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.
This has become popular as a fungicide. The sulphide is best kept in well-stoppered bottles, as it decomposes quickly when exposed to the air. For indoor plants 1 oz. to 5 gal. water is sufficient, but for outdoor plants 1 oz. to 3 gal. water is not too strong. A little whitening may be added to show where the spray falls. It discolours paint and woodwork. By adding a little soft soap to the fluid it adheres to the foliage better, and if a fine sprayer is used may be applied hot.