OF THE PINE-APPLE. 



329 



for a short time, the farther trouble of boiling the 

 water, when put upon the quicksilver. 



Secondly, The mealy substance on the under-side 

 of the leaves of the Pine is of such a nature as 

 seemingly to resist all watery matter, and has, 

 therefore, prevented all decoctions hitherto'used 

 for the above purpose from penetrating to the bot- 

 tom of the leaves in the centre of the plants, 

 whereby insects in those parts have always escaped. 



Thirdly, It is allowed, that if boiling water be 

 poured upon a sufficient quantity of quicksilver, it 

 receives a power capable of destroying lice or in- 

 sects : but there wanted something to enable it to 

 reach to the insects in question. Soap seemed to 

 be the most proper vehicle for that purpose, on a 

 double account : it is a penetrating substance, and 

 contains a quality of the former nature. 



Fourthly, Soap-suds have, perhaps, as great 

 powers of penetration as oil ; but oil being added 

 to the second dipping, must make the mixture of 

 equal force. From hence it is probable that the 

 directions given in respect to brushing the in- 

 sects from off the leaves of the Fine, as also the 

 nice inspection recommended, may be quite un- 

 necessary. 



Fifthly, The quantity of soap used renders the mix- 

 ture of a thick, slimy consistence, and, consequently, 

 leaves a kind of coat, or covering, upon the leaves 

 of the Pine, which very probably may prevent the 

 insects from remaining, or even coming upon the 

 plants, in case any of them were left in the hot- 



