ON THE COMMERCIAL KINDS OF INDIA-RUBBER. 9 
Some time since, a small parcel, described as “ rubber milk," from 
Para, came into the market;. but whether ever used I cannot say. 
It came in gourds and iiaii lumps. It was hard, broken with dif- 
ficulty, of a colour from yellowish-white to yellowish-brown ; not at all 
elastic, except when heat was applied, quickly regaining its rigidity ; 
burning quickly with a bright flame and dense black smoke. It was 
lighter than water. When placed in hot water, it quickly became soft, 
and much like gutta percha or balata gum (Sapota Mülleri). I for- 
warded a description of this substance to Dr. Spruce, and in his letter 
he says :—“ The so-called india-rubber milk from Para you mention is 
probably the milk of trees of the Apocyneous genus called Couma in that 
region. I know two species, Couma Guayanensis, Aubl. (Cerbera tri- 
phylla, Rudge; Collophora utilis, Mart.) ; and Couma dulcis, Spruce, 
in Pl Am. The milk of these trees is copious, sweet, innocuous, 
elastic when fresh, but not when dry unless heated. I had a cere- 
cloth coated with it, to cover the roof of the piragoa in which I travelled 
on the Casiquiare, also Orinoco, etc., and found it impervious to 
rain.” Subsequently, on the receipt of a specimen, Dr. Spruce wrote 
that he did not recognize it as the product of any Siphonia, and yet it 
might be. “Tf,” says he, “it has been collected near the city of 
Para, it is probably the gutta-percha of the Para Cow-tree, called by 
the inhabitants ‘Maceranduba’ (Mimusops sp.); but if obtained on 
the Rio Negro, it may be from the Cow-trees of that region (Couma 
sp.).” In the * Kew Journal of Botany’ (vol. v. p. 239), the milk of 
the Cow-tree of the Rio Negro is described as ** sweet, thinnish, and 
very viscid ; when dry more brittle than caoutchouc, which it otherwise 
much resembles.” 
Occasionally we get small parcels of india-rubber from Ceara. It 
has a different appearance to those above mentioned, leaving it a 
matter of doubt as to the tree which produces it. It consists of 
reddish-brown, string-like pieces, rolled up in the form of a ball, and 
thus called Ceara scrap. Only small quantities arrive here, which are 
soon bought up at prices from ls. 6d. to 1s. 9d. per lb. 
Hancornia speciosa is another plant which produces a very fine caou- 
tchoue, known as “‘ Pernambuco rubber,” the fruit of which Brazilians call 
Mangava or Mangaba. Gardner describes the tree as reaching to the 
size of an ordinary Apple-tree, though its small leaves and dubjing 
branches give it more the appearance of the Weeping Birch. The fruit 
