T

ydlow pine ST^S Ponderosa)

^^^^C&aoisBiTparis noot-

•w*,~ii««lwe©d {feeartwood).. fSejaoia semper-" virens)

Western white pine----

(Pinus palustris)

Douglas fir

(Pseudotsuga taxi-folia)

Western larch

(Larix occidentalis)

White spruce

{Picea canadensis)

Tanbaik oak

(Quercus densiflora)

Mesquite

(Prosopis juliflora)

Balsa

(Ochrona Iagopus) Hickory (shellbark) ...

(Hieoria ovata) Eucalyptus (Eucalyptus globulus)

Bass wood

. (Tilia americana)

Yellow birch

(Betula lntea) Sugar marie

methyl pentosans are also determined, but these seem to have little significance and are not included in Table 4.

Cellulose is such a poorly defined material that there is much difference of opinion as to what wood residue should be called "cellulose" and there is a tendency to write the word in quotations so as not to convey the impression that a certain definite compound is meant, but in this discussion cellulose is fairly closely defined by the method of separating it. By treating the wood with chlorine gas, a water solution of sulphur dioxide, and hot water in this order repeatedly until all color has been removed, a residue is obtained which

Fig. 8.—Loading the Buggies with Wood.

is the "cellulose" of this discussion. This is the "Cross and Bevan" cellulose which has been the basis of the analysis of many cellulosic materials and the results of its determination can be duplicated with accuracy.4 That this cellulose is not of the same composition when prepared from different woods is shown, however, by the variation in the values for "pentosan in cellulose" and for the alpha, beta and gamma cellulose.

The lignin is obtained as a residue on treating the wood with 70 per cent sulphuric acid. The cellulose as separated by the method described above is subsequently divided into three kinds of cellulose, the alpha cellulose being insoluble in 17.5 per cent sodium hydroxide,

* See Schorger and Mahood and Cable for detail«. Loc. cit.

the. beta being soluble but reprecipitated by acetic acid and the gamma being soluble and not reprecipitatecl.

It should be noted here that each of these determinations except those under the heading "In cellulose" is made on a separate sample of wood and that many of the constituents overlap. .lror instance, most of the cold water soluble is also determined in the hot water soluble, most of the cold water, hot water, and ether soluble in the alkali soluble, most of the methoxyl in the lignin, and part of the pentosans in the alkali soluble.

Aside from the results shown in Table 4 there arc a few series of determinations of single constituents of woods which should be mentioned here. Methoxyl determinations on a large number of woods have been made by Beneclikt and Bamberger." In comparing their figures with those in Table 4 it should be noted that they express their results in terms of "methyl numbers" instead of methoxyl and that their figures should, therefore, be multiplied by 31/150 for proper comparison. They suggest this methoxyl determination as a measure of the "lignification" of the wood, but Table 4 shows that there is 110 close relation between the amounts of methoxyl and lignin.

The nitrogen content of several species of wood has been determined by Koenig and Becker" and their results arc; .shown in Table 5.

TABLH «J. N;tk(i(5hn Conthnt up Wood.
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