One of the first attempts at explaining the difference between acids and bases was made by a scientist called Antoine Lavoisier. He was a French chemist. He was born in 1743 and was killed (beheaded) during the French Revolution in 1794. The years between 1770 and 1790 are often referred to as the “Chemical Revolution”, since it was the
beginning of modern chemistry. Furthermore, Lavoisier is considered to be the father of modern chemistry, because he adopted new methods of practical chemistry. He made countless essential contributions to the science of chemistry during his lifetime. For instance, one of his successful theories was the theory about combustion. By observing that during the combustion of sulfur and phosphorus these substances increased in weight, he assumed that sulfur and phosphorus combine with another substance in the air. He later developed his theory and proved that that substance in the air was oxygen. He even proved that sulfur and phosphorus make an acidic solution when dissolved in water.
His attempt at defining the difference between acids and bases in year 1777 was the first classified attempt to distinguish acids and bases on a chemistry level, even though we now know that it turned out to be wrong. Lavoisier indicated that all acids contained oxygen. He also indicated that oxygen was causing acidity, since he had isolated it from several acids. Today, we know that Lavoisier’s theory about acids is incorrect since ‘hydro-halic’ acids do not contain oxygen, but, obviously, they are still acids. Hydro-halic acids are made up of hydrogen and of one of the halogens, forming for instance HCl or HBr. Hydro-halic acids were unknown to him, he therefore claimed that oxygen in a compound was the cause of acidity which he stated in "General Considerations on the Nature of Acids" in 1778.
Nevertheless, he is as a matter of fact the creator of the word oxygen (from the Greek oxys=sour and genes=born) making it an “acid former” or an “acid maker”.