. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. chalk should dissolve readily in dilutemuriatic acid, and the solution should afford no precipitate with water of am-monia. CHALK-J5/rtcfc. A mineral, called also drawing-slate. CHALK-Fre»ic/i. Steatite, or soap-stone ; a soft magnesian mineral. CHALK-iJcd. A clay colored with the peroxyde of iron, of which it contains about17 per cent. CHARCOAL. The fixed residuum of vegetables exposed to ignition out of contact ofair. In the article Carbon, I have described the general properties
. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. chalk should dissolve readily in dilutemuriatic acid, and the solution should afford no precipitate with water of am-monia. CHALK-J5/rtcfc. A mineral, called also drawing-slate. CHALK-Fre»ic/i. Steatite, or soap-stone ; a soft magnesian mineral. CHALK-iJcd. A clay colored with the peroxyde of iron, of which it contains about17 per cent. CHARCOAL. The fixed residuum of vegetables exposed to ignition out of contact ofair. In the article Carbon, I have described the general properties of charcoal and thesimplest mode of making it. I shall here detail the best systems of manufacturing thisproduct upon the continent of Europe. To carbonize wood under a moveable covering, the plan of mei7er,or heaps, is employed very much in Germany. The wood is arranged either in horizontal layers, or in nearly vertical ones, with a slight slope, so as to form conical rounded heaps of diflferent sizes. The former are called lying meiler,fig. 272; the latter standing meiler, figs. 273. and 274, 272 273 274. Both are distributed in much the same way. In districts where the wood can be transported into one place by means of rivers, ormountain-slides, a dry flat space must be pitched upon, screened from storms and floods,which may be walled round, having a slight declivity made in the ground, toward thecentre. See fig. 275. Into this space the tarry acid will partially fall, and may beconducted outward, tlirough a covered gutter beneath, into a covered tank. Themouth of the tank must be shut, during the coaking, with an iron or stone slab, lutedwith clay. A square iron plate is placed over the inner orifice of the gutter, to prevent it being choked with coal 275 represents a walled meilerstation ; a, the station ; 6, thegutter ; c, the tank, which is cov-ered with the slab d ; e, a. slabwhich serves to keep the gutterclear of coals. The cover of the heaps is formed of
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