Historical Notes. 
159 
4. Fuel consumption . — Owing to the conditions of running 
of these plants it is important to know the fuel consumption, 
including the amount burnt at night when the plant is 
standing. The general practice in the case of an engine doing 
constant work is to light the fire on Monday morning, bank 
the fire during the night, and only draw it on Saturday to 
clean out the producer. This practice was kept in mind when 
arranging the trials. 
Although anthracite can be obtained in most districts it is 
easier to get coke, and, apart from the difficulty already 
mentioned in connection with tar, it will generally prove to be 
a cheaper fuel, notwithstanding the greater weight consumed. 
The coke trial was therefore of special importance. 
It was borne in mind that in the case of these plants the 
cost of fuel is relatively far less important than in the case 
of a steam engine, because in the former from 1 lb. to 1^ lb. 
of coal or coke is required per B.H.P.-hour, whereas in the 
case of non-condensing steam engines of a suitable class for 
“ estate ” engines from 5 lb. to 6 lb. are needed, and with 
small condensing engines about 3 lb. 
The water consumption and the last three points require 
no comment. 
These regulations seem to cover all the essential points for 
consideration in trials of this nature. 
Historical Notes. 
The combination of a gas engine with a suction gas pro- 
ducer is of such recent origin that a few historical notes do 
not appear to be out of place in this Report. 1 
Producer gas was first introduced in 1861, by Sir William 
Siemens, for steel melting, but only air was used, and in 
these circumstances at least 30 per cent, of the heat of the 
coal would be wasted if used in a gas engine. In 1878, 
Mr. Emerson Dowson applied steam as well as air ; that is, 
he combined Siemens gas with water gas. In this way a pro- 
ducer gas was made which not only contained 80 to 90 per 
cent, of the energy in the fuel, but was more readily ignited 
in a gas engine owing to the free hydrogen it contained. 
The first step towards a suction gas producer was made 
by Mons. Benier, in Paris, in 1894, when he succeeded in 
utilising some of the waste heat in the producer itself to obtain 
the necessary steam, instead of having a separate boiler burning 
a considerable amount of fuel, as is necessary in the case of 
pressure producers. The gas engine he employed was of the 
1 These historical notes are principally taken from a paper on “ Suction 
Gas Producers,” by Mr. W. A. Tookey, before the Junior Institution of 
Engineers. 
