CALCAREOUS MANURES— APPENDIX. 185 



general reader of these and other agricultural works, of the nature of what 

 is called marl, in England, as well as what is so named in this part of our 

 country. I do not mean that' other authors have not thought more cor- 

 rectly, and sometimes expressed themselves with precision on this subject. 

 Mineralogists define marl to be a calcareous clay*— and in this correct 

 sense, the term is used by Davy, and other chemical agriculturists. Such 

 authors as Young and Sinclair also could not have been ignorant of the 

 true composition of marl— yet even they have used so little precision or 

 clearness,, when speaking of the effects of marling, that their statements, 

 (however correct they may be in the sense they intended them,) convey no 

 exact information, and have not served to remove the erroneous impres- 

 sions made by the great body of their predecessors. Knowing as Young 

 did [see first quotation] the confusion in which this subject was involved, 

 it was the more incumbent on him to be guarded in his use of terms so 

 generally misapplied. Yet considering his practical and scientific know- 

 ledge as an agriculturist, his extensive personal observations, and the quan- 

 tity of matter he has published on soils and calcareous manures, his omis- 

 sions are more remarkable than those of any other writer. In such of his 

 works as I have met with, though full of strong recommendations of marl- 

 ing, in no case does he state the composition of the soil, (as respects its 

 calcareous ingredient,) or the proportion added by the operation— and ge- 

 nerally notices neither, as if he viewed marling just as most others have 

 done. These charges are supported by the following extracts and re- 

 ferences. 



10. Young's Farmer's Calendar, 10th London edition, page 40. — On 

 marling. Through nearly four pages this practice is strongly recommended 

 — but the manures spoken of, are regularly called " marl or clay," and 

 their application, "marling or claying." Mr. Rodwell's account of his 

 practice is inserted at length. On leased land he " clayed or marled" eight 

 hundred and twenty acres with one hundred and forty thousand loads, and 

 at a cost of four thousand nine hundred and fifty-eight pounds — and the 

 business is stated to have been attended with great profit. At last, the 

 author lets us know that it is not the same substance that he has been 

 calling " marl or clay" — and that the marl effervesces strongly with acids, 

 and the clay slightly. But we are told nothing more precise as to the 

 amount of calcareous ingredients, either in the manures, or the soil — and 

 even if we were informed on those heads, (without wiiich we can know little 

 or nothing of what the operation really is,) we are left ignorant of how 

 much was clayed, and how much marled. It is to be inferred, however, 

 that the clay was thought most serviceable, as Mr. Rodwell says— 



" Clay is much to be preferred to marl on those sandy soils, soait of which are loose, 

 poor, and even a black sand." 



11. Young's Survey of Norfolk, (a large and closely printed octavo vo- 

 lume,) has fourteen pages filled with a minute description of the soils of 

 that county— but without any indication whatever of the proportion, pre- 

 sence, or absence, of calcareous earth in that extensive district of sandy 

 soils, so celebrated for their improvement by marling— nor in any other 

 part of the county. The wastes are very extensive : one of them (page 

 385) eighteen miles across, quite a desert of sand, " yet highly improveable." 

 Of this also, no information is given as to iti calcareous constitution. 



12. The section on marl (page 402, of the same work) gives concise 

 statements of its application, with general notices of its effects, on near 



♦ Cleavelaiid's Mineralogy. 



