XXXVm INTRODUCTION. 



fast." On the north of Scotland, and in some 

 parts of England and Ireland, the collecting and 

 cutting of the large Fucacese is carried on for the 

 purpose of being made into lielpy which is an im- 

 pure carbonate of soda, employed in the pro- 

 cess of glass-making, and for the purpose of 

 soap - boiling. After being well dried, the sea- 

 weed is then burned in pits or ovens lined with 

 stones, till it becomes a solid mass, which is 

 broken by the means of iron bars into large 

 pieces, and sent to market in this state. Fucus 

 vesiculosus or kelp-weed is by far the most pro- 

 ductive kind — from five ounces of the ashes, it 

 is affirmed, may be procured two ounces and a 

 half of fixed alkaline salts. Iodine also, a 

 valuable medicine in diseases of the glands, is 

 obained almost exclusively from the plants of the 

 Fucacese. It was discovered in the year 1811, by 

 the late M. Courtois of Paris. ^^ Without his ge- 

 nius and labour," writes M. Claudet, ^^the beautiful 

 discoveries of the Daguerreotype and Talbotype 

 processes would never have been made, for iodine 



