COMMERCIAL MANURES. 201 



I do not propose to treat of them all in detail, but only to touch 

 briefly upon the leading features of the more prominent among 

 them ; — and the first I will mention is Lime. 



On some soils lime is useless or even injurious, but on others it 

 may be used to great advantage, and it might be profitably used to 

 far greater extent than it is. 



It has happened with lime as it has with many other things in 

 iJiis world of ours ; after having been extolled above their merit, 

 they sink in estimation as far below their true value. The truth 

 is, that lime is a special manure, and by no means a general one. 

 Some things it can do with great advantage, and others it cannot 

 do, but if attempted, perhaps harm instead. To a very limited 

 extent lime may be usefully applied to furnish plant food — but 

 ordinarily, soils contain enough for this purpose. 



The chief office of lime seems to be that of an alterative. When 

 applied to stiff clays, and to some soils neither clayey nor stiff, 

 but rather mossy and wet and indolent ; in a condition resembling, 

 as near as anything, the chronic shiftlessness of some people we 

 occasionally meet ; — upon all such soils lime frequently causes 

 highly beneficial changes, partly chemical, and these only partially 

 understood ; partly mechanical, but certainly beneficial ; thus 

 stiff clays are rendered more friable, and wet lands are made 

 drier, as well as unproductive lands more fertile. Increase of 

 fertility, by means of the use of lime, is probably as often due to 

 its action in liberating potash from its insoluble combination with 

 silica in the soil, as to any other effect of its application. 



Lime is also usefully employed as an ingredent in composts of 

 peat and muck, since it promotes the decay of vegetable fibre, and 

 the destruction of certain harmful compounds of iron not un- 

 frequently met with in mucky deposits. * 



The next I mention, is Gypsum ; — Plaster of Paris, — or, as the 

 chemists call it. Sulphate of Lime. On some soils this is a very 

 efficient manure and the cheapest to be had. On other soils it is 

 useless, and its price, whatever that may be, is thrown away. 

 How it operates, — whether by furnishing plant food directly, or 

 indirectly, or in whatever way inducing fertilizing results, nobody 

 fully knows. There are plenty of guesses about its mode of 

 operation, and some actual knowledge, but I am not aware that 

 the numerous researches directed to this point, have resulted 

 in satisfactory conclusions. If you would know — each for your- 

 self — whether it will pay for you to use it — my advice is, that you 



