to render its continued employment most deplorable. The coagula- 
tion with* soap as practised in the Isthmus of Panama is barbarous 
in the extreme, and it is not surprising that it yields a product of 
very bad quality indeed. 
Amongst the above-named process I have not enumerated a pro- 
cess said to be practised in Mexico, and simply consisting in the 
boiling of the latex in earthen vessels (jacaras). If this process is 
actually used, it can certainly not he carried out with the fresh latex 
for the simple reason that over and over again I have satisfied my- 
self that even on very prolonged boiling of the slightly diluted latex 
furnished by the tree at Las Cascadas no coagulation can be ob- 
tained. The cause of this is to be found in the fact that the aqueous 
vehicle of the latex, although it certainly contains a large amount of 
albuminous matter when rapidly separated from the latex immedi- 
ately after this has been obtained, is of a very light olive green 
colour and even ^on very prolonged boiling does not coagulate, nor 
The following' footnote should be inserted oil page 1 7 ° • 
* NOTE Calonyction speciosutn and Ipomoea bona-nox, are the 
same thing. — Ed. 
U1 inc mLcx -as ouierwise no coagulation would take place. 
It is not very easy to see that the chief point in attempting t< 
prepare a pure rubber from the latex of Castilloa elastica, and as ; 
matter of fact, from the latex of any other rubber tree, must consis 
in the elimination from the rubber, prior to its " agglutination, ” o 
all albuminous matter. The first step in this direction is the dibit 
ing of the crude latex with water, of which at least five times thi 
volume of the latex treated should be used. In the case of thi 
thick, curdy latex yielded by the trees at Las Cascadas it is prefer 
able to use actually boiling water, but in how far this applies to th< 
latex obtained in other districts or from different trees is a matte 
for experiment. Boiling water at once converts this latex into ; 
thin, very fluid milk which through a common cotton gauze is strainec 
in order to remove from it any insoluble impurities such as earth 
wood, bark and the like. This milk is best strained into thorough 
ly weil washed petroleum barrels. As soon as the barrel is com 
pletely filled, about 8 ozs. of formaldehyde are added, the whoh 
well stirred and allowed to stand for 24 hours. The action of th< 
formaldehyde appears to be twofold. In the first instance, i 
effectually prevents any tendency of the albumen to coagulate it 
the hot solution, and thereby to cause mischief. But, as compara 
tive experiments showed beyond any doubt, it also has a mos 
istmct effect upon the india-rubber, which collects on the top o 
