=Comparison of the tests and commercial practice.=

In work of this nature and on this scale it is practically impossible to arrive at a cost figure which would be susceptible of commercial interpretation, and in this preliminary publication nothing will be attempted beyond a comparison of the process used with the hurds with that process commercially applied to poplar wood.  The process last used with the hurds should not be regarded as final, satisfactory, or most suitable, as it has been shown that progress was being made up to the conclusion of the work.

In comparing the method of using hurds with the method of handling poplar wood, a difference is apparent on the delivery of raw material at the mill.  Ordinarily, poplar is received at the mill in the form of logs about 4 feet in length, which may be stored in piles in the open.  Hurds very likely would be received baled, and it would seem advisable to store them under cover for the following reasons:  (a) Baled hurds would probably absorb and retain more water during wet weather than logs of wood, thereby causing excessive dilution of the caustic liquor; (b) prolonged excessive dampness might create heating and deterioration unless the hemp were properly retted; (c) wet hurds could not be sieved free from sand and chaff.  Should further work show that the first two reasons need not be taken into consideration, the third objection might be overcome by sieving the hurds before baling.  Even then, it is probable that baled hurds stored in the open would accumulate and retain considerable dirt from factory chimneys, locomotives, and wind.  Checked pulp wood exposed in the open invariably suffers from these causes.

In the preparation of the raw material for the digesters there is likewise considerable difference between hurds and poplar wood.  The former apparently requires only a moderate sieving to remove sand and chaff, which operation doubtless would require only a small amount of labor and the installation of some simple machinery of low power consumption.  In preparing poplar for digestion, the 4-foot logs are chipped by a heavy, comparatively expensive chipper of high power consumption, after which the chips are sorted by sieving, the large pieces being rechipped.  There would be a noteworthy difference in the installation, operating, and depreciation costs of the two equipments, and this difference would counterbalance to a considerable extent the difference in cost of raw material storage.

It is possible that in the use of the chip loft more care would have to be exercised in using hurds because of the tendency of the bast fiber to cause lodgments, but this should not be considered a serious difficulty.