254 CHEMICAL FERTILIZERS 



boiled for 8 hours in 5 times their weight of water, the 

 liquor poured off, and the chips again boiled with the same 

 amount of fresh water. The second weak extract is used 

 for fresh chips. The extract is treated with enough soap 

 to equal one-half the weight of quassia chips taken. The 

 strong extract thus obtained can be diluted with 10 or 20 

 times its weight of water as required. The chief use of 

 quassia is to remove aphis. 



Pepper. Waste pepper can be extracted with water in 

 the same way as quassia. Pepper can also be used dry by 

 dusting it on to gooseberries and other fruits infested with 

 caterpillars. Red pepper is more potent than black pepper 

 for such purposes. 



Pyrethrunv Persian Insect Powder. Seeds of 

 Pyrethrum roseum or Pyrethrum carneum (Chrysanthemum 

 coccineum or Chrysanthemum cinerariaefolium) are sown in 

 May and the flowers collected when ready, which may not 

 occur till the following summer. The insecticide consists of 

 the pollen from the male flowers. Care should be taken 

 not to heat the powder either by sun heat or fire, as the 

 poison is volatile. The poisonous principle is soluble in 

 alcohol ; an extract can be made in a percolator by 

 slowly allowing methylated spirit to trickle down a long 

 column of pyrethrum powder loosely packed in a tube. 

 The effluent spirit should weigh about the same as the 

 powder taken. The alcoholic extract may be diluted with 

 water up to 300 times its bulk and sprayed on plants infested 

 with caterpillars. Pyrethrum powder must not be extracted 

 hot, as the poisonous ingredients are partly decomposed. 



Hellebore. The rhizome of Veratrum album is dried 

 and ground to powder to produce hellebore powder. The 

 powder is mixed with 300 times its weight of water and 

 used as a spray for biting insects. After a few days' ex- 

 posure to air the poisonous properties disappear and render 

 the fruits or other edible parts of plants safe to use. 



