FEB.] THE HOT-HOUSE. 179 



destruction of these insects, had never failed him ; its efficacy being 

 confirmed by nine years' experience/' 



THE RECEIPT. 



Take one pound of quicksilver ; put it into a glazed vessel, and 

 pour upon it one gallon of boiling water, which let stand till it be- 

 comes cold ', then pour off the water for use. Repeat this on the 

 same quicksilver (for it will retain its powers) till a sufficient num- 

 ber 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 dis- 

 engage 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 recommended, 

 you were to substitute corrosive sublimate, in the following or even 

 in a greater proportion, there is no doubt of its effectually answer- 

 ing 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 spirits ; 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 muriate of mercury, and consequently render it much 

 less active than before. 



Previously let it be observed, that this dressing cannot be effectu- 

 ally 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 dressing) 

 especially towards the bottom of the leaves, where they will some- 

 times be so numerous as in appearance to lie one upon another, in 

 which case the mixture might be prevented from penetrating to the 



