16 BULLETIN 309^ U. S. DEPARTMENT OF AGEICULTUEE. 



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." No 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 ^ method, as described in their book, 

 the yield of "cellulose" averaged 41 per cent. Renker, in his recent book,^ 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 Ugnin 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 chloriu 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 kt 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. Blow-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; 

 (6) slightly alkaline, with a small amount of free chlorin. With the stronger bleach 



1 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. 



