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Queries respecting the Manufacture of Caoutchouc. [Oct. 
At what age do the various caoutchouc trees begin to yield caoutchouc ? Is the 
caoutchouc prepared from the juice of a young tree inferior in quality, to that pre- 
pared from the juice of an old tree ? 
At what season of the year are the caoutchouc trees commonly wounded, for the 
purpose of obtaining from them the juice ? 
Is there any particular season of the year at which the juice is considered to be 
ripe, to yield caoutchouc of a better quality than the juice drawn from the tree at 
any other season ? If this be the case, what would be the consequence of preparing 
caoutchouc from a juice not fully matured ? Would the product of caoutchouc be 
smaller than usual ? Would it be of inferior quality ? 
What quantity of juice is afforded on an average by a full grown tree ? 
What is the average proportion of caoutchouc in this juice ? at what price can the 
manufactured caoutchouc be delivered by the grower ? 
Describe the process of preparing caoutchouc from the juice. Is heat at all em- 
ployed in it ? Are any precautions taken to have the caoutchouc unmixed with the 
other ingredients of the juice ? Is the caoutchouc coagulated by any means, and 
this directly separated from the juice ? or is the entire juice evaporated down to a 
dry mass ? 
Caoutchouc is imported into the country in two very different states. In the one 
it generally has the form of bottles, shoes, &c. the other of thick cakes. The for- 
mer kind of caoutchouc has a reddish brownish, or blackish colour; sometimes also 
reddish white : the latter is usually white or yellowish white. The former generally 
inodorous, or has only a weak vegetable odour ; the latter is sometimes inodorous, 
but in general, it has more or less of a very offensive odour, somewhat resembling 
that of rancid cheese, or of animal matter in a state of putrefaction. 
Whence, arise the differences ? we are inclined to believe, not only the caoutchouc 
in these two cases is the product of a totally distinct genera of plants, but also that 
the process of preparing the blown or bottle caoutchouc, is quite different from that 
of preparing the white or cake caoutchouc. 
It would probably lead to some useful result if a person who has some skill in 
vegetable chemistry, were to make a careful observation of the process of manufac- 
turing caoutchouc, as practised where the caoutchouc tree is cultivated, watching it 
closely from the drawing off of the juice from the tree, to the complete dessication 
of the caoutchouc. It is probable, that lie might be able to detect some imperfec- 
tion in the process, which would easily admit of remedy ; and that he might thus 
he able to suggest a modification of the process, which would yield caoutchouc of a 
purer quality than that which is generally delivered in commerce. The variations 
in the modes of manufacture, and the experiment which it would be worth while 
assaying, will of course be best judged on the spot, where he has an opportunity 
of observing the local process of the manufacture, and of familiarising himself ex- 
perimentally with the habitudes of the recent juice. 
We would however recommend all the following trials to be made. 
1. Prepare caoutchouc from the juice, by the ordinary process practised among 
the natives. 
2. Evaporate a quantity of the juice to dryness: and preserve the residuum. The 
evaporation should be performed either by simple exposure to the sun, or in a ves- 
sel placed over another filled with boiling water. For the properties of the caout- 
chouc would certainly be injured, if the evaporation were conducted in a temperature 
exceeding that of boiling water. 
3. Boil the juice for from half an hour to an hour, and collect the solid portion 
which separates. The juice of the caoutchouc appears to contain always a consi- 
derable quantity of a substance possessing the properties of albumen, and which is 
perhaps the most dangerous of all its extraneous ingredients. In this trial the al- 
bumen will certainly be coagulated by the heat, and thrown down iu a state of inti- 
mate intermixture with the caoutchouc. 
4. Dilate the juice with four times its bulk of cold water, and observe if the 
caoutchouc rises to the top. If it does, wash it several times, by agitating it with 
water, then coagulate it by a slight heat or otherwise. The principle object of this 
trial is to ascertain if the caoutchouc may be separated by simple dilution of the 
: uice with water, while the albumen (and other extraneous ingredients) will still 
remain in a state of solution. 
5. Mix the juice with four times its weight of water, and 5 ‘ 5 th of its weight of 
caustic potash, and boil the mixture for an hour. Let the solid portion which se- 
