CACTUS SOLUTION AS AN ADHESIVE. 13 



in this acre the aphis was making its appearance. The soap was 

 used at the rate of 3 pounds to 60 gallons of water. Very careful 

 notes were made on the sticking qualities of the soap, and it was 

 found that when compared at close range with the cactus spray the 

 soap equalled the cactus in spreading power, although lacking in 

 adherence. This information was obtained by observing sprayed 

 plants with and without a lens. It was soon seen that the cactus 

 spray adhered and dried on the foliage better than the soap spray. 

 This favored the cactus, since the heavy dews in the Rio Grande 

 Valley will wash poison having but slight adhesive qualities from the 

 foliage in a short time. 



COPPER SULPHATE AS A PRESERVATIVE FOR THE CACTUS. 



On April 6, 1914, 50 pounds of cactus were cut into small pieces and 

 placed in a barrel with 21 gallons of water, and on April 7, 1 pound 

 of copper sulphate was dissolved in 4 gallons of water and added to 

 the barrel which was numbered lot 6. 



The solid portion of the cactus or prickly pear was removed before 

 adding the copper sulphate. This made 28 gallons in solution. 

 No chemical action was observed. The solution kept perfectly for 

 about four weeks, when it had to be discarded to make room for 

 other experiments. The temperature during this time averaged 

 about 70° F. 



COPPER SULPHATE USED WITH ZINC ARSENITE. 



After using the copper sulphate as a preservative for the juice 

 extracted from the prickly pear, the possibility of a chemical reac- 

 tion upon the addition of the arsenical to the solution was tested. 

 Upon the addition of powdered zinc arsenite at the rate of 1 pound 

 to 60 gallons of water a slight chemical reaction was noticed, evi- 

 dently the copper changing places with the zinc to a small degree. A 

 slight precipitate was formed, but not enough to cause any trouble 

 when a good pressure was maintained in the tank of the sprayer. 

 The precipitate was not increased after the mixture was allowed to 

 stand for three hours. No difference was observed in the effective- 

 ness of the arsenical, either with or without the addition of the 

 copper sulphate. 



COPPER SULPHATE USED WITH LEAD ARSENATE. 



The use of lead arsenate in combination with prickly pear with- 

 out the addition of some other chemical has never been a success. A 

 precipitate is always formed which makes it impossible to use the 

 mixture to advantage as a spray. The same proportion of cactus and 

 copper sulphate utilized in the zinc arsenite spray was here em- 



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