Materials and Formulas. 173 



their fungicidal value, but the results have not been so satis- 

 factory as with the copper compounds, and therefore the sub- 

 stance is but little used. The solution may be prepared by 

 dissolving 1 pound in 10 to 20 gallons of water, although there 

 has been recommended the application of only ^ ounce in 10 

 gallons. The latter, however, can have but little value. The 

 cost of this substance varies from six to fifteen cents per pound. 

 SODIUM SULPHIDE WASH. 



(a) Whale-oil soap 30 pounds. 



Hot water 60 gallons. 



(6) American concentrated lye 3 pounds. 



Sulphur 6 " 



Boiling water 2 gallons. 



Mixture (6) should be very thoroughly boiled until it is of a 

 dark brown color. Chemically it is the sulphide of soda. 

 Solutions (a) and (ft) should then be mixed and boiled half an 

 hour. Before using, dilute with 90 gallons of warm water. 

 The remedy is of value for scab diseases of oranges. 



SUGAR. Sugar or molasses is sometimes added to copper 

 compounds to assist in holding a certain amount of the copper 

 in solution. It has long been known that when concentrated 

 solutions of sugar and copper sulphate are mixed there is pro- 

 duced a bluish-white precipitate, known as a sulpho-saccharate 

 of copper. It is soluble in water, but when heated the com- 

 pound is broken up, and the copper is deposited in the form of 

 a red powder, the protoxide of copper. Recommendations have 

 been made to add molasses at the rate of one-tenth by weight 

 of the amount of copper sulphate, or one-twentieth its weight 

 of sugar. This renders a portion of the copper in the Bordeaux 

 mixture immediately soluble ; but the advantage of the practice 

 is doubtful. (See, also, page 50.) The presence of an excess 

 of lime in the Bordeaux mixture is essential to the proper 

 manufacture of the fungicide with these materials. 



The following analysis represents approximately the com- 

 position of a high-grade molasses : 



Sugar 50 per cent. 



Other organic matter 20 " 



Ash 10 " 



Water 20 K 



