COMPOSITION OF THE ASH OF A N.S.W SEA-WEED. 



97 



kelp was then burnt for the sake of the potash and iodine, 

 but the kelp makers still persisted in burning their weed 

 to a hard slag, thereby losing most of the iodine. 



The difference produced by burning to a slag and loose 

 ash is shown by the following analyses 1 (a sample of Scotch 

 kelp being employed for each method): — 



Slag. 



K 2 S0 4 13-95 



KC1 17-79 



NaCl 14 



Na 3 00 8 3-92 



Na. 2 S ... ... ... heavy trace 



Na 3 S 2 3 -75 ... -17 



Nal -76 ... 1-48 



NaCNS ... ... ... heavy trace slight trace 



Soluble organic matter nil ... -42 



Insoluble 44-80 ... 49-75 



Water 4-05 ... 7-00 



Ash. 

 .. 12-71 

 .. 1809 

 .. 6-80 

 .. 3-43 

 slight trace 



100-02 



Total potash 18-77 



Iodine (pounds per ton) 14 \ 



Carbon in insoluble part nil 



99-85 



18-32 



28 



9-00 



More efficient methods of extracting iodine from sea- 

 weeds were later introduced by Stanford, i.e., (1) distilla- 

 tion process, (2) leaching-out process, both of which had 

 the further advantage of yielding valuable by-products. A 

 detailed account of these however would be out of place 

 here. 



The comparative yield of the three processes may be of 

 interest and is therefore quoted from Thorpe's Dictionary,, 

 the calculations in each case being based on 100 tons of 

 air-dried Laminarise : — 



Thorpe, op. cit., Vol. n, 339. 



G— Aug. 7, 1907. 



