THE BORDEAUX MIXTURE' 



55 



remain there for at least one minute. If metallic copper forms 

 on the blade, or, in other words, if the polished surface of the 

 steel assumes the color of copper plate, the mixture is unsafe 

 and more lime must be added. If, on the other hand, the blade 

 of the knife remains unchanged, it is safe to conclude that the 

 mixture is as perfect as it can be made. As an additional test, 

 however, some of the mixture may be poured into an old plate 

 or saucer, and while held between the eyes and the light, the 

 breath should be gently blown upon the liquid for at least' half 

 a minute. If tiie mixture is properly made, a thin pellicle, 

 looking like oil on water, will begin to form on the surface 

 of the liquid. If no pellicle forms, more milk of lime should 

 be added." 



Fig. 4. — Testing the Bordeaux mixture by tlie plate method. 



The Bordeaux mixture should be applied with a pump 

 designed especially for spraying. Such pumps may be obtained 

 of almost any hardware dealer. In spraying, it is necessary to 

 keep the mixture thoroughly stirred. Only freshly made mix- 

 ture should be used. 



Bordeaux Mixture in a Dry Form. — This, in the form 

 known as " Fungroid," has not proved satisfactory with us. 

 The potato vines, to which it was applied, showed little, if 

 any, benefit from its use. It is doubtful if any fungicide in a 

 powdered form will be as efficient as a liquid one. 



HOW TO SPRAY 



In Bulletin loi of the Cornell Experiment Station, Prof. L. 

 H. Bailey, among many other things worth quoting, says, in 



