Soaps.
Dyes, Pigments, Loading Materials, &c.
The chemical examination is both difficult and somewhat misleading. A microscopical examination will often throw much light on their composition.
For comparing the tinctorial power of different samples, weighed quantities should be ground up with starch or some other white powder. In this way some idea of the intensity of colour can be readily arrived at.
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CHAPTER XV.SITE FOR PAPER-MILL, WATER-SUPPLY, WATER PURIFICATION, ETC.
In choosing a spot on which to build a paper-mill, the manufacturer has to take into consideration several very important circumstances. Chief of these is the necessity for having a large supply of water at command. Not only is a large quantity needful, but it should be free from impurities, such as suspended matter and iron. The former, it is true, can be removed by settling and filtration; the latter cannot, and is liable to injuriously affect the colour of the paper. Again, as a question of economy in working, it is advantageous to have convenient water-power; therefore for this, as well as for the former reason, paper-mills are usually situated on the bank of a stream. In choosing such a site, paper-makers are probably also influenced by the fact that it affords a ready means for the removal of impurities. In properly conducted mills, where suitable apparatus is employed for evaporating the liquors in which the raw material has been boiled, the stream should not be polluted to any very great extent. Generally speaking, the greater the pollution, the more are valuable materials being lost to the manufacturer. It is obvious that the site for a mill should also be chosen with reference to its proximity to means of transit for the raw and manufactured materials.
The disposition of the different divisions of a paper-mill depends of course upon the nature of the paper it is intended to make and to a large extent upon local circumstances. Fig. 79 will give some idea of the general arrangement of a mill for manufacturing esparto paper. {211}
FIG. 79.