The Dutch method was in general use in Germany until comparatively recent times, and stable-litter was employed as the source of heat and carbon dioxide ; it has been superseded, however, by the chamber process, or the German method, as it is generally termed. This modification of the Dutch process consists in substituting specially built closed chambers for the stack or bed, and artificial heat for the heat generated by the decomposition of masses of stable-litter, or spent tan-bark, or other organic substances, as used in the Dutch process. Sometimes, however, the floors of the chamber in which the lead cast in sheets and suspended on laths is placed are covered with spent tan-bark, or other fermentable material, which is saturated with vinegar, this arrangement furnishing ,the gases necessary for the conversion of the lead, as well as the heat, which is also a prime factor in this transformation. Occasionally the plates of lead are suspended within wooden boxes which contain the acetic acid, the boxes being ranged along the floor of the closed chamber. It was formerly customary to mix with the acid wine lees, carbonate of potash, bits of marble, or other substances capable of disengaging, during decomposition, carbon dioxide. In later times this necessary element in the production of true white lead has been obtained from the combustion of coal, coke, or charcoal, or by other means, but it must be properly washed and purified before passing into the chamber. ,,The manufacture of white lead by the Dutch process was established at Klagenfurth, in Carinthia, as early, it is claimed, as 1760. A modification of the Dutch method, called by Gentele the " Klagenfurth process," was substituted for the old method in 1835. This new process has since been adopted by manufacturers at Villach, St. Veit, Wolfsberg, and at other places in Carinthia. The product of these factories has the reputation of being of very superior quality, not attributable perhaps altogether to the method employed in the manufacture, but in part to the excellence of the metallic lead produced in the district, the celebrated "Villacher " lead from the mines at Bleiberg. ,,The Klagenfurth process is a modification of the Dutch method. The vapors of acetic acid, and of carbon dioxide, in an elevated temperature, act upon metallic lead. The modification consists in the manner of producing the carbon dioxide, the acetic acid vapors, and in artificially heating the chamber, or stack. ,,The manufacture is conducted in solidly built closed rooms provided with double floors. The first floor, which is the ground floor, is occupied by a furnace, so arranged as to be fed from the outside ; the stone flue of this furnace passes on the ground from one end of the room to the other, and then passes up through the upper room and the roof to the outer air. This furnace, with its flue, is used for heating the upper room. The upper floor is formed of boards, loosely put together in order that the heat from below may freely pass into and warm it. Upon this floor water-tight boxes are placed, with spaces between and around them so that access may be had to them at all times. These boxes are provided with strong covers, which are pierced with holes to allow free passage ,to the gases which may be evolved from their contents. A strong framework is erected upon these boxes extending quite to the roof, and so arranged as to carry short sticks, upon which the lead, previously cast in long and thin plates and bent, can be hung. When the framework over the boxes is filled with lead, the spaces between the boxes are also filled ; this is accomplished by placing sticks across the passageways, resting them at either end upon the framework. This operation is continued until the chamber above the level of the boxes is completely filled with plates of lead hung upon sticks. The workmen then fill into the boxes a quantity of vinegar, and also a quantity of the extract of raisins, or dried grapes. The fires are now started, and the heat, ascending to the upper room, in which the boxes containing the liquid mixture and the plates of lead are arranged, gradually warms the contents of the boxes, and the vinous fermentation begins in the sweetish fluid ; this reaction disengages carbon dioxide in considerable quantities. The acetic fermentation also starts in the alcohol produced by the ,vinous fermentation ; thus both reactions are in process at the same time. The heat also volatilizes the vinegar, and in a short time the chamber is filled with the vapors of carbon dioxide, of acetic acid and steam ; the lead is warmed, and all the conditions demanded by the Dutch method are present. The workmen enter the chamber from time to time to stir up the mass in the boxes, to draw off the vinegar if it becomes too concentrated, and to add fresh material as it is needed. ,,The resulting product is exceptionally clean and white. The carbon dioxide produced by the vinous fermentation is free from soot, hydrogen sulphide, and other deleterious impurities so common to this substance when produced by the combustion of coke or of other forms of carbon. Much of the white lead as it is formed flakes off and drops upon the boxes or upon the floor, rendering it necessary to use extreme care on the part of the workmen to avoid staining or injury to the color of the product. 1 (1 J. G. Gentele, Lehrbuch der Farbenfabrikation, p* 135 etseq. ) Gmelin refers to what he terms a new German method. This is perhaps the original chamber method introduced into Germany. Plates of lead were suspended in wooden boxes into which a quantity of vinegar had been poured. The boxes were arranged in closed chambers. The floors were covered with spent tan-bark wetted with vinegar. These chambers were artificially heated, and the vapors of acetic acid produced by the heated vinegar, and of carbon dioxide evolved in the decomposition of the tan-bark effected the corrosion of the lead. 1 According to Preschel, white lead was made at Frankfort early in this century by precipitation, or the Thenard process. 2 This method is still in use, it is said, in some factories in the Rhenish provinces. ,,1 Gmelin, Handbook of Chemistry, vol. v. p. 118. ,,2 J. S. Preschel, Technologische Encyclopedic (Stuttgart, 1830), vol. ii., ,article Blei.