PREFACE. 



241 



puts the method in practice. However, I could 

 wish to recommend that the principal part of the 

 directions, so marked, should be adopted ; espe- 

 cially as they are not attended with much additional 

 expense. 



There is the greatest probability that a much 

 easier method may yet be practised, than that which 

 I have hitherto pursued, and that the insects on 

 Pines may be destroyed by infusing quicksilver in 

 the water kept for the use of the hot-house. This, 

 however, I only give as a probable speculation, 

 because after I had destroyed all the insects on the 

 Pines in the stoves of which I had the care, I was 

 deprived of the means of making any farther ex- 

 periments. 



It may be objected by some, that simple water 

 is not capable of taking any thing from the quick- 

 silver, and that I should have proposed other me- 

 thods to keep that metal in a state of suspension. 

 In answer to this I shall only observe, that as the 

 composition I have recommended for the destruc- 

 tion of insects had never failed me, I judged it 

 unnecessary to make any alteration in it. Such 

 persons as choose to enter upon a course of expe- 

 riments, in which the suspension of quicksilver 

 in water becomes necessary, will be able to produce 

 that effect, by means of a strong mucilage of gum 

 arabic ; . and indeed many other substances are 

 capable of performing that office. 



R 



