176 Bulletin 245. 



excess of lime does no harm, but an excess of copper solution brings injury to the 

 foliage. A test for Bordeaux is made with ferrocyanide of potassium. An ounce 

 of this substance, known to the drug trade as yellow prussiate of potash, is dis- 

 solved in a pint of water. When Bordeaux is made, it may be tested by letting 

 three or four drops of this solution fall upon the surface. If there is too much 

 copper salt, the ferrocyanide solution will turn brown. Lime should be added 

 till the test liquid fails to change color. Even then it is best to add more lime 

 to make a sure thing. 



Soda-Bordeaux. 



Soda (commercial lye) 2 pounds. 



Copper sulfate 6 " 



Lime i to. f " 



Water 60 gallons. 



Commercial soda lye may be used, but the mixture must be tested to insure its 

 alkalinity. The amount of lime may in some cases be slightly diminished accord- 

 ing to strength of the lye. 



Dissolve the lye and dilute to 10 or 15 gal. and pour into the copper solution 

 and then add lime as required. Paris green may be safely used in connection 

 with this mixture. 



"Process" Lime for Bordeaux Mixture. 



The so-called "new process" or prepared limes, now offered on the market are 

 of two classes. One consists of the quick-lime that has been ground to a powder. 

 The other is the dry water-slaked lime, made by using only enough water to slake 

 the quick-lime, but not enough to leave it wet. When the hard "stone" lime 

 becomes air-slaked it is evident to the eye from the change to a loose powdery 

 mass. Should one of these prepared limes be to any considerable degree air-slaked, 

 its appearance would be no indication of its real condition. 



A simple test for the presence of much carbonate of lime in these prepared limes, 

 can be easily performed. A small amount of the lime — J teaspoonful — dropped 

 on a little hot vinegar, will effervesce or "sizzle," if it contain the. carbonate of 

 lime, acting about the same' as soda. 



A sample of a new process lime analyzed at this Station, showed 30 per cent 

 magnesia. This came from burning a dolomitic limestone, that is, one containing 

 carbonate of magnesia with the carbonate of lime. The magnesia does not slake 

 with water like the lime, and hence is useless in the Bordeaux mixture. There 

 is no easy way outside a chemical laboratory of telling the presence of magnesia. 



As a general rule more "process" lime is required to neutralize the copper sulfate 

 than good stone lime. 



Lime-Sulfur Wash. 



Lime, 20 lbs. 



Sulfur, 15 lbs. 



Water sufficient to bring the boiled product up to 45 gallons. 



General Directions for Preparing. The lime and sulfur must be boiled or steamed. — 

 Mix the sulfur into a thin paste, using only enough water to break up all the lumps. 

 Place about 15 gallons of water in a kettle, or boihng tank, or vat, if steam is 

 employed, and heat to the boiling point. Add the sulfur paste to the boiling water 

 and mix thoroughly. Next, add the stone lime — which should be previously 

 weighed out and ready for use — and while the lime is slaking stir often enough 

 to keep the lime and sulfur well mixed. In this way the entire heat of the slaking 



