VERDIGRIS COPPER ACETATE. 279 



onions and tubers, which by steeping for one to two hours in a 1 per 

 cent bouilhe are disinfected. A twenty-four hours' steep does not 

 injure them. Fairchild points out the remarkable results obtained in 

 the struggle against Entoviosporium maculatum, Lev. (leaf scald of 

 the pear-tree). Its action is surprising on the larvae of the goose- 

 berry saw-fly (Nemahis ribis, Scop). To destroy it as soon as the 

 false caterpillar appears, a spray is applied of 2-5 per cent of blue 

 vitriol and 2d per cent of carbonate of soda. In less than an hour the 

 larvte die, blacken, fall, and its ravages are stopped. 



loo. Bouillie Bordelaise Celeste. — This bouillie is a mixture of 

 insoluble copper carbonate and soluble bicarbonate. 



Preparation. — Dissolve 1 kilogram of blue vitriol in a few litres 

 of hot water, and add after cooling 870 grammes of carbonate of soda, 

 then dilute to 100 litres. A proportion of 90 per cent of copper is 

 precipitated as insoluble carbonate, and the remaining 10 per cent of 

 copper is converted into soluble bicarbonate. This small amount of 

 dissolved copper is not enough to cause the bouillie to burn the 

 trees, but it suffices to impart to the bouillie the anticrs ptogamic 

 properties of eau celeste. Bouillie bordelaise celeste, I'ecommended by 

 Fery, combines the properties of the anticryptogamic bouillie bour- 

 guignonne and eau celeste. It is one of the best anticryptogamic 

 bouillies. 



loi. Basic Acetate of Copper. — Definition. — Commercial verdi- 

 gris consists largely of basic acetate of copper. 



Preparation. — The verdigris industry is localized in the South of 

 France. Le Verdet extra sec en grains, of interest here, because of its 

 more uniform composition, is made throughout the whole of Lower 

 Languedoc as follows. The method of manufacture consists in cor- 

 roding sheet copper by the acid marc of grapes. The marc is chosen 

 as rich in alcohol as possible. It is preserved before use in vats, 

 where it is strongly compressed without access of air. The sheets of 

 copper used weigh about 100 grammes (say 34 oz.), are 6 centi- 

 metres (say 2^ inches) wide, 16 centimetres (say 64^ inches) long, and 1 

 millimetre (.t^ inch) thick. When the marc is to be used, it is taken 

 from the vats and air admitted to convert the alcohol into vinegar or 

 acetic acid. The fermentation which ensues raises the heat to 

 40° C. (104° F.). When the alcohol of the marc is converted into 

 acetic acid, a little vinegar is added to strengthen its action if it be in- 

 sufficient, then it is put in contact with copper. New copper with a 

 smooth surface only being attacked difficultly, the sheets undergo a 

 preparation which consists in rubbing them with a pad dipped in 

 verdigris acidulated with vinegar. After drying them in the sun, they 

 are submitted to a temperature of 60°-70° C, which greatly facilitates 

 the first attack. They are then brought quite hot and arranged in 

 layers on the marc, spread out on the ground of a special spot ; a layer 

 of marc is spread on them, a fresh layer of copper sheets, and so on 

 until the mass rises 1 metre above the ground. Under the influence 

 of the heat the acetic acid attacks the copper sheets. After six to 

 eight days the marc bleaches ; it is exhausted. The gi-een layer formed 

 on the plates is not yet verdigris. To finish the operation the plates 



