ent of the metal has become converted. The horse dung acts as the starter for the tan-bark, causing the fer- mentation to begin more quickly and proceed more rapidly in the initial stages. If it were not for the discoloration of the white lead, due to the action of hydrogen sulphide and other… … FIG. 13. — COMPLETED STACK. — HAMMAR BROTHERS. correct tempering of the tan -bark is the most important part of the process. If an excessive amount of water is used, or the water is too hot, or the heap of bark allowed to overheat, the tan will be " killed/' as it is termed, i.e.,
Pigments · White lead · Zinc
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