This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Modified "Eau Celeste" is made by dissolving 4 lb. copper sulphate in 10 to 12 gal. water, and stirring in 5 lb. of washing soda. Dissolve 1 1/4 lb. of soda in hot water; then add 3 pt. of ammonia, and dilute to 50 gal. of water. (See "Ammoniacal Copper Fungicide").