[ -24- ]Table II.—Comparison between wood and hemp hurds.
| Material. | Pulp yield. | Rawmaterial required per year. | Annual growth per acre. | Acres required for sustainedsupply. | |
| For 25-ton mill. | For 1 ton of fiber peryear. | ||||
| Wood | Two cords yield 1 ton offiber. | 15,000 cords | 0.37 cord (about 0.55 ton). | 40,500 | 5.4 |
| Hemp hurds | One ton yields 600pounds of fiber. | 25,000 tons | 2.5 tons | 10,000 | 1.33 |
The most important point derived from this calculation is in regard to areas required for a sustained supply, which are in the ratio of 4 to 1. Every tract of 10,000 acres which is devoted to hemp raising year by year is equivalent to a sustained pulp-producing capacity of 40,500 acres of average pulp-wood lands. In other words, in order to secure additional raw material for the production of 25 tons of fiber per day there exists the possibility of utilizing the agricultural waste already produced on 10,000 acres of hemp lands instead of securing, holding, reforesting, and protecting 40,500 acres of pulp-wood land.
The annual growth per acre, although decidedly in favor of hurds, has little bearing on the project, because the utilization of the hurds is subordinate to the raising of hemp, and the paper manufacturer probably could afford to use only hurds resulting from the hemp industry.
PHYSICAL TESTS OF THE PAPERS PRODUCED.
Samples of paper produced in the seven tests were submitted to the Leather and Paper Laboratory of the Bureau of Chemistry. The report of that bureau on its tests is given in Table III.
Table III.—Report of the Leather and Paper Laboratory of the Bureau of Chemistry on papers manufactured from hemp hurds.
| Laboratory No. | RunNo. | Ash. | Weight of 500 sheets. | Thickness, 1/10000. | Strength (Mullen). | Strength factor (25 by 40, 500). | Folding endurance. | ||||
| 25 by 38. | 25 by 40. | Average. | Maximum. | Minimum. | Longitudinal. | Transverse. | |||||
| Per ct. | Pounds. | Pounds. | |||||||||
| 31570 | 144 | 13.9 | 48 | 50½ | 33 | 15.0 | 17.0 | 11.0 | 0.30 | 5 | 3 |
| 31571 | 143 | 14.5 | 49 | 51½ | 35 | 14.0 | 14.0 | 13.0 | .28 | 4 | 4 |
| 31573 | 141 | 10.9 | 48 | 50½ | 38 | 19.0 | 20.0 | 19.0 | .37 | 8 | 6 |
| 31572 | 142 | 9.5 | 49½ | 52 | 33 | 16.5 | 18.0 | 11.0 | .33 | 10 | 8 |
| 31574 | 140 | 11.4 | 42 | 44 | 30 | 14.5 | 16.0 | 13.0 | .33 | 7 | 6 |
| 31575 | 139 | 13.4 | 55 | 58 | 40 | 19.5 | 20.0 | 17.0 | .34 | 8 | 5 |
| 31576 | 138 | 10.4 | 56 | 59 | 40 | 20.0 | 20.0 | 19.0 | .34 | 23 | 15 |
There is no system of numerically recording the general appearance and "look through" of a paper, but it can be stated that only papers [ -25- ]Nos. 143 and 144 are satisfactory in these respects, the other samples being more or less thickly specked with shives. The general character and tests of these papers correspond very closely with No. 1 machine-finish printing paper, according to the specifications of the United States Government Printing Office, which call for a sheet not exceeding 0.0035 inch in thickness, strength not less than 12 points, free from unbleached or ground wood pulp, and ash not over 10 per cent. The strength factor of such papers is about 0.28. The ash should not be over 10 per cent for this grade of paper, but in spite of the larger amount used the physical tests are sufficiently high. It is to be noted that the physical tests of samples Nos. 138 to 142, inclusive, are higher than in Nos. 143 and 144, in which 23 per cent of soda poplar was used, which shows clearly that hemp-hurd stock imparts strength and folding endurance to a greater extent than does soda-poplar stock. From these preliminary tests it would be concluded, therefore, that hemp-hurd stock acts similarly to soda-poplar stock, but will produce a somewhat harsher and stronger sheet and one of higher folding endurance. Undoubtedly, there is more dirt in the samples than would be tolerated by the trade, but this was to be expected, since in this preliminary work the raw material was sieved by hand screens instead of by automatic machines which would sieve more thoroughly.