Mr. G. W. Brown on Drift Wee Kelp from Orkney. 211 



ammonia, a white pulverulent precipitate, proving the presence of lime, 

 which must originally have existed as carbonate or oxysulphuret. After 

 the oxalate of lime had been removed, phosphate of soda and ammonia pro- 

 duced a white crystalline precipitate, indicating the presence of magncf=i:i. 



Quantitative Analysis of Insoluble Salts. 



JEstimaiion of Organic Matter. — As has been already mentioned, the 

 specimen of kelp under examination had not been entirely freed from 

 nitrogenous matter. This was discovered while deflagrating a portion of 

 the kelp with nitre, when a strong smell of ammonia was given out. At 

 first it was supposed that this might originate from the decomposition of 

 the nitre, but on further investigation it was observed that the kelp, when 

 ignited without the nitre, produced the same odour. A quantitative 

 determination of the nitrogen, hydrogen, and carbon was therefore made. 



Estimation of Nitrogen — The nitrogen was determined in the usual 

 manner, by combustion with soda lime, and passing the ammonia through 

 muriatic acid. The muriate of ammonia thus formed was precipitated by 

 means of the bichloride of platinum, as the yellow ammonia muriate of 

 the bichloride of platinum, which was thrown on a weighed filter washed 

 with alcohol, and dried at 212° Fahrenheit: — 



■Jellow salt. „,, „,, , 



NH3 HCl Ft Clj. Nitrogen. Nitrogen, per cent. 



20 grains gave 2-1 ... -1317 ... 658.5 



Carbon and Hydrogen. — To prepare the carbonaceous matter for ana- 

 lysis, 300 grains of the kelp were carefully washed with distilled water, 

 by which process the soluble salts were removed. The matter which was 

 insoluble in water was digested in dilute acid when the insoluble salts 

 were taken up, and organic matter, with silica, remained unacted on. 

 The carbonaceous matter and silica in 300 grains were equal to 14'46 

 grains. The residue was then subjected to combustion with oxide of 

 copper. The following are the results : — 



Carbon. Carbon p. ct. 



Amount of carbonic acid obtained, -= 1012 ... 276 ... -920 



Hydrogen. Hydrogen p. ct. 



Amount of water obtained, = 3-47 ... '433 ... -144 



When the matter insoluble in water was subjected to ignition in a pla- 

 tinum crucible, it lost in weight from the dissipation of the organic matter ; 

 but along with organic matter a minute quantity of sulphur and carbonic 

 oxide, from the decomposition of the carbonate of lime, were also driven 

 oif, which rendered the results, as far as concerns the organic matter, not 

 strictly accurate : — 



Loss by ignition. Loss by ignition, per cent. 



400 grains gave 11-52 ... 2-88 



500 " " 12-18 ... 2-437 



500 " " 12-15 ... 3-431 



Mean, 2582 



