150 
■Rotes, Communications, anb 
IReviews. 
OIL-ENGINES IN RELATION TO AGRICULTURE. 
Although liquid fuel has been employed during the last twenty years 
for the production of mechanical energy, it is only lately that its use 
for this purpose has been sufficiently successful to justify the 
question, May a farmer use an oil-engine 1 
Meanwhile, certain preliminary considerations of great import- 
ance in the choice of such an engine beset this inquiry, and must 
be disposed of before it can be usefully answered. 
Liquid fuel has been employed in the past in four different ways. 
1. It has been burned as, and instead of, coal, by means of suit- 
able spray-making devices, in the furnace of an ordinary steam- 
boiler. 
2. In one or other of its more volatile forms, such as naphtha or 
benzoline, it has formed the fuel of a boiler, itself containing naph- 
tha or benzoline, whose vapour takes the place of steam in the 
motor. 
3. It has been evaporated at low temperatures, and the resulting 
vapour, mixed with a suitable proportion of air, exploded in the 
cylinder, as in the gas engine. 
4. It has been gasified at high temperatures, and the resulting 
gas, mixed with a suitable proportion of air, exploded in the cylinder 
as in the former case. 
These plans are all defective, for various reasons. Method No. 1 
is costly ; for, although experiment has proved that a pound of oil 
burned, in the best way, in the furnace of a steam-boiler will evapo- 
rate some twenty-five per cent, more water than the same quantity 
of Welsh coal, the oil costs four times as much as the coal, weight 
for weight. 
Method No. 2 is dangerous ; for only the volatile mineral oils, 
such as naphtha or benzoline, whose vapour ignites at comparatively 
low temperatures, can be employed for the purpose. In addition, 
these “ spirits ” (rather than oils) are not easily procurable in the 
country, are dangerous to handle or store, and are regarded with 
profound dislike by both railway and insurance companies. 
Methods Nos. 3 and 4 are surrounded with difficulties ai-ising 
from the fact that the petroleum of commerce is not a simple body, 
