470 
The Ohio Naturalist. 
[Vol. XII, No. 4, 
The liquid is white, slightly acid and acrid odor. This liquid 
failed to coagulate after addition of more acid. Slight excess of 
alkali increased its viscosity, changed its color from white to 
brownish yellow, but did not coagulate or precipitate it. Boiling 
had no effect. Excess of acetone gave a finely divided precipitate 
the particles of which were not cohesive. Evaporation of the 
mixture, after washing with water and treatment with boiling 
acetone, gave a small quantity of black, soft rubber, destitute of 
strength. The cheese was composed of: 
Water 33.46% 
Rubber 3.99% 
Resin 62.95% 
Working up this cheese of the plant in the usual manner with 
solvents, straining through gauze to remove dirt, evaporating, 
with low heat, the excess of solvent adding an excess of precipitant, 
washing the precipitant and dissipating the precipitating agent, 
gave a good grade rubber. 
The rubber obtained in this manner is black, firm, not tacky, 
odorless and strong. In quality it is much better than the product 
obtained from its neighbor, Milkweed. The qualities of this 
rubber confirm the old adage “that blood is thicker than water,” 
and proves a more apt one, “that Apocynaceous rubbers are good 
rubbers.” 
Milkweed latex, however, is richer in rubber than that of 
Indian Hemp. The proportion of rubber in the entire plant 
remains on the same ratio as the amount of latex remains equal, 
and in both cases is entirely too small to be profitable. Of the 
total rubber present in the latex, 96% of it is won in the cheese 
formed by the natural coagulation of the latex. Ninety-six 
per cent of the total rubber found, ranks as Grade A, and four 
per cent grades as C. 
The resin is mahogany red, transparent, medium hard, slight 
characteristic odor and tasteless. 
During this investigation we have found that the soil condi- 
tions under which the plant was grown, exerts an influence upon 
the amount of rubber in the latex. Plants grown upon dry, 
sandy soil of West Akron, gave a latex containing 2.27% rubber 
and 20.69% resin. The latex of plants grown upon the wet swamps 
of South Akron, contained 1.12% rubber and 15.04% resin. 
Rubber from dry grown plants is of better quality than that of 
wet grown plants. 
Natural latex from dry land Apocynum contains: 
Water 72.29% 
Solids 26.21% 
Ash 1.59% 
