12 SPRAYING CROPS 



pick up on the point of a penknife ; tilt the plate at a 

 slight angle and gently tap the edge, just enough to 

 cause the green to flow down leaving a streak across 

 the plate. If the green is of good quality, the streak 

 will be a bright, light emerald green ; if adulterated, a 

 whitish or a sickly dull green. Any samples which 

 exhibit the latter are either adulterated or of low grade 

 and as such are not worthy of further consideration." 



Arsenate of Lead This poison has recently come 

 into general use as an insecticide. It has many ad- 

 vantages as it is a very fine insoluble powder, that 

 remains in suspension a long time and does not burn 

 the foliage even when applied at the rate of 3 or 

 more pounds to 50 gallons of water. It also adheres 

 to the foliage better than Paris green and may be seen 

 upon the leaves more readily so that the thoroughness 

 of the spraying may be more easily determined. On 

 the other hand it is rather slow in its action. It should 

 be bought in the form of a thick paste. "For the 

 garden or for the small orchard," writes Professor 

 John B. Smith, "this arsenate of lead in paste form 

 is the most convenient and reliable arsenical poison 

 that we have. There is no danger of using too much 

 of it, and it can be employed on plants of all kinds. 

 I used it on my roses to destroy the slugs and applied 

 it on all other plants that were subject to caterpillar 

 attack. It has the advantage of whitening the foliage 

 somewhat, so that its presence is easily recognizable, 

 and it has lasting qualities superior to any of the other 

 arsenical poisons known to me. In the peach orchard 

 there is nothing so good if leaf -eating insects are to be 

 combated." The forms of arsenate of lead upon the 

 market are Bowker's Disparene and Swift's Arsenate 

 of Lead. 



London purple generally contains nearly the same 

 percentage of arsenic as Paris green ; but the arsenic 



