52 Preparation of Substances 



much thicker if the preparation has stood 

 for several days. Decant the clear Hquid 

 into the special Ume-suifur hydrometer cyl- 

 inders and take the density on both the 

 specific gravity and Beaume scales. From 

 the concentrated clear liquid prepare two 

 sprays, one for use when the buds are dor- 

 mant and one for use on the green foliage 

 in summer. Take the density (Be.) of both 

 diluted sprays and record the data in the 

 notebook. 



If any lead arsenate is available make a 

 thin paste of this and add some of it to the 

 dilute summer spray. Notice the gradual 

 darkening as some of the lead is withdrawn 

 from the combination with arsenic acid and 

 combined with sulfur to form black lead 

 sulfid; small amounts of arsenic acid are set 

 free at the same time. This is a combination 

 spray having two functions, insecticidal and 

 fungicidal. 



NOTES 



The 1910 Geneva Formula, 36 pounds 

 of lim.e; 80 pounds sulfur; 50 gallons water, 

 is here made over for laboratory use. The 

 directions are based on bulletin No. 329 

 of the New York Agricultural Experiment 

 Station, by Van Slyke, Bosworth and Hedges. 



If the lime is pure 36 grams should be used, 

 if 95 per cent CaO (i.e., 5 per cent MgO) 



