IODINE AND OTHER CHEMICALS 67 



from which a number of long string-like leaves grow. 

 Small amounts of this kelp were harvested along 

 with the macrocystis. It contains more potassium 

 salts but much less iodine than macrocystis. 



As harvested, a ton of kelp contained about seven- 

 teen hundred pounds of water, fifty pounds of po- 

 tassium chloride, fifty pounds of alginic acid, and 

 a half-pound of iodine. 



In the early days of the industry the kelp was 

 reaped by hand with large scythes from scows. Some 

 drift kelp was also collected on the beaches. The 

 kelp was partially dried either on the beach or upon 

 frames, and then chopped and sold as a fertilizer 

 or burned upon open hearths to obtain the ash which 

 was then used as fertilizer. Such methods are prac- 

 ticable only when potassium salts are very dear, as 

 the cost of harvesting kelp by such crude methods is 

 very high. During the growth of the industry, vari- 

 ous types of harvesting equipment were tried out. 

 The most satisfactory device for this work resembles 

 mechanically the ordinary hay-mowing machine. 

 This mowing machine, with a cutter-bar about 

 twelve feet in length, was mounted in front of a belt 

 conveyer placed before a scow in such a position that 

 the cut kelp was carried upon the scow. As fast as 

 the kelp accumulated at the bow of the scow, it was 

 hauled back by means of a grab-hook operated by a 

 winch. A harvester of this type could harvest about 

 fifty tons of kelp per hour. 



At most plants the kelp was unloaded by means 

 of a clam-shell bucket operated by a double drum 



