LEAD AND SILVER. 135 



sides are sometimes built to project slightly above the front in 

 order that the gases may be directed away from the charsrino; 

 floor and blower at the back. The front of the furnace is made 

 of a double wall of brickwork which can be pulled out and renewed 

 when necessary. It contains the slag hole, situated a little way 

 above the depression which forms the hearth. The tapping hole 

 is at the side of the furnace. Its clay plugging is pierced by 

 means of an iron rod, and the molten metal flows into a mould 

 in a bed of sand. 



The blower is raised two or three feet above the level of the 

 furnace hearth, and the tuyer is made to slope directly down upon 

 the hearth. Great importance is attached to the direction given 

 to the tuyer. The blower is of the ordinary cylindrical type about 

 five or six feet long. It is worked by manual labour or by means 

 of the upright-axled water wheel. 



All the material put into the furnace is first weighed. To 

 help the fusion at the commencement, a small quantity of old 

 slag is sometimes added. The usual charge appears to be about 

 two-thirds charcoal to one-third of ore, but of course there is no 

 fixed rule and much depends on local conditions. Each group 

 of furnaces is under the direction of one chief smelter, always 

 an old man of great experience ; beyond the careful regulation 

 of the charges there does not appear to be any difficulty in working. 

 The lead is cast into small pigs and is then sent to the cupellation 

 furnace which is generally placed under a neighbouring shed. 



The furnace, or as Rocher describes it, the oven, from its resem- 

 Cupollation hlance to a baker's oven, is generally of a 



hemispherical shape. (The Bawd win furnaces 

 were more of a beehive pattern than any I have seen in Yunnan.) 

 Its diameter is between five and six feet, though I have seen larger 

 furnaces than this, and the height is Somewhat less. The hearth 

 is only slightly concave and has a slight slope towards the door 

 to permit of easy manipulation of the charge. Two doors in the 

 wall which forms the front of the furnace serve, in the case of the 

 lower as a charging door, and in the case of the ujoper as 

 the door from which the firing is done. The most striking thin" 

 about the Chinese method is that the metal is placed under 

 the lire and is heated by radiation from above. The section of 

 the dome-shaped oven is semi-circular and at about half the dis- 

 tance up, that is to say between the level of the hearth and the 



