A leavening agent is an organism or substance that when added to a dough[?] of flour and water causes it to "rise" by evolving carbon dioxide or other gasses that become trapped as bubbles[?] within the dough.
... serially in the periodical Ruskii Vestnik ("Russian Messenger"), but Tolstoy clashed with the editor, Mikhail Katkov, over issues that arose in the final installment. ...