378 MARL NOT KNOWN TO BE CALCAREOUS. 



11. Kir wan, on the authority of Arthur Young and the Bath 

 Memoirs [1783,] states that, 



"In some parts of England, where husbandry is successfully practised, 

 any loose day is called marl ; in others, marl is called chalk, and in others, 

 clay is called loam." Kirwan on Manures, p. 4. 



12. A Practical Treatise on Husbandry (second London edition, 

 4to. 1762,) which professes to be principally compiled from the 

 writings of Duhamel, Evelyn, Home, and Miller, supplies the fol- 

 lowing quotations : 



"But of all the manures for sandy soils, none is so good as marl. There 

 are many different kinds and colours of it, severally distinguished by many 

 writers ; but their virtue is the same ; they may be all used upon the same 

 ground, without the smallest difference in their effect. The colour is either 

 red, brown, yellow, gray, or mixed. It is to be known by its pure and un- 

 compounded nature. There are many marks to distinguish it by ; such as 

 its breaking into little square bits; its falling easily into pieces, by the 

 force of a blow, or upon being exposed to the sun and the frost ; its feeling 

 fat and oily, and shining when it is dry. But the most unerring way to 

 judge of marl, and know it from any other substance, is to break a piece as 

 big as a nutmeg, and when it is quite dry, drop it into a glass of clear 

 water, where, if it be right, it will dissolve and crumble, as it were, to 

 dust, in a little time, shooting up sparkles to the surface of the water." 

 p. 27. 



Not the slightest hint is here of any calcareous ingredient being 

 necessary, or even serving in any manner to distinguish marl. But 

 afterwards, in another part of this work, when shell marl is slightly 

 noticed, it is said : 



" This effervesces strongly with all acids, which is perhaps chiefly owing 

 to the shells. There are very good marls which show nothing of this effervescence ; 

 and therefore the author of the New System of Agriculture judged right in 

 making its solution in water the distinguishing mark." p. 29. 



The last sentence declares, as clearly as any words could do, that, 

 in the opinion of the author, no calcareous ingredient is necessary, 

 either to constitute the character, or the value of marl. And 

 though it may be gathered from other parts of this work, that what 

 is called marl generally contains calcareous earth, yet no import- 

 ance seems attached to that quality, any more than to the particular 

 colour of the earth, or any other accidental or immaterial appearance 

 of some of the varieties described. 



The " shell marl" alluded to above, without explanation might 

 be supposed to be similar to our beds of fossil shells, which are 

 called marl. The two manures are very different in form, appear- 

 ance, and value, though agreeing in both being calcareous. The 

 manure called shell marl by the work last quoted from, is described 

 there with sufficient precision, and more fully in several parts of the 

 Edinburgh Farmers' Magazine,* and in the Memoirs of the Phila- 



'* See Farmers' Register, vol. i., p. 90. 



