428 On the Application of Claij to Moor -Land. 



perfectly black, containing lignite, abounding with pyrite, wliicli im- 

 pregnates the water with the results of its decomposition : the white 

 clay, which does not appear to contain any nutritive matter, is reckoned 

 useful as a top-dressing ; the carbonaceous clay is rendered poisonous 

 by the pyrites with which it abounds, from the w^ant of calcareous 

 matter to correct the sulphate of iron produced by the decomposition of 

 the pyrites by the application of lime. Land thus poisoned has been made 

 by lime to yield most luxuriant crops of clover, because gypsum has been 

 formed by the decomposition of the sulphate of iron. But although our 

 heath appears to be totally devoid of any form of calcareous matter, 

 white clover is produced spontaneously by the ashes of the heather. 

 This seems to point out a cheap and easy method of converting the 

 lieath-land into sheep pasture; but it would not be durable on a soil 

 which has so little power of retaining moisture. This is one of the 

 benefits conferred by clay on peaty soils as well as on sand ; this is also 

 one of the advantages of chalk, which, although it rather assists the 

 transmission of water, retains the last portions of it with great tenacity : 

 this is one of the valuable properties of soils enumerated by Berzelius. 

 I have been strongly advised not to use chalk, by persons who have used 

 it here ineffectually ; but I have learnt that good turnips were produced 

 on a heath-farm where chalk was used, and that on another part of it, 

 where no chalk was used, the turnips failed. I am using chalk of the 

 very best kind, free from Hints, and very powdery. Some of the chalk 

 near the course of the Thames is rendered detrimental by the presence of 

 magnesia, indicated by the production of Epsom salt. Mr. Anderson, 

 of the Botanic Garden at Chelsea, supposed that from this cause the 

 mud left by the waters of the Thames had produced injurious effects at 

 Battersea; but this I should rather attribute to the salts of iron, the 

 presence of which in the mud of the Thames is indicated in various ways, 

 — by blackening the top leather of boots, and by converting the mortar 

 of the Thames Tunnel into a water-proof cement during its filtration. 



I remain. Sir, 



Yours, &c. 

 Poole, Dorset, S. Solly. 



VII. — Simple and Effectual Method of Destroying Bats and Mice, 

 By J. Stanley Carr, of Tiischenbeck. 



During the twenty-four years that I have " turned my sword into a 

 ploughshare," I do not think there has been a greater alloy to the plea- 

 sures of farming than the destruction caused by rats and mice, their 

 fearful increase in favourable localities, and the hopelessness, in a large 

 establishment, of even checking their devastations. Two years ago, rats 

 of an extraordinary size and fierceness trooped about this old house at 

 niglit, with a clatter which a little imagination and the stillness of the 

 hour magnified into charges of cavalry ; young pigs were torn from the 

 sows and devoured, despite their formidable defence ; nor was it possible 

 to calculate anything like the quantity of grain consumed by them. 



