Here is another type of high voltage capacitors - a Salt Water Leyden Jar!

Don't know what a leyden jar is? No worries! Read here on Wikipedia!

The water leyden jar is easier to make than a normal leyden jar because putting foil tape perfectly on the inside of the container can be very difficult. If the foil tape job is messy, it can cause a lot of corona discharge, therefor draining its charge very quickly. So instead of having a hard time of perfectly putting foil tape on the inside of the container, just simply pour salted water in!

Disclaimer:
The leyden jar is a high voltage capacitor, high voltage capacitors are one of the most dangerous things you could ever use in electronics. A large charged leyden jar is potentially lethal if you touch its live terminals, and a small charged leyden jar can cause injury and it still be lethal in some ways.
So, I am not responsible what ever you do with this information and leyden jars.

Step 1: Get the Things!!

Okay, what you will need is...

Plastic or glass container
Water
Salt
Stainless steel nail
Aluminum foil (or even better, use AL foil tape if you have any!)
Tape (you won't need it if you are going to use foil tape)

Step 2: And the Tools...

Not many tools are needed to make a Leyden Jar.

Hammer
Hot glue (or anything to seal up the container to prevent water coming out)

I think that is just about it.

Step 3: Take the Sticky Stuff Off!

Before we start making a Leyden Jar, take all of that sticky stuff off! It can reduce the performance of the Leyden Jar, or even cause problems if you don't take the sticky tags off!

Step 4: The Construction of the Leyden Jar Begins...

Cut out a narrow sheet of foil about a centimeter or two shorter than the jar. Then wrap the foil around the jar, I used tape to hold the foil onto the jar. You can use glue if you want, but don't use flammable glue because of sparks, it is likely to catch on fire. There has been a report a leyden jar had exploded because the creator used flammable glue on the inside of the leyden jar.
After you wrapped the jar with foil, put some more tape on the top and the bottom of the jar to give the foil more protection from damage.

You can use something much much better than foil, use foil tape. You can just simply tape around the jar and not have a hard time wrapping the jar with foil and tape (or glue).

Step 5: The Wet and Salty Part...

Fill the jar with warm tap water. Then add a few teaspoons of table salt, and stir well!
After that, put the lid of the jar back on! Now it is a Leyden Jar!! (Well, almost.)

Step 6: Hammer in the Nail!

Well?

Hammer in the nail in the center of the lid, and leave the head of the nail about a centimeter away from the lid.

Step 7: Seal It.

After that, put some hot glue around the nail and the lid to stop the water coming out.

Step 8: Mission Almost Completed...

Attach a piece wire to the foil of the leyden jar.

Step 9: Completed!

There! You made a salted water leyden jar!

I also added a magnet and a ball to make it more "Leyden Jar" like.

I measured the capacitance of my leyden jar, and my meter reads 946pF, that is about 1nF! that is quite high for this small leyden jar!

Step 10: What to Use It For.

If you want to electrostaticly charge your Leyden Jar, read this site, it will show you how to make a simplest charger you can ever make.

Or even far more dangerous, treat it as a normal high voltage capacitor, you can use it as a capacitor bank for the tesla coil, or something like that.
I tested my leyden jar with high voltage power supply to see if it works. Never ever do that, unless you have good experiences with high voltage.

Step 11: My Set Up.

That is not my only leyden jar I made, I made many more, even leyden jars made out of wine bottles, but they did not turn out right, so, I threw them out..

I used my high voltage power supply (flyback transformer driver) to test the leyden jar I made, it works very well, and makes very bright sparks! I could probably use this as a Tesla Coil capacitor bank..

Well, I hoped you enjoyed this instructable!
If you have any questions, or need help, or found an error, or anything, make a comment! ^{I like comments! :)}