384 ERRORS OF ARTHUR YOUNG. 



shells, or marl), is held to be injurious to the sandy soils, which 

 are so generally improved by what is there called marl. 



"Claying a term in Suffolk, which includes marling; and indeed the 

 earth carried under this term is very generally a clay marl ; though a pure, 

 or nearly a pure clay, is preferred for very loose sands." Young's Suffolk, 

 p. 186. 



After speaking of the great value of this manure on light lands, 

 he adds : 



"But when the clay is not of a good sort, that is, when there is really 

 none, or scarcely any clay in it, but is an imperfect and even a hard chalk, 

 there are great doubts how far it answers and in some cases has been spread 

 to little profit." p. 187. 



"Part of the under stratum of the county is a singular body of 

 cockle and other shells, found in great masses in various parts of the 

 country, from Dunwich quite to the river Orwell, &c." " I have seen pits 

 of it to the depth of fifteen or twenty feet, from which great quantities had 

 been taken for the purpose of improving the heaths. It is both red and 

 white, and the shells so broken as to resemble sand. On lands long in 

 tillage, the use is discontinued, as it is found to make the sands blow more." 

 [That is, to be moved by the winds.] p. 5. 



21. The Essay on Manures, by Arthur Young, for which the 

 author was honoured with the Bedford medal, speaks distinctly 

 enough of the value of marl being due to its calcareous ingredient 

 (as this author doubtless always knew, notwithstanding the loose- 

 ness of most of his remarks on this head) ; but at the same time 

 he furnishes some of the strongest examples of absurd inferences, 

 or of gross ignorance of the mode in which calcareous earth acts 

 as an ingredient of soil, and the proportion which soils ought to 

 contain. These are his statements, and his reasoning thereon : 



"It is extremely difficult to discover, from the knowledge at present 

 possessed by the public, what ought to be the quantity of calcareous earth 

 in a soil. The best specimen analyzed by Giobert had 6 per cent. ; by 

 Bergman, 30 per cent. ; by Dr. Fordyce, 2 per cent. ; a rich soil, quoted 

 by Mr. Davy, in his lecture at the Royal Institution, 11 per cent. This is 

 an inquiry, concerning which I have made many experiments, and on soils 

 of the most extraordinary fertility. In one, the proportion was equal to 

 9 per cent. ; in another 20 per cent. ; another, 3 per cent. ; and in a spe- 

 cimen of famous land, which I procured from Flanders, 17 per cent. But 

 the circumstance which much perplexes the inquiry is, that many poor 

 soils possess the same or nearly the same proportions as these most 

 fertile ones. To attain the truth, in so important a point, induced me to 

 repeat many trials, and to compare every circumstance ; and I am disposed 

 to conclude, that the necessity of there being a large proportion of calcareous 

 earth in a soil depends on the deficiency of organic [i. e. vegetable or animal] 

 matter ; of that organic matter which is [partly] convertible into hydrogen 

 gas. If the farmer finds, by experiment, that his soil has but a small 

 quantity of organic matter, or knows by his practice that it is poor, and 

 not worth more than 10s., 15s. or 20s. an acre, he may then conclude that there 

 ought to be 20 per cent, of calcareous earth in it ; but, if, on the contrary, it 

 abound with organic matter, and be worth in practice a much larger rent, 



