78 Report of State Board of Horticulture. 



mixing, but to complete this work the barrel of liquid should 

 receive a final stirring for at least three minutes with a broad 

 wooden paddle. 



Testing the mixture — It is now necessary to determine 

 whether the mixture is perfect — that is, if it will be safe to 

 apply it to tender foliage. To accomplish this two simple 

 tests may be used. First, insert the blade of a penknife in 

 the mixture, allowing it to 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 copperplate, 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 per- 

 fect 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 the 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. 



Preparing large amounts — The foregoing directions apply to 

 cases where small quantities of the mixture are needed for 

 more or less immediate use. If spraying is to be done upon 

 a large scale, it will be found much more convenient and 

 economical in every way to prepare what is known as stock 

 solutions of both the copper and lime. To prepare a stock 

 solution of copper sulphate, procure a barrel holding fifty gal- 

 lons ; weigh out one hundred pounds of copper sulphate, and, 

 after tying it in a sack, suspend it so that it will hang as near 

 the top of the barrel as possible ; fill the barrel with water, 

 and in two or three days the copper will be dissolved ; now 

 remove the sack and add enough water to bring the solution 

 again up to the fifty-gallon mark, previously made on the 

 barrel. It will be understood, of course, that this second 

 adding of water is merely to replace the space previously oc- 

 cupied by the sack and the crystals of copper sulphate. Each 

 gallon of the solution thus made will contain two pounds of 

 copper sulphate, and, under all ordinary conditions of tem- 

 perature, there will be no material crystalization, so that the 

 stock preparation may be kept indefinitely. 



Stock lime may be prepared in much the same way as the 

 copper sulphate solution. Procure a barrel holding fifty gal- 



