SPRAYING PROBLEMS 147 



Economy of labour might be effected if we could 

 devise a spray ready for use, thus obviating the pro- 

 cess of mixing ingredients. Several commercial ready- 

 made spraying compounds have been invented which 

 are said to fulfil this requirement, but none equal in 

 efficiency freshly - prepared Burgundy or Bordeaux, 

 since they do not retain the valuable adhesive proper- 

 ties which are obtained when these mixtures are freshly 

 prepared. When used as a dry spray in districts where 

 disease is habitual and severe, more sprayings appear 

 to be necessary in order to produce the same fungi- 

 cidal result as that obtained when using Burgundy. 

 Hence the advantage gained through using a single 

 compound is lost, and an adverse balance remains 

 through the labour and time involved in increasing 

 the number of spraying operations. 



Commercial efforts have been made to supply Bur- 

 gundy mixture prepared as a single powder, but such 

 powders contain a substitute for washing-soda; actual 

 mixtures of copper sulphate and washing-soda have 

 not yet proved satisfactory, since the mixture tends to 

 deteriorate. 



Copper sulphate of 99-per-cent purity can now be 

 obtained in powder form. This preparation should 

 supersede the old bluestone crystals, owing to the 

 rapidity with which the powder dissolves in cold 

 water. If we could find an efficient substitute for 

 washing-soda and several substitutes have been 

 suggested either in the form of a powder or small 

 crystals that would not react either physically or 

 chemically with the other chemical ingredients, the 

 problem of a one-powder Burgundy mixture would 

 be solved. 



Probably the best way of improving Burgundy is 

 to increase its wetting power. Liver of sulphur dis- 

 solved in water was formerly used a great deal in 



