77 



SOME OBSERVATIONS UPON THE CHEMICAL 



COMPOSITION AND THE POSSIBLE 



COMMERCIAL VALUE OF SEAWEEDS. 



By HERBERT \V. R. HASETJIURST, B.Sc. 



The published accounts of chemical observations upon sea- 

 weeds are not numerous. On the west coast of Scotland, in the 

 Scilly Isles, and in some parts of Kent seaweed is largely used as 

 a manure, and in 1898 Professor J. Hendrick, of Aberdeen 

 University, published an account""-'" of some analyses of seaweed, and 

 gave the results of some field experiments in which it was used 

 as a manure. Somewhat earlier than this, E. C. C. Stanford gave 

 an account---' of a substance, " Algin," obtained from seaweed ; this, 

 it was hoped, would have a commercial value. These two 

 publications, along with certain analyses in works on agricultural 

 chemistry, comprise the whole of the chemical literature upon the 

 subject. 



In Cullercoats Bay and on the neighbouring beaches many 

 tons of drift weed are thrown up, more especially from the end 

 of September to the beginning of April. At the request of 

 Professor Meek I undertook to analyse chemically the seaweed at 

 Cullercoats. 



The material worked upon was taken from two localities, the 

 first being the outcrop of magnesian limestone near the Ninety 

 Fathom Dyke at Smuggler's Cave, and the second an outcrop of 

 carboniferous sandstones to the north of Browm's Point. The 

 seaweeds used were always fresh cut, and no drift weed whatever 

 was used. The commoner seaweeds of this locality are Laminaria 

 digitata, Fucus serratiis, Fucus nodosus and Fucus vesiculosus; 

 indeed, the two former weeds compose the greater part of the 

 local drift weed, and for this reason were chosen as subjects for 

 this investigation. 



A fairly large quantity (50 grammes) of Laminaria digitata 

 was incinerated and all organic matter thus got rid of. The ash 

 was then analysed with the following result. Bases present in 

 fair quantity were potassium, sodium, magnesium and calcium, 

 whilst the acids identified were chloride, sulphate and phosphate. 

 In five subsequent analyses iron in traces was recognised in three 



♦ Journal of Highland and Agric. Foe. 1898. 

 ♦Chemical News, Vol. 47, pp. 254—267. 



