372 MARL AND MARLING IN EUROPE. 



and frequent use in English books, with very different meanings. 

 The existence of these differences, and errors, has been stated 

 generally in a foregoing part of this Essay, and here will be adduced 

 the proofs, in quotations from many authors. I maintain, and will 

 establish the following propositions : 



1. By nearly or quite all of the older (and even some of the 

 modern) British authors, the term marl was applied to clays (or 

 earths) containing no calcareous matter ; dnd even when calcareous 

 earth was known to be contained in marl, that ingredient was not 

 deemed (if indeed it was) the essential or the most valuable fertiliz- 

 ing quality of the manure. 



2. The marls of Europe, whether as correctly defined or under- 

 stood by modern writers and scientific agriculturists, or as often 

 miscalled and misunderstood by illiterate culti-vators are very dif- 

 ferent from the deposits of fossil shells, called marl in this 

 country. 



3. Even when the chemical character, and the manuring action 

 (in like applications) of the marls of England and Virginia are 

 the same (that is, agreeing in being both calcareous) still the ordi- 

 nary mar lings of the former are quite a different manuring opera- 

 tion from the marling (or calxing) advised in this Essay inasmuch 

 as the lands so manured in England were mostly calcareous before, 

 either by natural constitution, or by previous marling and there- 

 fore were not made calcareous (or ealxed) by the dressing in 

 question. 



4. In many cases of published statements of, or references to 

 marling labours or improvements in England, the reader is left in 

 doubt whether the marl or the soil was calcareous or which the 

 most so and therefore, whether the "marling" served to increase 

 or to lessen, or had not materially altered the proportion of tho 

 previous calcareous contents of the soil. 



5. The marling of England, especially, Las been almost entirely 

 empirical and not directed by theory, reasoning, or by inferences 

 drawn from the known (or even surmised) chemical constitution 

 of either the soil or the earthy manure applied.. 



These assertions refer principally, but not exclusively, to the 

 writers on agriculture of former and less enlightened times than 

 the present or recent. Scarcely any exception is known in works 

 much older than the institution of the British Board of Agricul- 

 ture, in 1795. Before that time, the errors which I shall adduce 

 prevailed almost universally, in books as well as in vulgar language- 

 and opinion. And these older writers were, to much later times, 

 the unquestioned authorities of the earliest agricultural writers of 

 America, as well as of all our other readers and thinkers. And 

 the aid of all the more correct information as to the true character 

 of marl, afforded by the more recent British writers, it seems has 



