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246 E. N. Kent on Gutta Percha. 
5 A wr. XXIV.—On Gutta Percha; by Epwanp N. Kenr. 
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~ Gurra Percha is soluble in pure chloroform, bi-sulphuret of 
carbon, rectified oils of turpentine, resin, gutta percha and tar, 
and also i 
so in terebene, hydrochlorate of terebene, and slightly in 
pure ether. Of these solvents the first two are the best, and dis- 
solve the gutta percha at low temperatures. The other solvents 
~ act only at a temperature above 70° F., and when the solutions 
are cooled much below 60°, the gutta percha is deposited in a vo- 
luminous granular mass. The length of time required for the 
production of this precipitate, depends upon the degree of cold; 
sometimes it requires several days, and at other times the expo- 
sure of an hour suffices to produce it. By warming this mixture, 
the precipitate is readily redissolved, and by exposure to cold is 
again precipitated at will. 
Solutions of gutta percha aré naturally of a reddish brown co- 
Jor, and do not become colorless by standing at rest for several 
months in a warm situation. If the solution is made sufficiently 
dilute, which is the case when one part of the gum is used to 
sixteen parts of the solvent, it can be filtered slowly through pa- 
per or muslin, and is then colorless. 
Solutions of gutta percha are precipitated by alechol, and when 
chloroform or bi-sulphuret of carbon are used as the solvent, the 
gum is recovered in its natural state either by evaporation or pre- 
cipitation ; but when any of the hydro-carbons are used for a sol- 
vent, a portion is retained with such tenacity that it cannot be 
removed withont decomposition of the gum. 
A solution in chloroform, filtered, and precipitated with alco- 
hol, leaves the gutta percha when dry, of its natural strength, 
translucent, colorless, and pure. - 
“When two or three parts of washed ether are mixed with a 
filtered solution of gutta percha in chloroform, and the mixture 
left for a short time at a temperature below 60°F, it precipitates 
in a perfectly white powder, which when washed with alcohol, 
filtered and dried, leaves the gutta percha in a pure white, opaque, 
voluminous mass, very soft and delicate to the touch, not unlike 
the pith of a young tree. 
_ If a small quantity of the above mixture (before precipitation) 
is poured upon a glass plate and allowed to evaporate spontaneous- 
ly, a thin opaque film of pure white gutta percha remains, which 
has the appearance and delicate feeling of the finest white glove 
leather. By a géntle warmth it loses its opacity and beautiful 
appearance, and becomes transparent or translucent, according to 
the thickness of the film. The state of aggregation which eau- 
ses the opacity and delicate feeling of gutta percha prepared in 
the above manner, is owing to the precipitation of the gum, caus- 
_ed by the cold produced in the rapid evaporation of the ether. 
