12 BULLETIN 404^ U. S. DEPARTMENT OP AGEICULTUEE. 



pieces often were found to be a quarter or half of the rounded rectan- 

 gular woody shell of the stalk, although there appeared to be no 

 regularity in this respect. 



From the pulp-maker's standpoint the great irregularity in thick- 

 ness, length, and mass of the woody pieces militates decidedly against 

 economy in pulp production. The smaller pieces reduce by chemical 

 treatment sooner than the larger fragments and are thereby over- 

 treated, which results in a lower yield of cellulose fiber and a product 

 composed of undertreated and overtreated fibers, the production and 

 use of which are not satisfactory or economical. It probably would 

 be found more satisfactory, therefore, to screen or sort the hurds and 

 treat the various sizes separately and differently. 



Associated with the hurds was a small quantity of chaff and dirt, 

 composed chiefly of sand, soil, particles of hemp leaves and flowers, 

 and other extraneous matter. The sand and soil were present 

 because of the practice of placing the stalks in shocks in the field, the 

 butts of the stalks being in contact with the soil. It is a simple 

 matter, however, to remove the chaff and dirt by sieving, and this 

 practice was followed in most of the paper tests conducted with this 

 material. 



CHARACTER OF THE TESTS. 



Because of the similarity of hemp hurds to other materials which 

 have been tested by the Office of Paper-Plant Investigations, semi- 

 commercial tests were conducted in cooperation with a paper manu- 

 facturer without prehminary laboratory tests. Laboratory pulp and 

 paper tests are regarded only as a preliminary to semicommercial 

 tests and therefore are not employed imless the material in question 

 presents new features which should receive investigation before 

 larger sized tests are undertaken. 



The advantages of cooperative mill tests are many, among which 

 may be mentioned the counsel and advice of the mill management 

 and employees, the services of speciahzed and skilled labor, facilities 

 for comparing the processes and the results of tests with commercial 

 processes and results, and the use of commercial or semicom- 

 mercial types and sizes of machinery. Tests conducted in this 

 manner and on this scale are of a different quality than is pos- 

 sible in those conducted in a laboratory, and the results are suscep- 

 tible of commercial interpretation with a fair degree of reliability. 

 It is found, in general, that the cost of securing such equipment and 

 service for a complete and comprehensive test does not exceed $500, 

 while the installation of an equally satisfactory equipment alone 

 would cost at least $50,000 and in many cases very much more. 

 Tests conducted in this manner constitute a direct demonstration to 

 the manufacturer, and the results obtained are found to carry more 

 weight when presented to other manufacturers for consideration. 



