96 PHILOSOPHICAL TRANSACTIONS. [aNNO 1771. 



them the whole room. The smoke, which has a free passage, is carried off by 

 the funnels. 



The furnace may be placed either in the room itself, or in the next room, or 

 without doors. The poor, who are glad to make the most of the firing that 

 warms the koa-kang, on which they sit by day, and sleep by night, place the 

 furnace in the same room ; the middling sort put it in an adjoining room ; the 

 rich and great have it on the outside, and most commonly behind the north wall. 

 The furnace must be much below the level of the stove, that the heat and flame 

 may ascend with the greater impetuosity into the conductor, and not drive up 

 the ashes. The furnace is in the form of a cone, somewhat arched, that the 

 activity of the heat and flame may be all impelled into the stove, and not fly off" 

 when the aperture at the top is left open. The two little moveable slips are 

 planks, that take up occasionally, when people want to go down into the cellar 

 and empty out the ashes. The opening in the furnace is narrow, and the lower 

 end of the conductor must go quick up into the stove. The conductor is to be 

 walled in very close on all sides with bricks, and well cemented with mortar made 

 of quick lime. That which the Chinese use, is made with 1 part of white lime 

 to 2 of black. The black lime is found at the entrance of the coal pits, and 

 seems to be no other than coals dissolved by rain waters. This substance mixed 

 with white lime makes excellent mortar, nearly resembling cement. It is proof 

 against rain and sun, and is used here to cover and shelter whatever is exposed to 

 the weather. We should rejoice if this hint could prove useful to the British 

 nation. If their country affords black lime, they are possessed of a great treasure. 



The ground or flooring of the stove may be of beaten clay, or, what is infi- 

 nitely better, bricks placed edgewise, or large paving tiles. The funnel for the 

 smoke, or rather the two funnels, must be made with great care. Some make 

 them terminate in little chimneys, that carry off" the smoke above the roof. In 

 the model, they open into the room, as the city poor have them ; but in the 

 country, and in gentlemen's houses, they are on the outside. It is of conse- 

 quence ttiit the little piles which support the great square bricks of the floor be 

 very solid, and the bricks very thick and perfectly square. The Chinese bind 

 them with a sort of cement made of white and black lime, tempered with tong 

 yeou, which is a kind of varnish. We are apt to think walnut or linseed oil 

 boiled would do as well. As soon as the kang is completed, fire is kindled in 

 the furnace, to dry it quick and even. Great diligence must be used in exa- 

 mining it, in order to stop up all the little holes through which the smoke might 

 escape. The wealthy, to make their kang neater, and to moderate its heat, oil 

 the bricks of the floor, and Mght the fire, to make the oil penetrate deeper, and 

 to dry them the faster. This oil is again the tong yeou, and may be supplied 

 with walnut oil. 



