CONCLUSIONS. 53 



non and technique of the various processes employed. The chemical 

 utilization of wood in the ways suggested requires the adaptation 

 and coordination of the equipment and processes which have been 

 employed successfully in other industries. This is a comparatively 

 imple problem for the experienced chemical engineer, but is not 

 within the scope of this publication. 



There are a number of ways in which the machinery for the manu- 

 facture of pulp and other products may be assembled, and many 

 forms of apparatus may be employed. Some general suggestions, 

 however, may be made. The observations and experiments of the 

 bureau fully warrant the conclusion that a rotary digester will give 

 larger yields of crude oils at less expense than will fixed retorts. It 

 is also best to use a rotary digester in pulp making. The greater 

 yield of oils with the rotary digester is due to the more rapid and com- 

 plete penetration of the chips by the steam. Hand labor should be 

 reduced to a minimum by the use of machinery. The arrangement 

 of the plant should be such that repeated and useless handling of 

 material is avoided and the products should be carried to the ultimate 

 Form iu which they find industrial application. Incoming wood 

 should be unloaded directly into the chipper and only the excess 

 stored. Indeed there should be as little storage of wood as possible. 

 It is far better that the wood should be brought daily to the works 

 as soon as it is cut and split in order to avoid the great loss of turpen- 

 tine which occurs at the surface of freshly cut and split pine. 



Such a plant should be managed by a man skilled in its technical 

 control in order that an accurate knowledge may be had of the quality 

 and quantity of the raw material used and of the products obtained 

 therefrom. Undoubtedly much of the dissatisfaction which has 

 existed with regard to wood turpentine has been occasioned by the 

 ignorance of the producer of the properties which the material should 

 possess, or of the methods of producing a turpentine uniform in com- 

 position and resembling closely gum turpentine. 



The wood should be cut diagonally across the grain and chipped to 

 a fairly uniform size. The chips should not be more than three- 

 Fourths of an inch through nor less than one-fourth of an inch and 

 may be subsequently shredded with advantage. Great care should 

 be exercised to avoid the production of dust on the one hand and 

 large slivers or chunks on the other. Very fine material loses tur- 

 pentine before it reaches the digester, and is overcooked, resulting in 

 low yields of turpentine and of weak pulp. Penetration of the large 

 chips by steam or alkali is very slow and often incomplete, and con- 

 sequently the time of steaming and digestion is prolonged, the yield 

 of turpentine is lowered and the pulp is insufficiently cooked, which 

 results in inferior pulp and paper. 



