CHAPTEE XV. 



EAU CELESTE— COPPER PHOSPHATE— COPPER BORATE— COPPER 

 FERROCYANIDE. 



92. Eau Celeste. — Preparation. — By dissolving a copper salt 

 in water and treating the solution with an excess of ammonia a pale 

 celestial blue precipitate of copper hydrate forms, then an intense 

 celestial blue solution. Eau celeste is an ammoniuret of copper oxide 

 dissolved in water. Audoynaud, who first advised this liquor to replace 

 bouillie bordelaise in the struggle against cryptogamic diseases, pre- 

 pared eau celeste by dissolving 10 lb. of blue vitriol in 3 gallons of hot 

 water, cooling the solution, then adding about 1^ gallons of commercial 

 ammonia. The concentrated eau celeste thus obtained keeps in- 

 definitely. When required for use it is diluted with 200 gallons of 

 water. Bellot des Minieres advised for the preparation of eau celeste 

 another method of manufacture, that of Schweizer's capro-ammoniacal 

 liquor, which is endowed with the remarkable faculty of dissolving cellu- 

 lose. This method is based on the property of ammonia of dissolving 

 metallic copper in presence of air, producing cuprammonium hydrate. 

 A funnel is filled with red copper turnings, and ammonia of 22° Baum6 

 poured on the top. The ammonia is passed and repassed several times 

 over the copper. The solution is not finished until after a great many 

 passages. With 1 lb. of copper 15 gallons of anticryptogamic liquor is 

 produced. To distinguish it from the eau celeste of Audoynaud, this 

 solution is termed "Bellot des Minieres ammoniaco-cupric liquor, "or 

 "ammoniate of copper". Copper carbonate likewise dissolves in 

 ammonia, and the blue solution so obtained dissolves cellulose, like 

 Schweizer's liquor, whilst, on the contrary, the ammoniuret of copper 

 hydrate, prepared from the sulphate nitrate, or the phosphate of copper, 

 is not endowed with this special property. The anticryptogamic 

 liquor obtained by dissolving copper carbonate in ammonia is called 

 eau celeste modifiee, or ammoniacal carbonate of copper bouillie. Its 

 preparation is more simple than that of any other copper bouillie, for it 

 suffices to weigh a certain quantity of commercial copper carbonate, stir 

 it up with the necessary water, and add ammonia to complete solu- 

 tion. The same result is obtained by adding ammonia to bouillie 

 bourguignonne until it is converted into a deep limpid blue liquor. In 

 America it is customarj^ to dilute ammonia to 26' B. with seven to eight 

 times it weight of water, and to add copper carbonate whilst stirring until 

 a small amount remains insoluble — a proof that the liquor does not 

 contain an excess of ammonia, a condition which is not attended to in 

 the greatest number of instances. If it be desired to prepare modified 

 (261) 



