places is blue in otliers yellow. The clay is a heavy 



I tenacious loam, consisting principally of argil, some silex and oxide 



of iron. I have found, by experiment, that it contains so little calca- 

 reous earth, that no effervescence takes placb when it is submitted to 

 the action of dilute marine acid. This clay is prepared in tlie usual 

 manner; being first dug from the pit, and then frequently turned for 

 some time and exposed to the air and frost, for at least one season. 

 When it has undergone this necessary preparation, it is again turned 

 and tempered by treading ; in this state it was formerly the custom to 

 prepare it for moulding, but since the discovery of the value of an in- 

 termixture of a certain quantity of anthracite coal, the clay should be 

 deposited in layers of five or six ihches, on which is laid the proper 

 proportion of anthracite coal, powdered and skreened through a wire 

 skreen, the opening of which should not be so much as half an inch 

 wide J it should thus be mixed in alternate layers with the prepared 

 clay, and duly and regularly incorporated with it, previously to its be- 

 ing moulded in the form of bricks, which are first dried in the air and 

 afterwards placed in the kihs in the usual manner, to undergo tlie 

 process of burning. Kilns of the average size, contain about one 

 hundred thousand bricks ; to burn these effectually in the accustomed 

 manner, required about forty five cords of good wood, and the op- 

 eration was seldom completed in less time tlian ten or twelve days. 



The value, however, of this new method of burning the brick be- 

 comes now apparent, as tlie process of burning which formerly took 

 ten or twelve days, is now completed in five, and instead of its con- 

 suming forty five cords of valuable wood, it requires not more than 

 fifteen cords, whilst at the same time the bricks are more completely 

 and equably burnt to tlie centre, and as far as we can at present, 

 judge by experience, tliey are rendered as hard and as durable as the 

 English brick. Thus, a saving of thirty cords of wood valued here at 

 one hundred and fifty dollars, is made, in the burning of one hundred 

 thousand bricks,' while tlie process of burning them is completed in 

 half the time. 



T 



Vol. XVIII.— No. 1. 16 



