Sentence:  The next question that occurs relates to the composition of this crystallized carbonate of potash, which I am induced to call <WSD>bi-carbonate</WSD> of potash, for the purpose of marking more decidedly the distinction between this salt and that which is commonly called a subcarbonate, and in order to refer at once to the double dose of carbonic acid contained in it. 
Meaning of the word marked with <WSD> tags:  the univalent anion HCO<sub>3</sub>-; any salt of carbonic acid in which only one of the hydrogen atoms has been replaced. (from 1814)