REPORT OF THE SOCIETY 71 



sulphate is added, we get copper hydrates formed. The curious thing about 

 this reaction is that even when equal parts of lime and copper sulphate are 

 present there is a great excess of free lime and as more lime is added more of 

 the lime combined chemically with the copper. This reaction is important 

 in that potatoes will stand basic sulphates and double basic sulphates, while 

 apples demand that a portion at least of the copper be in the hydrate form. 

 Hence the recommendation of excess lime Bordeaux or 3 — 10 — 50 for apple 

 spraying. It has been found that magnesium lime has greater neutralizing 

 power, or makes a safer Bordeaux, than high calcium lime. 



Copper sulphate for use on ground crops such as potatoes may be combined 

 with a number of basic salts, such as magnesium oxide, magnesium hydroxide, 

 sodium carbonate, sodium hydrate, sodium silicate, potassium carbonate, 

 fish oil soap or even free nicotine. 



Copper Combinations with Arsenic. 



It is not generally recognized that copper is a safer and more reliable neu- 

 tralizer for soluble arsenic than is lime. The copper of Bordeaux reduces the 

 killing value of arsenicals used with it by around 43 per cent. Almost any arsen- 

 ical can be used in Bordeaux mixtures if the proper precautions are taken in 

 combining it. 



The most commonly used poison in Aroostook County, Maine, is arsenate 

 of soda, which is sold under the name of arsenoid. The arsenate of soda is dis- 

 solved in water and added to the completed Bordeaux. The majority of the 

 arsenate combines with the lime to form arsenate of lime, but a portion at least 

 combines either wholly or partially with the copper. 



The old "Kedzie" formula, which results in an arsenite of soda solution, 

 is an excellent Bordeaux poison, but when added to the completed Bordeaux 

 it frequently gave some burning on account of too great a proportion. If the 

 arsenite of soda is poured into the copper sulphate solution and caused to form 

 green arsenite of copper before the lime is added that burning is almost entirely 

 eliminated. 



D. E. L. Mixture is 50 per cent superfine dust collector white arsenic and 50 

 percent hydrated lime. The lime causes the arsenic to wet readily and when in 

 solution the two combines to form what we think is acid arsenite of lime. If 

 copper sulphate is dissolved into water containing this mixture, green cooper 

 arsenite is formed and the stock solution of copper sulphate containing the 

 green precipitate of copper arsenite may then be used in the regular way and 

 combined with the proper quantity of lime to make Bordeaux. This is by all odds 

 the cheapest Bordeaux poison on the market and it has been used successfully 

 for three years now in New Brunswick and Nova Scotia. 



