578 
Supplement to the " Tropical Agriculturist.'* [Feb. 1, 1900. 
as follows : — A fresh speciifieU having been boiU-d 
in the dilute ulkiili (1 per cent N!i2 0), is well 
washed and expot-ed for one hour, at the ordiiinry 
temperature, to an afmos])bere of chlorine gas. 
It is then reraoved, washed, mid trented with a 
solution of sodium sulphite, which is slowly raised 
to the boiling point. After two or three minutes' 
boiling it is washed on a iilter when necessary, 
though in most cases it luiiy be so placed in a 
funnel as to act as its own filter. Lastly, it is 
treated with dilute acetic acid, washed, dried, and 
■weighed. The percentage yield on the raw fibre 
is the most important criterion of its composition 
and value. 
Mercerxinff.—lihis refers to the action of con- 
centrated solutions of the alkalis upon vegetable 
fibres, particularly the compound fibres or those 
whicli are made up of a numher of fibrils aggre- 
gated into a bundle, the larger portion of fibre 
consisling of such bundle-. The action of the 
alkali often causes a very profound change in 
structure, not only dissecting the bundles, but 
altering the contour of the fibrils. The treatment 
takes its name from Mercer, whose original st udies 
were for the determination of the struc'ural 
modification which cotton undergoes when treated 
with strong alkalis. 
Nitration. — When a fibre is exposed for one 
hour to a nitrating acid, such as a mixture of 
equal volumes of concentrated nitric and sul- 
phuric acids, one of the most important results 
which follow is an increase in weight. An ex- 
ternal characteristic which should also be noted 
is colour. A great deal of information regarding 
the constitution of a fibre is ascertained by this 
process. 
Carbon percentages from Combustion. — This pro- 
cess consists in burning the substance with chromic 
anhydride in presence of sulphuric acid and 
leading over the gaseous products (CO and CO2 ) 
into an apparatus in which their volume can be 
exactly measured. The two oxides of carbon 
having the same volume, the quantity cf carbon 
in unit volume is independent of the composition 
of the gas, which therefore only requires to be 
measured^ The carbon in the typical (cotton) 
cellulose is 44'4 percent; the compound cellulo.'-es, 
on the other hand, range themselves for the most 
part into two groups (1) of lower carbon percen- 
tage (40-4:-i), (2) of higher (4.'^-50), in the frrmer 
the pecto-celluloses are included, the ligno- 
celluloses in the latter. This is considered a 
prominent chemical constant of the fibre sub- 
stance. 
Acid Purification. — The object of this treatment 
is to clean the fibre and remove accidental im- 
purities, while occasioning the minimum loss of 
weight and therefore alteration in composition. 
V'or this purpose acelic acid (20 per cent) is chosen, 
the fibre being heated with the acid to the boiling 
point, then removed and washed first with alcohol, 
and lastly with water, dried, and weighed. The 
loss in weight sustained is thus determined. It 
is in the fibre thus purified that the carbon per- 
centages are determined 
In a report on the. miscellaneous fibres in the 
Colonial and Loudon Exhibition of 1888, by C. I"'. 
Cross, the 
in tabular 
scheme of analysis 
form : — 
is thus briefly Stated 
r 
Moisture. 
Ash. 
Hydrolysis («). 
Hydrolysis (6). 
Cellulose 
Sepprate 
rortion 
tat<i 11 for 
each ileter- 
niinati'D. 
Ri suits 
calcu ated 
in percen- 
tMge of dry 
substance. 
Mercerizing. 
Nitration. 
Acid Purification.. 
Carbon percentage 
Hygroscopic water, 
or water of con- 
dition. 
.Total residue left 
on ignition. 
..Loss of weight on 
boiling raw fibre 
five minutes in one 
percentsolution of 
caustic soda. 
..Loss of weight on 
continuing to boil 
one hour. 
..White or bleached 
residue from fol- 
lowing treat- 
ment (1) Boil 
in one per cent. Na 
0 H five minutes ; 
(2) exposure to 
chlorine gas one 
hour; (3) boil in 
basic sodium sul- 
phite. 
..Loss on treating 
one hour with .33 
per cent solution 
caustic potash, 
cold. 
..Weight of nitrated 
product obtained 
by treatment with 
mixture equal vo- 
lumes of nitric and 
sulphuricacids one 
hour, in the cold. 
...Raw fibre boiled 
one minute with 
acetic acid (20 per 
cent), washed with 
water and alcohol 
and dried. 
...The carbon in the 
fibre from above, 
determined by 
combustion. 
THE MICBO-CHEMICAL STUDY OF FIBRES. 
The microscope is a valuable adjunct to the 
study of fibres, not only for the purpose of de- 
teimining the dimensions of the ultimate cell, 
the thickness of the cell walls, the arrangement 
of the different kinds of cells in the plant tissue, 
and the relative abundance of the fibre cells, but 
all these taken together, with the employment 
also of certain chemical reagents, giving a ready 
means of determining the identity of the species 
ot fibre where doubt exists as to the kind of fibre 
that has been employed in the particular manu- 
facture under investigation. The methods to be 
pursued in this kind of fibre analysis should be 
fully understood by the textile student, as well as 
the industrialist and all others who handle fibres 
and fabrics commercially. 
Among the text-books that may be consulted no 
bettor can be suggested than the valuable woik of 
