Q. How can water be converted into a gas?
A. By increasing its latent heat, the particles, of water are again subdivided into invisible steam.
Q. Why is pump water called hard water?
A. Because it is laden with foreign matters, and will not readily dissolve substances immersed in it.
Q. What makes pump-water hard?
A. Because when it filters through the earth, it becomes impregnated with sulphate of lime, and many other impurities from the earths and minerals with which it comes in contact.
Q. Why is it difficult to wash our hands clean with hard water?
A. Because the soda of the soap combines with the sulphuric acid of the hard water, and the oil of the soap with the lime, and float in flakes on the top of the water.
N.B. Sulphate of lime consists of sulphuric acid and lime.