Feb.] THE HOT-HOUSE. 17| 
cold: then pour off the water for use Refieat this on the same quick- 
silver (for it will retain its powers') till a sufficient number of gallons 
are provided to Jill a vessel intended for the purpose. One in the form 
of a trough, that will hold eight or ten gallons, is the most convenient, 
especially for the large-sized plants. 
Then to every gallon of this mercurial water add six ounces of soft 
green soap, dissolved in a portion of the prepared water. Let the 
mixture stand till it becomes milk-warm, which is the degree of warmth 
it must be kept to during the time of dipping. 
Before I proceed to the method of applying the above mixture 
to the plants, I cannot avoid calling in question, any virtue that 
may be attributed to a mercurial efficacy therein; first, as it is the 
opinion of the most experienced Chemists, that crude mercury is 
not soluble, in any degree, in pure water, whether poured on, in a 
cold or boiling state; secondly, that if it contained any acid when 
put on, which might decompose a part of the mercury, the adding 
thereto of soap, would by virtue of its alkali, neutralize the acid, 
and thereby disengage and precipitate the mercury: therefore, it is 
at least very questionable, whether its efficacy is not exclusively 
attributable to the alkali of the soap. 
If in place of the quicksilver or crude mercury, above recom- 
mended, you were to substitute corrosive sublimate, in the following 
or even in a greater proportion, there is no doubt of its effectually 
answering the end, without doing the shadow of injury to the plants. 
Dissolve half an ounce of corrosive sublimate, in a pint of gin or 
other spirit; when dissolved, incorporate therewith four gallons of 
soft water, and it will be ready for use. 
The soft soap may be added thereto, in the proportion above men- 
tioned, but its alkali acting on the acid of the sublimate, will convert 
it into a mild muriat of mercury, and consequently render it much 
less active than before. 
Previously let it be observed, that this dressing cannot be effect- 
ually applied with propriety to fruiting pines, either after they have 
started their fruit, or for two months before it, as disturbing their 
roots at that time would prevent their fruit growing to the full size; 
however, succession plants may be dressed at any period, but in the 
month of October that work can be done with the greatest success; 
and fruiting plants, if infested, may at any time be washed with the 
solution, which will destroy such insects as affect them above 
ground. 
Before the plants are taken out of their pots, I would advise 
the brushing off a few of the scaly insects (as in a common dress- 
ing) especially towards the bottom of the leaves, where they will 
sometimes be so numerous as in appearance to lie one upon ano- 
ther, in which case the mixture might be prevented from penetrat- 
ing to the bottom insects. I do not know that this business of brush- 
ing is absolutely necessary; but as the whole operation in a large 
Hot-house may be performed in one day, the labour of a person or 
two extraordinary, for this purpose, can amount to but a very incon- 
siderable expence. 
