Salem Press

Jean-Antoine Nollet
Jean-Antoine Nollet was born into a peasant family November 19, 1700, in Pimpré, Oise, France. After training for the priesthood, he was appointed to a deaconship (1728) and eventually served as abbot of the Grand Convent of the Carthusians in Paris. Although trained primarily in theology, Abbé Nollet was better known for his work in experimental physics. He was a member of both the Royal Society in London and the Paris Academy of Science, and he was appointed as a professor of experimental physics at the University of Paris. He worked for the Duke of Savoy in Turin, Italy, and was Physics Teacher to the Royal Children under King Louis XV of France.

Much of Nollet's work centered on the nature of electricity, which he viewed as a flow of matter taking place between charged bodies. In 1748, he invented the electrometer, an instrument capable of detecting and measuring electric charges. He also demonstrated the flow of electricity in a form of parlor trick: An electric charge was allowed to pass through a row of men, resulting in a simultaneous jump by the participants.

Nollet's religious views, as well as the questions dealing with the nature of electricity, became the basis for conflict with the American statesman and naturalist Benjamin Franklin. During the 1740's, Franklin began a series of experiments on the nature of electricity, culminating with recognition of the concept of "conservation of charge." During the summer of 1752, he conducted what posterity has called his "kite experiment," demonstrating that lightning represents a form of electricity. As a result, he invented the lightning rod, a device to protect buildings from fire resulting from lightning strikes.

Nollet, perhaps jealous of an "amateur's" discovery (or possibly zealously guarding his religious views), argued that the lightning rod was an "offense to God": Lightning originated from the heavens, so by "interfering with an instrument of God" Franklin was in effect acting against God. Although the lightning rod was quickly adopted through both Europe and the rest of the western world, the controversy resulted in harsh words between Franklin and Nollet. Ironically, Nollet's recognition of the importance of the presence points on the ends of electrical conductors led to the lightning rod's modern design.

Science and Scientists
Osmosis

The Science
Known primarily for his work on the nature of electricity, Jean-Antoine Nollet was the first to demonstrate the process by which a solvent passed selectively through a membrane. René Henri Dutrochet later termed this process osmosis.

The Scientists
Jean-Antoine Nollet (1700-1770), Abbot of Grand Convent of the Carthusians
      in Paris most noted for his work in experimental physics and electricity
Benjamin Franklin (1706-1790), American statesman and naturalist whose work
      included demonstrating lightning was a form of electricity
René Henri Joachim Dutrochet (1776-1847), French physician and naturalist
      who coined the term osmosis, as he applied the principle to
      cell membranes
William Pfeffer (1845-1920), German botanist whose study of osmotic pressure
      explained the movement of liquids in plants
Jacobus van't Hoff (1852-1911), Dutch chemist who described the
      mathematics of diffusion and osmosis

From Electrical Flow to Water Flow
In the 1750's, the Carthusian abbot Jena-Antoine Nollet adapted his interest in physics, particularly electrical flow, to crude experimentation in biological systems. He was aware of German experiments observing the effects of electricity on the flow of water. Water in a thin capillary tube would simply drip from the open end. However, if electricity was applied to the tube, the water would flow in a constant stream. Nollet began a series of experiments in which he measured the rate of water transpiration in plants (and as well, in animals) either in the presence, or in the absence of electricity, noting an increase in rate if the organism was electrified.

Nollet also carried out the first experiments in which what is now known as the principle of osmosis was discovered. He prepared a vessel containing alcohol ("spirits of wine") and enclosed the vessel within a piece of pig's bladder. After placing the covered vessel into a larger container filled with water, Nollet observed that only the water would transverse the bladder wall. In some experiments, the bladder would expand until it burst. In contrast, the alcohol did not transverse the bladder. This earliest known experiment demonstrating osmosis would have more immediate application in experimental physics. In addition to the principle of what would later be called osmosis, Nollet had also demonstrated the "semi-" or "selective" permeability of the bladder wall; the term itself would not be applied for some 150 years.

Dutrochet and Cell Membranes
Although Nollet had utilized a biological membrane layer, the pig's bladder, the discovery would not be immediately applied to cell theory. In the early decades of the nineteenth century, Henri Dutrochet became of aware of his countryman's earlier work and attempted to apply the same principle to movement of fluids across cell membranes. While studying both plant and animal cells with the microscope, Dutrochet observed the movement of (solvent) water through the cell membrane, a process he termed osmosis. Dutrochet further observed the direction of solvent flow was determined by the nature of the solvent, such as a function of the quantity of salt dissolved in the water, and was not determined by the nature of the membrane itself.

Dutrochet tested his ideas by building an osmometer, an instrument capable of measuring the movement of water across an artificial barrier. Dutrochet referred to the movement of water across the barrier as "endosmosis," while the reverse movement was termed "exosmosis."

Impact
Although the idea of the cell membrane as a barrier capable of regulating osmosis was a concept inimical to cell theory--and thus was beyond immediate application by Nollet--Nollet's discovery nevertheless represented one of the first in the developing area of experimental physics. Furthermore, once a similar process was found to occur in conjunction with biological membranes, applications in several scientific fields quickly developed. Wilhelm Pfeffer explained a role for osmotic pressure in the action of fluids within plant vessels.

Finally, the mathematics of osmosis and chemical equilibrium was worked out by Jacobus Henricus van't Hoff, the result of which was his being awarded the first Nobel Prize in Chemistry in 1901. Van't Hoff referred to the principle behind Nollet's bladder wall as "semi-permeable," the first use of that term in conjunction with cellular membranes.

See Also
Cell Theory.

Further Reading
Franklin, Benjamin. Autobiography of Benjamin Franklin. New York: Buccaneer Books, 1984.

Gay, Peter. The Enlightenment: The Science of Freedom. New York: W. W. Norton, 1996.

Isaacson, Walter. Benjamin Franklin: An American Life. New Yord: Simon & Schuster, 2003.

Kirkham, M. B. Principles of Soil and Plant Water Relations. St. Louis: Elsevier, 2005.

Mason, E. A. "From Pig Bladders and Cracked Jars to Polysulfones: an Historical Perspective on Membrane Transport." Journal of Membrane Science 60 (1991): 125-145.

Tompkins, Peter, and Christopher Bird. The Secret Life of Plants. New York: Harper & Row, 1973.

Richard Adler