Since all plants that grow are made up of cells, and the walls of cells are cellulose and paper is but matted or felted cellulose fibres, it is impossible to outline the future of the paper industry under chemical control and with abundant research. The waste liquors of sul phite pulp mills, in which one-half the cellulose has been lost, still pollute streams and cause waste. The sugar in the waste liquor may be converted into alcohol and uses arc gradually being found for the gummy products that now cause trouble. As soon as it can be made to pay, then waste liquors will be evaporated to dryness and the nuisance avoided.
Drying, mixing, grinding, filtering, heating, refrigeration and distillation and work under pressure as well as in vacuo are problems to which the chemical engineer has addressed himself ; and the making of apparatus for these special purposes has become a series of special industries. Just as, considering pure science, we found the line between chemistry and phys ics fading away, so in industry we find that there is no more a clear dividing line that sep arates chemistry from engineering.
In conclusion it is fair to say that there has been great advance in the knowledge of how closely chemical processes touch us on every hand. It is needed in the preparation of our food and clothing, in the materials of our houses, in the care of the water we use and in cleaning streets. It is needed in the control of the production of metals and it prepares for us paints, varnishes, paper, ink; indeed nearly everything we use or handle has needed chemical control in the making. Its language is ugly and seems difficult, although it is not so hard to learn as many of us are disposed to think. We need a better understanding of it because through it we may learn to avoid the flagrant waste of the riches of the earth, of which our generation has been guilty. And with a sense of chemistry in our minds all the processes of nature take on a new and added interest.