140 CHEMICAL INDUSTRY IN KWANGTUNG PROVINCE 



The kilns in Ko Chow are not built on the sides of the 

 hill as those in Shek-waan, but are built like small towers. 

 The work done here is much finer than that in Shekwaan. 



Building bricks are chiefly made in Nam Kong j|j gg. 

 Ching Yuen f5f H and Tung Koon ^ ^ (green bricks) and 

 also at Im Bo H *£ (white bricks). For making bricks the 

 river mud and clay which contains no sand is the best. The 

 bricks are formed in moulds. 



The oimplest form of moulding consists in pressing the 

 soft clay into wooden frames which have been dusted with 

 sand to prevent sticking. The operation is done by hand. 

 Each man makes about 300 bricks a day. 



After moulding, the bricks have to be dried before burn- 

 ing. This is done by spreading the bricks and allowing them 

 to dry in the sun. The bricks having been thoroughly dried 

 are placed in kilns and burned. The temperature and time 

 of burning depends upon the kind of clay employed and the 

 degree of hardness desired. Each kiln can hold 70.000 

 bricks, and usually the bricks are burned for 7 days, and 

 cooled for 2 days. In Nam Kong there are about 10 kilns. 

 Green bricks are made in Tsing Yuen and white bricks are 

 made in Im Bo. 



Lime is burned in kilns dug out of the earth. You can 

 see this in Tung Shan ^ 111 (not far from Canton). Shells 

 which contain calcium carbonate are used and they are mixed 

 with fuel and burned until they are changed to lime and 

 carbon dioxide. 



There are two kinds of lime kilns, namely continuous and 

 periodic. In the continuous kilns less fuel is used and much 

 time is saved. In Kwangtung, you can only find periodic 

 kilns. They are 12 feet in diameter and 3 feet deep. 



In America, the kilns are built of bricks and are usually 

 from 40-45 feet high, by 7 feet in diameter. 



The lime kilns in this province require much fuel and 

 time, but are probably preferred because of the simplicity 

 and cheapness of building. The lime obtained is not pure, 

 but is contaminated with ashes. 



After burning, the kiln is allowed to cool. During the 

 time of cooling, discharging, and recharging, the kiln stands 

 idle, and thus much time is lost. Moreover, a large amount 

 of fuel is necessary to heat the walls of the kiln after each 

 recharging, so. that the method is not an economical one. 



No attempt is made in this province to save the carbonic 

 acid gas which escapes from the" kiln. In Europe, the gas is 

 often collected and used for technical purposes. 



In America and Europe lime is used for mortar and 

 cement mixing, bleaching powder, in the Leblanc soda 



