JACK PINE AND HEMLOCK FOR MECHANICAL PULP. 



19 



thai/ each of the various grades of pulp has its particular use in cer- 

 tain qualities of paper, though no attempt has been made to classify 

 them according to uses. The standards selected are shown in Plates 

 IV, V, and VI; in each case the fibers are enlarged 15 times. For 

 the purpose of comparison the spruce sulphite standard fiber is shown 

 hi Plate IV, figure 1, and the No. 1 spruce ground- wood standard in 

 figure 2. It is indeed very seldom that a sample of pulp is obtained 

 which corresponds to the No. 1 spruce ground- wood standard. As 

 will be noted, the fibers are very similar to the sulphite fibers, although 

 there is a certain amount of short material and coarse fiber present 

 which does not occur in the sulphite pulp. 



Plate V shows the No. 2 ground- wood standard and No. 3 coarse 

 ground- wood standard. The No. 2 differs from the No. 1 standard 

 only in the amount of short fiber and coarse fiber present, the No. 2 

 having larger amounts of these two kinds. The coarse standard 

 needs no description. It is a kind of fiber often made by mills during 

 their low-water periods in order to maintain production with less 

 power consumption. 



The No. 4, medium ground-wood standard, and the No. 5, fine 

 ground- wood standard, seem to follow in logical sequence those pre- 

 viously given. The No. 4 standard has the appearance of being a 

 mixture of No. 3 and No. 5. The No. 5, as will be noted, contains an 

 extremely small amount of fiber and is composed largely of dust and 

 short-fiber particles. 



Table 2 gives the data furnished by the manufacturers of the 

 various pulp samples selected as standards. These data, for the 

 most part, are only approximate, but they will serve to give some 

 idea of the conditions under which the material was produced. 



TABLE 2. Conditions of manufacture of spruce ground-wood standards. 



