Feb., 1912.] 
Another Ohio Grown Rubber. 
469 
ANOTHER OHIO GROWN RUBBER. 1 
Chas. P. Fox. 
Of the many kinds of crude rubber, the botanical family, 
Apocynaceae, produces its share of good grades. Mangabeira 
(genus Hancornia in Brazil), Benguela root rubber (Landolphia) 
and Funtunia, both Africans, are notable examples. 
The Apocynaceae are trees, shrubs, and herbs, with a milky 
acrid juice, numbering some 1000 species, grouped into 130 
genera, inhabiting sub-tropical areas. This family of plants 
produces a varied line of economic products, such as edible fruits, 
dyes, drugs, fibres, ornamental plants and caoutchouc. The 
Madagascar Ordeal Plant, whose seed contains the most powerful 
poison known, and Eden’s Forbidden Fruit, register here. 
Several members of the type genus Apocynum, of this family, 
are common to the United States, the so-called Indian Hemp, 
Apocynum cannabinum and A. androsaemifolium. During the 
past summer, I have examined the latex of the latter species for 
quantity and quality of its rubber. The results of this investi- 
gation show that the latex of this plant gives a small quantity of 
good grade rubber. 
The latex is white, viscous, neutral or slightly acid, and has the 
strong acrid odor peculiar to this plant. The latex reacts with 
the usual coagulating reagents, in the following manner: 
Acids do not coagulate; latex becomes thin. 
Alkalies do not coagulate; restore the viscosity; change the 
color from white to brownish yellow. 
Boiling coagulates slightly and slowly. 
Acetone in proportion of 1/10 volume, coagulates immediately 
and completely; liquid is colored chocolate red. 
Formaldehyde coagulates readily, but is much slower than 
acetone. 
Phenol coagulates the latex, but gives a soft product. 
Salt Solution coagulates slowly, giving a finely divided precip- 
itate, hard to coalesce. Boiling the saline solution gives a soft 
product; not successful. Of the above methods, the use of 
acetone or alcohol, and formalin, are the only ones recommended. 
Of these two, acetone is preferred. 
The latex of Apocynum differs from that of Asclepias in that it 
coagulates spontaneously, even if it is kept in closed containers. 
The spontaneously coagulated latex gives : 
Liquid portion 67.58% 
Cheese (wet) 32.42% 
1. Presented at the Twenty-first Annual Meeting of the Ohio Acad, of 
Sci., Dec. 1, 1911, Columbus. 
