The Trial* of Oil Engines at Cambruhje. 
719 
The flywheels had all been turned flat in accordance with 
the instructions of the Society’s engineers, and the brake horse- 
power was measured by a double rope brake completely encir- 
cling the wheel and loaded with a dead weight at one end and 
a spring balance at the other. The weight was kept constant 
throughout the trials, and the spring balance was read every hour. 
The oil w T as weighed into the engine tanks at the commence- 
ment, and the surplus weighed back at the end of the run. 
Where the tanks could not be drained dry, a point gauge was 
inserted, and the oil adjusted to the same level at the beginning 
and end of the run. An error of less than a quarter of a pound 
could in all cases be clearly detected. 
The engines having been started, and the brake-load adjusted 
to give as nearly as possible the power which the exhibitor 
thought best, the time was noted, and the trial commenced. 
The general dimensions and declared speed of the fixed engines 
were as stated in the table on p. 720. 
The oil used was a Russian oil, known as “ Russolene,” 
the price of which, delivered at Cambridge, was at the rate of 
3 \d. per gallon. It was analysed by Mr. Charles J. Wilson, 
F.C.S., who had made the analysis of the oil used on the 
Plymouth trials of 1890. He reports as follows : — 
“ I have made an examination of the sample of Russolene oil received 
from Mr. F. S. Courtney on July 2, 1894, with the following- results : — 
“ Specific gravity at 60° F. = 0-8239. 
“ Flash point (Abel test) = 86° F. 
“ Calorific value . — To determine this the oil was completely burned in a 
closed bomb with compressed oxygen (a modification of Berthelot’s appara- 
tus), and the heat produced carefully measured. Calculated to calories per 
gramme of oil, the mean of two concordant experiments is 11-055. This 
figure includes all heat obtained by condensation of produced water, and 
cooling this and the gaseous products to 28°C. In order to obtain a 
correction for the water produced by combustion, the percentage of hydrogen 
in the oil was determined and found to be 14-05 per cent. ; the produced 
water will, therefore, be 1-2645 times the weight of the oil. Taking the 
latent heat of water at 28°C. as 587 gives 0 742 calories per gramme, and 
deducting this from 1T055 gives 10-313 calories as the heat of combustion of 
one gramme of the oil ; products of combustion in the gaseous state at28°C. 
“ This Russolene oil seems very constant in composition, for a sample 
which I examined more than a year ago gave 14-07 per cent, of hydrogen 
and a calorific value of 10-3 calories — practically identical figures with those 
yielded by the present sample. “ Chakles J. Wilson.” 
The heat value is therefore nearly 18,600 B. thermal units 
per lb. Comparing this with Welsh steam coal with a calorific 
value of 14,500 thermal units per lb., 1 lb. of oil will, in 
heating value, be equivalent to 1-28 lb. of coal, ancl with 
London gas, having a calorific value of 19,200 B. thermal units 
per lb., it would be equivalent to 0-97 lb. of gas. 
3 n 2 
