The 1827 Christmas Lectures
of Michael Faraday

Lecture #6

Metals and their Oxides -- Earths, Fixed Alkalines and Salts, &c

Chemists of the first half of the nineteenth century were engaged in an attempt to classify the known substances. Chemistry was carried out exclusively on the macroscopic level and because little was known of basic structure, all of the information was discussed in macroscopic terms. Classification was achieved by making observations of physical properties and of chemical reactions. In this sixth lecture of the Christmas series, Faraday illustrated common characteristics of metals and organized and classified the various types of compounds that metals form with oxygen.

Faraday believed that everything could be well understood if it could be directly observed. For him, there was nothing too simple or too trivial to demonstrate to his audience. His energy was boundless, his enthusiasm was contagious, and audiences flocked to his demonstrations.

A lecturer should exert his utmost effort to gain completely the mind and attention of his audience, and irresistibly make them join in his ideas to the end of the subject. He should endeavor to raise their interest at the commencement of the lecture and by a series of imperceptible graduations, unnoticed by the company, keep it alive as long as the subject demands it.... A flame should be lighted at the commencement and kept alive with unremitting splendor to the end.

The pedagogy used by Faraday in 1827 is still one of the most effective ways of teaching.

For the corresponding modern demonstrations, click on the icons .

NOTE: In this lecture, the numbering of the original experiments
does not exactly match that of the modern demonstrations.

Metals - Oxides

Exp. 1: Metals: A table with an array of samples and materials is arranged near the speaker for reference during the lecture. A chart with the printed names of some common metals is displayed.
Exp. 2: Lustre: The lustre of clean pieces of silver, mercury, lead, gold, and steel is displayed. They are placed near a piece of stone for comparison.
Exp. 3: Opacity: The opacity of metal is shown using a sheet of tin, tin foil, and the even thinner gold leaf.
Exp. 4: Malleability: Malleability is shown using gold and silver leaf and ordinary metallic (tin) foil. Copper wire is used as an example, also.
Exp. 5: Brittleness: Very fine wire of the type manufactured by Wollaston is exhibited. The reaction of samples of antimony, bismuth, zinc, and lead to hammer blows illustrates brittleness.
Exp. 6: Tenacity: Iron and steel wires are hung with weights to show tensile strength. The strength of inch square iron rods that support a bridge is shown.
Exp. 7: Conducting Power: Metal, wooden, and paper rods are placed in very hot and very cold water to show conductivity.
Exp. 8: Weight: Samples of iron, lead, and gold are observed as heavy for their volume. They are compared with samples of mercury and marble. Balls of iron and marble and a piece of platinum are placed in a container of mercury.
Exp. 9: Heat: Crystals of lead, zinc, and antimony are heated and the changes observed.

Metals - Oxides

Exp. 10: Potassium in air: A piece of potassium is placed in air and ignited.
Exp. 11: Potassium in water: A piece of potassium is reacted with water.
Exp. 12: Zinc in candle flame: Zinc is placed in a crucible and heated in a candle flame. Powdered zinc is sprinkled in a candle flame.
Exp. 13: Iron filing in lamp flame: Iron filings are sprinkled into the flame of a lamp.
Exp. 14: Oxides of silver and lead: Samples of silver and lead are heated on a charcoal block using a blowpipe flame.
Exp. 15: Tin oxide and rust compared: A sheet of tin is heated and the tarnish compared to the rusting of iron.
Exp. 16: Lead compared to lead sulfide: Lead sulfide is compared to lead.
Exp. 17: Iron in oxygen: Iron filings are heated in oxygen.
Exp. 18: Zinc foil in oxygen: Zinc foil is heated in oxygen.

Alkalies - Earths - and Acids

Exp. 19: Iron in oxygen: Iron is burnt in oxygen.
Exp. 20: Observe rust: A sample of rust is displayed and described.
Exp. 21: Oxides of copper: A sheet of copper is held in the fire and the colors of the oxides formed are observed.
Exp. 22: Oxides of metals: Oxides of lead, tin, copper, and iron are exhibited.
Exp. 23: Table of oxides: Table of some oxides displayed.
Exp. 24: Observe oxides in water: Oxides of iron, copper, and tin are placed in water and lack of reaction observed.
Exp. 25: Metallic Acid: A solution of arsenious acid (oxide of arsenic) in water is tested with litmus paper.
Exp. 26: Zinc Oxide in acid: Oxide of zinc is dissolved in dilute sulfuric acid.
Exp. 27: White Vitriol, Blue Vitriol, Green Vitriol: Zinc sulphate, copper(II) sulphate, and iron(II) sulphate are exhibited in solid form.
Exp. 28: Copper sulphate precipitated by base: A solution of copper(II) sulphate is reacted with a solution of potassium hydroxide precipitating copper hydroxide.
Exp. 29: Iron in Copper Sulfate: Iron is added to a solution of copper sulfate, and displacement demonstrated.

Neutralization of Metallic Acids

Exp. 30: Chromate Tungstate: Examples of chromates and tungstates are exhibited as examples of the salts of metallic acids.
Exp. 31: Chromates Precipitated: Chromates of silver, mercury, lead, etc. are precipitated using solutions of metallic acetates and potassium chromate.
Exp. 32: Properties of Potassium in water: A solution produced by the reaction of potassium with water is tested with turmeric paper and is shown to be alkaline like ammonia. It feels soapy and neutralizes acids.
Exp. 33: Neutralization: An acid solution is neutralized with the potassium hydroxide solution using an indicator.
Exp. 43: Properties of Hydrate of Potassium: Exhibit pure solid hydrate of potassium and compare to gaseous ammonia.
Exp. 44: Ashes of charcoal: Ashes of charcoal are extracted with water and the filtrate tested with turmeric paper.
Exp. 45: Wood Ashes: Ashes from a wood fire are extracted with water and the filtrate tested with turmeric paper.
Exp. 46: Display Nitre: A specimen of nitre, potassium nitrate, is exhibited.

Earths

Exp. 47: Forming oxides: Samples of marble and flint, are heated to form the oxide.
Exp. 48: Observe the oxides: Calcium oxide and flint, products of above calcination, are displayed and described.
Exp. 49: Basic properties of calcinate solutions: Solutions of lime and flint are tested with turmeric paper.
Exp. 50: Solubility of sand and limestone: Acid is added to sand and to limestone separately.
Exp. 51: Indicators in Sulfate solutions: Solutions of calcium sulfate, magnesium sulfate, and barium nitrate are tested with indicator.
Exp. 52: Alkaline earths reacted with potassium carbonate: Solutions of alkaline earth salts are reacted with potassium carbonate.