On Soap-Suds as a Manure . 29i 
compost would not be compensated by any superior effica- 
cy, that may be expected to arise from the combination 
of the horse- dung. 
It also appears from the experiment, that the compost 
is a more useful discovery than Dr. Hunter himself 
could justly infer from his own limited experience of its 
effects. 
2. This mixture of an oil and an alkali has been more 
generally known than adopted, as a remedy against the 
insects which infest wall-fruit trees. It will dislodge 
and destroy the insects, which have already formed theiy 
nests and bred among the leaves. When used in the 
early part of the year, it seems to prevent the insects 
from settling upon them ; but whether by rendering the 
surface of the leaf disagreeable to the bodies of the ani- 
mals, and thus repelling them, or by neutralizing the 
acid they deposit, and thus preventing the leaf from con- 
tracting into a necessary form for their reception, I can- 
not presume to determine. One of the modes, by which 
this mixture indirectly contributes to the fertility of the 
ground, may be by its destruction of the insects, which 
prey upon the plants. 
It is also, I think, to be preferred to the lime water, or 
the wood ashes and lime, which Mr. Forsyth recom- 
mends to be used for the removal of insects. It is prefer- 
able to the lime water and the lime, because lime loses its 
causticity, and with that its efficacy, by exposure to air, 
and must consequently be frequently applied; and to the 
dredging the leaves with the fine dust of wood ashes and 
lime, because the same effect is produced by the mix- 
ture without the same labour, and is obtained without ex- 
pense. 
Mr. Speechley, in his treatise on the Vine, published 
in 1796, has used this mixture with great success ; but he 
has applied it awkwardly and wastefully. He directs it 
