Biffen . — The Coagulation of Latex. 167 
On adding acetic acid to the crude latex of Hevea 
coagulation occurs immediately. This process of smoking 
the latex may then be classed with those mentioned by 
De Bary under the heading of treatment with acids. As 
other examples, the preparation of Lagos rubber from the 
latex of Ficus Vogelii (Miq.), in which case lime-juice is 
added L , and Heifer’s process of adding acetic acid to the 
latex of Artocarpus Chaplasha (Roxb.) 1 2 , may be quoted. 
It is worthy of note that the latex of Hevea brasiliensis is 
in itself alkaline, and that the addition of a solution of 
ammonia preserves it indefinitely from spontaneous coagula- 
tion. The addition of alkalies bring about coagulation, 
however, in the latex of Castilloa elastica. In Mexico and 
Nicaragua, where this tree abounds, a decoction is made 
of the stems of the Moonflower, Ipomoea bona-nox ( Calonictyon 
speciosum [Choisy] ), and added to the latex 3 . The alkaline 
properties of this extract are well known to the native Indians, 
who frequently employ it in the manufacture of soap. The 
latex has an acid reaction towards litmus-paper, and the 
addition of acids does not cause coagulation. 
Another method of clotting latex is to add an excess of 
common salt. This method is almost invariably applied in 
the case of Hancornia speciosa (Gomez) to produce the 
‘ mangabeira ’ rubber. It is also reported to have been 
employed at times to coagulate the latex of species of Hevea 
and Manihot Glaziovii (Muell. Arg.). 
Coagulation may also be brought about by boiling the 
latex, as, for example, in the preparation of ‘ balata ’ from 
Mimusops globos a (Gaertn.) in Venezuela and Trinidad. 
There are several other methods in general use besides the 
few that have been quoted, and many others have been 
suggested from time to time 4 . 
1 Kew Bulletin, 1890, Art. 142, p. 89. 
- Watt’s Diet. Economic Products of India, vol. iv. p. 343. 
8 Belt, Naturalist in Nicaragua, p. 33. 
4 For a complete account see Le Caoutchouc et la Gutta-percha , Seeligman, 
Lamy, and Falconnet, Paris 1896. 
N 
