234 THE TREE DOCTOR 



14 London Purple. 



If desirable, London purple may be substituted for Paris 

 green, but it has the disadvantage of being somewhat variable 

 in composition and containing more soluble acid. For the latter 

 reason use it somewhat weaker, or else with an abundance of 

 lime, so as to prevent burrn'ng of foliage, or in Bordeaux mix- 

 ture. It has the advantage of not settling as readily as Paris 

 green. 



15 White Hellebore. 



Hellebore is often employed in cases where arsenical poisons 

 would be objectionable. Use one ounce to three gallons of 

 water. 



16 Pyrethrum. 



Pyrethrum is usually applied as a powder, with a bellows, 

 but may be used as a spray at the rate of one ounce to two gal- 

 lons of water. 



17 Whale Oil Soap Solution. 



Use from one to two pounds of the soap to one gallon of 

 water. Be sure that the soap is thoroughly dissolved, and then 

 apply in the form of spray. 



18 Arsenite of Soda. 



Dissolve two pounds of commercial white arsenic and four 

 pounds of carbonate of soda (washing soda) in two gallons of 

 water and use one and one-half pint to a barrel of Bordeaux mix- 

 ture (50 gallons). 



The easiest way to make the solution is to put both the 

 white arsenic and carbonate of soda in a gallon of boiling water 

 and keep boiling about fifteen minutes, or until a clear liquid is 

 formed, and then dilute to two gallons. 



Caution This cannot be used alone safely, but must be ap- 

 plied in Bordeaux mixture. 



