50 



THE PRACTICAL GARDENER. 



have not the same effect ; Hme-stones, containing ahmine and 

 silica, are less fitted for the pin-pose of manure, than pm'e hme- 

 stone ; but the Hme formed from them has no noxious quahty : 

 such stones arc less efficacious, merely because they furnish a 

 less quantity of quick lime. There is seldom any considerable 

 portion of coaly matter in bituminous lime-stones, never ex- 

 ceeding five parts in one hundred, but such lime-stones make 

 very good lime. The carbonaceous matter can do no injury to 

 the land, and may, under certain circumstances, become a 

 food for the plant. Lime that contains certain portions of 

 magnesia has been found to do much injury to the crops on 

 which it has been applied ; while, in other cases, it has been 

 found to be productive of much good. It is a general remark, 

 that lime containing magnesia may be applied in large quan- 

 tities to peats ; and that when lands have been injured by the 

 application of too large a portion of magnesian lime, peat will 

 be the most proper and efficient remedy. Nitric acid, or aqua- 

 fortis, is a simple test to detect the presence of magnesia in lime- 

 stone. The application is to steep the stone in the diluted 

 liquid, and the magnesia will be detected by its turning the 

 liquid of a milky hue. Magnesian lime-stones are usually of a 

 brown or pale yellow color. 



Coal was first discovered by Hazenfrez to be an essential 

 ingredient in the food of vegetables, and is now used as a 

 manure with good effect. Mr. Kirwan observes, that coal, 

 " though hitherto little attended to, appears to be one of the 

 primeval principles, as ancient as the present constitution of 

 our globe ; for it is formed in fixed air, of which it constitutes 

 above one-fourth part, and fixed air exists in lime-stones, and 

 other substances, which have their date from the origin of 

 things." 



Manures, whether animal or mineral, are of such import- 

 ance to vegetation, that we should use all possible diligence in 

 the collecting and preparing of them for the different purposes, 

 for which they may be required. By a proper application of 

 them, and by a rotation of cropping, founded on just principles, 

 the worst garden-ground may be not only improved, but ren- 

 dered fit for the production of every vegetable, that is usually 

 cultivated in these islands. 



