APPENDIX. 461 



of clay, leaving- a hole at the bottom, for the entrance of the air, and 

 another at the top, for it to pass otf. Such, at least, was the method 

 former]} practised in Greatbritain ; but the modern improvement of 

 retaining the smoke within the mass, agreeably to the plan spoken 

 of by Mr. Cobbett, for burning earth, ought also to be pursued in 

 burning clay. After the fire has been set to the wood, you continue 

 cliging up fresh clay and piling it around and over the heap, as fast as 

 the fire penetrates the mass ; taking care, however, not to pile on so 

 much at once as to extinguish the lire. It there be danger of its be- 

 coming extinguished, it may be advisable to make one or more holes 

 in the sides of the heap by runing a pole into it. The fresh earth 

 is to be added during pleasure, or until a sufficient quantity is burn- 

 ed. After the heap has cooled it is fit for use, by mixing with the 

 soil, as directed by Mr. (Jobbctt* for applying burnt-earth, of which 

 we will next speak. 



By a late improvement, earths, other than those of clay, are suc- 

 cessfully converted into good manure, by the process of burning. 

 It is effected by retaining the smoke within the mass of earth, while 

 in a state of ignition. Mr. Cobbctt says he has tried this manure for 

 the ruta-baga-crop, and found it as efficacious as barn-dung. His 

 manner of preparing it, and which we believe would also be the best 

 method of preparing burnt-clay, is as follows : 



1 make a circle ^says Mr. Cobbctt) or an oblong square. I cut 

 sods and build a wall all round, three feet thick, and four feet high. 

 I then light a fire in the middle with straw, dry sticks, boughs, or 

 such-hke matter. 1 go on making this fire larger and larger, till it 

 extend over the whole bottom of the pit or kiln. 1 put on roots of 

 trees or any rubbish-wood, till there be a good thickness of strong 

 coals. I then put on the driest of the clods that 1 have ploughed up 

 round about, so as to cover all the fire over. The earth thus put in 

 will burn. You will see the smoke coining out at little places here 

 and there. Put more clods wherever the smoke appears. Keep on 

 thus, for a day or two. By this time, a great mass of fire will be in 

 the inside. And now you may dig out the clay, or earth, any where 

 round the kiln, and fling it on without ceremony, always taking care 

 to keep in the smoke; for, if you suffer that to continue coming out 

 at any one place, a hole will soon be made ; the main force of the fire 

 will draw to that hole ; a blaze, like that of a volcano, will come out, 

 and the fire will be extinguished. 



A very good way is, to put your finger into the top of the heap 

 here and there ; and, if you find the fire -very near, throw on more 

 earth. Not too much at a time, for that weighs too heavily on the 

 fire, and keeps it back; and, at Jirst, will put it partially out. You 

 keep on thus augmenting the kiln, till you get to the top of the walls, 

 and then you may, if you like, raise the walls, and still go on. No 

 rain will afreet the fire, when it is become strong. 



The principle is to keep, out air, whether at the top or the sides, 

 and this you are sure to do, if you keep, in the smoke. I burnt, the 

 last Summer, about thirty wagon-loads in one round kiln, and never 

 saw the smoke at all, after the first four days. It put in my finger to 

 try whether the fire was near the top ; and, when I found it ap- 

 proaching, put on more earth. Never was a kiln more completely 

 burnt. 



Now, this may be done on the skirt of any wood where the mat- 

 ters are all at hand. This mode is far preferable to the above grou?id- 

 burning in heaps. Because, in the next place, the smoke escapes 

 there t which is the finest part of the burnt matter. Soot, we know 

 well, is more powerful than ashes, and soot is composed of the 



