1836.] 



FARMERS' REGISTER. 



245 



The stone marl of liilly countries is fi'cquently 

 slill more abundiint in calcareous substance; but it 

 also, in many other places, contains such large 

 quantities of extraneous matter, that it may be pro- 

 jjerly considered as belonging to the earthy spe- 

 cies, and has, in some instances, been laid upon 

 tlie land to the extent of 400 to 600 single horse 

 cart-loads per acre, which heavy labor renders 

 the use of lime more economical, altliough carried 

 from a greater distance, except in cases where the 

 chief object is to loosen very stiff clays, on which 

 it acts with considerable effect. 



The origin of earth-marl is a subject of curious 

 inquiry. It is an object, however, of only secon- 

 dary importance to iiirmers; but we rcli^r those 

 who feel interested in it to an ingenious treatise, 

 which may be found in the Appendix to Holland's 

 Survey of Cheshire.* Those kinds of which we 

 are now treating are often found at the base of 

 chalk hills, or in the valleys formed between them, 

 and have probably arisen from the chalk which 

 has been washed down by the rains, together with 

 the vegetable and animal matter of various de- 

 scriptions which collect and combine together; for, 

 on analyzing them, they are found to contain clay, 

 sand, loam, and chalk, and in proportion to the 

 quantit}' of other substances with which they are 

 combined, they are either saponaceous and clam- 

 my, or crumble if largely mixed v>ith calx. Earthy 

 marls are, however, found in beds of such distinct 

 substance, that a body of sandy marl has been 

 known with a regular bed of limestone under it, 

 and a stratum of day-marl under that; in Avhich 

 case it is evident that the clay at the bottom, if it 

 was not the native soil, must have formerly formed 

 some pari of the hill towards its base. The color 

 of marl is thus occasioned by the nature of the 

 mixtures of which it is composed; for pure calx, or 

 chalk, being white, necessarily imparts a similar 

 hue in proportion to the quantity of calcareous 

 matter which it contains; while the red tinge so 

 perceptible in much of the clay-marl is a strong 

 evidence of the existence of iron. There is also 

 a sort of clay which, from its soapiness. is often 

 mistaken for marl, though differing essentially in 

 its requisite properties. This earth appears to be 

 impregnated with sulphur, and other mineral sub- 

 stances injurious to vegetation, which renders it 

 expedient that farmers who are not already well 

 acquainted with its nature should either use it at 

 first cautiously, or have it carefully analyzed by 

 Bome competent chemist. j 



cent, of sand, consequently chalk and sand are the 



predominant inj^redients. Kirwan on Manures, p. 13. 

 The analysis made by Von Thaer, of a quantity 



dug out of pits at Oldenburgh, in Germany, showed it 



to contain in 100 parts 



Of fine sand - ... - 36 

 Clay of a soapy kind - - - 44 



Mould 5 



Carbonate of lime - - - - 14 

 Gypsum ------ 1 



— Principes Raisonnes (TJIgricullurc, 2de ed. torn. 

 Xi. p. 423. 



* On the nature and origin of marl, by J. J. Stan- 

 ley, F. R. and A. S. 



t See Malcolm's Compendium of Husbandry: Anal. 

 of Main., vol. ii. p. 70—85. 



.Shell-marl. 



Shell-marl is usually of a bluish color, soft to the 

 touch, and somewhat resembling potters' earth; 

 hut when exposed to the air it crumbles, and fidls 

 into a powder, nearly in the same manner as lime 

 does in slaking. 



The' natiu-e of this marl is very different from 

 those of earth or stone; for it contains both stimu- 

 lant and fertilizing properties which do not belong 

 to the former, and from its effects upon the soil it 

 has been classed among animal manures, though 

 it more properly resembles a compost formed of 

 earth and lime, with animal and vegetable sub- 

 stances, lor which reason it is justly considered pre- 

 liirable to the others. It exists at the bottom of 

 most lakes, and under bogs and morasses, or other 

 |)ieces of stagnant water which have been drained, 

 and might, no doubt, be found in every place where 

 water has originally rested; though, as it is usually 

 under other la^'ers of earth or peat, its depth below 

 the surfiice is oi'ten too great to admit of its being 

 searched for with advantage. Every farmer 

 should, therefore, carefully examine the sides and 

 bottoms of his ditches and ponds, for, by doing so, 

 he may often find appearances of marl in places 

 where it was not suspected, and large beds of the 

 most valuable sort have been in that manner dis- 

 covered, which might have remained unnoticed for 

 years.* 



It is chiefly composed of those myriads of small 

 shell-fish which, with other iiy and insects, usually 

 procreate wherever there are pools of water, and 

 the remains of which have, in the course of past 

 ages, been deposited along with sand and decayed 

 vegetables, or other matter swept from eminences, 

 or by the decomposition of aquatic plants. This 

 process of alluvion has, in the lapse of time 

 produced those masses of shell-marl which display 

 the most striking effects when employed as ma- 

 nure; for the shells, when decomposed, are con- 

 verted into lime of such purity, that some moss- 

 marl, examined by Dr. Coventry, was found to 

 contain 84 per cent, of pure chalk — which is more 

 than is generally possessed by the purest lime — 

 and the mould formed of the other substances 

 must be very rich.f It may, therefore be convert- 

 ed into quick-liaie, by burning, or it may be used 

 in its natural state; but then it is not so minutely 

 divisible, nor so soluble in water, and is of course, 

 more tardy in its operation; its effects, however, 

 continue longer, and it is apparent that, as it con- 

 tains more calcareous matter than the common 

 qualities of lime, it may be used in smaller quali- 

 ties. When spread upon grass, or clover, it is 

 found to promote the growth of the herbage, for 

 it partakes of the nature of pounded limestone, 

 and possessing none of the caustic properties of 



* Malcolm's Compendium of Husbandry, vol. ii. 



p. 85. 



f Farmer's Mag., vol. iv. p. 156. By other experi- 

 ments made by Sir G. Mackenzie (ib. vol. v., p. 271,) 

 it appeared that some shell-marl was composed of 



Lime - - - - 41 25^ 



Carbonic acid - - 32 



Silex - - - - 14 



Argil - - - - 4 )-in 100 parts. 



Oxide of iron - - 2 5 | 



Inflammable matter - 2 j 



Loss . - - - 4 70j 



