282 INSECTICIDES, IT NdUI DES, AND WEED KILLERS. 



copper turnings by acetic acid until complete solution is effected.. 

 (2_) By double decomposition between blue vitriol and lead acetate. 



CuSO, + Pb(C,H,0,)-' = Cu(C,H.,0,)-^ + PbSO, 



(V)]ipLT Lead acetate. Copjier Lend 



siilphiite. acetate. sulphate. 



Properties. — Coppei- acetate forms greenish-blue crystals with a 

 molecule of water of crystallization. These crystals contain 31 per 

 cent of metallic copper. They are completely soluble in five times, 

 their weight of boiling water at 15° C. Used to overcome cryptogamic 

 diseases copper acetate behaves like blue vitriol, and in general, like 

 all solubh copper salts, that is to say, it is poisonous to plants, whilst 

 at the same time it acts very energetically on parasitic fungi. However, 

 this action is ephemeral, because cupric acetate decomposes on the 

 surface of the leaves into a basic acetate behaving like copper hydi-ate. 

 Used in Italy at 1 per cent against Leaf Curl of Peach it caused, like all 

 other copper preparations, the total fall of the leaves and the fruit 

 treated (Brioni). A 0*5 percent solution of cupric acetate destroys the 

 germinative power of the spores of Giiignardia Bidwelli in twenty 

 minutes, whilst 0-5 per cent of blue vitriol takes thirty minutes to pro- 

 duce this effect. Its action on the spores of this fungi is therefore re- 

 latively identical with that of blue vitriol, for copper acetate contains. 

 31 per cent of metallic copper, whilst blue vitriol only contains 25 per 

 cent. The action of copper acetate lasts longer than that of blue 

 vitriol. Chuard and Duserre found that this was due to the neutral 

 acetate being converted on the leaves into an insoluble, very adherent 

 derivative. 



Use. — Copper acetate has been used in Italy and Switzerland 

 especially against mildew, Peronospora viticola, De By., in 0-5-0*8 per 

 cent doses. It is sometimes used in France in the last treatment of the 

 vine, so as not to soil the grapes, and avoid introducing sulphuric acid 

 into the wort or any other substance capable of changing the quality 

 of the wine. Copper acetate is, so to speak, abandoned to-day and re- 

 placed by the copper bouillies in the struggle against parasitic fungi, 

 for it has no advantage over the latter preparations and it is a little 

 more costly in use. 



1 02a. Perret's Bouillie is a bouillie bordelaisc containing a por- 

 tion of its hydrated oxide of copper in solution as cupric saccharate. 



Preparation. — By mixing, in a certain order, a solution of blue 

 vitriol and sugar with milk of lime. Perret, the inventor, prepares it 

 as follows : Beat up 20 lb. of quicklime after slaking with 80 gallons 

 of water, and whilst stirring constantly add this milk of lime to 1 lb. 

 of sugar in 10 gallons of w^ater ; then run this mixture of lime and 

 saccharate of lime into a solution of 20 lb. of blue vitriol in 100 gallons 

 of water. It is essential that the copper solution be cold. Prillieux 

 advises that care be taken to see that the bouillie is slightly alkaline. 

 Barth, in 1896, advised the preparation of cupric saccharate bouillie 

 thus : Dissolve 20 lb. of blue vitriol in 40 gallons of water, and after 

 cooling run in a vsolution of 3 lb. of sugar or 5 lb. of 50 per cent, 

 molasses in 30 gallons of water, then a milk of lime with 1^ lb. o£. 



