CALCAREOUS MANURES— THEORY. J 5 



quantities are too small, and their presence too rare, to require considera- 

 tion. If all the. numerous different combinations of lime, having perhaps 

 as many various and imknown properties, had not been excluded by my 

 definition of calcareous earth, continual exceptions would have been neces- 

 sary, to avoid stating what was not meant. The carbonate of lime, to 

 which I have confined that term, though only one of many existing combina- 

 tions, yet in quantity and in importance, as an ingredient of soils, as well as 

 a part of the known portion of the globe, very far surpasses all the others. 



But even if calcareous earth, as defined and limited, is admitted to be the 

 substance which it is proper to consider as one of the three important earths 

 of agriculture, still there are objections to its name, which I would gladly 

 avoid. However strictly defined, many readers will attach to terms such 

 meanings as they had previously understood : and the word calcareous has 

 been so loosely and so difl^erently applied in common language, and in 

 agriculture, that much confusion may attend its use. Anything " partaking 

 of the nature of lime" is " calcareous," according to Walker's Dictionary ; 

 Lord Karnes limits the term to pure lime;* Davyf and Sinclair| include 

 under it pure lime and all its combinations ; and Kirwan,|| Rozier,ir and 

 Young,5 whose example I have followed, confine the name calcareous earth 

 to the carbonate of lime. Nor can any other term be substituted without 

 producing other difficulties. Carbonate of lime would be precise, and it 

 means exactly the same chemical substance ; but there are insuperable ob- 

 jections to the frequent use of chemical names in a work addressed to or- 

 dinary readers. Chalk, or shells, or mild lime, (or what had been quick-lime, 

 but which, from exposure to the air, had again become carbonated,) all these 

 are the same chemical substance ; but none of these names would serve, 

 because each would be supposed to refer to such certain form or appear- 

 ance of calcareous earth, as they usually express. If I could hope to revive 

 an obsolete term, and with some modification establish its use for this pur- 

 pose, I would call this earth calx — and from it derive calxing, to signify the 

 application of calcareous earth, in any form, as manure. A general and 

 definite term for this operation is much wanting. Liming, marling, applying 

 drawn ashes, or the rubbish of old buildings, chalk, or limestone gravel, all 

 these operations are in part, and some of them entirely, that manuring that 

 I would thus call calxing. But because their names are different, so are 

 their effects generally considered— not only in those respects where differ- 

 ences really exist, but in those where they are precisely alike. 



Calcareous earth in its different forms has been supposed to compose as 

 much as one eighth part of the crust of the globe.** Very extensive plains 

 in France and England are of chalk, pure enough to be nearly barren, and 

 to prove that pure calcareous earth would be entirely so. No chalk is to 

 be found in our country — and it is only from European authors that we 

 can know any thing of its agricultural characters, when nearly pure, or 

 when forming a very large proportion of the surface of the land. The 

 whiteness of chalk repels the rays of the sun, while its loose particles per- 

 mit water to pass through, as easily as sand ;tt and thus calcareous earth is 

 remarkable for possessing some of the worst qualities of both the other 



* Gentleman Farmer, page 264, (2d Edin. ed.) 



t Agr. Chem. page 223, (Phil. ed. of 1821.) 



X Code of Agriculture, page 134, (Hartford ed. 1818.) 



II Kirwan on Manures, ciiap. 1. 



IT " Terres" — Cours Complet d'Agriculture Pratique. 



§ Young's Essay on Manures, chap. 3. 



** Cleaveland's Mineralogy — On carbonate of lime. 



tt Cours Complet d'Agriculture, etc. par i'Abbe Rozier — Art. " Terres." 



