450 
Graffin and Little” give the following method for calculating the percentage of 
air-dry material: A representative sample of the substance to be tested is dried 
in a water-jacketed air bath at 100° to constant weight. The loss in weight rep- 
resents the moisture in the sample and is calculated into percentage, the differ- 
ence between this figure and 100 giving the percentage of absolutely dry fiber. 
On a 10 per.cent basis every 90 parts by weight of dry material is equivalent to 
100 parts of air-dry substance; on this basis, dividing the percentage of dried 
material formed by 90 and multiplying the quotient by 100 gives the percentage 
of air-dry substance. 
Example: A sample of waste lost 15 per cent on drying, then 85 per cent 
represents the dried fiber; if the standard is 10 per cent, then 85/90 * 100 = 94.4 
per cent," or the percentage of air-dry fiber actually in the amount of material 
paid for on a 10 per cent basis. 
The effect of this water of condition on commercial dealings in fibrous 
products is emphasized when values are considered, In the delivery of, 
say, 2,272.7 kilos of material at 4.4 cents per kilo,” the difference is 
127.2 kilos or $5.60. 
Ash.—“The ash in isolated fibers is low, viz, 1-2 per cent; in fiber 
aggregates it is often high—thus, in esparto and straw from 3 to 6 per 
cent—and should be taken into account in calculation of yields or loss of 
weight.” 78 | 
I have found several samples of rice straw to average 18 per cent of 
mineral matter; but this is an extreme case. Griffin and Little give 
the range from 3 to 7 per cent, or in exceptional cases as high as 12 
per cent on the dry straw, and further add that the strongest straw 
yields the most ash. 
Alkaline hydrolysis —*This is obviously the first stage toward the isola- 
tion of cellulose. When the numbers obtained for the short period (a) 
and for the long digestion (b) show a marked difference, it is an obvious 
general indication of low paper-making quality.” * 
Cellulose.—Cross and Bevan’s chlorination method gives the maximum 
theoretical yield. Various other available methods give figures which 
are 2 to 5 per cent lower, but in comparison they consume much time. 
All the cellulose determinations recorded in this paper have been made 
on the residue from hydrolysis (b) which yields results more nearly in 
accord with other methods, at the same time avoiding their tediousness. 
After this preliminary discussion of methods and their meaning, the 
results of the chemical investigation of abaca fiber will be given. 
” Chemistry of Paper Making, 451. 
94.4 pounds of normal, air-dry fiber per hundredweight. 
#24 tons at 2 cents per pound, 
3 Cross and Bevan: Text book of Paper Making, p. 92. 
* Loc, cit. 
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