What are we made of.

Sugar and spice and everything nice.
(Blanks?) and snails and puppy dog tails.
Other than that, I mean. :wink:
The shit thread made me think of this (again), so I’ll ask what is very possibly a silly question.
What are living things made of? Trees, us, whatever?
A tree can’t possibly be made from the earth it grows in, there just isn’t enough. Does it get all that mass from carbon in the air?
Do we?
Please be gentle with the chemistry stuff, ok?

[Carl Sagan]
We are all made of star stuff.
[/Carl Sagan]

Yes, trees get most of their mass from the atmosphere. I don’t recall the details, but a couple hundred years ago, a scientist tested this, but meticulously weigh a growing young tree periodically by digging it up and knocking all the soil from its roots before taking a measurement. He concluded that the tree was gaining mass not from the soil and water, but from the air. Since animals (for the most part) either eith plants or eat animals that eat p;lants, they get their mass from the air too, mostly.

We are mostly water. 80-90%, IIRC.

Oops, forgot to add:

I think the next biggest bit would be the calcium in our bones. I’m guessing that’s around the 10% area.

No, Helmont actually concluded that the tree’s mass came from water. I don’t know of an experiment which actually showed, in this fashion, that air was the source.

Nametag wrote:

I think you’re mistaken (unless you can come up with an awfully good cite). Water is hydrogen and oxygen. The bulk of a tree is carbon in one form or another. You know, that process where it eats the carbon dioxide out of the air anp poops out free oxygen for us to breathe.

But there’s so little CO[sub]2[/sub] in the air;
78.095% nitrogen, 20.938% oxygen, 0.033 noble gases and 0.031% carbon dioxide.
Something like that, :wink:

He could be both wrong and right. Helmont could have concluded that the mass came entirely from water. This experiment was done before plant respiration was understood in the least.

mangeorge wrote:

I think it’s actually a tad bit higher than .031%. But you’re right it isn’t a very high percentage. But in actual terms there are some gillion billions of tons of CO2 floating around. How much CO2 does the world add to the atmosphere every year? I think it’s on the order of billions of tons. Yet the increase in CO2 is only going up slowly.

It seems to me that your argument is sort of like saying there isn’t enough food available for all the animals on earth because the food makes up only .000000001% of the weight of the earth.

Nope, water is hydrogen and water. Trees are virtually all carbon. Well…maybe virtually is a tad high, let’s call it mostly.

Astonishment more than arguement, actually. :slight_smile:
Ever seen the giant redwoods in California? I realize they take centuries to grow, and contact a lot of air in that time, but golly.
So anyway, are we made largely (minus the H[sub]2[/sub]O) of carbon from the air? I say “yes”, but it is a little hard to grasp.
I like the “star stuff” idea.

After removing my head from my ass I determined that a trip to google was called for. Turns out Helmont did conclude that trees were essentially water. The expirement took place in the early 1600’s.

But I’m still going with: We are made of mostly water and calcium.
Trees are mostly carbon.

No, SandyHook, I know from Star Trek that we are indeed carbon-based life forms.

Well, can’t argue with that.

From an elemental point of view:

By mass: oxygen (61%), carbon (23%), hydrogen (10%), nitrogen (1%)…

By number of atoms: hydrogen, oxygen, carbon, nitrogen…

Here is a complete list, down to radon.

From a chemical compound point of view:

By mass: water (65%), proteins (20%), lipids (12%)…


That includes us.

SPONCH - sulfur, phosphorus, oxygen, nitrogen, carbon, hydrogen. Top 6 atoms in our bodies, in no particular order.

Carbon-based life-forms…

Seriously, though. QED forget to mention the tag line to Carl Sagan’s famous line…

“and we longed to return”

A lot of neutrons, protons, and electrons. :smiley:

Taco Bell

BTW if I am like 80%-90% H2O why is it such a big feat to swim the English Channel? I mean you are only moving 10%-20% of your body.

First of all, water makes up about 65% of your body (see above).

Second of all, you are moving 100% of your body, including the water (which is intimately a part of you down to the cellular level).

One could of course remove all of the water first from the body in question, decreasing its mass, but one would find it somewhat difficult to reconstitute the resulting dessicated corpse. :frowning:

A ship with a mass of 100,000 metric tons must have engines sufficiently powerful to accelerate this mass. It doesn’t matter whether the mass contained within the ship’s hold is seawater, crude oil, or chicken feathers.