446 THa POTATO. 



cause if left in the ground the diseased spots spread and deepen. 



7. The disease may be prevented by placing the seed (cut if desired) 

 in coarse sacks like coffee-sacks through whicli liquid will readily pass 

 and soak for an hour or two in the following: to two ounces of finely 

 pulverized corrosive sublimate (murcuric bichloride) add three gallons 

 of hot water and allow to stand over night or until it is dissolved. To 

 this add twelve gallons of water and stir thoroughly for five or six 

 hours. The potatoes after being in the liquid for the required time 

 should be dried before being planted. 



Caution. Plant all potatoes treated. This solution is a deadly 

 poison, but at this strength is not dangerous unless taken into the 

 stomach. The poison being corrosive should only be placed in waoden 

 vessels. Never use METAttic vessels. 



Bordeaux Mixture. This fungicide originated in France. For 

 directions how to make see page 540. 



How to Prepare Carbonate of Copper. Dissolve in a barrel 

 twenty-five pounds of copper sulphate in hot water. In another barrel 

 dissolve thirty pounds of sal soda in hot water. Allow both solutions to 

 cool, then slowly pour the solution of sal soda into the copper sulphate 

 solution, stirring the same. Fill the barrel with water, and allow the 

 precipitate of copper carbonate to settle. Upon the following day 

 siphon off the clear liquid. This operation washes the carbonate free of 

 most of the sodium sulphate which contaminates it. Make a filter of 

 stout muslin, by tacking the same to a square wooden frame, which will 

 just fit over the Jop of the second barrel, letting the muslin hang down 

 loosely so as to form a sack; through this filter the precipitate, so as to 

 drain off the excess of water, and as the filter fills remove the precipi- 

 tate, and allow it to dry in the open air, when it is ready for use. 



Carbonate of copper is commonly used in the form of an ammoniacal 

 solution, made by dissolving four ounces of carbonate of copper in two 

 quarts of ammonia, and then adding to a barrel of water. The carbon- 

 ate will dissolve more readily if mixed with water enough to form a 

 paste before it is added to the ammonia. It is a simple fungicide, easy 

 to make and apply, and as it is a clear solution there is no trouble with 

 it clogging nozzles. 



