OF MANURE. 20" i 



dung, yet where calcareous substances are applied, as Mr 

 Brodie of Garvald has found by long experience, a less 

 quantity of animal manure will answer the purpose. This 

 is making the farm-yard dung go farther, with more power- 

 ful and more permanent effects ; and from weightier crops 

 being thus raised, the quantity of manure on a farm wiU 

 be most materially augmented. 



7. The use of pounded limestone, where fuel is scarce or 

 dear, was strongly recommended by Lord Kames. He 

 observes, that three pounds of raw lime is, by burning, 

 reduced to two pounds of shell lime, though nothing is ex- 

 pelled by the fire but the air that was in the limestone, the 

 calcareous earth remaining entire. Two pounds of shell 

 lime, therefore, contain as much calcareous earth, as three 

 pounds of raw limestone. Shell lime of the best quality, 

 when slacked with water, will measure out thrice the quan- 

 tity : but as limestone loses none of its bulk by being burnt 

 into shells, it follows, that three bushels of raw limestone, 

 contain as much calcareous earth, as six bushels of pow- 

 dered lime j and consequently, if powdered lime possess 

 not some virtue above raw limestone, three bushels of the 

 latter, beat small, should equal, as a manure, six bushels of 

 the former. These suggestions, however, have not been 

 acted upon, probably owing to the difficulty and expence 

 of beating the limestone sufficiently small. At the same 

 time, the advantage derived from the use of limestone gra- 

 vel in Ireland, is, however, highly favourable to Lord 

 Kames's doctrine.* 



* It would be extremely desirable to ascertain, whether limestone 

 gravel might not be found in Scotland ; to the discovery of which, I 

 hope the attention of that public-spirited institution, the Highland So- 

 ciety of Scotland, will soon be directed. 



