THE PAPER-MAKING QUALITIES OF BAGASSE. 
Mernops or Maxrne Curemicat Purp. - 
There are various well-known methods of making paper pulp. 
(1) The Sulphite or acid process, of which there are two 
forms :— ; 
(a) The Quick or Ritter-Kelner form, in which the digestion is 
carried out at a temperature of 150°C., using direct steam 
heating for ten hours at a pressure of 70 to 75 lbs.; and 
(b) the Slow or Mitscherlich form, in which the temperature 
and pressure are much reduced, while cooking is carried 
on by externally-applied heat for a much longer period. 
The raw materials which are required to make the cook- 
ing liquor of bisulphite of lime for either form are sulphur 
and quicklime. 
(2) The Alkaline processes, which make use of one of the follow- 
ing substances :— 
(a) Milk of lime, (b) caustic soda, (c) sodium sulphate, of, the 
various processes above mentioned, the soda’ (caustic) 
is usually employed with short- fibred wood, and sulphite 
and sulphate with long-fibred woods. 
For cooking bagasse, either a vertical cylindrical digester or one of 
the rotary type may be used. Of the rotary digesters, the spherical 
has the advantage over the cylindrical, as it requires less floor space and 
_ is better designed to withstand high cooking pressures. The spherical 
is more difficult to load. The rotaries hold from 8 to 5 tons, whereas 
uhe vertical stationary holds about 20 tons. The conclusion is drawn 
that the spherical rotary type is the best for bagasse. Direct steam is 
used for heating. The ratio of cooking liquor to the weight of bone- 
dry fibre, or the liquor ratio, has an important bearing on the yield of 
pulp—8 : 1 was found to be satisfactory. 
Resutts anp YreLtp or Pute Oprarnep. 
The most suitable cooking liquor employed was 15 per cent. caustic 
soda, 7.5 per cent. soda sulphide. 
The time and pressure of cooking are reciprocals—the longer the 
time; the lower the pressure, and vice versd. The greater part of the 
experimental work was carried out at 100 Ibs. pressure, and five hours 
cooking. 
The amount of bleaching powder required to convert the brownish- 
grey unbleached pulp into a white bleached pulp varies considerably, 
being greatly influenced by the cooking conditions and by the extent to 
which pith has been removed. About 15 per cent. of bleaching powder 
will easily bleach all iitin, On a large scale this may be reduced to 
12 per cent. 
Hawaiian ‘naga can be successfully reduced by either the soda or 
the sulphate process. - The experimental difficulties as to yields and 
quality of pulp were found to be small. The sulphate process is 
slightly cheaper on account of the lower cost of chemicals, but it has 
the more objectionable fumes, and this may prevent its use in settled 
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