112. EXPLOITATION OF PLANTS 
The most important vegetable mordant dyes fall into 
three groups of closely allied chemical’ substances—the 
hematoxylin group, the flavone group, and the alizarin 
group. 
The hematoxylin group of dyes come from a series 
of South American woods used for dyeing under the 
names of logwood and the red woods. Logwood is 
produced from the hematoxylin tree (Hematoxylon 
campechianum). The wood must be matured by age- 
ing. To do this chips and raspings are stacked in heaps 
20 feet long, 10-12 feet broad, and 3-4 feet high ; water 
is added and a fermentation probably goes on. The 
process is very touchy, and depends largely upon the 
state of the weather; on a warm, dull, foggy day the 
whole of the wood may be destroyed, for dyeing 
purposes, in a few hours. 
The matured chips are exported, and the colouring 
principle hematein dissolves out in the dye bath. 
Logwood is still used a good deal for dyeing black on 
iron or chromium mordants for silk or wool; it also 
gives a dull blue with alum mordant and a dingy purple 
with tin. 
The soluble red woods (Brazil wood, peach wood, 
etc.) from various species of Cesalpinia give, in a 
similar manner, a closely allied colouring principle 
“ Brazilin,’” which gives shades of pinks and purples 
with the different mordants. 
The insoluble red woo. (barwood, camwood and 
saunderswood) contain the principle Santalin, of un- 
known composition, which gives very fast shades of 
dull red and rich claret brown, which are used for wool 
dyeing in compound browns. 
