84 W.E.A. Aikin on the Illuminating power of Coal Gas. 
when kept four days will require the consumption of 460 a 
inches per hour to give the same light. My first attempt to 
tain some definite results began on the evening of the 8th ult 
when I filled a large receiver from the street main and place 
on the shelf of the pneumatic trough, the next evening I filled 
a second one and put it alongside of the first, the following eve — 
ning I filled a third receiver, and still the following evening, the 
11th inst. I filled a fourth receiver. On the evening of the 
12th I was‘thus provided with four jars of gas, one of which hat 
been standing 24 hours or one day over the pneumatic trough, 
this I will call No. 1; another, No.2, had been standing two 
days; No. 3 had been standing three days, and No. 4 had been 
four days in contact with the water. The diminution in volume 
by such exposure was indicated by a receiver graduated to cubic 
inches into which I introduced 130 cubic inches of gas on WE 
evening of the 8th; on the evening of the 12th this had lost 
about 104 cubic inches, indicating a loss of about 8 per cenb 
The effect produced on the illuminating power of the gas by 
the loss of volume became at once apparent as I roceeded 10° 
contrast the value of the flames furnished by the contents of the 
several receivers, 1, 2,3, and 4. I used for this purpose the or 
dinary photometer arrangement, taking the relative intensity of 
the light. The candle employed for the comparison was the pa 
ent candle already referred to, and the burner was the ind 
known as fish tail burner, which had been previously guaged, 
and known to consume a trifle more than 5 cubic feet per hour 
with the average maximum pressure of the gas works. need 
hardly add that the burner was the same in all the trials, and of 
cupied exactly the same position. The burner and the sere? 
on which the shadows fell were not moved at all during the 
most luminous gas the adjustment became simply a gradual with 
* 
the receiver and the gas burner. This arrangement gave ™ 
a steady, equable flame, which continued perfectly uniform 
