144 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



drate of magnesia, or a compound of h3^drato with carbonate or bi-carboi> 

 ate of magnesia, which latter dissolves in fifty times its weight of water. 

 Carbonate of lime is applied to the compost heap in its various natural 

 forms, of these marl occurs most abundantly, and is extensively used in 

 every part of the world where agriculture is carried on extensively. 

 Marls are of many colors, yellow, blue, gray and white, and of various 

 degrees of coherence arising from the earthy matters they contain, and the 

 nature of their locality. Their efficacy is due to the carbonate of lime con- 

 tained in them in the state of powder, which is diiTuscd through the mass. 

 The experience of every farmer that I have spoken to on the subject of 

 marl and lime, is that it has proved far more enriching to land when com- 

 posted, and a much smaller quantity placed on the land in this form, will 

 produce an equal effect with a large quantity put on alone, probably, for 

 • tli^ reason that rai^ji cannot act upon it in compost as it would in the open 

 soil. The older the compost containing lime is the more fertilizing will be 

 its action, and it will be perceived more sensibly the second and third 

 year than in the first, particularly wh?n applied to the driest and lightest 

 soils, and to such that does not abound in vegetable matter. These sub- 

 stances supply inorganic food, which is indispensable to the well being of 

 all cultivated plants. They neutralize acid substances which are in the 

 compost, and render them harmless, they change the inert vegetable matr 

 ter into useful mould, and facilitate the production of inorganic and 

 organic compounds in the heap, promote their decomposition and speedily 

 prepares them to enter into the circulation of plants. 



The following crops contain lime as mentioned below : 



25 bushels of wheat growing upon an acre. 8 lbs. 



89 " barley " " 16 " 



60 " oats " " 9 " 



80 tons of turnips " " 139 " 8 oz. 



10 " potatoes " " 265 " 1 " 



2| " clover " *' 130 " 2 " 



2I " ryegrass " " 34 " 1 " 



All these crops require that lime should be used in some form in the 

 compost heap, otherwise their functions will be delayed in the performance 

 of their duty. 



The agency and decomposition of saline matters are necessary constitu- 

 ents of the compost heap, as they are found in numerous instances, when 

 employed properly to contribute largely to the support and growth of vege- 

 tation. The materials generall}'- made use of in this way are the refuse of 

 bleaching and soap-boiling manufactories, peat, pit coal, and .wood ashes, 

 sea salt, soot, &c. The different alkaline principles contained in these sub- 

 stances, form the facility' and power which they possess of acting upon and 

 dissolving the parts of vegetable and animal matters, particularly such as 

 have been rendered insoluble by absorbing oxygen. When they are com- 

 bined in the compost heap, they are usually found to be the noost advantar 

 geous and useful upon stiff clay and loamy soils, where they contribute to 

 increase the crops by furnishing such soluble matters as can be readily 

 taken up by the absorbent roots of plants, after the stiffness and tenacity 

 of the land is lessened. 



