698 Journal of AgricuUiirc. Victoria. \10 Wov.. 1917. 



copper to poison tlie spores, and that their bad jireparation and bad 

 quality do not render them inactive." Ooucerning the dose of copper 

 sulphate, it says: — "Although formulse at 1 per cent, have given good 

 results to some growers, the Commission considers that for Bouillie 

 Bourguignonne (copper soda) as for Bouillie Bordelaise (Bordeaux mix- 

 ture) proportions of 2 per cent, and even 3 per cent (2 and 3 lbs. to 10 

 gallons) are to be most strongly recommended for violent invasions." 

 Several of these well-known sprays are described, as well as Verdet (ver- 

 degris or copper acetate) and copper ammonia, but no mention is made 

 of their having proved superior to the older mixtures. 



iSpacewill not permit further details here. The following will be 

 found a simple method of preparing Bordeaux mixture: — 



"Weigh 2 lbs. of bluestone and dissolve in 5 gallons of water in a 

 cask or tub in which the 10 gallon level is marked by a peg. Solution 

 is facilitated by tying the bluestone in a small piece of hessian just 

 below the surface. When dissolved, mix thoroughly with a wooden stick. 



Take about 2 lbs. of quicklime, slake same in another tub with small 

 quantities of water at a time, make up to 5 gallons with water, and 

 stir thoroughly so as to make a thin milk. 



Prepai-e the mixture, dipping out the milk of lime with a dipper 

 and pouring it through a fine sieve into the bluestone solution,* carefully 

 stirring. As soon as a couple of gallons have been thus added, test 

 with testing paper, a small piece of which is dropped into the mixture. 

 Usually, if the milk is thin enough, the first piece remains white; more 

 milk is then added with thorough stirrinii'. A second fragment of paper 

 is added, and so on, until the paper becomes slightly pink, which indi- 

 cates neutralization. There is now enough lime; make up to 10 gallons 

 with water, and stir well. The rest of the lime may be thrown away. 



After the first addition (2 gallons) of lime milk, stir very thoroughly 

 — energetic stirring should likewise be, given before each subsequent 

 addition of lime. Cease adding lime as soon as the first symptoms of 

 colour change are shown by the test paper. (The above applies to 

 Phenolphthalein paper.) Litmus paper may also be used — it is red 

 when acid, and blue when alkaline. 



Another good indicator is a 10 per cent, solution of ferrocyanide 

 of potash. So long as there is any unneutralized copper sulphate a few 

 drops of the spray mixture added to a like quantity of this test solution 

 in a saucer, turns it a deep brown colour — with this indicator cease 

 adding lime as soon as this colour is no longer produced. 



If either of the above indicators be used, it is not necessary to care- 

 fully weigh the lime ; good fresh building lime is best for the purpose. 

 If 2 ounces of sugar dissolved in a little water be added to every 10 

 gallons of the mixture, it will keep its power for some days. It is, 

 nevertheless, better to use freshly prepared mixture. 



A slightly acid mixture is generally preferred to one which is quite 

 neutral or slightly alkaline. In order to obtain a slightly acid mixture 

 proceed as above, but before pouring in the milk of lime withdraw half 

 a gallon of the bluestone solution in an earthenware jug; this will be 



• Caro must be observod always to pour lime (or soda) into the bluestone solution ; if tlie process be 

 reversed, a different reaction talses "place and the mixture is unsatisfactory . 



