Letters on the Diseases of Flants. 51 



XI. Prepaeation and Use of the Bordeaux Mixture. 

 1. Preparation. 



"Where the Bordeaux mixture is in rather constant use it is a very good 

 plan to keep its two constituent parts in solution, so as to be able to make 

 fresh mixture expeditiously whenever it is required. The following sug- 

 gestions will be helpful to this end : — 



Sulphate of Copper Solution. — Fill a wooden upended cask nearly full of 

 water, putting in (say) 40 gallons of water. Hang in this cask, just under 

 the surface of the water, 8 lb. of sulphate of copper, done up in a piece of 

 sacking. On the morrow the copper sulphate will be found to have dissolved, 

 so that each 5 gallons of the water will contain 1 lb. of copper sulphate. 

 Cover it well, and mark the inside of the cask where the surface of the 

 solution stands, so that if, when the cask is next examined, the solution has 

 somewhat evaporated, the requisite amount of water can be added to make 

 up the deficiency. This is a stock solution to be kept on hand, from which to 

 make mixtures as required. 



Whitewash. — If quicklime be kept long in stock it " air-slakes," and this is 

 undesirable, because the whitewash made from partly slaked lime is inferior. 

 Adopt, therefore, the mason's plan of slaking a large bulk of lime and 

 keeping the whitewash in stock. Slake the lime in the usual way while it is 

 still all good, i.e., freshly burned and " quick." Make a rather thick white- 

 wash, of smooth consistency, free from lumps. Store this in an iron tank or 

 large cask. As soon as it is poured in it begins to settle, and in a day or 

 two the top part will be found to be quite clear. If the tank or cask be 

 kept covered this subsided whitewash can be kept a long time, it being only 

 necessary to keep the surface covered with water. Evaporation will take 

 place and the deficiency thus created must be supplied by adding water from 

 time to time. This is the second stock solution from which to make mixtures 

 as required. 



With regard to the first of these stock solutions the copper sulphate 

 solution, I would remark that it is a matter of no particular consequence 

 how much copper sulphate is dissolved so long as the amount is known. 

 Thus if the orchardist prefers to make a stronger solution by dissolving 

 40 lb. of copper sulphate in 40 gallons of water, there is not the slightest 

 objection, in fact there is some advantage, inasmuch as the solution will occupy 

 a smaller space for a given quantity of the copper sulphate. The main point 

 is to know how much hy weight of the copper sulphate there is in each gallon 

 of the stock solution when it is made. 



Bordeaux mixture. — To make up a mixture from the two stock solutions 

 proceed as follows : First decide what strength of Bordeaux mixture is 

 to be made. Suppose it is decided to make a mixture that shall contain 

 3 lb. of copper sulphate to each 40 gallons of mixture, and the stock 

 solution of bluestone contains 1 lb. of bluestone in each gallon of water. 

 Take 3 gallons of the stock solution of bluestone (which of course will 

 contain 3 pounds of the sulphate) and dilute it to about 20 gallons. 

 Stir up the settled whitewash with a paddle until a smooth thin whitewash 

 can be dipped out. Dilute this with water, making sure, however, not to 

 dilute it so much that more than about 10 gallons will be required to 

 combine with or neutralise the 20 gallons of copper sulphate solution. 

 This is something that has to be learned by practice, but it is easily learned. 

 Strain the whitewash if necessary, in order to remove lumps, but it ought 



