The Prentice Gallery Chemistry book defines photosynthesis as, “The procedure by which green plants and algae use radiant power from the sun to fuse glucose from carbon dioxide and water.” The glory of discovering photosynthesis does not belong to any one scientist, but rather numerous scientists contributed to refining the concept we now know as photosynthesis. Before describing the process of photosynthesis, I will provide a brief description of several of the important events that led to its discovery.
In 1643 Jan Baptista Van Helmont crafted an examination where he observed the development of a willow tree inside a plant pot. From this examination he surmised that a willow tree acquired its nutrients from the water it was supplied. Van Helmont erred by deducing that the physical development of all parts of the tree came solely from the water that he added over a five year sequence. However, he did ...view middle of the document...
The mouse eventually expired. Again he concluded this was the result of the “injured” air within the jar. He then observed that the “injured” air in the jar could be repaired by placing a plant within the jar. Although he didn’t realize exactly what had happened, he demonstrated that the plant was converting the carbon dioxide in the jar into oxygen.
The next scientist to contribute to the discovery of photosynthesis was a Dutchman, Jan Ingenhousz. In 1778 he duplicated Priestley’s examinations. Going further, he noted that submerged plants gave off tiny bubbles, but if he moved the plants into a shaded area the bubbles soon ceased. Ingenhousz designed a variety of experiments that led him to conclude that it was not heat but rather light that caused the existence of the bubbles. In a next step, he found that the accumulated bubbles re-ignited a glowing ember suggesting to him that the bubbles contained oxygen. Moving the bubble producing experiment into the shade allowed him to observe that the burning ember eventually extinguished meaning oxygen was not being created. This led him to state that in light plants produced oxygen but not in darkness.
Another scientist that contributed to the understanding of the process of photosynthesis was Jean Senebier. In 1796 he demonstrated that Priestly’s “injured” air was carbon dioxide. He also concluded that this carbon dioxide was used by the plants in the process of photosynthesis. Senebier determine that light caused the plants to take in the carbon dioxide and create oxygen. He further noted that, without the presence of carbon dioxide, the plants could not synthesis oxygen.
The last scientist I will discuss is a Swiss chemist and plant physiologist named Nicolas-Théodore de Saussure. In 1804, Saussure reconstructed van Helmont’s experiment mentioned previously. He carefully measured the quantities of both carbon dioxide and water that were given to the plant. He was able to conclude that the carbon added to the plant came from the carbon dioxide and that only the hydrogen came from the water. Thus, he demonstrated the increased mass of the plant was not solely from the water as van Helmont had previously incorrectly concluded.