65.WHY DIAMONDS ALWAYS CONSIDERED VALUABLE?
The first records we have of people deliberately looking for diamonds indicate that this happened in India. Diamond mining as an industry started there more than 2,500 years ago!
Diamonds were prized from the very beginning. In fact, before the fifteenth century, diamonds were still so rare that only kings and queens owned them.
64.WHAT MAKES DIAMONDS PRECIOUS?
Why is a diamond so precious? Diamonds, of course, are rare, and anything rare has a high value. But rarity isn’t enough. A thing must also be desirable, and diamonds are very desirable, indeed.
A diamond’s capacity to reflect light gives it an appearance unlike anything else in the world. The diamond is also the hardest substance known to man. A thing of beauty that can last for thousands of years, it has come to be a symbol of enduring love and loyalty.
63.WHAT IS THE NITROGEN CYCLE?
All living things need nitrogen in a form their bodies can use. It is important to plants and animals as well as to humans. It is a necessary part of the protein substance which is man’s body-building material. Without this substance, no one could grow or repair damaged or worn-out tissues.
While oxygen makes up only 21 per cent of the air we breathe, nitrogen makes up 78 per cent. There are about 7,200,000 tonnes of nitrogen above a square kilometer of the earth’s Surface. It is a colorless, odorless, tasteless gas that dissolves only slightly in water.
