Gallileo illumined the first part of the seventeenth century, Newton the last.  However, the middle was repleat with the men that made this century truly the beginning of the Age of Enlightenment.  The intervening period extended Galileo’s dynamics of solids to the mechanics of fluids. 

Galileo’s assistant, Evangelista Torricelli, added the motion of liquids.  Moreover, he suspected that air had weight and that the liquid in a barometer was supported by the pressure exerted by the atmosphere rather than Aritotle’s horror vacui.  He died before he could study the phenomenon.

Prior to he death though, Torricelli wrote of his findings to a friend in Rome.  Michelangelo Ricci quickly realized that current Church opinion would not take kindly to this news.  (Just consider Galileo’s plight with the Inquisition!)  What to do? Ricci mailed a copy of the letter to Father Marin Mersenne, a Minorite friar living in Paris.  (Notice how far from Rome?)  Mersenne ran a kind of scientific salon for many of the more radical thinkers of the day.  He in turn mailed a copy of the letter to Blaise Pascal, the son of a Paris tax collector.  Pascal was interested but for two years it languished.  It seems taht Pascal was doing some work for the king- developing the rudiments of probability theory. Then he performed a full scale repeat of the experiment with water. In 1648, he directed his brother-in-law to perform the experiment at the Puy de Dome, a 4000 foot mountain in central France. And so the baromenter was born. This was a year after Torricelli’s death.

In 1642, Otto von Guericke was elected mayor of Magdeburg. He was forty-two years old and had developed a reputation as a scientific dabbler.  In 1652, the German Emperor Ferdinand III held a state meeting. He had heard of Guericke’s work with vacuums and demanded a demonstration.  What Guericke did was to modify a fire extingusher commonly in use. So for the Emperor, he evacuated two joined brass hemispheres.  Then the evacuated sphere was attached to opposing teams of horses. The teams could not pull the sphere apart. However when a valve on the spheres was opened they fell apart. Well Ferdinand was so impressed that he ordered the experiment written up by Caspar Schott, professor of mathematics at Wurtzberg  University. The work was published in 1657 and Guericke’s work came to the attention of scholars all over Europe.

It was probably Schott’s book that gave Robert Boyle the basic insight for his experiments. Boyle with assistant Robert Hooke developed an improved vacuum pump.  Thus he set about his investigations on the properties of air.  His first results were published in 1660 under the title New Experiments Physico-Mechanical Touching the Spring of the Air and it Effects.  He later repeated his experiments because of an arguement with two contemporary Aristotelian philosophers.

Objectives

In this lesson, you will:

1. Be able to state Boyle’s Law either verbally or mathematically.
2. Be able to define pressure, explain how it is measured and state the standard conditions of Temperature and Pressure.
3. Be able to use Boyle’s Law to calculate the volume-pressure change at a fixed temperature.
4. Perform and analyze a simple experiment demonstrating Boyle’s Law

[Gas Laws] [Boyle's Law]