Capillary Filtering

Capillary Filtering

You will need: Two bowls, water, knitting wool or flannel strips, earth.

Here is another way of filtering suspended matter from water. This time, instead of blotting paper we will use a wick which you can make from a thin strip of flannel or several strands of knitting wool woven to form a thin 'rope.'

Stir some earth into a bowl of water. The earth will not dissolve, but will remain suspended and will discolor the water.

Now comes the problem of filtering the water so that it will once again be clean and free from earth.

Raise the bowl of muddy water onto a box or pile of books and suspend a length of wick over one side so that it hangs down into a lower bowl. After a time you will notice that drops of clear water are falling from the free end of the wick. Capillary attraction draws the water from the top bowl down into the lower bowl, but the suspended matter is left behind. The same arrangement can be made to ensure that a favorite plant receives regular watering while you are away on a vacation. Place a bowl of water on a box, above the plant. Connect the water to the earth in the plant pot by means of a single thread of wool. While you are absent, water will flow slowly along the wool and down into the plant pot, keeping the earth nicely moistened.