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article is on the market by the name of “Purub,” and is 
at present fairly widely advertised in the trade journals. 
The main and effective substance in it appears to be hydro- 
fluoric acid, which is well known from its application in 
etching glass. 
The germs of putrefaction (tackiness) are always pre- 
sent in latex, and the proteids therein offer them a suitable 
feeding ground. Various measures may be taken ta prevent 
putrefaction. In the smoking process the strongly anti- 
septic smoke kills the germs, while the acetic acid which it 
contains at the same time coagulates the latex. Smoke is 
effective because owing to the way it is applied it acts on a 
very thin layer of latex and therefore penetrates every part 
of it. The putrefactive organisms being killed there is no 
reason to withdraw the entire moisture. In the other 
methods employed if moisture is present, even when in the 
interior and shut off from the air, heating easily occurs 
during transport encouraging the putrefactive germs to 
develop. Hence rubber prepared by acetic or other acid 
coagulators must have practically all* its moisture extracted 
if it is to go on to the market free from “tackiness.” It 
has been shown recently that well dried rubber is not so 
good as that containing moisture. By the Purub method 
it is immaterial, as far as preservation of the rubber is con- 
cerned, how much moisture is left behind. 
Sand maun was led to experiment with fluorine com- 
pounds in coagulating rubber latex by his experiences in 
other fields. Thus it has been found that fluorine com- 
pounds possess the property of killing putrefactive 
germs, but affect yeast considerably less. On this account 
they have for a long time been used in the distilling and 
fruit-preserving industry. A very small quantity of hydro- 
fluoric acid added to fruit juice keeps its fresh and pre- 
serves its aroma for years. 
Coagulation with the fluorine compound is most simple. 
The freshly collected latex, pure or mixed with water, is 
strained through a cloth to remove foreign bodies into not 
too large pans; the liquid fluorine preparation added and 
thoroughly mixed by stifiring. It is left for a few hours, 
after which the coagulated rubber, which in the meantime 
comes to the top, is removed, freed from water by pressure, 
and is then ready for shipping. 
The fluorine which, as is well known, does not attack 
rubber, is used in such a small quantity that it is totally 
removed by water. In removing the water by pressing it 
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