BY MIXED MANURES. 



297 



Vegetable matter 30.70 



Extract, matter & nitrog. 20.00 

 Carb. of lime and traces 



of magnesia 14.66 



Acetate of lime 5.65 



Sulphate of lime 5.00 



Phosph. of lime & of iron 1.50 



Bone dust not only acts with great power, but its effects 

 continue a long time ; and, as it contains salts of lime, it is 

 particularly useful to the soils of New England. 



8. Sootj in its composition, is allied to animal solids, and 

 may be described in thi^ connection. It is a very valuable 

 manure, as appears from its composition : 100 parts of soot 

 contain, of 



Acetate of potash 4.10 



Muriate of potash .36 



Acetate of ammonia .20 



Acetate of magnesia .53 



Silex .95 



Carbon 3.85 



Water 12.50 

 300.00 



If the value be determined by the quantity of salts and of nitro- 

 gen, in equal weights of soot and cow dung, the salts are as 

 20 in the former to 1 in the latter, and the ammonia as 40 to 1. 

 The application of soot-water (6 quarts of soot to a hogshead of 

 water) to green-house plants, has been attended with the best 

 effects. 



So valuable a substance ought to be saved with the utmost 

 care, and either applied directly to the soil or to compost 

 heaps. The latter use of soot is the most profitable, because 

 it is capable of decomposing a large quantity of vegetable 

 matter, as peat or swamp muck. 



III. Animal and vegetable substances destitute of nitrogen. 

 The only substances belonging to this class are oils and fats. 

 In order to understand the action of these bodies as manures, 

 it will be necessary to ascertain their constitution. Fatty bodies 

 are acids combined with a peculiar base called ^Zycerme, which 

 is similar to stearine and margarine or fats, and to oleine or oils. 

 The acids are stearic, margaric and oleic acids. 



When oils and fats are exposed to the air, they yield great 



quantities of carbonic acid, and become converted into the 



above acids. The carbonic acid acts upon the silicates, and 



the organic acids act upon the alkalies in the soil, and form 



25* 



