1 26 LESSONS IN CHEMISTRY. 



vital importance to the farmer that none of this ingredient of 

 manure, so essential to the full development of his crops, 

 should be allowed to escape, one or other of the chemical 

 substances above described should be employed. When 

 describing the method by which Liebig detected the ammonia 

 existing in the atniosphere (19), I mentioned that he added 

 to the rain water in which it was dissolved a small quantity 

 of muriatic acid, by which the heat used in evaporating the 

 water was prevented driving it away. Several other acids 

 also possess this property ; and when the salts which sulphuric 

 acid fonns by combining with iron, green vitriol (163), and 

 with lime, gypsum^ are mixed with decomposing manure or 

 night soil, the acid enters into chemical combination with the 

 ammonia and converts it into a solid compound, which, 

 though soluble in water, and therefore capable of being taken 

 up by plants, is securely ^icec? in the manure heap.* 



1 84. It is not necessary that the small farmer should con- 

 struct an expensive tank ; a treacle hogshead, or even a large 

 tub sunk in the ground close to the manure heap, wUl be found 

 a very good substitute for it. In a small establishment, 

 nearly all the liquid manure of the stable and cow-houses may 

 be completely absorbed by the litter; or, where enough of 

 straw cannot be obtained, by spreading under the cattle dry 

 peat-mould, saw-dust, or even dry soil from the fields, as is 

 done by the careful farmers in many parts of this country. 

 The manure, when removed from the houses, should be 

 placed in a sheltered position upon a bottom of earth well 

 beaten down, so as to be rendered as retentive of moisture as 

 possible, and made to slope towards the tub ; a trench dug 

 round the heap will serve to prevent the entrance of 

 surface water. In districts where peat mould can be con- 

 veniently procured, its use will be found of great value to the 

 farmer; by adding a layer of it occasionally to the manure 



* The teacher may usefully impress the above remarks on the minds 

 of his pupils, by placing before them some sal ammoniac and quicklime, 

 and allowing them to examine them. Neither of these substances, he can 

 show them, gives out any smell ; but by rubbing together in the mortar 

 one teaspoonful of the former with two of the latter, the pungent odour 

 of ammonia will be immediately evolved. The nature of the escaping 

 gas may be tested (11) by bringing near the mortar a piece of moistened 

 red test-paper, which mil be rendered blue by the alkaline gas. The 

 property which certain substances possess of fixing ammonia may be 

 convincingly shown by pouring into the mortar a teaspoonful of spirits 

 of salts, when the pungent odour of smelling salts will be destroyed. 



