gas – Awesci – Science Everyday

The Greenest Invader in the History

By Anupum Pant

Background

The impact of human activities on climate change is by no means new. It is not an 1800s or 1900s thing. It did not start happening when we started burning huge amounts of coal or oil. In fact, human impact on the climate has been here for a long long time now. It started happening about thousands of years ago when our ancestors started clearing forests to make land for cultivation. The impact was less back then, but it had started.

So, basically an overly simplified equation has been like this – more humans, more cleared forests (for cultivation), more carbon emissions.

All these years humans have also been hit by some very unfortunate historical events which have resulted in the death of a great number of people. Of course these events like the fall of Ming dynasty, Black death and Conquest of America were sad events. They resulted in a massive wipe-out of human population which we would not wish to see ever again.

However, the huge number of deaths that happened due to these unfortunate events did have a common salubrious effect on our planet. Huge tracts of cultivated lands turned back into forests. As a result, great amounts of carbon dioxide got absorbed and there was effectively a global cooling happening.

The Mongol Invasion

Among all these historical events, one stands out – The Mongol invasion which lasted for about 150 years and covered more than 20% of Earth’s surface.

After founding the Mongol empire, Genghis Khan has been believed to have started these Mongol invasions. Time and again he was involved in the decimation of huge settlements. It is estimated that these invasions led by Genghis Khan resulted in the death of a whopping 40 Million people!

Death of so many people meant that the cultivated lands of settlements started turning back into forests and these forests ended up absorbing huge amounts of carbon dioxide from the air. Result – Global cooling (kinda).

It is estimated that the Genghis Khan invasions helped remove about 700 Million tons of carbon from the atmosphere. That about the same as a whole year of carbon that is being put back into the air due to burning of petrol today, in this industrialised world!

Genghis Khan has been branded the greenest invader in history.

Random Genghis Khan fact:
1 in 200 men are direct descendants of Genghis Khan – [Source]

Hit like if you learnt something today.

Why Do Bad Eggs Float?

By Anupum Pant

Instead of cracking up an egg which has been stored for a long time, to end up disgusted by the ‘rotten egg smell’, or the smell of a gas called Hydrogen Sulfide, a simple and a fairly well known way to check if an egg has gone bad, is to drop it in a glass of water and see if it floats. I found out about this first, from an article written at Frugal Living, and spent some time to confirm its claims – Bad eggs float.
If you take my word for it (you should!), it really does work. The article describes this three-point test to find out if an egg is good to eat.

If the egg sinks and lies on its side, it is a fresh one. It is good enough to be eaten.
If it sinks and stands up on a point, or is at an angle, it is good enough. You can still use it up for making hard-cooked eggs or bake it.
But, if an egg floats, it needs to be discarded.

Why does this happen?

To understand, you’ll have to think of a chick – a young chicken.

Poor Chicks: Before chickens come out of the egg, they develop lungs and need oxygen to breath. Sitting inside a sealed egg, with no cords attached, for the chick to survive, oxygen has to come in from somewhere. For that, let us look inside.

Egg Science: The outer shell of an egg has two membranes under it. When an egg is laid, it is warm and starts cooling which contracts the inner part of the egg more than the shell and pulls the two membranes apart. As a result, air gets trapped in between the membranes (not enough air initially for it to float).

How does the air come in? The shell of an egg isn’t as simple as it looks. It has about 7000 tiny pores in that shell which let the air pass in and let the carbon dioxide pass out of it. This is how the chick breathes. And the reason, eggs boiled in colored water during Easter, get colored from the inside.

So, as there are pores present in the shell, bacteria enter the egg and start decaying the biological matter inside. This produces a smelly gas (and other gases too), Hydrogen Sulfide (also present in smelly farts). The gases from this decomposition, and the air from outside, keep increasing in volume as time passes.

Corollary: This is exactly what explains these floating bad eggs – Greater the amount of gas inside, older is the egg and the better it floats in water.

Side note: Egg shells and the two membranes inside have the ability to stop the invasion of micro-organisms and bacteria, but over time bacteria manage to enter.

Plasma Speakers

by Anupum Pant

Not many would have heard of speakers other than those which use magnetic materials to produce sound. But if you still haven’t heard about Plasma speakers or ionic plasma tweeters, you are really missing something great. Read on for more.

About Plasma Speakers

I talked about sound a few days back and mentioned that it is something that propagates through a medium due to pressure changes. Normally, magnetic speakers create these pressure waves by moving a diaphragm with the help of a varying magnetic field. But, plasma speakers do this by varying the air pressure through a high energy electric arc. This arc is produced by ionizing the gas present in between two terminals (ionizing reduces the electrical resistance of air which creates a visible arc).

These speakers use an extremely high energy arc which also increases the temperature of surrounding volume of gas to very high levels. So, before learning anything about them, the first thing you have to know is that these seemingly harmless things can kill you.

The Dangers

Plasma speakers are not toys. Old men, people with heart problems, kids etc should stay away from them. Even if an adult is handling them, they need to be informed about what they are doing first. It is better to have someone close who knows well, how these things work. Although the commercially available speakers are fairly safe, DIY kits can prove to be fatal. The kind of dangers involved with these devices:

1. The electric discharge – Think of it as a lightning. The dangerous high voltage device has the potential to kill you, if any of your body part comes close. Keep all bodily parts away.

2. Gas danger – The constant supply of ozone used for this project can actually be much more dangerous than the electric arc. Ozone used in this project, silently increases in concentration which can be fatal. It is important to keep the room well ventilated.

A few more things about them

Invented by WIlliam Duddells in the year 1900 these are not speakers, but tweeters. That means, that there will be no window cracking bass that is going to come out of them. Unlike magnetic diaphragms, the arcs have no weight and are able to produce a very crystal clear sound by moving back and forth very quickly. See the video below.

They work by changing temperature inside the gas chamber which makes them go red to purple as the frequencies of a song change. However, an un-modulated arc will just produce noise, something like you hear at first in the video. Also, they need a constant supply of Helium and Ozone coming into the chamber. These gases get ionized inside to produce the arc.

[Read this for more history]

Where can I get them?

In 1970 Magnat used to produce them, but they no longer produce plasma speakers now. The point is, they were the pioneers in bringing this to the masses.
Acapella sells them for an eye-popping price of 23000$. These costly ones are revered for their sound quality.
Other DIY kit can be bought for as low as 100$ [here]
Build one on your own for cheaper. (if you are willing to risk your life) [tutorial here]