172 Bulletin 235. 



III. MAKING BORDEAUX MIXTURE WITH " NEW PROCESS " 



OR PREPARED LIME 



In addition to the stone lime commonly used in making Bordeaux 

 mixture, there are on the market several " new-process " or prepared 

 limes. All of these prepared limes are in the form of a fine powder, like 

 lime that has air-slaked. Some of them are quick or stone lime that 

 has been ground to a powder, while others are the quick-lime dry water-' 

 slaked, using only enough water to slake the lime, but not enough to 

 leave it wet. Alany New York fruit-growers and others who spray are 

 using these prepared limes in making their Bordeaux mixture. For this 

 reason, and on account of some dealers selling air-slaked lime for these 

 prepared limes, there has been considerable discussion in the agricultural 

 press on the merits of these limes, and many queries have come to me re- 

 garding them. 



These facts led me to undertake a series of tests in making Bordeaux 

 mixture with prepared limes. Some interesting and valuable results were 

 obtained. 



To make a good Bordeaux mixture, it is necessary that the lime be 

 so constituted chemically as to combine with the copper sulfate and 

 neutralize it; then it is equally as essential that the combination be made 

 in such a way as to produce a very fine-grained or flocculent precipitate, 

 which will settle very slowly so as not to require constant agitation in 

 the spray pump. Such an ideal Bordeaux mixture can be easily made with 

 any good stone lime, freshly slaked, provided both the lime and copper 

 sulfate are much diluted before they are poured together. One cor- 

 respondent has just described for me his method of making Bordeaux 

 mixture, which is simple and easily accomplished, and one that will pro- 

 duce almost an ideal mixture. He says : " In making Bordeaux mixture 

 as we do in batches of 150 gallons, we start with three barrels upon a 

 platform elevated above the top of the sprayer tank, each barrel emptying 

 into a trough common to all. Into one barrel we put 15 pounds of dis- 

 solved copper sulfate and fill the barrel with water; in another barrel 

 from 18 to 20 pounds of " new-process " lime is poured and the barrel 

 is then filled with water; the third barrel is filled with clear water. After 

 thoroughly agitating the contents of the barrels we open the faucets of all 

 tliree and let them flow together into a spray tank, and get good results, 

 there being little sediment ever in the bottom of our tank, and the 

 Bordeaux stands up well." 



I secured four dififerent brands of "new-process " limes, all of which 

 were made from dolomitic or magnesium limestones. A chemical analy- 



