Qreta Shale for the Manufacture of Gas. 7 



Averaging forty seconds for the time expended in charging 

 each retort. The total quantity produced amounted to 1,128 

 cubic feet from 224 lbs. coal in 2 h. 29 min., or at the rate 

 of 11,280 feet per ton of shale, thus showing a very close 

 approximation to the quantity produced in the first experi- 

 ment, the difference being only an increase of 20 feet, or at 

 the rate of one foot per cwt. 



You will observe that the time occupied was less than in 

 the former experiment. This arose from the quantity being 

 used in three retorts instead of two, thereby reducing the 

 quantity in each retort. 



Previous to commencing this experiment I had prepared a 

 small burner, and had carefully weighed and noted the 

 weight of the sperm candle to be used. At the conclusion 

 of the experiment I found the experimental meter indicated 

 a consumption of 2-2 cubic feet per hour, and that the candle 

 had been burning 136 grains per hour. At various times 

 during the distillation of the coal I tested the quality of the 

 gas, and recorded its illuminating power. 



Each value I noted was the average of ten observations, 

 and resulted in showing an average illuminating power of 

 20 '014 candles (say 20 candles) then as— 



2-20 : 5 :: 20 to 4545 



However, as the candle consumed 136 grains per hour, 

 instead of the standard quantity of 120 grains, it was 

 required to find what number of standard candles was 

 represented by 4 5 '4 5, thus — 



. • . 120 : 136 :: 45-45 : 51-51 candles. 



After making various other experiments, both as to quality . 

 and quantity, I obtained the following results as the average 

 of the whole, viz. : — That the shale produces marketable gas 

 at the rate of 11-280 cubic feet per ton ; that 5 cubic feet of 

 the said gas gave a light equal to that derived from or 

 afforded by 51-51 sperm candles, each consuming at the rate 

 of 1 20 grains per hour ; and that one foot of gas gave a light 

 equal to that derived from 1,236-24 grains of sperm ; and 

 finally that one ton (2,240 lb.) of Hartley shale produces 

 the same amount of light as 1,.992 lb. of sperm candles. 



Subsequently I weighed off" 100 lb. shale, and after 

 carbonizing the same, I carefully weighed the coke, &c., 

 and found that it amounted to 32| lb., thus showing that 

 the volatile matter given off* in the destructive distillation 



