REMARKS ON THE NATURAL HISTORY OE COTTON. 175 
ferences which exist between the high-priced and low-priced 
cottons, and those which are useful for one purpose rather than 
another. 
The hairs of the cotton plant are made of the same materials 
as all other parts of the plant. Whether the tissues of plants 
are ultimately disposed in the form of cells or of vessels, 
the raw material of their construction is the same. The 
cells and vessels of plants are made of a material called cellulose, 
— at least, this is the name given to the matter out of which 
cotton-hairs are formed. When we take a piece of wood, and, 
sawing it, collect the dust and obtain the chemical substance 
out of which the vessels that formed the wood were made, it is 
called lignine ; and when the cells get very hard indeed, as 
they do in cherrystones, the material is called sclerogen. But 
these three things differ but little from one another ; and the 
first name will serve us to distinguish everywhere the matter 
out of which cells are formed, and which is found in those of 
the hairs of cotton. Cellulose is insoluble in water, either hot 
or cold. Herein it differs from the material out of which animal 
cells are formed, for this is soluble in hot water, and is called 
gelatine. It is the insolubility of cellulose which makes it so 
useful to man in the manufacture of textile fabrics, and in the 
building of houses and ships. Althoug’h insoluble, it is 
easily convertible into starch . By pouring sulphuric acid on to 
cotton-hairs we can convert them into starch. It was at one 
time the dream of the chemist to be able to convert deal boards 
into Suffolk dumplings; but the feat has yet to be accomplished. 
Nevertheless, cellulose can be detected by its ready conversion 
into starch, and its affording then the reaction of starch with 
iodine. This experiment may be readily performed with a piece 
of paper, which is cellulose. 
This cellulose, then, has a definite chemical composition, and 
can be changed in its properties and qualities by combining it 
with other things. One of the most remarkable chemical 
changes which it undergoes is its conversion into a rapidly com- 
bustible agent by the action of nitric and sulphuric acids. If we 
take a quantity of cotton, and immerse it in a mixture of these 
two acids, and then take it out and wash it in water and dry it, 
we shall find that, chemically, its character is entirely changed ; 
although, under the microscope (fig. 18), it has lost little of 
its original appearance, its inflammability has vastly increased. 
It is, in fact, gun-cotton. We are indebted for the discovery 
of this agent to Schonbein, the Swiss chemist, whose name is so 
familiar as the discoverer of ozone. Gun-cotton is technically 
called Pyroxylin, a name significant of its combustible nature. 
Cellulose consists originally of nearly equal proportions of 
carbon, oxygen, and hydrogen ; but, by plunging it in the acids, 
