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commend the white and grey, others the blue, and red, (which I thinkthe best) according as it is more or lefs apt to resolve after wetting j butnone of them discover their virtues for the first year: It does incompar-ably on pastures; some on arable, a good coat of compost suitable to theland being first spread where you will lay it: If your marl be very unctu-ous and rich, apply it lefs copiously; the too thick covering is the worstextreme, nor is it always to be used without allay and mixture with otherproper soil; for some marls are more sandy and gritty than others, andshould be qualified with a contrary. Give lean and emaciated earth acovering of the fattest marl; apply hot and dry to the cold and moist:and this is also to be observed in the application of all other compostsand medications x .
calcareous. If too great a quantity of the former be used, vegetation will be greatly re-tarded, it being experimentally found, that the spot on which a heap of magnesian limehas laid, will remain in a state of barrennefs for a number of years; while, on the con-trary, the land on which a heap of'calcareous lime has laid, will, in a short time, be pro-ductive of white clover, and other natural grafses. Beds of these two kinds of limestone,are often found contiguous to each other. In the neighbourhood of Doncaster, , the mag-nesian limestone is discovered, and at Knotting])', the calcareous kind predominates. Theneighbouring farmers practically know the difference, using the one liberally, and the .other sparingly. The difference between those two kinds of lime is this. The Doncaster lime contains about three parts of calcareous earth, and two parts of magnesia. TheKnottingly lime is wholly calcareous. It is remarked, that magnesia is highly injurious tovegetation, a circumstance that explains the reason why magnesian lime is so injurious toland on which too large a quantity has been put. These two kinds of lime differ in anotherquality. During an exposure of three months, the calcareous lime has been found toabsorb four-fifths of the fixed air requisite to saturate it, while in the same space of time, .the magnesian lime does only absorb forty two hundredths of that combined with it beforeit was burnt. In the county of Derby there is found a limestone wholly calcareous, ofwhich, when burnt into lime, the farmers lay from eight to twelve chaldrons per acre ontheir grafs lands. This subject is learnedly discufsed in a paper read by Mr. Tennantbefore the Royal Society of London , and which will probably be published in their Trans-actions, in the course of the present year. For this Discourse the farming world is muchindebted to Mr. Tennant, as it gives the ready solution of a pliamomenon that, before histime, was only practically known.
31 When marl can be procured, we need not be scrupulously nice either in its kind orapplication; for, as far as.I can learn, it never disappoints the expectations of the farmerwho has spirit and industry to use it. It invariably loosens a stiff soil, and gives texture toa loose one : a circumstance of the utmost importance to the tillage farmer ; and indeed allthat, is necefsary for him. to know concerning the nature, of this earth..