1 1 2 
per man should the estate be already overworked. As each man 
works 200 trees, this would place the yield of one tree, when 
worked under satisfactory conditions at / to kilos, per annum. 
On the same basis and taking the whole of the crop from the 
Amazon district as being 24,000 tons (about) per annum there 
would appear to be about 120,000 labourers employed in cutting 
rubber at present. Calculating still on the same basis there should 
be some 24,000,000 trees being tapped, and these on a basis of one 
tree to every 2 acres would give an area of about 50,000,000 acres 
of forest at present being worked for rubber. When it is con- 
sidered that the district in question embraces well over r,ooo,ooo 
square miles, and that it is by no means easy to find virgin rubber 
forest within 200 or 300 miles of Para or Manaos, it will be seen 
how comparatively scarce is the Hevea, in the Amazonian forests. 
The Hevea , is found to yield its latex more freely at the base than 
higher up the trunk. In some places, however, where the trees 
have already been considerably worked, and the lower part of the 
trunk is already covered with knobs due to excessive tapping, it is 
the custom to build stagings in order to enable the rubber cutters 
to reach a higher portion of the trunk. A good tree will still yield 
freely to a height of some 20 or 30 feet. 
If allowed to rest for three or four years, even a completely ex- 
hausted tree will quite recover itself, and may be worked again 
from the base. As has been already stated, the tree is not kfiled 
when the supply of latex runs short, and as a rule sufficient dam- 
age has not been inflicted to prevent the tree from recovering it- 
self. This fact is important, as owing to it the supply of rubber 
available will probably not run short as has been often prophesied 
of late. Trees have been known to have been tapped off and on 
during 50 years, and to be still yielding a plentiful supply of latex. 
The latex having been obtained and collected the ‘‘caoutchouc,” 
or rubber known to commerce, may be obtained from it in various 
ways. The only method, however, that has met with practical 
success is that of evaporation, by which the watery portion of the 
latex is driven off and solid caoutchouc remains. The object to be 
secured is that as little water and proteid matter shall remain in 
the caoutchouc, the putrefaction of the caoutchouc, owing to the 
presence of these matters being extremely detrimental to its elas- 
tic properties, and, therefore, to its market value. In the Amazon 
district the method followed is to light a fire upon the ground and 
to invert over it a specially constructed funnel-shaped-chimney. 
From the narrow end of the funnel, which is open, the smoke and 
heated gases pour out in a concentrated form. The fuel used for 
the fire consists, as a rule, of chips from any hardwood tree that 
grows^ handy to the labourer’s hut. The nuts of the “ Urucury 
palm ( Attalea excelsa) are sometimes used, their smoke contain- 
ing a trace of acetic acid and creosote being found particularly 
effective in curing the rubber and preventing 'putrefaction, ft is, 
however, a mistake to suppose that all or even a large proportion 
of the rubber coming from the Amazon district is cured in this way. 
It is, on the contrary, very rarely that the rubber-cutter will be at 
