2 : ON THE COMMERCIAL KINDS OF INDIA-RUBBER. 
Morchella crassipes, Pers.; pileo subconico, fusco, basi adnato ; 
costis irregularibus, undulatis, crassis ; areolis polymorphis, magnis, 
profundis, imo fundo celluloso-plicatis ; stipite magno, elato, basi i in- 
crassato, lacunoso, supra attenuato, glabro, subincarnato. 
Morchella crassipes, Persoon, * Synopsis Methodica Fungorum,’ 
1801, p. 621; De Lamarck et De Candolle, * Flore Française, vol. ii. 
p- . -* 
Phallus crassipes, Ventenat, ‘Mémoires de l'Institut National,’ 
1798, p. 509, tab. 2. 
Exrtawation or Prares LXXIIIL axp LXXIV. 
1. Morchella crassipes, Pers. 2. Section through walls of pileus. 
3. poe the last figure magnified. 
ON THE COMMERCIAL KINDS OF INDIA-RUBBER, OR 
CAOUTCHOUC. 
By James Couns, Esq. 
What is India-rubber, or Caoutchouc ?—It is not a true gum or resin ; 
yet, being an inspissated juice, it is generally classed among them. 
By some it is termed an elastic gum, but this is incorrect, as gums 
are soluble in water, and caoutchouc is not. The nearest, however, . 
to which it agrees are the gum-resins, being opaque, not melted by 
heat, but only softened and swelled out, regaining when cold its ori- 
ginal form. It differs, however, from them in one important respect ; 
whereas gum-resins are partially soluble in water, caoutchouc is not in 
the least. Thompson, in his ‘Organic Chemistry of Vegetables,’ 
classes it amongst the “neutral vegetable principles.” If stretched 
quickly and allowed to regain its form, a great deal of latent heat is 
disengaged, as will be felt by placing a piece against the cheek during 
the operation, When solid it cannot be dissolved by acids, alcohol, or 
water, but it is soluble in ether, or in the better known and used 
naphtha. e milky juices yielding caoutchouc are found in the 
middle layer of the bark called the mesophleum, stored up in anasto- 
mosing tubes known as laticiferous tissue. In the Apocynacee latex- 
vessels occur also in the liber, or endophleum. The milky juice, when 
allowed to stand, separates into two parts, by the globules of caoutchouc 
