ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
121 
Microscopical Examination of Paper.* — Mr. Herzberg, who has 
charge of the examinations of paper at Charlottenburg, has just published 
a very exhaustive work upon the subject, with numerous reproductions 
of microscopic preparations. He brings specially into prominence the 
peculiarities of certain fibres for rendering them easily distinguished. 
The author uses a solution of iodine for recognizing the various 
fibres, which, according to their origin, assume various colours : (1) Wood- 
wool and jute are coloured yellow ; (2) straw, “ cellulose,” and alfa do 
not change ; (3) cotton, flax, and hemp are coloured brown. 
For disintegrating the paper, Mr. Herzberg does not employ lie 
processes in common use. Mechanical appliances, either needles or a 
mortar, do not remove the size, starch, and weighing substances which 
in part conceal the structure of the fibres and render the examination of 
them difficult. He recommends that a small quantity of the paper to be 
examined be submitted to ebullition for a quarter of an hour in a 1 to 
2 per cent, solution of soda. In this way the foreign substances are got 
rid of and the fibres set free. The presence of wood-wool will be 
ascertained, during the boiling, by the paper becoming yellow. 
After this treatment the whole is poured upon a brass strainer with 
fine meshes, and is washed with pure water. The washed residuum is 
reduced to a homogeneous paste in a porcelain mortar. 
In the case of coloured paper the colouring matter must be removed 
if the boiling does not effect the removal. To this end, hydrochloric 
acid, chloride of lime, &c., is used according to the chemical nature of 
the colouring matter. When the paper is not sized, nothing but water 
is used for the boiling. If the presence of wool in the paper is suspected 
an alcoholic solution, instead of an alkaline one, is used, as the latter 
would dissolve the wool. The solution of iodine in iodide of potassium 
may be more or less concentrated. The colour produced varies in depth 
according to the concentration. The author generally uses the following 
formula : — Iodine, 18 grains ; iodide of potassium, 30 grains ; water, 
5 drachms. 
For spreading the paste upon the object-holder of the Microscope he 
employs two platinum needles. The object-holder is placed up >n a 
white ground, so that the fibres will stand in relief more prominently. 
The paste is covered with a glass, and the excess of water is removed 
with blotting-paper. For the determination of the fibres a magnifying 
power of 300 diameters is best adapted, but for ascertaining the relative 
proportion of the fibres, one of 120 diameters, that permits of taking in 
a wider surface, is preferable. 
* Amer. Mon. Blicr. Journ., x. (1889) pp. 271-5, from ‘ Guttenberg Journal.’ 
