COPPER CARBONATE. 277 



Use. — It is used under the same conditions as emerald green. 



98. Silicate of Copper, CuSiOg.— Preparation. — Dissolve 4 lb. 

 of blue viti iol in 50 gallons of water, and add after cooling whilst 

 stirring a solution of 12| lb. of silicate of soda in 50 gallons of water. 

 A gelatinous precipitate, insoluble in water, is formed. 



Properties. — Copper silicate was prepared by Fairchild, with the 

 object of obtaining a more adherent cupric bouillie than bouillie 

 bordelaise. He, however, found, contrary to his expectations, that this 

 bouillie did not adhere so well as normal bouillie bordelaise. Copper 

 silicate, less soluble than copper hydrate, cannot perform the same 

 services as the latter, and although the silicate of soda used in its 

 preparation is endowed with antiseptic properties, the insoluble 

 product which it forms with copper is, owing to its insolubility, an 

 inert body. 



Use. — Fairchild used the silicate of copper bouillie against 

 Ent07)iosporium maculatum, Lev. (leaf scald of the pear-tree), and 

 found that it did not damage the leaves of the tree. That is not 

 surprising, as only soluble cupric salts and their derivatives are poison- 

 ous to plants. 



99. Carbonate of Copper, CUCO3 (bouillie bourguignonne). — 

 Preparation. — By adding a solution of a copper salt to a solution 

 of carbonate of soda. To convert 1 kilogramme of blue vitriol, 

 CUSO45H0O, into carbonate of copper, it requires theoretically 453 

 grammes of dry sodium carbonate or 1146 grammes of soda crystals, 

 NaoCO^lOH^O. 



CuSO^ + Na^COg = Na^SO^ + CuCO^ 



Copper Sodium = Sodium Copper 



sulpiiate. carbonate, sulphate, carbonate. 



The bouillie bourguignonne designed by Masson to overcome 

 parisitic fungi is merely carbonate of copper suspended in a given 

 amount of liquid. It is prepared thus : (1) Dissolve 20 lb. of blue 

 vitriol in 5-6 gallons of hot water, and add thereto after cooling a 

 solution of 8f-9 lb. of soda ash or 23 lb. of soda crystals, and dilute 

 the whole to 100 gallons with water. (2) Dissolve each compound in 

 50 gallons of water and mix the solutions as cold as possible at the 

 time of use. The second bouillie is better than the first. To obtain 

 a quite neutral bouillie soda ash must be used, for soda crystals, which 

 normally contain 62-8 per cent of water, are efflorescent, and a neutral 

 bouillie cannot be prepared from them without groping in the dark. 

 Moreover, they always contain larger or smaller quantities of sulphate 

 of soda. The limpid liquid which separates from the blue precipitate 

 after the bouillie has settled should neither be acid nor alkaline ; if 

 blue litmus paper dipped in the liquid turns red, carbonate of soda 

 must be added ; if red litmus paper turns blue, blue vitriol must be 

 added. 



Properties. — Cai-bonate of copper is insoluble in water but soluble 

 in organic acids. The deposit formed on the leaves by spraying with 

 bouillie bourguignonne may become soluble as the cupric hydrate of 

 the bouillie bordelaise and eau celeste, or by the juices transpired 



