16 BULLETIN 309, U. S. DEPARTMENT OF AGRICULTURE. 
by volatilizing with hydrofluoric acid. In one case silica was 7.5 per cent of the 
original straw and in the second 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 
is found. This has. for example, nearly five times as much silica as esparto grass, as 
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. 
(d) The 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. 
The loss under this treatment was 5 per cent in one case, and 5.6 per cent in the 
second. As straws go, this shows a high degree of resistance, it being possible to 
extract as much as 70 per cent of some straws in this way. This value for Epicampes 
puts it between rye and wheat straw, roughly speaking, although of course there are 
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 pro- 
cess 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 '" cellu- 
lose" reported is always relative to the analytical method followed. 
(/) According to the original Cross and Bevan 1 method, as described in their book, 
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, 
dried, and weighed. The losses averaged 45.1 per cent on the bone-dry straw, with 
a residue of 54.9 per cent. This certainly leaves little for the chlorin to do in bringing 
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; 
(b) slightly alkaline, with a small amount of free chlorin. With the stronger bleach 
• Cross, C. F., and Bevan, E.J. A Text-Book of Paper-Making. 411 p.. illus.. 2 fold. pi. New York, 
1907. 
2 Renker, Max. Ueber Bestimmungsmethoden der Zellulose. Aufl. 2, 107 p. Berlin, 1910. 
