Use of Wood in Paper-making. 205 



converted into the material so highly prized for flavoring and 

 perfume. 



CHAPTER XX. 



USE OF WOOD IN THE MAXl'KACTURE OF PAPER. 



820. In recent years, the employment of wood for paper has 

 come into extensive use, both in Europe and America. For this 

 purpose it must first be reduced to pulp, and mixed with a certain pro- 

 portion of rags. The chief kinds used in this country are the poplar 

 and the spruce, and in Europe, besides these, various pines and the 

 white birch. The wood should be worked up fresh, and in preparing it 

 the bark and defective or rotten parts must be first taken off. There 

 are two principal methods of reducing wood to pulp the mechan- 

 ical and the chemical ; and each of these is subdivided into several 

 distinct processes. 



821. By the more common of the former, known as the " Volter 

 Process," from Henry Volter, of Wurtemburg, who first brought 

 it into successful use, 1 the wood is ground into pulp upon the edge 

 of broad and large grindstones running vertically in water, the wood 

 being pressed firmly down sideways of the grain, by automatic 

 screws, at four or five places. The feed is about an inch in five 

 minutes, and the speed about 200 revolutions in a minute. 



822. Of course the power required to run such machines is very 

 great. The wood is sometimes boiled or steamed before grinding, 

 and the pulp is screened through fine wire cloth, and the coarser 

 parts ground with water between mill-stone like those for grinding 

 grain. This process began to be successfully used about 1846, and 

 is largely used, both in Europe and the United States. 



823. By the " Hartmauu Process" the wood is ground between 

 two smaller vertical stones, the approach being secured by a weight. 

 By the " Siebrecht Process" the grinding is done upon a great hori- 

 zontal stone, and the wood is held down by hydraulic pressure. 

 There are other processes by which the wood is sawn into short 

 lengths, and then crushed under heavy rollers, or the fibers are torn 



1 The inventor of this process was F. G. Keller, who took out a patent in 

 Germany, in 1844, for a wood-pulp grinding machine, but not having the cap- 

 ital sold out his interest. Ho afterwards fell into indigence and was aided 

 by a subscription among the German paper-makers. 



