VERDIGRIS COPPER ACETATE. 285 



capable, it is true, if they are used immediately after their preparation, 

 of depositing on the leaves a copper pellicle, a true varnish which 

 will-resist the weather indefinitely. But the thin pellicle which covers 

 the leaf may in the end, as shown by Galloway, stop the physiological 

 functions of the organs covered and injure the normal evolution of the 

 plant ; and these copper derivatives, insoluble in the atmospheric agents- 

 as well as in the exudation of plants, have lost, if not all, at least the 

 greater part of their anticryptogamic power. Under such conditions 

 they cannot, therefore, form like cupric hydrate an insuperable barrier 

 to the spores deposited on the leaves. Parasitic fungi are very often 

 seen to develop normally on leaves and fruit covered with a layer 

 of these copper varnishes. The effect of the greater part of these new 

 bouillies is, therefore, quite illusory. However, their quality depends 

 greatly on their composition. When the amount of binders prescribed 

 to render a bouillie adherent are not sufficient to convert the whole 

 of the cupric hydrate into an insoluble binding organic derivative, that 

 bouillie still contains the greater part of its copper under the active 

 form of cupric hydrate which maintains its good anticryptogamic 

 properties. The binders so used may encircle the active principles of 

 the bouillie and retain them on the leaves and so become useful. 

 Trials of comparative adherence made with bouillies normally and 

 freshly prepared, and thus at the moment when their adherence is at 

 a maximum, have not always given results in favour of the new bouillies. 

 The advantage of using binders in the bouillies may be regarded as 

 problematical, for the simple bouiUies now used show the same 

 tenacity which may be regarded as sufficient. Still more so than in 

 the case of ordinary bouillies is it necessary to use these bouillies 

 immediately after preparation, for the fine, flaky, organic precipitates 

 which they contain in the beginning agglomerate and resinify, rapidly 

 encrusting the machines and preventing a uniform distribution of the 

 bouillie on the plants. Finally, the binders used in these bouillies 

 may injure the organoleptic properties of the wine. It has been 

 observed after their use that the wine left something to be desired, 

 and the conviction was formed that it was these substances which 

 passed into the wine and profoundly altered its gustative properties. 



103. Albuminous Bouillies. — Preparation. — By adding to a 

 solution of blue vitriol bouillie bordelaise or bouillie bourguignonne a 

 sufficiency of an albuminous body to convert all the copper into 

 copper albuminate. 



104. Lactocupric Bouillie (Crouzel's). — Preparation. — Dissolve 

 20 lb. of blue vitriol in 10 gallons of water, add 4 gallons of unboiled 

 milk, say about 1| lb. of casein, stir strongly for five minutes, and run 

 into enough water to make 100 gallons. Skimmed milk does equally 

 well. 



Properties. — This bouillie is acid and forms a mixture of blue 

 vitriol and cupric caseate ; this latter forms a precipitate insoluble in 

 water, the role of which is to retain by encircling them the small 

 crystals of blue vitriol formed by the evaporation of the bouillies on 

 the surface of the leaves. If burns caused by contact of blue vitriol 

 with plants, especially with the proportions given above, be feared, it 



