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Clean

Clean

Season 1 Episode 1
55:11
Time

Time

Season 1 Episode 2
55:11
Glass

Glass

Season 1 Episode 3
54:40
Light

Light

Season 1 Episode 4
54:40
Cold

Cold

Season 1 Episode 5
54:40
How We Got to Now Season 1

Sound

Season 1 Episode 6
54:41
Episode 5: The Calling

The Calling

Season 4 Episode 5
53:05
When Whales Could Walk

When Whales Could Walk

Season 51 Episode 1
53:31
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How We Got to Now

The Development of Chlorine

When the toilet was first invented, it overwhelmed water systems and caused a real threat to public health. Here, Steven describes the story of how inventor John Leal doggedly pursued his idea to use chlorine to purify water.