INSECTICIDES, FUNGICIDES, ETC. 



181 



proportions between lime and sulphate being those used for 

 ordinary Bordeaux mixture. The contraction occurs after about 

 four hours, but if the mixture is stirred, it occurs much sooner. 



To obtain the most suitable liquid for spraying purposes, 

 therefore, the mixture should be used immediately after its pre- 

 paration, though as regards actual fungicidal properties, Bordeaux 

 mixture shows no deterioration on being kept (XI, 138). 



Considerable importance from the point of view of the bulkiness 



50 



C' 



Lightest shading shows level after 30 minutes. 

 Intermediate ,, ,, ,, ,, 2 hours. 

 Darkest ,, ,, 18 hours. 



Lime to Copper. 



Copper to Lime. 



in 



in 



FIG. 19. SETTLEMENT OF ORDINARY BORDEAUX MIXTURE 

 PREPARED IN DIFFERENT WAYS. 



of the precipitate attaches to the manner in which the lime and 

 the sulphate are mixed. The results are illustrated in Fig. 19, 

 and will sufficiently explain themselves, with the added statement 

 that the strong and weak solutions contained, respectively, 8 

 and 92 per cent, of the total water used. The variations accord- 

 ing to the conditions of mixing appear to be hopelessly erratic, 

 but, nevertheless, every feature which they present can be 

 satisfactorily explained (XI, 54) ; it is hardly necessary, however, 

 to enter into that explanation here, and attention need only be 

 drawn to the main result, namely, that when Bordeaux mixture 

 is to be used within an hour or two of its being made (as always 



