CARBONATES OF POTASH AND SODA. 159 



perform in the interior of the plant, does not yet appear. In 

 plants which grow at a distance from the sea, the relative pro- 

 portions of the soda and the potash differ very much, but gene- 

 rally the potash is present in much the larger quantity. This 

 would seem to imply that the functions of the potash cannot be 

 altogether performed by the soda. But the question is one that 

 is far from being solved, and in regard to which carefully con- 

 ducted experimental inquiries would be likely to lead to prac- 

 tically useful as well as physiologically interesting results. 



2. Results of published experiments with the carbonates of 

 potash and soda. 



The number of published experiments made with these car- 

 bonates is very small. The following are all with which I am 

 acquainted : 



1. On wheat, Taunton-dean variety, at Whitehill, Mid- 

 Lothian, by Mr Main. Top-dressed 30th July 1847.* 



Grain. Straw. 



Nothing gave . . 27^ bushels and 19i cwt, 



Carbonate of soda, 2 cwt., 29^ ... 23 J ... 



Increase, 2 bush. 4 cwt. 



2. On oats sown on old lea, trenched with the spade, by Mr 

 Fleming of Barochan, in Eenfrewshire, in 1844 : f 



Grain. Straw. Weight per bush. 



Nothing (average of four portions) gave 51 bush. 31 cwt. 40^ Ib. 

 Carbonate of soda, 2 cwt,, . . 53 ... 30f ... 43 ... 



Increase, 2 bush. 3 Ib. 



3. On oats after turnips, by Mr Main, at Whitehill, in 

 1846 : { 



Grain. Straw. 



Nothing gave ... 45 bush. 24 cwt. 



Carbonate of soda, 2 cwt., . 49 ... 21<| ... 



Carbonate of potash, (pearl ash,) 2 cwt., 58f . . . 23f ... 



In none of these experiments did the carbonate of soda pro- 



* Transactions of the Highland Society, March 1849, p. 530. 



f Ibid. March 1845, p. 410. Ibid. January 1848, p. 177. 



