6 BULLETIN 322, U. S. DEPARTMENT OP AGRICULTURE. 



are present in domestic unretted flax straw. For this reason alone 

 flax straw would require the use of more chemicals in its reduction 

 than does flax waste. 



(2) The proportion of wood in flax straw is far higher than in flax 

 waste, which probably would necessitate a higher consumption of 

 chemicals in treating the former. If it should appear necessary to 

 exclude wood shives from the finished product, it might be found 

 necessary to reduce the wood to a greater extent than when using 

 flax waste, in which case the reduction might require the employ- 

 ment of a higher steam pressure or a longer time of treatment, or 

 both. 



The greatest difference in a physical sense between straw and 

 waste is that the former, being composed of lengths of the whole 

 stalk, presents larger pieces, or masses, to the action of the chemi- 

 cals, thus necessitating the employment of more time in the chemical 

 reduction process. These chemical and physical differences, how- 

 ever, do not differ in kind but only in degree, from which it would be 

 concluded that the method found to be satisfactory with straw would 

 differ in no fundamental manner from that known to be satisfactory 

 with waste. 



LABORATORY EXPERIMENTAL TESTS ON THE PREPARATION OF PULP. 



In March, 1914, preliminary work was started by the Department 

 of Agriculture on the utilization of flax straw as a raw material for 

 sack or wrapping paper manufacture. It was decided that, of all the 

 fiber-treating processes, the milk-of-lime process was the most worthy 

 of trial, after the following factors, among others, had been con- 

 sidered carefully : 



Lower initial cost of factory installation. — On account of freight rates, which 

 figure so prominently in the final costs of manufactured products, and because 

 of the remoteness of the flax region from paper mills, it might appear advisable 

 to establish pulp or paper mills nearer the source of raw-material supply. It 

 would be inadvisable to install a process which demands a heavy expenditure 

 per ton, such as the soda, sulphate, and sulphite processes, before the true 

 value of the material were proved by actual manufacture for a reasonable 

 period of time. Such a practical test might be prohibitive because of the 

 shipping cost for such a distance, and few, if any, manufacturers could be 

 expected to operate at a loss or even at a low profit for a sufficient period to 

 determine the advisability of factory installation. The same remarks apply 

 to the milk-of-lime process, but not to the same degree. 



Tensile strength of the fibers preserved. — As is commonly known, caustic soda 

 pulping lowers the tensile strength of fibers more than the milder milk-of-lime 

 process. 



Class of employees required. — The milk-of-lime process does not demand the 

 employment of as large a staff or as great a variety of skilled help as the soda, 

 sulphite, or sulphate processes. 



