Page:Zacaton as a paper-making material (IA zacatonaspaperma309bran).pdf/22

 BULLETIN

16 by

U.

S.

DEPARTMENT OF AGRICULTURE.

with hydrofluoric acid.

volatilizing

original straw

309,

and in the second

In one case

silica

was

7.5

per cent of the

6.5 per cent.

(a) This is a rather high ash content and a particularly large amount of silica, in comparison with the analyses of other straws published by Mayer, Miiller, Hofmeister, and others. It fuses in a glass with the other constituents of the black liquor if sharply ignited, but on slower ignition gives a cake which easily falls to pieces on extraction with water. There will probably not be silica enough to interfere with the usual soda recovery on the large scale, especially if some of the English silica-removing processes are used. A trial of this point is. however, advisable where so much silica This has. for example, nearly five times as much silica as esparto grass, as is found. analyzed by Miiller. (c)

Ether-alcohol extraction was carried out. not so

much

for

the purpose

of secur-

ing very valuable information, but in order to note abnormality, if any existed. One analysis gave 0.8 per cent loss, and a second 0.9 per cent, the nature of the extract not

being further investigated.

It Is usually reported as fat, wax. and chlorophyll. ether-extracted straw was further extracted for 14 hours with water in the modified Wiley extractor, which extracts at the temperature of the boiling solvent. (d)

The

The

loss

second.

under

As

it

was 5 per cent in one

case,

and

5.6 per cent in the

being possible to way. This value for Epicampes between rye and wheat straw, roughly speaking, although of course there are

extract as

puts

this treatment

straws go, this shows a high degree of resistance,

much

as 70 per cent of

some straws in

it

this

wide variations in individual cases. (e) "Cellulose" was determined by three methods: in each case 'the ash in the resulting product was determined and the ash-free white fiber resulting from the process followed was reported as "•cellulose." Xo process now in use can claim to give a normal cellulose" from straw or wood, and the significance of the per cent of cellulose" reported is always relative to the analytical method followed. method, as described in their book, (/) According to the original Cross and Bevan the yield of '"cellulose" averaged 41 per cent. Renker. in his recent book. 2 advises omitting the treatment with dilute alkali both before and after chlorination. The yield of fiber by this method was 51 per cent average. Cross and Bevan claim incomplete removal of lignin by this method, but Renker is certainly right in saying that the dilute alkali attacks the cellulose considerably. As a test of this, weighed samples of the straw were boiled 50 minutes with 1 per cent caustic soda, then filtered, The losses averaged 45.1 per cent on the bone-dry straw, with dried, and weighed. a residue of 54.9 per cent. This certainly leaves little for the chlorin to do in bringing "

'"

1

the residue

down

to the 41 per cent found.

It is

probable that the true value

lies

between the two. Concordance in results may be obtained by either method, but of course adds nothing but confirmation of care in performance of the work. The method of heating for 7 hours at 70° with 10 per cent nitric acid gave white residues (ash free) averaging 39.3 per cent. This is no doubt a minimum value and agrees fairly well with the results of the drastic original Cross and Bevan procedure. 2. Blov:-pit stock. Loss on bleaching was determined on the long-fiber unbleached stock. The determination is necessarily crude, because (1) if the stock be dried the chemical nature of the cellulose is changed and the bleaching may have a widely different effect, and (2) the water in the undried stock is about as serious a source of error. Determinations were made on both dried and undried stock. As nearly as possible, average samples of the undried stock were taken and moisture determined in some, while others were bleached. Limit cases were taken with (a) strongly alkaline bleach, with much active chlorin; With the stronger bleach (b) slightly alkaline, with a small amount of free chlorin.

—

•

Cross, C. F.,

and Bevan, E.J.

A

Text-Book

of

Paper-Making.

411 p.. illus.. 2 fold. pi.

1907. 2

Renker, Max.

Ueber Bestimmungsmethoden der

Zellulose.

Aufl.

2,

107 p.

Berlin, 1910.

New

York,