443 



There is a great difference here shewn between the com- 

 position of the plants of hemp and flax, though they resemble 

 each other so much in their uses. The hemp contains a 

 large amount of nitrogen, the flax very little. The hemp 

 contains more oxygen than would form water with the hy- 

 drogen. Flax, on the contrary, contains an excess of hydro- 

 gen. The difference is also remarkable in the composition 

 of the ashes. 



The ashes of the flax plant consist of 



Potash 9.78 



Soda 9.82 



Lime V2.S3 



Magnesia 7.79 



Alumina 6.08 



Silica 21.35 



Phosphoric acid 10.84 



Sulphuric acid 2.65 



Chlorine 2.41 



Carbonic acid 16.95 



100.00 



The great quantity of lime which characterized the hemp 

 here disappears, and the peculiar quality of the ash is the 

 presence of soda and potash in equal quantities, much mag- 

 nesia, and especially the large proportion of phosphoric acid. 

 Dr. Kane has not met with any analysis of the ash of a 

 plant yielding the same amount of phosphoric acid, and 

 hence the exceedingly exhausting power of the flax crop is 

 easily understood. 



Dr. Kane notices in this ash of flax, that the potash, 

 soda, sulphuric acid, and chlorine are in a very simple rela- 

 tion to each other, the numbers given above coinciding 

 closely with those of two atoms each of sulphuric acid and 

 chlorine, six of potash, and nine of soda. So that if (in the 

 ash) all the soda be taken as carbonate, the potash will be 



