Sheridan McVean, age l2, of Calgary, Alta., Canada, for his question:

What color is liquid air?

The boiling point of air is minus 3l0 degrees Fahrenheit. This chilly temperature is possible only with special laboratory equipment and few of us ever see air in its liquid form. since ordinary air is transparent, we would expect it to be transparent when chilled to a liquid. And so it is. Liquid air looks very much like water, but oh what a difference when you touch it.

It would freeze your fingers all the way to the bone. A gob of mercury left in a beaker of liquid air freezes so hard and solid that it can be used to hammer nails into wood. If you tried to bounce a rubber ball that had been dunked in liquid air, it would shatter like glass. Lead, however, gains a stretchable quality somewhat like the elastic quality of a rubber ball in normal temperatures.