1a. Aristotle was a Greek teacher who lived 2 300 years ago. He was the teacher of Alexander the Great. Aristotle studied nature and developed ideas about natural processes. One of the natural processes he studied was burning.
Aristotle was a Greek teacher who lived 2 300 years ago.
He was the teacher of Alexander the Great.
Aristotle studied nature and developed ideas about natural processes.
One of the natural processes he studied was burning.
Aristotle’s theory was that all matter was made up of a mixture of three elements.
The elements were Earth, Water and Air.
Different materials contained different proportions of Earth, Water and Air, and
this is what gave the materials different properties.
Fire, a fourth element, could be used to combine or separate the Earth, Air and Water.
Aristotle argued that when something burnt the Air was liberated upwards as smoke
and the Earth fell downwards as ash.
DRAW a picture to illustrate Aristotle’s theory of burning.
Alchemists were early scientists who studied the different properties of matter.
They believed Aristotle’s theory was correct.
They thought different materials had different properties because they had different
proportions of Earth, Air, Water and Fire in them.
From Aristotle’s theory, alchemists thought it was possible to change lead to gold.
To do this they would need to heat the lead so some of the Fire went into the lead.
This would make the dull grey lead, which had too much Earth in it,
take on the bright shiny yellow colour of gold.
That was the theory.
In practice, they thought it was necessary to use the right technique to make this happen.
For alchemists, technique involved saying the right words at the right time and
adding magical ingredients to promote the transformation.
DRAW a picture showing an alchemist at work.
Georg Stahl was a German doctor who helped patients who were mentally disturbed.
He was also interested in what happened when things burnt.
Stahl developed his theory of burning in the closing years of the seventeenth century.
He thought when things burn they give out a substance called phlogiston.
Things that burnt brightly and fiercely contained a lot of phlogiston.
Things burnt slowly, or not at all, contained little or no phlogiston.
In support of his theory, Stahl was able to point to how what burnt
was quite different to what was left after burning.
Generally, things did weigh less after burning than they did before.
DRAW a picture to illustrate Stahl’s theory of burning.
Antoine Lavoisier was a French tax collector who lived between 1743 and 1794.
He studied what happened when metals were burnt.
From his careful experiments he confirmed that when metals burnt their mass increased.
Lavoisier’s theory was that matter is made up of many different elements
not Earth, Water, Air and Fire. One of these elements was oxygen.
Lavoisier suggested that elements combine in different ways to make new substances.
When something burns, oxygen combines with the other elements in the substance
to form oxides. Sometimes the oxides are solids - as with metals.
Sometimes the oxides are gases - as with carbon dioxide and sulphur dioxide.
During the French Revolution Lavoisier was executed by guillotine in 1794.
DRAW a picture to illustrate Lavoisier’s theory of burning.
John Dalton lived between 1766 and 1844.
He worked as a private teacher in England.
This gave him time to study natural phenomena.
He was interested in the weather and how rainfall gave rise to springs of water.
He published studies of colour blindness. Dalton also studied burning.
Dalton thought that elements were made up of tiny particles called atoms.
The atoms in any one element were all the same,
but different from the atoms in any other element.
Dalton’s theory was that when substances burnt,
the atoms of oxygen in the air combined with the different atoms in the substance
to produce new combinations of atoms.
The substance before and after burning had different properties
because they contained different combinations of atoms.
DRAW a picture to illustrate Dalton’s theory of burning.
In traditional African societies burning becomes a topic for conversation
when unusual events have taken place.
Such events may be a house that has burnt down,
or someone’s crops that have been destroyed in a bush fire.
The explanation for such unusual events may be sought in social behaviour.
The burning of a house or crops may be attributed to:
- someone outside the family having a grudge against the family;
- someone inside the family having committed a crime that has yet to be exposed.
The fire is seen to be a warning sign that the family’s social relations with the community
DRAW a picture to illustrate traditional views on burning.
Here is a fire triangle.
The fire triangle tells us what is needed for things to burn.
From the fire triangle DESCRIBE three ways of putting out a fire