Education

The True Story of How a False Theory Led to the Discovery of Boron

Asare Michael Baarffour (Devarsh) 1 year ago

Take time to read this true story of how a false theory led to the discovery of Boron, which is the element with atomic number 5.

Scientific theories can be applied to make predictions. Some of these predictions are successful, meaning they come true. Sometimes a theory accurately predicts the existence of a previously unknown phenomenon.

How does this happen? One seemingly plausible explanation is that the theory under consideration must be true. After all, how could a false theory make such an accurate prediction? However, there are examples of false theories that accurately predicted previously unknown phenomena.

One such example is the discovery of the chemical element boron. It was discovered by three chemists: Sir Humphry Davy (1778-1829), Joseph Louis Gay-Lussac (1778-1850), and Louis Jacques Thénard (1777-1857), who collaborated but worked independently of Davy.In 1808, these chemists were the first to decompose what chemists at the time referred to as boracic acid.They succeeded in isolating boron samples by extracting the oxygen from boracic acid with potassium..

Of course, before they succeeded in decomposing boracic acid, the chemists had no idea whether it contained oxygen. So, why did they believe that boracic acid contained oxygen?

The answer to this question is Antoine-Laurent de Lavoisier (1743-1794), a French chemist. Today, Lavoisier is best known as the chemist who discovered the role that oxygen plays in combustion. Most people today are unaware that Lavoisier assigned another role to oxygen: that of the acidifying principle, or the substance that gives acids their acidic properties. Lavoisier may have felt that this role of oxygen was more important than its role in combustion.

After all, Lavoisier’s proposed term for this particular substance, ‘oxygen’ (or, more precisely, the French term ‘oxygène’), is derived from the Greek words for ‘acid generator.’ Lavoisier’s oxygen theory of acidity states that all acids contain oxygen (the acidifying principle) and something else, which he refers to as the acid’s base or radical.

One of the primary ways acids differ from one another is in their radicals. For example, sulfuric acid and phosphoric acid are distinct acids because they contain different radicals, namely sulfur and phosphorus. However, the fact that these substances are acids rather than something else is due in part to the presence of oxygen.

So, why did chemists at the time believe that boracic acid, which no chemist had yet decomposed, contained oxygen? Gay-Lussac and Thénard responded by stating that they believed in Lavoisier’s theory of acidity. Boracic acid is an acid, so Lavoisier’s theory predicted that it would contain oxygen.

Lavoisier’s theory gave Gay-Lussac and Thénard a reason to try to decompose boracic acid using a substance with a high affinity for oxygen, such as potassium. This method worked, and the prediction that boracic acid contains oxygen was confirmed. In this sense, Lavoisier’s theory influenced Gay-Lussac and Thénard’s discovery of boron.

However, in that case, a false theory resulted in the discovery of boron. The idea that oxygen is the acidifying principle, or the substance that gives acids their acidic properties, has long been rejected. And today, we know of numerous acids that lack oxygen. Chemists at the time were aware of one such example. In 1787, French chemist Claude Louis Berthollet (1748-1822) demonstrated that prussic acid (hydrocyanic acid, HCN) contains no oxygen. Just a few years after discovering boron, Davy provided compelling evidence to conclude that muriatic acid (hydrochloric acid, HCl) also lacks oxygen.

Even though Lavoisier’s theory was incorrect, it did successfully predict that boracic acid contains oxygen. How can a theory that is clearly false lead to a prediction that turns out to be correct? Philosophers of science who have addressed this issue generally fall into one of two camps. Some people believe that if we just dig a little deeper, we’ll find some kernel of truth in that false theory that explains how it could make a correct prediction. Some argue that we should abandon the attempt to explain why a false theory makes true predictions by assuming that the theory must contain at least a kernel of truth.