80 



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The group A gives the results of the determinations of water 

 and dry matter in the original weeds ; B, the results of the 

 estimation of combustible matter and ash in the dry matter ; 

 C shows the composition of the ash, the amounts being calculated 

 as percentages of the dry matter ; while D gives the nitrogen 

 content. The analyses show that water constitutes on the average 

 83'24 per cent, of the growing plant. This, however, is no doubt 

 higher than the actual water content of the seaweed, for the water 

 was estimated immediately after the weed was cut, and adhering 

 moisture was not removed. In the analyses of the ash variations 

 are apparent, and though sometimes great, as in the case of 

 nitrogen and potash, they are no greater than the variations in 

 the amounts of certain constituents of land plants. The amounts 

 given in the analyses of the ash are means of three estimations 

 obtained with three different samples of the ash of the same 

 seaweed. Samples 1, 2, 3 and 4 were taken from the Smuggler's 

 Cave area, while the samples marked ■•• were cut from the rocks 

 to the north of Brown's Point. While conducting these analyses 

 I compared my results with those obtained by Hendrick (loc. cit.) 

 and Toms (Notes on Farm Chemistry), and found that the 

 amounts of phosphoric acid present in the samples taken were 

 much greater than those which they had found. Six samples 

 were therefore taken, three of each kind, from the rocks at 

 Brown's Point area, 700 yards to a half-mile to the north of the 

 former locality. These samples grew on a carboniferous sand- 

 stone bottom, whereas in the other area they grew on a magnesian 

 limestone bottom. After drying and incineration the amounts of 

 phosphoric acid in these samples were determined. The three 

 results for each of the two kinds are given in the column 

 marked.-'" The difference in the phosphoric acid content is most 

 marked. It seems that this is a remarkable example of en^dron- 

 ment upon the chemical composition of a sea plant. The 

 composition of seaweed is largely, if not entirely, dependent upon 

 that of the surrounding water. As the main current in this 

 locality sets in from the north, the water of the Smuggler's Cave 

 area does not pass the Browm's Point area ; hence the salts 

 dissolved (no matter how slowly) from the magnesian limestone 

 would not have a chance of acting upon the seaweeds growing in 

 the latter area, whereas those growing in the former area could 



