"Mary, I know it," replied the teacher with a voice of conviction, "I know it.
— from The Threatening Eye by E. F. (Edward Frederick) Knight

While not much is known in regard to the effect of atmospheric electricity upon the healthfulness of a country, it is generally believed by scientific and medical men that the proportion of electricity in the air has much to do with our physical well-being.
— from The Gist of Japan: The Islands, Their People, and Missions by R. B. (Rufus Benton) Peery

Besides, I acted for others, and not for myself.” “I know it,” replied Sheppard, “and therefore I spare your life.”
— from Jack Sheppard: A Romance, Vol. 2 (of 3) by William Harrison Ainsworth

The relationship is equally hard for the father, who must be aware, with the lively suspicion of the ignorant, that his son is not telling him all his thought but only the portion of it which he thinks fit to reveal, and that much more is kept in reserve.
— from Human Intercourse by Philip Gilbert Hamerton

Of the four fundamental vital properties of cell life the one which has been most studied and in regard to which most is known is reproduction.
— from The Story of the Living Machine A Review of the Conclusions of Modern Biology in Regard to the Mechanism Which Controls the Phenomena of Living Activity by H. W. (Herbert William) Conn

“Man, I know it,” replied Phineas.
— from The Rough Road by William John Locke

[Pg 53] The acidity of the milk may be abnormally reduced if milk is kept in rusty cans, owing to action of acid on the metal.
— from Outlines of Dairy Bacteriology, 8th edition A Concise Manual for the Use of Students in Dairying by H. L. (Harry Luman) Russell

'It is one of the most musical I know,' I replied.
— from The Pomp of Yesterday by Joseph Hocking