146 A PRACTICAL TREATISE 



When the inside of the kiln, however, begins to be filled up 

 with clay, then the wall must be raised as high as may allow 

 the earth to be thrown on without much additional labour; 

 and care should be taken, during the burning, to keep the 

 wall fifteen or eighteen inches higher than the top of the clay, 

 in order to prevent the wind from acting on the surface of the 

 fire. As soon as the fire is strongly kindled, the mouths of all 

 the flues, except the one to windward, should be stopped, and 

 even that will only be of use at tiie commencement of the 

 process; for, if the fire burns with tolerable keenness, the sods 

 of which the flues are composed will soon be reduced to ashes. 

 Some people, therefore, dispense with the use of flues alto- 

 gether; but the trouble of making them is very slight, and the 

 want of them often occasions difficulty in the management of 

 the fire. 



The kiln may be increased to any size, by raising a new wall 

 round tiie former when that one has been burned through; and 

 in this manner kilns have been made so large as to contain 

 more than 100 loads of ashes: but, as these walls cannot be 

 equally pulverized, they should be broken down, and blended 

 with the contents of the kiln, as that is burning out. No 

 precise period can be fixed for the time which the operation 

 will occupy, as much will necessarily depend upon the quantity 

 of matter, the nature of the fuel, its management, and the state 

 of the weather; most accounts, therefore, affirm, that it can be 

 well accomplished — that is to say, both sufiiciently burned, and 

 afterwards cooled, in a few days; some, in a fortniglit; others, 

 in a month; but Mr. Burroughs says, that it requires about six 

 weeks, and that it will not then be in good order for the land 

 until after two months longer, for it will take considerable 

 time to reduce it to powder. When the kilns are burnt out, 

 the ashes are still paler than the original clay, and are gene- 

 rally in a powdery stiite, or are easily rendered so by a slight 

 stroke of the shovel, either when filling the cart, or when they 

 are spreading upon the ground: this, indeed, should never be 

 neglected if there be any appearance of lumps, for if the earth 

 be not completely pulverized, it will have little other effect 

 upon the land than may be expected from bits of brick. The 

 expense of burning clay in the kiln here described is stated to 

 bp, in Ireland, from 'StI. to 4f/. an Irish load, or about 40s. or 

 50.V. the Irish acre, — ecpial to about 32s. Imperial measure ; 

 but, with the usual inaccuracy observable in all accounts of 

 manure per load, we are lefl to guess at its contents. 



