John Dalton: Pioneering the Atomic Theory and Unraveling the Mystery of Color Blindness
Considering that an atom measures approximately ten billionths of a meter, how was such a tiny unit discovered and analyzed? There are many people behind this discovery, but today we will focus on one of the first who investigated it: the chemist John Dalton. His desire to understand the world prompted him to develop one of the first scientifically based atomic models.
In this article, we will delve into the fascinating story of John Dalton to discover who he was and what the atomic model said about him. We will also learn about the eye condition that he suffered from and which he himself investigated: color blindness.
John Dalton Biography
John Dalton’s life was marked by science. His research and developments were not limited to a single scientific field, but he stood out as a naturalist, chemist, mathematician and meteorologist.
Born in England on September 6, 1766, he did not realize that his vision was different from that of the rest until he was 26 years old, when he observed the difference in colors of a flower under daylight and under the dim light of candles. overnight. Seeing such a great difference, he decided to ask his friends if they perceived that color change with the variation of light. However, they replied that it was not that notable. On the other hand, his brother did notice the same difference as John. Both suffered from what would later be known as color blindness.
Despite his family’s limited resources, Dalton was not limited in his learning. In fact, he became a great self-taught person and, at the age of twelve, he began giving private lessons to other children. One of his mentors was John Gough, who guided him in the study of optics, mathematics, astronomy and many other branches of knowledge.
In 1793, Dalton moved to Manchester, where he was Professor of Physics and Mathematics. That same year he published his first scientific works, marking a turning point in his life and in the scientific field.
The most important contributions of John Dalton
THE LAW OF MULTIPLE PROPORTIONS
While investigating the properties of gases, John Dalton did not anticipate that he would formulate a theory about the constitution of matter that would change everything: the law of multiple proportions. This law establishes that, if two or more elements are combined in a chemical reaction and the weight of one of them is kept constant, the rest of the substances will react maintaining a constant relationship between their respective weights. That is, they will maintain the same proportion.
To explain this constant relationship between weights, Dalton assumed that each element was composed of specific amounts of matter. Thus he returned to the atomic theory proposed by the Greek Democritus, who considered that matter was made up of indivisible particles.
DALTON’S ATOMIC MODEL
Research on gases led Dalton to what was his greatest scientific contribution: the development of Dalton’s atomic theory and model.
John Dalton published his conclusions on the atomic model in 1803, although they did not reach wide circulation until five years later. In them, he established that elements are made up of atoms — tiny material particles that cannot be created, destroyed or divided — and that all atoms of a given element are identical.
Furthermore, Dalton’s theory established that atoms combined with each other in simple proportions to form “compound atoms,” and that these “compound atoms” of the same substance are identical.
Thanks to the fact that humanity has not stopped investigating, we now know that many of the postulates of Dalton’s atomic model were not correct. However, his contributions and the extraordinary scientific outlook that Dalton possessed laid the foundations for future developments, with a significance almost comparable to that of the “father of chemistry”, Antoine Lavoisier.
John Dalton and color blindness
As we had already told you, John Dalton did not limit himself to studying the properties of matter. His curiosity crossed all fields and, when he discovered that he suffered from an eye disease, he decided to investigate it.
Two years after discovering his condition and finding more people who suffered from it, John Dalton began to carry out various investigations. In 1794 he published Extraordinary Facts Concerning Color Vision, where he first described a type of color blindness. A visual disease that would later be known as color blindness.
In that first work, Dalton stated that the cause of these deficiencies in color perception was due to an anomaly in the vitreous humor, the transparent liquid that maintains the shape of the eyeball, which, according to Dalton, would have a different color. Lacking the support of numerous scientists, Dalton left instructions to analyze his eye after his death.
This was done and, when the eye was analyzed, it was found that the vitreous humor had the same transparent color as the rest. In this way, it was shown that Dalton’s hypothesis was erroneous and that the problem did not lie in the eye. It was suspected that the problem could be in the optic nerve and the way the brain interprets colors.
After this analysis, John Dalton’s eyes were preserved in a container until a group of molecular biologists requested to take a sample in 1995. With this sample, they concluded that John Dalton lacked green retinal photoreceptors. That is, the retinal cones responsible for receiving light with a wavelength corresponding to the color green were absent.
By then, more had been discovered about this anomaly to which John Dalton had dedicated so much effort: color blindness. In fact, it was known that there were three types of color blindness: deuteranopia, which was what John Dalton suffered from, related to the perception of the color green; protanopia, in which the same thing happens, but with the color red; and tritanopia, with the color blue.
Conclusion
Considered by many as the “father” of the first atomic theory in history, John Dalton is an example of the tireless search for knowledge. Thanks to him, during the 19th century great advances were achieved in science and, although not all of his conclusions were correct, he established scientific bases that made it possible to expand knowledge in the future. For all this, he has become one of the most important chemists in history.
