215 



in combination with other compounds to insure their stick- 

 ing to the plants until they have done their work. 

 Composition. The formula employed is : 



5 pounds of pulverized re^in. 



1 pound of concentrated lie. 



1 pint of fish or some other animal oil. 



5 gallons of water. 



This mixture is the stock solution, which is still further 

 diluted as used. 



Making the mixture. The oil, resin and one gallon 

 of cold water are to be put into an iron kettle and heated 

 until the resin softens. Add the lime and stir well. Then 

 add four gallons of hot water and boil until a little mixed 

 with cold water gives a clear amber-colored liquid. Add 

 water to make up for what has boiled away, making five 

 gallons of the compound. 



Use. This spray, besides causing other mixtures to 

 adhere to the foliage of plants, is itself an excellent contact 

 insecticide. Its principal effect is through making a smoth- 

 ering coating over the body of the insect. It is used in 

 some regions as a dormant wash for the control of scale 

 insects. When used with Paris green or Bordeaux, two 

 gallons of resin-lime compound are mixed with eight gal- 

 lons of water, and this added to forty gallons of the spray. 



TOPICS FOR INVESTIGATION 



1. Copper sulphate costs from seven to ten cents a 

 pound, and lime, when bought in small quantities, about 

 fifteen cents a pound. What, then, should be the outlay in 

 making fifty gallons of Bordeaux mixture? What would it 

 cost for material to spray ten apple trees averaging a 

 twenty-five- foot spread ? 



2. Under the direction of the teacher and with great 

 care in handling both before and after mixing, let the class 



