The Microscope in the Paper-Mill. 
251 
From my own experience of paper-mill laboratories I find few 
microscopists who attempt to extend .their work much beyond the 
ground outlined above. Few also attempt to use the simplest 
form of microtome in spite of the fact that cross-sections may be 
quickly cut for temporary mounts of fibres, and much may be 
learned from same. 
3. A Plea for a Wider Application of the 
Microscope. 
The remarks I make under this head apply particularly to the 
paper-mill, but may also be studied with profit by workers in 
other industrial laboratories. A good training in practical micro- 
scopical technique is necessary, and a fairly wide knowledge of all 
branches of microscopical science desirable, together with a small 
but carefully selected bookshelf of reference works. The labora- 
tory worker who desires to get the best out of his microscope 
should be able to mount and stain a bacterial film, stain and cut a 
vegetable section, grind a mineral section, prepare and etch a 
metal, and be conversant with the practical elements of micro- 
chemical manipulation. He should also have a good working 
knowledge of four methods of illumination — viz. direct light, 
reflected light, dark-ground and polarized light — and he should 
also be able to record his work with the camera. 
The laboratory worker frequently pleads lack of time to study 
and cover such ground. I have found by experience and have 
always taught that such knowledge saves time. It is not neces- 
sary to aim at carefully prepared mounts for permanent collection. 
Speed, simplicity, a little care and practice are necessary. Every 
substance or material that comes to the laboratory for physical or 
chemical examination should first be submitted to suitable micro- 
scopical preparation and examination. The information so gained 
frequently solves problems qualitatively, leaving only the quantita- 
tive work to be done, and never fails to yield guidance for method 
in the latter work. 
“ What do you expect to see there ? ” I am frequently asked 
by someone when I take a substance to the microscope ; some- 
thing that is not usually examined microscopically. “ I do not 
know,” I reply, “ but I expect to find something.” 
4. The Microscope Teaches the Value of Detail. 
In the manufacture of paper numerous problems and difficulties 
arise. Some of the problems are chemical, some physical, and 
others physico-chemical. The processes of isolation of cellulose 
from raw materials by digestion and bleaching are largely 
