98 C. J. WHITE. 



Kelp process — Yield = 18 tons of kelp giving 9 tons of salts 

 -f 270 lbs. iodine — residue valueless. 



Distillation process — Yield == 15 tons of salts + 600 lbs. 

 iodine — residue = charcoal (36 tons), tar, ammonia, etc. 



Leaching process — Yield = 20 tons salts + 600 lbs. iodine — 

 residue = algin (20 tons) + algulose (15 tons). 



In the present example (Ecklonia) the plant was care- 

 fully incinerated at a low temperature in a muffle, and 

 there is good reason to believe that practically the whole 

 of the iodine was retained. The percentage found (*89) 

 works out to approximately 20 lbs. per ton, which is con- 

 siderably below the yield of the Scotch Laminarise quoted 

 above. 



la the present case the determination of iodine (in the 

 presence of chlorine) was made by the method of Jannasch 1 

 which depends on the fact that in a dilate solution of two 

 or three halogens, nitrous acid sets free iodine only. The 

 iodine is driven over in a current of steam and absorbed in 

 an ice-cooled mixture of caustic soda and hydrogen peroxide 

 (free of hydrochloric) and subsequently determined gravi- 

 metrically as silver iodide in the usual way. The reactions 

 taking place are as follows: — 



(a) 2 I + 2 XaOH = Xa I + NaO I + H 2 

 (j3) NaO I -f H 2 2 = H 2 + 2 + Na I. 



The detailed analysis of Ecklonia exasperata was as 



follows: — 



Sand ... 1*27 f 

 C ... *48 



Si0 2 ... 1*17 



H 2 ... 2*30 



S0 3 ... 11*98 



1 Ze.it. far Anorg. Chem., I., p. 144, and quoted by Treadwell, Quant. 

 Anal., p. 254. 



