In 1748 Jean-Antoine Nollet made a discovery that would prove more important to modern science than all of Galileo's astronomical discoveries from the century before. He had discovered osmosis. Osmosis explains how kidneys clean our blood, how plants control photosynthesis and, in part, how cells control their internal environment. History is fickle. The Abbe and his discovery have not received the attention they deserve.
Jean Antoine Nollet was a Catholic priest from the eighteenth century who was an advocate for the study and teaching of science in France. He became known as Abbe Nollet. His main area of experimentation was electricity. In 1748, Abbe Nollet conducted an experiment where he took a vial of alcohol, covered it securely with some pig's bladder then submerged it into a container of water. Abbe Nollet was careful to purge the alcohol of any air. Upon returning 6 hours later, he noticed that the piece of pig's bladder was bulging. On pricking the bladder, liquid from inside the vial shot 1 foot (30 cm) into the air. Suspicious that heat might somehow involved, he retried the same experiment accounting for temperature, and discovered that heat was not a factor. [_1_] .
This experiment was tremendously important. A means of moving water without an external input of energy had been discovered. The movement of water in biological systems is very important. Human beings,like many animals, are 50-70% water. The phenomenon was also capable of generating considerable pressure. There was a hidden benefit that wasn't so obvious. What if the water contained the minerals and other chemicals that could be either essential to life or toxic to life. This process, osmosis, could be used to regulate our internal environment; moving nutrients to where they are needed and flushing out toxins.
The main agent in osmosis is the semi-permeable membrane. These membranes have 'pores' that allow some molecules through and repulse other molecules. Solvent molecules (water) can pass through the membrane but solute molecules (e.g. salt or sugar) cannot. There's got to be more to it, however. The Abbe noticed a net increase in solvent on one side of the membrane. But solvent molecules can pass through the pores in a semi-permeable membrane as easily in one direction as the other. There should be no net increase on either side unless the solute (salt or sugar) is interfering with the process.
So what is happening? In the diagram above, Side B has only solvent molecules, and Side A has solvent and solute molecules. Lets also say that there are the same number of solvent molecules on either side. If the levels on Side A and Side B donot stay the same it might mean that the solute (e.g. salt) is interfering with the ability of solvent (e.g. water) on Side A to enter the pore. In fact, when solute molecules are repulsed by the membrane, their momentum away from the membrane is transferred to nearby solvent molecules, preventing them from reaching the pores. Fewer free solvent molecules are available at the pores on Side A. The availability of solvent at the pores on Side B hasn't changed. Over time this imbalance means that solvent (water) will build up on side A.
The short animation below gives you an idea of what is happening at the molecular level.
Osmosis is important to biology, medicine and civil and chemical engineering. The advantages of osmosis to biological systems means that it applies almost everywhere in animals and plants. The following examples illustrate why osmosis is so important to biology and medicine.:
There is much to learn about the workings of science from following the work on osmosis after Abbe Nollet. It is possible to know the what and how of a natural process without knowing the why. Abbe Nollet discovered osmosis in 1748 and in the following centuries its importance to biological systems was reinforced by discoveries in various sub-disciplines of biology. In spite of these advances, a proper understanding of the mechanism by which osmosis works had to wait until 1951, two centuries after Abbe Nollet's discovery. Even after the mechanism for osmosis was discovered, it did not make its way in to all medical, plant physiology, and biology textbooks. In some cases the wrong mechanism for osmosis is still being taught today.
There is much to learn about the workings of history from Abbe Nollet's experiment as well. You would expect the fame of an experiment and its author to correspond to its importance. That is not true with Abbe Nollet. It is not true with many other important experiments. Meanwhile, an experiment that never happened, Galileo's Tower of Pisa Experiment, is probably the most famous experiment in the history of science (see The Tower of Pisa Myth). Abbe Nollet was only one of many priest-scientists who made important discoveries or founded scientific disciplines (see List of Catholic Clergy Scientists). Because of the strange workings of popular history, few are recognized.