VEGETABLE MANURES. J 67 



these substances is much vahied in many districts. The good 

 effects of salt have already been mentioned. It has been 

 used for a long period as a manure, though, when applied in 

 too large quantities, it totally destroys vegetation. Tho 

 refuse salt of the provision stores can be procured at a very 

 low price ; and, as it is mixed with blood and other animal 

 matters, it will be found even more useful than pure salt for 

 maum'ing. The best method of intimately mixing lime and 

 salt, is to dissolve the salt in water and use it for slaking 

 the lime ; the effects of the mixture are mutual decomposition 

 of the lime and salt (chloride of sodium), chloride of calcium 

 and caustic soda being produced, both of which are readily 

 soluble in water. When peat-mould is added, a compost is 

 formed, of great value as a manure for soils deficient in vege- 

 table matter, and requirmg lime and soda. 



263. Soot^ which is occasionally employed as a top-dressing 

 to grass and wheat, is a variable mixture of clayey matters, 

 iron, sulphate of ammonia, gypsum, and certain organic 

 compounds. Its fertilizing qualities are to be ascribed chiefly 

 to the sulphate of ammonia which it contains.* The amount 

 of this ingredient, which different samples are capable of 

 affording, is shown by analysis to vary from 10 to 30 per 

 cent. It should be applied in damp weather. 



' The teacher may convince his pupils that ammonia is contained in 

 soot, by moistening a little of it with water, and mixing it with quick- 

 lime, when a pungent ammoniacal odour will be perceived. 



