71.   These same fishkeepers then wonder why their aquarium water is for ever murky and their fish losses high.

72.   This water is so weakly-bound to the clay minerals that it turns to steam at low temperatures.

73.   Up there, amid mountain fastnesses, its waters are sweet.

74.   Water is a basic requirement of life.

75.   Water is a key element in the ley system.

76.   Water is a precious commodity.

77.   Water is eight hundred times denser than air.

78.   Water is essential for life.

79.   Water is extremely attractive as a source of both propellants and life-support materials.