1. Joseph Priestley’s
Experiments
from the 1700s

2. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
Part 1
Priestley lit a candle.
He then placed a glass jar over it…
…and watched as the flame gradually died out.

3. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
Part 1
Priestley lit a candle.
He then placed a glass jar over it…
…and watched as the flame gradually died out.

4. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
Priestley reasoned that something in the air was necessary to keep the flame burning.

5. Candle-Burning Experiment:
Joseph Priestley’s
Candle-Burning Experiment:
Part 2
Priestley then placed
fresh mint leaves
underneath the jar
and allowed the
entire setup to sit for
a few days.

6. Candle-Burning Experiment
A few days passed…
Joseph Priestley’s
Candle-Burning Experiment

7. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
After a few days,
Priestley found that
he could relight the
candle and it would
burn for a while.

8. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
After a few days,
Priestley found that
he could relight the
candle and it would
burn for a while.

9. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
Priestley concluded that the plant had produced the substance required for burning.

10. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
What substance was consumed as the candle burned the first time?
water
oxygen
glucose
carbon dioxide
OXYGEN

11. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
What must have been added to the jar to enable the candle to burn the second time?
water
oxygen
glucose
carbon dioxide
OXYGEN

12. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
Where did this oxygen come from?
the jar
the pot
the plant
the air outside the jar
THE PLANT

13. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
What do you think would happen if Priestley had put the plant and candle back in the jar for a few days then once again tried to light the candle?
the plant would die
the plant would light on fire
the candle would light again
the candle would not light again C

14. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
Suppose Priestley had put the plant and jar into a dark closet for a few days. Do you think the candle would have lit again?
yes no NO

15. Candle-Burning Experiment
Joseph Priestley’s
Candle-Burning Experiment
What does this tell you about plants and oxygen? D
plants do not need oxygen
plants produce oxygen all the time
plants produce as much oxygen as they need
plants produce oxygen in the presence of light

16. Joseph Priestley’s Other Experiments
In another experiment,
Priestley put a mouse
under the jar and
waited to see what
would happen.

17. Joseph Priestley’s Other Experiments
In another experiment,
Priestley put a mouse
under the jar and
waited to see what
would happen.
Sadly, the mouse eventually died.

18. Joseph Priestley’s Other Experiments
Later, Priestley put
a mouse under the
jar with fresh mint
leaves and waited to
see what would
happen.
To his surprise, both the mouse and plant survived for quite some time.

19. OXYGEN Joseph Priestley’s Other Experiments
What important substance was produced by the plant?
water
oxygen
carbon dioxide
none of the above
OXYGEN

20. CARBON DIOXIDE Joseph Priestley’s Other Experiments
What important substance was produced by the mouse?
CARBON
DIOXIDE
water
oxygen
carbon dioxide
none of the above

21. SUBSTANCE THAT THE OTHER NEEDED
Joseph Priestley’s
Other Experiments
Why were both the plant and the mouse able to survive under the jar?
EACH ONE PRODUCED THE
SUBSTANCE THAT THE OTHER NEEDED

22. Figure 7-3
The products of photosynthesis are the chemical ingredients for cellular respiration, while the products of cellular respiration are the chemical ingredients for photosynthesis.