1894.] NEW-V'ORK MICROSCOPICAL SOCIETY. 39 



highly finished paper. From its name and general appearance 

 one would think it might be pure linen paper, but you will find 

 nothing but cotton in the specimen under the microscope. We 

 have not known any attempt of the manufacturer to palm off 

 papers made wholly of wood for linen, but the several kinds of 

 wood pulps are frequently mixed with linen and cotton-rag pulps, 

 and when finished are sold for high-class paper, while the cheaper 

 grades are made almost entirely from wood pulps. 



Both in the " mechanical " and " chemical " wood paper systems 

 the woody markings maybe distinguished by the aid of the micro- 

 scope, and more particularly the coniferous fragments (Plate 40, 

 Figs. 10, 11). 



Poplar-wood fibre, when torn up, somewhat resembles cotton, 

 but there is at least one distinguishing feature, even among the 

 disintegrated "mechanical" pulps — that is, the tangential frag- 

 ments have among them particles bearing a grate- or screen-like 

 appearance ; some of these evidences maybe seen in slide No. 7, 

 a section of the wood of Popiilus monilifeya (Plate 40, Fig. 7). 

 Slide No. 16, being paper of the Singerly Pulp and Paper Co., 

 also exhibits this peculiar feature, indicating poplar wood 

 " ground '' up by the " mechanical" process. Slide No. 17 is of 

 Woolvvorth &: Graham's "ground wood pulp," which also shows 

 a little of the poplar character, but the mass is so full of short 

 fibre as to be practically unrecognizable, and is only fit for 

 printers' low-grade work. The chemical tests, however, show 

 plainly by their peculiar colors that this is " ground wood." 



We have here a sheet of dried pulp from Norway, called 

 *' Eker,'* which is shown by the microscope to be composed of 

 spruce wood, and, as you will see by its bright-red color in its 

 chemical reaction, when I slightly touch it with para-phenylen- 

 diamine hydrochlorate, is proved to be " mechanical fibre." 



I will not go into further detail regarding the varieties of paper 

 intended for the higher classes of work. It is patent that there 

 is much yet to be learned about the methods of detecting mixtures 

 in paper, even for the ordinary qualitative tests; and as for 

 quantitative analysis, we have found no better method than those 

 adopted at the German testing station at Berlin, where an eye- 

 piece micrometer, ruled in squares, is used to count, as best may 

 be, the several fibres or parts of fibres of each admixture con- 



