May 1, 1917.] 



THE INDIA RUBBER WORLD 



443 



Kelp Might Provide a Rubber Plastic. 



OFF the coast of southern California, a business new to the 

 United States, and by no means devoid of interest to the 

 rubber industry, has sprung up, and since last July 

 achieved national importance. It is the extraction of potassium 

 chloride for munition manufacture and the separation of various 

 other by-products from certain large Algae or seaweeds, par- 

 ticularly Macrocystis pyriferd, known as kelp. 



Those who have followed the interesting developments in the 

 rubber trade for the past decade will perhaps recall that six 

 or eight years ago companies were formed both in England and 

 America for the manufacture of rubber from kelp. Nothing 

 came of either venture. "The India Rubber Journal" manifested 

 no faith in the British invention, and as stated in The India 

 Rubber World, the stock-selling circular issued by the promoters 

 of the American company indicated so conclusively their ig- 

 norance of rubber technology that the matter was never taken 

 seriously by the trade. The sample sent for inspection looked 

 very much like the compounded sheet and from a physical exami- 

 nation seemed to be the kelp product mixed with rubber dough. 



Kelp, however, abounds in a thick, gluey liquid, known as 

 algin, which possesses many useful properties. It slightly re- 

 sembles gelatin, but differs from 

 it in not coagulating to a jelly nor 

 being precipitated by tannin ; from 

 albumin in not coagulating by 

 heat, and from gum arabic in being precipitated by 

 mineral and several organic acids. Algin gum is a 

 leathery, nitrogenous substance, alginic acid, insoluble 

 in water, alcohol, ether and glycerin, although combin- 

 ing readily with the lighter alkaline metallic bases to 

 form substances many of which are soluble. Does this 

 not suggest the possibility that in kelp there may be a 

 plastic which the rubber trade can use? Solutions of algin have 

 14 times the viscidity of starch and 37 times that of gum arabic, 

 rendering it excellent as a glue. As it combines easily with 

 rubber, shellac and other gums, it can be made an important in- 

 gredient of waterproofing compounds for cloth. It can also be 

 utilized as a thickener and for fixing iron and aluminum mordants 

 in calico printing, and for emulsifying oils and clarifying wines 

 and spirits. 



With the heavier alkaline metallic bases, algin forms insoluble 

 compounds as pliable as gutta percha or as tough as horn, in 

 which latter state it may be turned and polished like ivory or 

 the ivory nut. In thin, transparent sheets it offers a substitute 

 for parchment paper, gutta percha. gelatin, celluloid, isinglass or 

 artificial leather. Like celluloid, too, it may be used for the manu- 

 facture of buttons, combs, knife handles, etc. Indeed, of the 

 four small kelp concerns at San Pedro, one at present makes such 

 articles, while another turns out pails and similar utensils from 

 the pulp, which is also excellent for the manufacture of paper. 



In coast regions the world over, wherever kelp occurs, it has 

 long been employed as a fertilizer, and until the close of the 

 eighteenth century, formed the chief source of the supply of 

 potash in western Europe. Kelp salt, the residual ashes of the 

 seaweed after separation of the potash, contains sodium sulphate, 

 carbonate and chloride, together with small quantities of po- 

 tassium sulphate, and was formerly much used in the manufacture 

 of glass and soap, but of recent years has been valuable almost 

 solely as a source of iodine, which is an important constituent. 

 Some bromine is also obtainable. Thus this industry is but a 

 reversion with improved methods to a business of bygone days. 

 Wlien the European war cut the United States off from the 

 world's supply of potash, the mines near Stassfurt, Prussia, 

 where carmallite and csenite are found in abundance, American 



scientists at once began to develop other sources. These min- 

 erals contain potassium and magnesium sulphate as well as 

 magnesium chloride, and among the products obtained from them 

 are saltpeter (potassium nitrate), the principal ingredient in the 

 manufacture of gunpowder, and potassium chlorate, used in the 

 arts as an oxidizing agent and essential to the manufacture of 

 several high explosives. Both have been in such tremendous 

 demand as to warrant the expenditure of millions of dollars in 

 the development of the kelp industry and extensive experimental 

 work for utilization of the by-products of potash manufacture. 



Potash, or potassium carbonate, the so-called vegetable alkali, 

 plays an important part in vegetable life, existing in all plants 

 in varying proportions, and in various combinations with both 

 inorganic and organic acids. When plants are burned, the in- 

 organic constituents remain behind in the ashes, and it was 

 by bleaching these ashes that potash was first obtained, the name 

 being derived from the fact that the solutions from wood 

 or other vegetable ashes were boiled down or concentrated in 

 great iron pots. 



Were potash the only consideration, this infant -American in- 



Kelp H.xrvester Showing Endless Drag Conveyors. 



dustry would be but temporary, for in peace times it can be 

 procured from the German mines more cheaply than in any other 

 way ; but so many useful by-products are made available through 

 its manufacture from kelp by chemical extraction rather than 

 burning that there is good prospect that the business will con- 

 tinue to be profitable after the war. Another vital factor in the 

 choice of kelp rather than other potash-yielding plants is espe- 

 cially favorable. No vast acreage of valuable land must be de- 

 voted to its culture ; there is no expense of planting, cultivation 

 or combating insect pests. It grows wild in the sea along rocky 

 shores and requires only to be cut and carried ashore for refining. 

 The harvesting and manufacturing are the only costs, and the 

 supply is seemingly inexhaustible. Being one of those flowerless 

 plants never having true stamens and pistils, it propagates rapidly 

 by spores or simple cell division. 



Kelp is found all along our Pacific Coast from Cedros Island, 

 Lower California, to Alaska. The report of the Department of 



