68 THE WEALTH OF THE SEA 



electric hoist. The large plant of the Hercules 

 Powder Company chopped the kelp finely on board 

 the scow, thus reducing the kelp to a fluid mass 

 which could be unloaded by means of a pump. 



Potash was recovered from kelp by several differ- 

 ent methods. The first operation of all the processes, 

 except the fermentation process, was the drying of 

 the kelp in horizontal rotary direct-heat driers. The 

 dried kelp was usually burned in rotary incinerators 

 or in reverberatory furnaces. In some plants the 

 ashes were leached and the potassium chloride ob- 

 tained fom the solution by crystallization. 



The United States Department of Agriculture 

 constructed an experimental kelp-potash plant at 

 Summerland, California. This factory was built for 

 the purpose of demonstrating the production of by- 

 products by the destructive distillation of kelp. 

 According to this process, the dried kelp is distilled 

 at a high temperature in vertical fire-clay retorts. 

 The vapors are led into condensers and scrubbers, 

 where ammonia, volatile oils, tar, and creosote are 

 obtained. The residue in the retort consists of kelp 

 charcoal and inorganic salts. The salts are extracted 

 with water, thus obtaining a solution from which 

 potassium chloride is crystallized. The charcoal 

 residue is washed with hot acid and then again with 

 water. After drying, it is ready for use as a de- 

 colorizing carbon, or for absorbing carbon for gas- 

 masks. Iodine is obtained from the mother liquor 

 from the crystallization of the potassium chloride. 



