164 CONSTRUCTION AND MANAGEMENT OF SMALL GASWORKS 



entered the number of exposures, from i up. From this 

 form we get on one sheet a plain statement of the position 

 in the purifier house, from which one can see what heaps 

 are fresh, and what heaps are getting stale and spent. 



At the end of this book may be kept a set of tables 

 referring to data in frequent demand. These may, if pre- 

 ferred, be on separate loose sheets, or they may be written on 

 stiff card. Tables I to III (pp. 182-6) enable the yield per 

 ton from any quantity of coal to be ascertained at a glance. 

 For example, if 30 cwts. of coal has been used in the 

 twenty-four hours, and the yield is 13,800 cubic feet of gas 

 and 1 8 cwts. of coke. Turn to Table I, find 30 cwts., follow 

 the horizontal line till we come to 13,800 and the figure at 

 the head of the column is 9,200, which is the yield per 

 ton. Proceeding in the same manner with regard to 

 Table II, we find the yield of coke per ton is 12 cwts. 

 The tar and liquor well may be gauged, perhaps, once a 

 month, and during that period the make of liquid is found 

 to be 300 gallons. If the coal used is 20 tons, the make is 

 easily traced, in Table III, to be 15 gallons per ton, by the 

 same procedure as in Table I. The tables can also be used 

 in another way. A coal is known to be capable of yielding 

 10,000 cubic feet of gas per ton and 13 cwts. of coke. If 

 the quantity carbonized in twenty-four hours is i ton 

 13 cwts., we know from Table I that the yield of gas should 

 be 16,500 cubic feet, and from Table II that the coke 

 should be nearly 21 J cwts. If a close approximation to 

 these quantities is not forthcoming, the reason for the dis- 

 crepancy should be discovered. The uses of Tables such 

 as IV, V and VI (pp. 187-9 f r pricing out various quantities 

 of gas or coke require no explanation. Table VII (p. 190) 

 is useful for taking out wages at an hourly rate, the cost 

 of various lengths of pipe, etc. ; and Table VIII (p. 191) 



