514 Appendix. 



C. Calcium Arsenate. 

 FORMULA AND PREPARATION. 



Add one part milk of lime to every one part of crystallised sodium 

 arsenate dissolved in 400 to 500 parts of water. 



USES, ETC. 

 The same as the former. 



D. London Purple. 



FORMULA. 



London Purple . . . . . . 1 oz. 



Lime ... 1 oz. 



Water 10 galls. 



USES, ETC. 

 The same as the previous arsenical washes. 



E. Arsenite of Soda. 



FORMULA. 



White Arsenic 2 Ibs. 



Sal. Soda 8 Ibs. 



Water 2 galls. 



PREPARATION. 



Boil until the arsenic is dissolved (about fifteen minutes) and keep up 

 to - gallons bv adding water. Use 1 pint of this to 40 gallons of water. 



USES. 

 The same as above. 



GENERAL NOTES ON ARSENICAL WASHES. 



Of the five mentioned there is no doubt that arsenate of lead is 

 best to use, Ijecause of its being more easily mixed and holding in suspen- 

 sion longer than Paris green, etc., and in the almost entire absence of 

 burning the foliage if properly mixed ; it has also more adhesive 

 properties. 



The paste form known as Swift's Paste has been found satisfactory in 

 many parts of the world, and is best to use unless great care is taken in 

 making the home-made wash. 



