22 
The reaction is simple: 
CuS0 4 , 5H 2 0 + CaO,H 2 0 = Cu (OH), + CaS0 4 + 5H 2 0. 
From this formula a simple calculation shows that to precipitate the 
G pounds of copper sulphate, there would be required 1.34 pounds of 
lime (CaO), which would in turn produce 2.34 pounds of cupric hy¬ 
droxide. 
The weight of lime to be used should be considerably increased above 
this amount, owing to its impure character as ordinarily purchased, 
but it is likely that 3 or 4 pounds of commercial lime will suffice to 
satisfy this reaction. 
The 22 gallons of water is capable of dissolving approximately .235 
pounds of lime, an amount sufficient to precipitate practically 1 pound 
of the copper sulphate. But since this quantity of lime is immediately 
thrown down as a nearly insoluble sulphate, the water is free to dis¬ 
solve another portion of lime, which in turn precipitates another portion 
of the copper, until all of the copper is thrown down. It is found that 
this complete precipitation of the copper takes place quickly, or by the 
time the matter in suspension has fully settled, leaving a clear super¬ 
natant liquid, which does not react for copper; hence a long standing 
of the Bordeaux mixture before use is hardly necessary. 
I 11 drying upon the plant the cupric hydroxide in the Bordeaux mix¬ 
ture undergoes no change, hence it is probably this salt of copper which 
is the active principle. 
EAU CELESTE. 
Formula .—Copper sulphate, 1 pound; strong ammonia, 1J pints; 
water, 22 gallons. 
In the addition of ammonia water to a solution of normal copper sul¬ 
phate, the copper is precipitated as a basic sulphate, forming at the 
same time ammonic sulphate, which remains in solution. With an ex¬ 
cess of ammonia, the basic copper sulphate dissolves to a blue fluid 
forming the ammonio-copper sulphate (0uSO 4 , 4NH 3 , tJ 2 0). 
In drying upon the plant the ammonio-copper sulphate gradually 
loses its ammonia and is reconverted into the basic copper sulphate. 
The following are the probable reactions : 
(1) 3CuS 0 4 , 5H 2 Q -f 4NHJ40 = CaS0 4 2Cu(OH) 2 -f 2(NH 4 ) 2 S0 4 -f 15H 2 0 
Normal cop- Basic copper 
per sulphate sulphate. 
(2) CuS0 4 , 2 Cu(OH> 2 + 2(NH 4 ) 2 SO, + 8NH 4 HO = 3(CuS Q 4 , 4NH 3 , H .O) -f- 
Iu excess. Ammonium copper 
9H 2 0 sulphate. 
(3) In drying upon the vine. 
3(CuS 0 4 , 4NH 3 , H 2 0) + H 2 0 = CuS0 4 , 2Cu(OH) 2 + 2(NH 4 ) 2 S0 4 + 8NH 3 
To satisfy the reactions (1) and (2), the one pound of copper sulphate 
would require .439 pouuds of ammonia gas (NH 3 ); or 1.G6 pints of the 
