1878, | 309 
[Briggs. 
by regular reference to the board of Secretaries, to be re- 
served until other papers of the series were received and pre- 
sented for publication at the convenience of the Society. 
Dr. Le Conte read a summary of the places where the col- 
lections were made. 
Mr. Briggs communicated his results in discussing the 
question where and how the heat generated by a gas burner 
disperses itself. 
In a recent investigation of the chemical and physical properties of ordi- 
nary coal gas and its products of combustion, which was made in preparing 
a statement exhibiting the various relations of chemical changes and heat 
effects, attendant upon gas lighting, the results of which were intended to be 
applicable to the heating and ventilation of habitable rooms, has given a 
value for the heat evolved by burning of coal gas, of so large amount, that 
it is difficult to account for the dispersal of this heat, at all in accordance with 
the common observation of the result of gas burning. No facts in physics 
are so positively established as the heat effects upon bodies, and the determi- 
nations of Favre and Silbermann and Regnault have been corroborated by 
numerous examiners, and are accepted by all physicists. The combustion 
of coal gas, as it is consumed in lighting, is so nearly a perfect one, with 
the products of H,O and CO, completely effected, that it must be asserted 
that the full equivalent of heat due to the chemical combination of the en- 
tire Hydrogen and Carbon or Carbonic oxide is produced by the burning. 
The coal gasitself may be taken as having a specific gravity of 0.426, which 
gives at 70° a weight of 0.0319 lbs. per cubic foot. Careful computation 
gives about 19,450 units of heat as the effect of burning one pound, or 622 
units as the effect of one cubic foot, and it follows that a four foot gas bur- 
ner, that is such a burner as will burn four cubic feet in one hour, will 
produce 2488 units of heat. Taking an extreme case of lighting, a small 
bed-room which may be assumed to have a floor area of about 100 square 
feet (that is 8/12’ or 10’/x10/ on the floor) and to be 8 feet in height of 
walls, thus having a cubic capacity of 800 feet; this room would be ap- 
propriately lighted by a single gas burner, consuming four cubic feet per 
hour. If it could be imagined that the room was closed against the ad- 
mission of any fresh air whatever, and that the air at the commencement 
of the experiment was at 70° Fah. with 60 per cent. of humidity, and be- 
sides these conditions, that no loss of heat occurred from the enclosing sur- 
faces, floor, walls, ceiling, doors or windows, then at the end of an hour’s 
time the following changes.in the air would have occurred : 2.42 cubic 
feet of carbonic acid, and 0.253 pound, = 5.42 cubic feet of aqueous 
vapor would have been generated, while 4.91 cubic feet of oxygen would 
have been taken up ; and 2488 heat units would have been produced. The 
changes are as follows: 
