1 60 LESSONS IN CHEMISTRY. 



II. That where the soil is poor in vegetable matters, and 



especially when Hme has akeady been applied, it 

 should be laid on the land in the mild state, or 

 made into a compost with the scourmgs of ditches, 

 clay, peat-mould, or other vegetable matters. Wlien 

 applied in this compost form, a smaller dose of lime 

 is found to be sufficient, and the fertility of the soil 

 is most effectually maintained. 



III. That as it has a tendency to sink down in the soil, it 



should not be buried too deep. 



IV. That on commencing to improve a farm to which lime 



has not been applied for some time, the most judi- 

 cious method is to add a sufficient amount of it to 

 influence the composition of the soil, and after five 

 or six years to maintain its condition by short doses, 

 at the rate of about 8 bushels yearly per acre. 



V. That quicklime, for the reasons already given, should 



not be mixed with, or applied at the same time as 

 farm-yard dung, guano, or other manures which 

 afford ammonia by their decay (183). 



VI. That where the soil is naturally deep, or where new 



soil has been brought to the surface and the land 

 has not been properly drained, a larger dose of lime 

 will be required than would be sufficient for a light 

 or well-drained soil, 



251. Marl^ shell-sancL, coral-sand. — Besides limestone, 

 there are several other sources of lime accessible to the Irish 

 farmer. The most important of these are the deposits of 

 marl and shell-sand, which are found in so many parts of the 

 kingdom. The term marl is applied by the farmer to a kind 

 of calcareous earth, found at the bottom of bogs, and forming 

 beds in the small lakes which exist in so many counties. 

 Agricultural writers usually confine the term to earths con- 

 taining not less than 20 per cent of lime. In this country, 

 however, the quantity of lime in the substances regarded as 

 marl, varies from 5 to 96 per cent. The marls met with in 

 Ireland differ very much in their composition ; some of them 

 contain a considerable amount of organic matter, and are 

 dried with difficulty (^peaty marls) ; others, again, appear to 

 be almost entirely composed of minute shells, and crumble 

 readily into powder when exposed to the air {shell-marls) ; 



