10 SPICES 



CHAP. 



bluestone" or "agricultural sulphate of copper" must be 

 avoided, as these are usually adulterated with iron sulphate. 



The strength of Bordeaux mixture at present most widely 

 recommended in the United States is 4j Ib. of copper 

 sulphate, 4f Ib. of quicklime, 50 gallons (Imperial) of water. 

 This strength is expressed in America by the formula 4:4:50, 

 since, as Mr. Pickering has lately pointed out, the relative 

 value of the American and Imperial gallon is different, the 

 former weighing 8*345 Ib. and the latter 10 Ib. As, however, 

 excellent results have followed the use of Bordeaux mixture 

 made of the strength 4:4:50 (Imperial), it would seem advisable, 

 for the present, at any rate, to continue to use this as the 

 " standard " mixture. 



Dissolve the 4 Ib. of copper sulphate in a wooden tub or 

 bucket iron or tin vessels must not be used. The easiest way 

 to do this is to suspend the material, wrapped in a piece of 

 coarse sacking, in a few gallons of cold water, from a stick 

 placed across the top of a tub, or wooden bucket. If this be 

 done over night, the copper sulphate will be found to be 

 dissolved in the water by the morning. (If hot water be used, 

 the copper sulphate can be placed at the bottom of the tub or 

 bucket, and be dissolved in a few minutes.) Then add the 

 water to make 25 gallons. Now take the 4 Ib. of quicklime, 

 and put it in a tin pail. Add a few pints of water till all the 

 lime is slaked, taking care to add only a little water at first ; 

 in this way a thick creamy paste is obtained. Add water to 

 make 25 gallons. We have now 25 gallons of copper sulphate 

 solution, and 25 gallons of "milk -of -lime." When the two 

 substances are thus diluted with water, they can be mixed 

 together by pouring one into the other, or a bucketful of each 

 can be poured simultaneously or alternately into a third tub 

 a wooden bucket being used for the copper sulphate solution. 

 The " milk-of-lime " must be well strained, and it is advisable 

 also to strain the Bordeaux mixture before spraying. In this 

 way we 'obtain 50 gallons of Bordeaux mixture of the best 

 quality. 



Two points are of primary importance in making Bordeaux 

 mixture. The first is that quicklime, in lumps, that is to say, 

 as freshly burnt as possible, should be used. Powdered air- 

 slaked lime, such as is often found in builders' yards, will not 

 make Bordeaux mixture. The second point to observe is that 

 the two constituents, viz. copper sulphate and lime, are diluted 

 with water as much as possible (consistent with the formula) 

 before being mixed together. If concentrated solution of copper 

 sulphate and lime are mixed together, and water then added to 



