An English clergyman and scientist named Joseph Priestly became interested in the phlogiston concept, and attempted some experiments with plants and animals. He used mint plants and found out that they would not die. He started to doubt the phlogiston theory and tried the experiment with other plants, and got the same results. The plants did not die. He found that if a mouse or a burning candle were in the same airtight container, that they would not die or stop burning, as long as the plant was in there too. He believed that the plant could remove the phlogiston from the air, and provide enough air for breathing and combustion.

Although Priestly had a good theory, it was discovered to be wrong by a French chemist named Lavoisier, who said that the plants did not remove something from the air, but to put something back into it. He called th

Since 1900, biologists have studied the box to see what they could get out of it, and have found that they could separate the overall process into two different reactions. One reaction requires light and water, and is called a light reaction, the other require carbon dioxide but do not require light so they are considered a dark reaction. Dark reactions are not restricted solely to darkness but take place in both light and darkness, the term dark reactions means that light is not required.

The Hatch-Slack Pathway, also known as the C-4 Pathway is a more efficient photo synthesizer. Plants like sugar cane, corn, and crabgrass use this cycle. These plants use two different photosynthetic cycles, the C-3 cycle, and the C-4 cycle. Two Australian plant physiologists, M. D. Hatch and C. R. Slack, share the credit for the C-4 cycle.

The general equation for photosynthesis was:

Another of Priestly’s problems with the phlogiston theory was the fact that it only worked some of the time, and many times the experiment failed. In 1779, an Austrian scientist, Jan Ingenhouz discovered that the plants only restored oxygen “in clear daylight, or in sunshine” and only the green stalks and leaves were capable of this reaction. This helped to show that light was required and only the green parts produced oxygen. Other scientists helped to discover that the oxygen was a byproduct of the reaction, and water and carbon dioxide were the original reactants, with sunlight as a catalyst for the reaction.

Some topics in this essay:
H2O Light, Hatch Slack, Priestly Ingenhouz, Jan Ingenhouz, Joseph Priestly, War II, Dark Reactions, CAM Pathway, , ATP A�P~P, carbon dioxide, dark reactions, light energy, hydrogen ions, hydrogen ions electrons, electron carriers, ions electrons, light reactions, c-4 plants, hatch-slack pathway, + �p, glucose + oxygen, sugar glucose +, e- + atp, 4 e- +,