Materials and Formulas. 143 



whose foliage is not so tender as that of peaches or beans. It is 

 valued also because it does not stain the parts treated. 1 On 

 dormant wood it can be used freely. It is then made of 



Copper sulphate , 1 pound. 



Water 15-25 gallons. 



The more dilute solution is for such tender wood as peaches. 

 Grain is often soaked in a solution of copper sulphate to destroy 

 spores of smut. The preparation is then made of 



Copper sulphate 1 pound. 



. Water 1-2 gallons. 



The use of a one-half per cent solution has been recom- 

 mended for a similar purpose, the seed being soaked for twelve 

 or fifteen hours. 



COPPER SULPHATE AND SULPHURIC ACID SOLUTION. An- 

 other, and a rather restricted use of copper sulphate, is to make 

 a saturated solution, and to this add about 1 per cent of com- 

 mercial sulphuric acid. The preparation is, of course, used 

 only upon dormant wood, and is especially recommended for 

 anthracnose of the grape. 



The price of copper sulphate varies greatly. The granulated 

 form may be bought for four to fifteen cents per pound, and the 

 crystals at four to eight cents. 



COPPER SULPHATE AND AMMONIUM CARBONATE MIXTURE. 

 See JOHNSON'S MIXTURE. 



COPPER SULPHATE, ANHYDROUS. When copper sulphate 

 crystals (CuSO 4 + 5 H 2 O) are heated, the water of crystallization 

 is driven off and only a pale blue powder remains (CuSO 4 -f 

 2 H 2 O). This dissolves readily in water, and possesses the prop- 

 erties of the original crystals, although the weight is reduced, 

 which leaves a greater proportionate amount of actual copper. 

 The powder has been applied when mixed with sulphur or other 

 powders for the prevention of mildew, but it is now little used. 



CORNELL MIXTURE. This preparation consists of a mixture 

 of Bordeaux mixture, kerosene emulsion, and an- arsenical com- 

 pound. The combination is made with difficulty, but success 

 may follow if a few points are observed. The Bordeaux mix- 

 ture must be exactly neutral, and here the ferrocyanide of 



1 American Agriculturist, middle edition, 1895, July 20, 34. 



