APPENDIX 
459 
The sample of paper to be examined is disintegrated, as described above, to 
such a degree that individual fibers are obtained. This pulp is dried, a large drop 
of the reagent is placed upon a slide and a little of the dried pulp is introduced 
into the drop and evenly distributed; a cover glass is carefully laid upon the drop, 
pressed down gently and the preparation examined under the microscope.* 
Chlorzinc iodide stains fibers as follows: 
A. RED {Red, Wine red, Violet-red, Brownish pink. Pink.) — Cotton and 
Linen rags, bleached hemp, bleached manila. 
B. BLUE {Dark blue. Light blue, Violet-blue, Blue-violet). = Chemical wood; 
bleached straw, jute, esparto, adansonia. 
C. YELLOW {Greenish yellow. Lemon yellow. Golden yellow. Dark yellow. 
Brownish) = Mechanical wood; raw straw, jute, manila, esparto, ramie, 
flax. (The larger the amount of lignin (ligno-cellulose, hgnone) the 
yellower will be the preparation.) 
Vn. OIL IMMERSION OBJECTIVES AND DARK-FIELD ILLUMINA¬ 
TION. See pages 37-46. For specific instructions see Bulletin Board. 
VIII. HANDLING SMALL AMOUNTS OF MATERIAL. 
1. Decantation. — pvige 278. {a) Dissolve a tiny fragment of an aluminum salt 
in a drop of water, precipitate with NH4OH. Decant. 
{b) Precipitate AgCl from a drop of AgNOs acidified with HNO3, using HCl. 
Decant. 
(c) Precipitate BaS04 from BaCb acidified with HCl, using H2SO.1, warm gently. 
Decant. 
2. Filtration. — Filter drops prepared as indicated in i. a, b, c, using both the 
methods of filtration described on pages 285-288. 
3. Sublimation. — {a) Make a series of fractional sublimations of Benzoic acid 
and study the fractions under the microscope. 
{b) Fractionally sublime Phthalic anhydride. Study the fractions under the 
microscope. 
(c) Make a mixture of approximately equal parts of Benzoic acid and Phthalic 
anhydride. Fractionally sublime and carefully study the fractions. 
* The Paper Testing Committee of the Technical Association of the Pulp and 
Paper Industry gives the following directions for adjusting the Herzberg reagent: 
“ Make up a mixture of about equal parts of bleached soda pulp, bleached sul¬ 
phite pulp and rag filter paper .... If the stain is correct then the soda pulp 
should show a dark blue color, .... the sulphite pulp should show a light blue, 
and the rag fibers will show a red or wine red.” If the blue color is more 
of a violet than a blue, water should be added, a few drops at a time, to the mixed 
reagent until a pure blue color is obtained with the soda pulp. 
See Clark, F. C.: Paper Testing Methods; Tappi Publishing Corp., N. Y., 1920. 
Sutermeister, E.: Chemistry of Pulp and Paper Making. Wiley & Sons, N. Y., 
1920. 
