PKEPAKAXr N OF THE COPPEK SPKAYS. 147 



Bordeaux mixture — Continued 



*2 pounds copper yidphate, 5 pounds lime. 



*6 pounds copper sulphate, 4 pounds lime. 



*6 pounds co]iper sul]ihate, 'A pounds lime. 



*3 pounds copper sulphate, 2 pounds lime. 

 Eau celexfe: 



*i jiounds copper sulphate, 3 pints ammonia (2t>°). 



*2 pomids copjxM- sulphate, 3 pints ammonia (26°). 

 Modified eau celeste: 



*4 pounds copper sulphate, 5 pounds sal soda, 3 pints ammonia (26°). 



*2 pounds copper sulphate, 3 pounds sal soda, 2 pints annnonia (26°). 

 Ammoniacal copper carhunate: 



*5 ounces copper carbonate, 3 pints annnonia (26°). 



*3 oimces copper carbonate, 2 pints ammonia (26°). 



* Prepared and tested by the writer, and in many cases also tested by growers. 



Tho propjiratioii of the copper sprsiys eoDtiiiiiiiio- diffei-ent chemical 

 constituents will be considered In the order in which they appear in 

 the preceding list. 



COPPER SULFIIATK SOLUTION. 



Copper sulphate (CuSO^.oHoO), commonly caHed blue vitriol or 

 bluestone, forms, when dissolved in water, one of the most active 

 fungicides known. This chemical, the composition, maiuifacture, and 

 sources of supply of which will bo more fully consid(>red in a follow- 

 ing chapter, dissolves in cold water, but somewhat more readily in 

 hot water. As usually sold, the crystals are large, but a tine form 

 may also be had in the market. If the large crystals are purchased 

 and it is desired to dissolve them rapidly, they may be ground in a 

 bone or shell mill before placing in the water. This has frequentl}'^ 

 been done by the writer when quick work was necessar3^ 



Copper sulphate ma}' be manufactured by dissolving the black oxide 

 of copper in sulphuric acid, or by the various modifications of this 

 process hereinafter discussed. A watery solution of this chemical is 

 strongly acid, and for this reason a simple solution of copper sulphate 

 is very corrosive and injurious to tender plant tissues, as foliage and 

 opening buds. To avoid this injurious action, efforts have been made 

 to obtain from the copper sulphate solution a spray retaining the 

 fungicidal action of the copper, but by the addition of other chemicals 

 to neutralize or largely remove its acid reaction and consequent cor- 

 rosive effects upon plants. As a result there are a very considerable 

 number of copper sprays, representing various modifications of the 

 simple solution of copper sulphate. 



Owing to the acidity of a solution of copper sulphate, the sulphate 

 should not be dissolved or handled in metal dishes of any kind, espe- 

 cially those of iron. The copper will often go to the metal, thus 

 injuring the effectiveness of the spray, and the acid may also injure 

 or destroy the dishes. The most suitable vessels for dissolving copper 



