266 MONTANA EXPERIMENT STATION. 



It has been found that the method of combining the ingredients 

 has an important bearing on both the chemical composition and 

 the physical structure of the mixture. The best results have been 

 obtained from the use of the Bordeaux mixture made in accordance 

 with the following directions : 



In a barrel or other suitable vessel, place 25 gallons of water. 

 Weigh out 6 pounds of copper sulphate, then tie the same in a piece 

 of coarse gunny-sack and suspend it just beneath the surface of the 

 water. By tying the bag to a stick across the top of the barrel no 

 further attention will be required. In another vessel slack 4 pounds of 

 lime, using care in order to obtain a smooth paste, free from grit 

 and small lumps. To accomplish this it is best to place the lime in 

 an ordinary waterpail and add only a small quantity of water at 

 iirst, say a quart or a quart and a half. When the lime begins to 

 crack and crumble and the water to disappear add another quart or 

 more, exercising care that the lime at no time gets too dry. Toward 

 the last considerable water will be required, but if added carefully 

 and slowly a perfectly smootli paste will be obtained, provided, of 

 course, the lime is 01 good quality. When the lime is slacked, add 

 sufficient water to the paste to bring the whole up to 25 gallons. 

 When the copper sulphate is entirely dissolved and the lime is cool, 

 pour the lime milk and copper sulphate solution together into a 

 barrel holding 50 gallons. The milk of lime should be thoroughly 

 stirred before pouring. The method described insures good 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. 



It is now necessary to determine whether the mixture is per- 

 fect — that is, if it will be safe to apply it to tender foliage. To ac- 

 complish this, two simple tests may be used. First insert the blade 

 of a pen-knife 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 cop- 

 per plate, the mixti;re 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 safe 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, look- 

 ing like oil on water, will begin to form on the surface of the liquid. 

 If no pellicle forms, more lime should be added. 



If spraying is to be done upon' a large scale, it will be found 

 more convenient and economical in every way to prepare what are 

 known as stock solutions of both copper and lime. To prepare a 



