220 On Manures. 



especially to lands exhausted by injudicious cropping, or weak, 

 from a deficiency of manure. 



In the neighbourhood of Grantham, the farmers desisted 

 from the use of lime, because they found their lands had been 

 exhausted by it ; but the limestone being employed" to repair 

 the roads in the neighbourhood, the scrapings, which consist- 

 ed of mild lime, were, with great advantage, applied to the 

 same lands. Lime made of chalk, has often been condemned 

 as exhausting ; yet the same chalk, uncalcined, has been found 

 beneficial. In Dumfriesshire, where mild or effete lime is 

 used for potatoes, it makes the crop more productive, and 

 greatly assists the dung ; arid where mild lime is used in com- 

 post, it is supposed that a portion of dung may, without loss, 

 be mixed with the heap. The pounded shells of oysters have 

 lately been applied, as a manure, with much success ( za4 ). 



In order to render caustic lime perfectly mild, it is some- 

 times necessary to turn it over frequently, so as to have it 

 completely saturated with fixed air, or carbonic acid, before it 

 is applied (* a5 ). 



2. Pounded Limestone. This substance differs from calcined 

 lime, in containing fixed air, or carbonic acid, and likewise as 

 being insoluble in water. Machines for pounding limestone, 

 were erected in Scotland many years ago, but unfortunate- 

 ly, were destroyed before the experiment had been fairly 

 tried. There is evidence, that the attempt was attended with 

 success so far as the experiment had gone ( zz6 )* The prac- 

 tice might certainly be of use in districts where fuel is scarce. 

 The scrapings or dust of roads made with limestone, (which are 

 in fact pounded limestone), have been employed with advantage 

 as a manure, in Yorkshire, Gloucestershire, and other dis- 

 tricts, and ought never to be neglected. The dust of marble, 

 and the splinters of limestone quarries, are also of use. 



3. Limestone Gravel. This excellent manure, (by some 

 called corn gravel, from its productive qualities in arable soils), 

 is peculiarly calculated for peat-bogs, the weight of the article, 

 giving a pressure that is much wanted. It has likewise been 

 tried on sandy soils with success, when mixed with substances 

 of a gluey or adhesive nature ( z * 7 ). Kirwan considers this 

 substance to be a species of marl, mixed with large lumps of 

 limestone. Its effects are equal in fertility, and more perma- 

 nent than lime. It has been of immense benefit to Ireland, 

 and may probably be found in many other parts of the United 

 Kingdom, if diligently searched for. Its value was acciden- 

 tally discovered in a parish in Scotland, where it has since been 

 used with the greatest success ( 33H ), 



