REPORT ON THE CAOUTCHOUC OP COMMERCE 
39 
tion it is wedge-shaped. Above the blade a shoulder projects. The 
wedge-shaped cutting edge opens the hark just sufficient to allow of 
the escape of the milk. The shoulder prevents the knife penetrating 
too deeply, thus preserving the wood from injury. The relative 
distance between the knife-edge and the shoulders can be made 
according to the thickness of the bark in different species, as all 
that is necessary is to rupture the milk vessels ( laticiferom tissue 
or Cinenchyma). The advantages of this instrument I take to be 
that of • removing no portion of bark, and thus not Tiindering 
cicatrization ; doing away with the possibility of u hacking and also 
I believe if tried would prove itself a simple and effectual instrument. 
The handle can be made long or short, or both, as experience may 
dictate. It may also be made in clasp knife form, the blade 
when opened forming a more or less obtuse angle with the back of 
the handle. 
Collecting Vessels . — The general collecting vessels are leaves 
folded up in funnel fashion, clay plastered to the trunk of the tree, 
or calabashes. Clay contaminates the milk in a very objectionable 
manner. Iron vessels large enough to hold the product of a 
single tree might be provided. One side of them might be slightly 
concave in order to accommodate its side to the tree. Large vessels 
of the same material would be necessary for the different 
gatherings. 
Preparation of the Caoutchouc. — In reviewing the different 
methods by which the particles of Caoutchouc are caused to coalesce, 
from the whey like liquid in which it is suspended in its recent 
state, we find they are various. We may however classify them 
thus : — 
Group i. — Coalescence brought about by heat — Examples : 
(1.) Artificial heat (dry) - Para, Madagascar. 
(2.) „ (hot water) - Assam. 
(3.) Natural heat - - -Assam, Ceara. 
Group ii. — Coalescence brought about by the addition of various 
substances: 
(4.) Alum - - - ' Para. 
(5.) Liq. Ammonite fort ? - Para, African (best kinds). 
(6.) An acid ? (acetic acid ?) Para. 
(7.) Certain plants - - Nicaragua. 
(8.) Eresh water - - Nicaragua. 
(9.) Salt water - - - Borneo, Madagascar. . 
(10.) Sulphur - - - Para. 
