Was the Chemical Formula of Water “wrong” as HO?

For a period of about 40 years leading up to 1826, the chemical formula of water was adopted to be HO, in which one atom of Hydrogen and one atom of Oxygen are composed together. In this article, the examples and discussion refer to the chemistry treatise of Dr. Khalil Aʿlam al-Dawlah which was a training resource of newly established academy of Dār al-funūn in Iran, which, according to the scientific belief of that time, the chemical formula of water was introduced as HO. Before than Dār al-funūn, it wasn`t considered any formula for water, but water was one of the four basic elements, according to the Natural Hikma`s point of view. Nowadays chemical formula of water is known as H2O. Although from a presentist point of view, the water formula in that treatise can be described as “wrong” for the time being, whatever in the present article, from the perspective of the philosophy of chemistry, an attempt has been made to show that the sentence is not so easy. The fact that the water formula has been accepted as HO for some time in the past, as a historical experience of science, recommends further reflection on the meaning of correctness or inaccuracy of a scientific proposition, as well as challenging the assurance on theory and the reliance on empirical evidence; because this false statement belonged to a theory that ironically is valid till now, and also had not shown a significant inconsistency with the empirical evidence for a long time. Finally, this paper concluded that assigning an incorrect formula for water over half a century resulted from at least a pair of mistakes that have concealed the matter from the view of experience: supposition of an incorrect principle along with misinterpretation of empirical evidence.