184 EXPERIMENTAL FARMS 



9-10 EDWARD VII., A. 1910 



2. With Bordeaux mixture. This is the more common method as it allows the 

 employment of a fungicide and insecticide in one spray. Bordeaux mixture made 

 according to the formula used so successfully for many years, viz.: 4:4:40, contains 

 a sufficient excess of lime to allow the addition of 1 pint of arsenite of soda solution 

 per barrel of 40 gallons, that is, the excess of lime in the Bordeaux converts all the 

 soluble arsenic into the insoluble arsenite of lime. All that is necessary is to simply 

 pour the requisite quantity of arsenite of soda (1 pint) into the barrel of Bordeaux, 

 stirring meanwhile. We have now Bordeaux mixture containing as much arsenic 

 (in the form of arsenite of lime) as the ' poisoned Bordeaux mixture,' in which 

 4 ounces of Paris green per barrel has been used. 



If sprays of greater insecticidal strength are desired, our experimental work 

 shows that 1 quart (instead of 1 pint) of the arsenite of soda solution may be used 

 in either of the above No. 1, or No. 2, and the resultant sprays (now containing the 

 equivalent of 8 ounces Paris green per barrel of 40 gallons) will be found non-injurious 

 to apple and potato foliage. 



Following upon our experimental work in the preparation of the above sprays, it 

 occurred to us that it might be unnecessary to first form the arsenite of soda, and 

 that the white arsenic, in proper portions, might be added directly to the lime 

 water (No. 1) or to the Bordeaux mixture (No. 2). This simplified method has 

 proved with us quite satisfactory, so far as the complete formation of arsenite of 

 lime and the non-injurious character of the spray to apple and potato foliage are 

 concerned. The two points to be regarded in this method of preparation are (1) that 

 the white arsenic must be in the form of powder, (if lumps are present they may 

 be crushed by rolling the arsenic between sheets of paper with a bottle) ; and (2) that 

 in order to insure complete conversion of the arsenic into arsenite of lime it is 

 desirable that thorough stirring at intervals for say an hour should follow the addition 

 of the white arsenic. 



The formulae corresponding to the sprays, already described, but in the prepara- 

 tion of which white arsenic is used directly are as follows: — 



Arsenite of Lime Sprays. 



(A) Lime 2 lbs. 



White arsenic (powdered) 2 ounces. 



Water 40 gallons. 



(Equivalent in arsenic to a spray containing 4 ounces Paris green per 40 gallons.) 



(B) Lime 2 lbs. 



White arsenic (powdered) 4 ounces. 



Water 40 gallQns. 



(Equivalent in arsenic to a spray containing 8 ounces of Paris green per 40 

 gallons.) 



Bordeaux Mixture with Arsenite of Lime. 



(C) Lime 4 lbs. 



Copper sulphate 4 lbs. 



White arsenic (powdered) 2 ounces. 



Water 40 gallons. 



(Equivalent in arsenic to Bordeaux containing 4 ounces Paris green per 40 

 gallons.) 



(D) Lime 4 lbs. 



Copper sulphate 4 lbs. 



White arsenic (powdered ) 4 ounces. 



Water 40 gallons. 



(Equivalent in arsenic to Bordeaux containing 8 ounces Paris green per 40 

 gallons.) 



