82 Properties of Wood Ashes. 



laid upon a board. In two minutes the " fire went out" of both 

 these coals. 



2. A wooden pill-box of the largest size was filled with sifted 

 ashes, and an oak coal weighing seven grains was barely buried 

 in them. In thirty five minutes the box was very warm all over ; 

 and at this time I surrounded it with cold ashes. In twenty 

 minutes more, the ashes within and immediately around the box 

 were uncomfortably hot. 



3. I renewed the second experiment, with the exception of not 

 wholly covering the box. The edge was left exposed, to ascer- 

 tain whether it would not act as a vent to the accumulating ca- 

 loric. In half an hour I examined the coal, and found it extinct 

 and the ashes cold. The coal in this case was of beech. 



4. This beech coal lighted at one corner, was placed on a cone 

 of sifted ashes, as in the first experiment, and in twenty minutes 

 it was thoroughly ignited. I now pressed a cylinder of paste- 

 board perpendicularly into the ashes, so as to include the coal and 

 most of the heated ashes. The upper edge of the cylinder was 

 left uncovered. I did not examine the coal for an hour ; it was 

 at that time not consumed but dead, and the ashes were entirely 

 cold. 



5. I built a cone of a quart of pale ashes, and deposited eight 

 or ten dead coals some distance apart, near the base and re- 

 mote from the surface ; at the apex I buried a live coal as before. 

 In three quarters of an hour, stiff paper or a splinter of wood 

 thrust into the centre of the heap took fire ; and on demolishing 

 the pile, I found that the heat had descended to the coals below, 

 and ignited them ; indeed they were partially consumed, and the 

 whole interior of the base of the cone was extremely hot. 



6. A wooden box ten inches deep and eleven inches square, 

 was filled with unsifted ashes as cold as an exposure of several 

 weeks in winter could make them. A pint of hot ashes was 

 thrown upon the middle of the surface and left uncovered. In 

 eight hours all the central portion of the ashes was hot enough 

 to fire wood thrust into it, and two sides of the box were inca- 

 lescent. In twenty three hours, the bottom of the box was quite 

 warm, the top of the ashes cool, and the sides of the box were 

 becoming cool. A stick plunged to the bottom of the ashes, was 

 drawn out ignited or burnt at the end, bat not even charred above 

 it. In thirty hours the bottom of the box was almost insupport- 



