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.
Copper sulphate (98 per cent) ......... 2 1b.
Lime (freshly burnt) ............ 1 „
Water ... ... ... ...... ... 10 gal.
Dissolve copper sulphate in 5 gal. water in wooden vessel. When lime has slaked to a tine powder, mix it with remaining 5 gal. water, and then pour into copper solution. Stir the mixture thoroughly to secure even distribution. Bordeaux mixture is regarded as one of the most useful and effective fungicides. To test the liquid add a few drops of potassium ferrocyanide (1 oz. to 10 oz. of water), and if the liquid becomes brown add more lime. To make a strong solution add an extra 1/2 lb. of copper sulphate to 10 gal., and to make a weak solution reduce the copper sulphate 1/2 lb. from formula.