HEMP HURDS AS PAPER-MAKING MATERIAL. 23 
against possibly six to eight hours; 11.5 per cent bleach as against 
8 to 10 per cent. Thus, it is evident that the cooking conditions 
employed were slightly more severe and expensive than those in 
commercial use with poplar wood. 
The yield of total fiber obtained from the hurds may be placed at 
35 per cent of bone-dry fiber calculated on the bone-dry weight of 
hurds used, or 33.1 per cent of air-dry fiber calculated on air-dry 
hurds. The yield of bleached fiber was not determined in this pre- 
liminary work, but may be safely estimated as 30 per cent, which is 
low when compared with a yield of about 47 per cent of bone-dry 
bleached fiber from bone-dry poplar wood. It is believed quite 
possible that satisfactory cooking conditions may be found which will 
give a higher yield than was obtained during these tests. The stock 
should be classed as easy bleaching, and 11.4 per cent of bleach is a 
satisfactory figure, although a little high. 
As to beating cost, in the last two and most satisfactory tests the 
total washing and beating time was three hours, which may be about 
an hour more than ordinarily is used in making papers of this grade, 
although the practice varies to a considerable extent. 
In regard to furnish, there is such a diversity of practice that it is 
difficult to make a comparison, but if the hurd stock can be produced 
as cheaply as soda-poplar stock, the furnish used in these last two 
tests should be regarded as satisfactory to the book and printing 
paper manufacturer. , 
The finish of the paper was not all that might be desired, but that 
was due almost entirely to the calender stack available for the work, 
which was composed of nine light rolls, many of which were about 
6 inches in diameter and which had not been reground for some time. 
From a small test on a large calender stack it was readily shown that 
the paper produced is capable of taking a satisfactory finish. 
This comparison, satisfactory in many respects, develops two 
factors which are decidedly unfavorable to hemp hurds, namely, raw- 
material storage and digester capacity, and they must be taken into 
full account in considering the paper-making value of this material, 
although it should be recognized that investigation may result in the 
material improvement of these conditions. Moreover, it is not at all 
improbable that further investigation would develop more satisfac- 
tory treating conditions and more suitable furnish compositions, and 
the belief in this possibility is strengthened by the fact that material 
progress was being made at the conclusion of this preliminary work. 
Calculations, on the raw material and acreage for a permanent sup- 
ply for a pulp mill producing 25 tons of fiber a day for 300 days per 
annum, or 7,500 tons per annum, give the comparison between hurds 
and wood shown in Table II. 
