210 Mr. O. W. Brown on Drift Weed Kelp from Orkney. 



Analysis of Orkney Drift Weed Kelp. 

 For the specimen of kelp subjected to examination, I am indebted to 

 W. Paterson, Esq., alkali merchant, Glasgow. The investigation was 

 conducted in the laboratory of the University of Glasgow, under the 

 superintendence of Dr. R. D. Thomson. In making these analyses, the 

 first points to be determined were the quantity of soluble and insoluble 

 salts and water. To effect the first object, a portion of the kelp was 

 digested in water, the solution and residue thrown upon a weighed filter 

 and washed, till all the soluble salts were removed. The insoluble salts 

 were then dried at 212° Fahrenheit: — 



TnoniiiMo Qoifo Soluble salts Insoluble salts, Soluble salts 



insoiuDie salts. ^^^ ^^^^^^ p^^. ^^^^ ^^^ ^^^^^^ p ^^ 



400 grains gave 114-80 ... 285-20 ... 28-700 ... 71-3 



500 " « .... 155-49 ... 344-51 ... 31098 ... 68-902 



1000 " " .... 294-10 ... 705-90 ... 29410 ... 70-59 



Mean, 29-736 ... 70264 



Water, — The quantity of water was estimated by heating the kelp at 

 212° Fahrenheit, till it ceased to lose weight. 



Water. Water, per cent. 



200 grains gave ....13-60 6-8 



If the quantity of water be subtracted from the soluble salts and water, 

 the real amount of soluble salts will be obtained, which is as follows : — 



Insoluble salts. Soluble salts. Water. 



29-069 ... 63-464 ... 6-8 



Analysis of Insoluble Salts. 

 The following is the description of analysis and results obtained from 

 the insoluble salts: — 



Testing Analysis of Insolvble Salts. 



Before proceeding to the quantitative analysis of the insoluble salts, a 

 qualitative investigation was made. The kelp under examination was 

 very hard, with a strong alkaline taste, and greyish colour, with black 

 portions of carbonaceous matter interspersed through it. It was partly 

 soluble in water. That which remained undissolved in water was a 

 greyish powder, which, when ignited, became perfectly white. On addi- 

 tion of acid to the insoluble matter, carbonic acid and sulphuretted 

 hydrogen were evolved, and the greater part of the salts dissolved, that 

 which remained being silica. The portion thus dissolved in acid gave on 

 addition of ammonia, a copious precipitate, which proved on examination 

 to be phosphate of lime, with a trace of iron. To prove the presence of 

 phosphoric acid, it was converted into phosphate of iron by Berthier's 

 method, and the phosphoric acid precipitated as ammonia phosphate of 

 magnesia ; the iron being detained by tartaric acid. On the phosphate of 

 lime being separated by filtration, the filtrate gave, with oxalate of 



