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Abbe Nollet and Osmosis

In 1748, while studying the behaviour of liquids under reduced pressure, Jean-Antoine Nollet discovered osmosis. This discovery would have a greater influence on modern scientific activity than all of Galileo's astronomical discoveries from the century before. The map of modern scientific activity (see Eigenfactor-Mapping Science) tells us why. The concept and applications of Osmosis are important to Cell Biology, Medicine, Agricultural Science, Botany, and Chemical Engineering. From the diagram it seems that Astronomy is only important to Astronomy. We will look at how Osmosis works, why its important, and why Abbe Nollet is not better known.

Map of Science

Abbe Nollet's Experiment.

Jean Antoine Nollet was a Catholic priest from the eighteenth century who was a major advocate for the study and teaching of science in France. He became known as Abbe Nollet. His main area of study and 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_] .

The importance of the experiment is not obvious. Dissecting the experiment might help. Firstly, there seemed to be a net movement of water from the outside container into the vial of alcohol. Secondly, this was happening against some resistance and building considerable pressure along the way. And all this seemed to happen without an external input of energy (e.g. heat).

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.

Importance of Osmosis

We might know osmosis by its alternate names; dialysis and kidney function. The compelling advantages of osmosis to biological systems means that it is used almost everywhere in animals and plants. A short list of its applications in modern science and engineering follows:

  1. Explains how plant roots are able to overcome the resistance of the soil.
  2. Explains how roots are able to absorb water from the soil.
  3. Explains how the flow of gases into and out of leaves is regulated (osmosis acting through stomata and guard cells). This is used in the regulation of photosynthesis and respiration.
  4. Explains the state of a plant's stem, branches and even leaves (e.g rigid or wilting).
  5. Explains how organelles in the cell and the cell itself can maintain a consistent chemical environment conducive to chemical reactions in biological systems.
  6. Explains much of Kidney function.
  7. Explains why salt-water fish die in freshwater and freshwater fish die in salt-water.
  8. Explains why sugar can be used to preserve fruit and why salt can be used to preserve meat,fish and vegetables.
  9. Explains why brine is an effective agent to adjust the moisture content of cheese.
  10. Explains some types of hemolysis (bursting of blood cells).
  11. Explains why intravenous drug delivery must be done using saline solutions. Intravenous delivery of drugs with ordinary water could cause hemolysis.
  12. Forward osmosis (the one Abbe Nollet discovered) is used to desalinate water.
  13. A process associated with osmosis, reverse osmosis, is used widely in the chemical, desalination and sanitation industries. Some of you reading this may be drinking water that has been purified by reverse osmosis.
  14. And many, many more.

Osmosis Light

Osmosis is achieved through the use of semi-permeable membranes. These are membranes with 'pores' that allow some molecules through and block or repulse other molecules. What happens in osmosis is that solute (e.g. salt or sugar) molecules cannot pass through the membrane but solvent (e.g. water) can. This can't explain osmosis on it's own. Remember that the Abbe noticed a net increase in solvent in one direction. Solvent molecules can pass through the pores in a semi-permeable membrane as easily in one direction as the other. This should mean that over time an equal number of solvent molecules go in either direction. With osmosis this is not what is happening.

So what is happening? In the diagram below, 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 in some way with the ability of solvent (e.g. water) on Side A to enter the pore. In fact, solvent molecules will attach to the solute molecules. This means fewer free solute 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.

Osmosis Diagram

Galileo vs. Abbe Nollet

If osmosis is so important to so many different disciplines, why is Galileo's astronomical work discussed so much more than Abbe Nollet's wine spirits experiment. Galileo wasn't always considered more important. The word cloud below shows the major names that were being cited in science in 1758, about 100 years after Galileo's death. Nollet is in the word cloud but Galileo and Kepler are not. There are probably several reasons why Galileo is so well known now and Abbe Nollet is not.

Word Cloud - Scientific Citations

Abbe Nollet starts at a disadvantage to Galileo. Discovering what happens when you separate water and alcohol with a pig's bladder can hardly inspire the imagination as much as speculations on the motions of the cosmos. There were other handicaps. Most of the important early historians of science were trained as physical scientists (physicists, chemists, astronomers). Physical scientists would not have known the biological significance of osmosis. For Abbe Nollet, being a Catholic priest didn't help either. Early historians of science were biased towards the "Conflict Thesis"; a belief that religion and science naturally conflict. Historians that went against the theme were even censored (see The Real da Vinci Code).

There was a real Galileo but the one we know from popular history is part fact and part myth. Popular accounts embellished the real Galileo with at least 18 major myths (see The Galileo Myths). These myths even show up in acclaimed biographies of Galileo ( see Galileo's Battle for the Heavens). The real Abbe Nollet would have no chance against the mythical Galileo.

Does it really matter whether Nollet or Galileo is more important? Probably not! The better lesson from Abbe Nollet is that science is much more than the sum of the work of famous scientists. How many other Abbe Nollets are there? Modern Science discusses why the Great Man approach to science history is a bad idea.



Abbe Nollet Jean-Antoine NolletOsmosisGalileoChurchScienceSolventSoluteBenefitsWine spiritsHistory of Science
Copyright Joseph Sant (2017).
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1. , John Hinton Publishers, 1755., Universal Magazine for Knowledge and Pleasure. Vol. 16, , pp. 72
This early encyclopedia published only eight years after Abbe Nollet's experiment contains a good description of Abbe Nollet's experiment. Full access is available at Google Books,
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