15 



until they are completely dissolved. About two quarts of 

 cold water are required to dissolve a pound of blue vitriol. This 

 is a good way of dissolving the blue vitriol when it is not wanted 

 for immediate use, and is preferable to putting the crystals 

 loose in the bottom of the vessel, for in that case they will dis- 

 solve very slowly unless kept constantly stirred. 



Our actual practice has been to make a stock solution, by 

 dissolving the blue vitriol in a sufficient quantity of hot water 

 and then adding enough cold water to make half as many gal- 

 lons as there were pounds of blue vitriol. Two quarts of this 

 stock solution therefore represents one pound of blue vitriol. 

 This is a very convenient way, especially where small quanti- 

 ties only of Bordeaux mixture are used at a time. A stock 

 solution of lime also may be made. These stock solutions 

 should be carefully protected from evaporation. 



The slaked lime should be strained before adding to the solu- 

 tion of blue vitriol ; or better still, perhaps, the completed Bor- 

 deaux mixture should be strained before pouring into the pump 

 tank, in order to remove the coarser particles, which would be 

 liable to clog the spraying nozzle. The straining may be done 

 through coarse sacking, or a wire strainer with a mesh about 

 one-sixteenth of an inch wide. 



The Bordeaux mixture should be kept thoroughly stirred up 

 during the time of spraying. It is at its best for only a few 

 hours after its preparation ; it soon develops a greater tendency 

 to settle and loses a part of its valuable property of sticking to 

 the foliage. We would recommend as a formula for Bordeaux 

 mixture for general use : 



Blue Vitriol, 1 pound. 

 Lime, fresb, =3 " 

 Water, 10 gallons. 



This makes a 1 to 10 mixture. To make a combined insecti- 

 cide and fungicide, Paris green or London purple may be added 

 to the Bordeaux mixture, in the proportion of four ounces 

 (^ pound) to fifty gallons. This combination is useful in the 

 spraj'ing of apple trees just after the blossoms fall, as it serves 

 to destroy both the scab and the codling moth. A second 

 spraying with it ten days or two weeks later is also advisable. 



