New Delhi, June 12 -- "You must have a sip," the guide insists, in a gentle but persuasive tone. The sip in question is from a thin shooting geyser around which is built a wide, shallow basin, enveloped in warm steam. In the bright afternoon sun, falling droplets and steam from the geyser catch the light rays and convert them into rainbows that vanish as quickly as they appear. Any lingering doubt about the nature of the spring is swiftly dispelled by the distinct sulphurous smell that hangs in the air. A changing tableau of people approach the spring, fill tiny, fist-sized juglets from the geyser, chug it and move on. How bad can it be, I think to myself and follow suit-and promptly gag. The water is metallic, acrid and vile. Yet, in the...