Happy Saturday! Here are five notable things that happened this weekend (August 1 and 2) in history, from the discovery of oxygen to the launch of MTV. Ladies and gentlemen, rock and roll!

1. 1774 - Joseph Priestley Discovers Oxygen

On August 1, 1774, English theologian, chemist, and author Joseph Priestley discovered oxygen. The ancient Greeks had identified air several millennia earlier, but its composition was still mysterious in the eighteenth century.

Priestley conducted experiments, discovering that "air is not an elementary substance, but a composition" of gases. Quoting the American Chemical Society's page on Priestley (emphasis added):

In the course of these experiments, Priestley made an enormously important observation. A flame went out when placed in a jar in which a mouse would die due to lack of air. Putting a green plant in the jar and exposing it to sunlight would "refresh" the air, permitting a flame to burn and a mouse to breathe. Perhaps, Priestley wrote, "the injury which is continually done by such a large number of animals is, in part at least, repaired by the vegetable creation." Thus he observed that plants release oxygen into the air — the process known to us as photosynthesis.

On August 1, 1774, he conducted his most famous experiment. Using a 12-inch-wide glass "burning lens," he focused sunlight on a lump of reddish mercuric oxide in an inverted glass container placed in a pool of mercury. The gas emitted, he found, was "five or six times as good as common air." In succeeding tests, it caused a flame to burn intensely and kept a mouse alive about four times as long as a similar quantity of air.

Priestley called his discovery "dephlogisticated air" on the theory that it supported combustion so well because it had no phlogiston in it, and hence could absorb the maximum amount during burning. (The year before, Swedish apothecary Carl Wilhelm Scheele isolated the same gas and observed a similar reaction. Scheele called his material "fire air." But his findings were not published until 1777.)

2. 1790 - First U.S. Census Completed

On August 2, 1790, the first United States census was completed. It had only six inquiries for each household:

1. The name of the head of the family

2. The number of free white males 16 years and older.

3. The number of free white males under 16 years of age.

4. The number of free white females.

5. The number of all other free persons.

6. The number of slaves.

The total count of U.S. residents (including nearly 700,000 slaves) was 3,929,214. The project cost $44,000 (1.1 cents per capita), and required an estimated 650 census enumerators.

3. 1880 - British Parliament Adopts Greenwich Mean Time (GMT)

On August 2, 1880, the British Parliament formally adopted Greenwich Mean Time (GMT) as the universal time standard. This meant that various local times (maintained by towns, railways, and so on) would be replaced by a single master system that we still use today.

I include this entry not just because standardized time is important, but because I want you to enjoy this absurd and hilarious segment about it from Charlie Brooker's Weekly Wipe:

4. 1944 - Anne Frank's Final Diary Entry

Anne Frank's signature. [Public Domain, via Wikimedia Commons.]

On August 1, 1944, Anne Frank wrote her final diary entry. It's a long one, concluding:

... A voice within me is sobbing, "You see, that's what's become of you. You're surrounded by negative opinions, dismayed looks and mocking faces, people who dislike you, and all because you don't listen to the advice of your own better half."

Believe me, I'd like to listen, but it doesn't work, because if I'm quiet and serious, everyone thinks I'm putting on a new act and I have to save myself with a joke, and then I'm not even talking about my own family, who assume I must be sick, stuff me with aspirins and sedatives, feel my neck and forehead to see if I have a temperature, ask about my bowel movements and berate me for being in a bad mood, until I just can't keep it up anymore, because when everybody starts hovering over me, I get cross, then sad, and finally end up turning my heart inside out, the bad part on the outside and the good part on the inside, and keep trying to find a way to become what I'd like to be and what I could be if… if only there were no other people in the world.

Yours, Anne M. Frank

Three days later, she and the other residents of the house were arrested and Frank was soon sent to Auschwitz. After a transfer, she died at Bergen-Belsen concentration camp in February or March of 1945. She was 15 years old.

5. 1981 - MTV Premieres

On August 1, 1981, MTV premiered at 12:01 a.m. With the bold statement, "Ladies and gentlemen, rock and roll," this is how the channel started:

And the first video shown on MTV was, of course, "Video Killed the Radio Star" by The Buggles. It looked like this, minus the subtitles: