Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 4, 1802).djvu/474

438] M. MANURE.—The utility of clay on poor lands has already been stated in this article, : we now submit the following fact to the consideration of our readers.—In the 2d vol. of "Communications to the Board of Agriculture," a paper is inserted on the use of clay and marle, by Mr., on whom the Board conferred their gold medal. Thirty years since, Mr. R. hired a farm, consisting of 1400 acres, the greater part of which was poor heath land: during that period, he has broken up and manured the soil with nearly 140,000 loads of clay and marle, at the expence of 4958l.: his indefatigable labours have been amply compensated, and the rental of the farm has been increased from 150l. to 700l. per annum.—Facts, like these, demand most serious attention; and those of our readers, who wish to acquire minute information respecting Mr. R.'s management, will consult the valuable work above cited.  MERCURY.—This mineral being of extensive utility, both in the arts and in medicine, various base metals are frequently combined with it, in order to increase its weight: such fraud may, however, be detected by the dull aspect of the quicksilver; by its tarnishing on exposure to the air; and by the black sediment deposited, when it is shaken with water, in a bottle. The substance, chiefly employed for this nefarious practice, is lead; a very large proportion of which unites with mercury, especially if zinc or bismuth be previously added.

In order to ascertain the adulteration with lead, quicksilver should be agitated with a little water; after which the fluid must be strained, and the mercury digested in distilled vinegar. By this process, the oxyd of lead will be dissolved, and will deposit a blackish precipitate with sulphurated water. If mercury has been sophisticated with bismuth, the latter will appear in the form of a white sediment; on pouring a solution of nitre, prepared without heat, into a vessel containing the suspected metal and distilled water.—Tin may be discovered, in a similar manner, by a weak solution of nitro-muriate of gold, which produces a purple sediment; but zinc may be detected by simple exposure to heat.  MILDEW, a distemper which, from its clammy nature, is equally injurious to trees and plants, by closing up their pores, so that their perspiration is obstructed, and their growth is checked.—Contrary to the commonly received opinion, Mr. has observed, that fruit-trees are more liable to this malady, when planted against South and West walls, than those exposed to the East; and, by removing such diseased trees to North or East walls, they have perfectly recovered.

Where danger is apprehended from the mildew, Mr. F. advises the trees to be sprinkled with urine and lime-water; but, if the young shoots be much infected, it will be necessary to wash them with a woollen cloth, dipped in the mixture, which has been specified in the article (p. 399, of this Supplement), with a view to clear them