MATERIALS 



Arsenical preparations. — These are used for 

 the destruction of caterpillars, etc., by poisoning their 

 food, the application of them being generally made 

 to the trees when just coming into leaf. Great care 

 must be taken in using them, as they are intensely 

 poisonous, to both man and beasts. Work in this 

 country and in America has shown, however, that the 

 use of arsenic compounds is not, under ordinary 

 circumstances, attended with any danger of poisoning 

 the fruit, or the herbage under trees in grass orchards ; 

 but they should not be applied within three or four 

 weeks of the ripening of the fruit, nor during the 

 blossoming of the trees, otherwise bees visiting the 

 flowers may be poisoned. Arsenical compounds must, 

 also, always be used in an insoluble condition, for, 

 when soluble, they are injurious to plant-life, scorching 

 the leaves, and even killing the plant. None of the 

 compounds in use are absolutely insoluble, and, con- 

 sequently, a little scorching of the foliage is liable to 

 occur in some cases. Considerable preference has 

 been given of late to the arsenates as compared with 

 the arsenites. 



The compounds in most general use are the 

 following — 



I. Aceto-arsenite of copper : Paris green. — It is best 

 for the grower to buy this, instead of trying to make 



