The 1827 Christmas Lectures
of Michael Faraday

Lecture #3

Water and Its Gases

The third Christmas lecture of 1827 focuses on the nature of water... an agent of the first necessity to the organic kingdom. The essential character of water in living systems was clearly apparent in the first part of the nineteenth century. Most of water's physical properties were quantitatively known -- freezing point, boiling point, density -- but the underlying structural reasons had not yet been elucidated. Faraday recognized that water was ``compounded'' of two substances, hydrogen and oxygen. He emphasized the constancy of the chemical composition of water, no matter what the physical condition of the substance or the source from which it was obtained.

Faraday begins with a discussion of water in its three physical states, illustrating specific properties such as refractive index and density. He demonstrates the phase changes of ice to water to steam, pointing out the large heat of fusion of ice, its ability to exert great pressure as it expands and the ``bulkiness'' of steam (Exp. 1-16).

Faraday then turns his attention to the chemical nature of water. He demonstrates reactions that involve water, focusing on the energy released or absorbed (Exp. 18-20). The next section of the lecture deals with the decomposition of water through various reactions (Exp. 21-24). A study of the resultant gases from the decomposition of water is made, starting with the preparation of and the reactions involving hydrogen (Exp. 17, Exp. 25-34). The remainder of the lecture deals with the relationship between combustion and oxygen (Exp. 35-39). Finally, the reaction of hydrogen and oxygen is viewed as a specific type of combustion. The point is made that while water is formed in the combustion of these two gases, water is also formed as a product of other types of combustion (Exp. 40-42).

The elegance of this lecture lies in its simplicity. Through the theme of water and its elements, Faraday illustrates a number of important principles using a substance and demonstrations with which the audience has great familiarity.

Water

Exp. 1: Water-the type of fluids-when pure always alike-distilled water

Display distilled water.

Exp. 2: Retort and globe receiver difference of sea water, river water, rain water, well water

Distill water from several sources (river water, sea water, well water, rain water and a colored solution).

Exp. 3: Jar of clear water, tasteless - weight

Display properties of distilled water (tasteless). Weigh a sample and compare density to other fluids by means of a pre-prepared table.

Effects of temperature

Exp. 4: A specimen - clear - hard - burning glasses of it - when warmed then becomes water

Display a sample of ice and discuss properties (clear, hard, lens-like). Lens made from ice can be used to concentrate the sun's rays.

Exp. 5: Ice thawed

Exp. 6-7: Hot water poured on to fine ice and on as much ice water, observe evident difference

Pour a given volume of hot water over equal masses of ice and ice water. The higher temperature reached in the second system indicates that more heat is needed to melt ice than to simply raise the temperature of the liquid water.

Exp. 8: Expansion during formation very great, ? lbs or more exerted - The freezing point constant - know it every winter - is what is marked 32° on thermometer - thaws above that - freezes below that point

Water is put in a capped case iron sphere (or other container). The container is placed in a salt-ice water bath and allowed to freeze. The container bursts showing the great pressure caused by expanding ice.

Exp. 9: Flask and lamp - boiling explained - steam condensed into water again when cold

Boil water in a flask. Allow steam to condense on cold watch glass.

Exp. 10: Steam into globe. Steam whilst hot a clear, dry fluid

Fill heated flask with steam. Heat the top of the vessel with a burner.

Exp. 11: Sent through a hot and dry glass tube. When it condenses it gives out much heat

Let steam pass through a hot, glass tube.

Exp. 12: Globe receiving steam soon heated and by little water - heating pipes or vessels

Allow steam to condense in a globe. Note that the volume of the liquid water is very small, but the heat given off is great. Mention the implications for steam heating of houses.

Exp. 13: Steam sent through a pipe into a vessel

The temperature of these changes 212° - scalding hot. Steam very bulky. ``One gallon of water makes [1325] gallons of steam.''

Exp. 14: Flask and bladder from last lecture

Allow steam to exit from a small flask into a larger balloon. This illustrates that gases expand and take the shape of the container.

Exp. 15: Candle cracker - outwards force

Heat a small amount of water in a cylinder. The vaporized steam pushes the piston out.

Exp. 16: Square bottle with steam - then plunged in water - power of air when steam condensed

Dry steam is put into a square bottle and allowed to condense. The air pressure shatters the bottle. CARE!

Exp. 17: Wollaston's apparatus

This demonstrates the electrolysis of water.

Exp. 18: Water on to quicklime - heat fire phosphorus

Pour water onto quicklime (calcium oxide). Note that the reaction is exothermic. Sufficient heat is released to ignite white phosphorus.

Exp. 19: Crystal of sul lime heated

Heat the product of #18 (hydrated calcium oxide) or hydrated calcium sulfate. Water is given off. This shows the reversibility of the reaction.

Exp. 20: Hydrate of copper heated. But it is really a compound body and we can decompose and recompose it at pleasure

Heat blue hydrated copper sulfate. Notice the water and the white, anhydrous copper sulfate that is produced. Add water back to the anhydrous copper sulfate. It turns blue and energy is released in the form of heat (heat of hydration).

Decomposed

Exp. 21: Potassium in air burnt

Potassium self-ignites in the presence of air. Note that the oxygen required for combustion comes from the air.

Exp. 22: On water - metal takes oxygen in both cases and produces a new body the same in both cases - turmeric paper

Potassium placed in water ignites. Test the solution that remains with turmeric paper which serves as an acid-base indicator.

Exp. 23: Potassium in tube into water - same body formed as before - and a gas set free - this the other element

Drop potassium in a glass tube that contains water. Stopper the glass tube. A medicine dropper should be protruding from the end of the stopper. Hold a second glass tube over the medicine dropper and collect the hydrogen gas that is generated. Keeping the gas collection tube inverted, bring a lighted wooden splint towards the mouth of the tube. The hydrogen generated will make a ``popping'' sound.

Exp. 24: Steam over ignited iron. Try this gas and compare it with oxygen and nitrogen - find it different & combustible

Pass steam over heated iron filings. The gas that is generated can be collected by water displacement. Compare the physical properties of this gas with samples of oxygen gas and nitrogen gas.

Exp. 25: The hydrogen gas burnt

quite different. This gas called hydrogen - and water is a compound of it with oxygen - Proceed now to the properties of this gas.

Hydrogen

Exp. 26: Zinc & dilute acid

Gas prepared - collected & operations. Is transparent - colourless - not absorbed by water - not acid or alkaline - is inflammable.

Exp. 27: Burn in jar

pale flame but great heat.

Exp. 28: Jet of hydrogen and platinum wire

Place a platinum wire into a jet of hydrogen gas.

Exp. 29: Singing tubes

A jet of combustible gas is passed through tubes of glass or other materials and ignited from within the tube. The combustion results in sounds of various frequencies emanating from the tube.

Exp. 30: Hydrogen & air exploded - if oxygen be used can imagine the results from the former lecture

Burn hydrogen gas in presence of air. Note the explosion.

Exp. 31: Hydrogen and oxygen exploded

Burn hydrogen gas in the presence of oxygen gas. Note the explosion.

Exp. 32-33: Two jars lightness of it. Jars of - pour it upwards

``Pour'' a sample of hydrogen gas upward from one container to another. Note the ``lightness'' (density difference between hydrogen gas and air).

Exp. 34: Balloon [Soap bubbler]

Fill balloon or soap bubble with hydrogen gas. They float rapidly upwards, demonstrating the ``lightness'' of hydrogen gas.

Exp. 35: Instantaneous light machine by platinum

Insert platinum wire into sample of hydrogen gas. Note the glowing of the platinum. Dobereiner apparatus.

Oxygen

Exp. 36: Jet of hydrogen and bell glass - dampness

Burn a jet of hydrogen to show that water is a product of the combustion of hydrogen.

Exp. 37: Hope's apparatus - same result when oxygen is employed in a pure state - but then can measure the quantities used - find that two vessels of hydrogen for one of oxygen are required

Hope's apparatus was a kind of eudiometer.

Exp. 38: Gases mixed and fired in Cavendish app. absorption - results

Mix two volumes hydrogen with one volume oxygen. ``Spark'' this mixture. Note the explosive reaction.

Exp. 39: Jet and wire

Place a coil of wire in a burning hydrogen jet. The combustion of the hydrogen gas produces a great amount of heat (heat of combustion). This makes the wire glow.

Exp. 40: Candle burning - still water formed

Burn a candle. Note that water condenses on a nearby cool surface.

Exp. 41: Spirit lamp and globe - great heat if oxygen used

Burn a kerosene lamp. Blow oxygen over the flame. The flame burns brighter and hotter. Oxygen acts as an aid to combustion.

Exp. 42: Oxyalcohol jet & lead, silver, or iron - quantity of water formed in these cases often very great

Burn an alcohol lamp. Direct the resultant gases into a cool pipe. Show that water condenses on the cool surface.

Editors

Pam Fujinaka, George Hussey, Jeffrey M. Green, Edgar Johnson, Michael J. Kelly, Cristina Kerekes, Louise Komp, Patty A. Kreikemeier, and Daniel Lane.

Woodrow Wilson Leadership Program in Chemistry lpt@www.woodrow.org
The Woodrow Wilson National Fellowship Foundation webmaster@woodrow.org
CN 5281, Princeton NJ 08543-5281 Tel:(609)452-7007 Fax:(609)452-0066