LOST GOLD--Through September 13 at the National Geographic Society, 15th and M Streets NW. Monday through Friday, 9 to 6; Saturdays and holidays, 9 to 5; Sundays, 10 to 5.

National Geographic Society curator Peter Pupura has fixed it so you can get your hand on a genuine gold bullion bar from a sunken Spanish treasure ship.

You can stroke it, heft it and squeeze it, but then you have to put it down.

The bar, weighing more than five pounds and worth far more than its weight in gold, is in a clear plastic case with a hole that admits one hand. There is an armed guard standing by to discourage feats of strength or cunning.

The touchy-feely bar is "bait" for Lost Gold of the Florida Keys, a new exhibit in Explorers Hall at NGS headquarters. "It's hard to get the tourists up here from the Mall and White House during the dog days of summer," Purpura said. "Gil Grosvenor [president of the Society] suggested we put in a 'hands-on' display. We're hoping it will be a real grabber."

Judging from one previewer's response, it will be a real show-stopper, it's goinhg to be hard to get visitors to let go of the bar and move on to the other fabuous but "hands-off" items recovered by Treasure Salvors, Inc. from two galleons lost in 1622.

Guard ships Nuestra Senora de Atocha and Santa Margarita were shepherding 26 other vessels homeward from Havana when a September hurricane drove the fleet down on the Marquesas. The galleons and five merchant ships were cast away, with the loss of over 550 lives and a kingdom's ransom in gold, silver and gems plundered from New World Indians.

The salvors so far have recovered more than $60 million worth of rare objects and precious metals, and that is only a tenth of what is known to have been aboard. "It's meaningless to talk about weight of metal," said company spokeswoman Bleth Curtis, "because the historical value is perhaps ten times greater than the gold content."

Treasure Salvors won't know how much their haul is worth until it can be sold. The company has spent more than $750,000 fighting Florida and federal government claims, and awaits a Supreme Court ruling.

Meanwhile seven salvage boats remain at sea, hauling up more treasure almost every day. This is the second plate fleet the company has found off Florida in 15 years, and Curtis sounds wistful when she talks about the good old days when it was just boss Mel Fisher and a scrappy band of divers. "We have a support staff of 70 at headquarters now," she said. "Specialized departments, interoffice memos. . ."

While she has yet to grow blase about the gold that streams through her hands, Curtis finds even more fascination in the story still unfolding from the bits and pieces as they're found where tides and storms have strewn them for miles across the ocean floor.

Smugglers, for instance, were stealing His Most Christian Majesty blind.

For every bullion bar found bearing the sella real showing that the royal tax of 20 percent had been paid, another, unmarked one has turned up. There were so many that it smacks of official connivance, since the penalty for being caught was 200 lashes plus 10 years in the galleys.

Because personal jewelry worn by passengers was tax-exempt, many of them had had Indian slaves form heavy masses of gold into chains and necklaces. It is possible, and certinly would have been fitting, that some of the bluebloods sank with their spoils while seamen and soldiers swam safely to shore.

Another item recovered is a pocket-size combination sundial and compass. Curtis thinks, or likes to think, that it may have, been lost overboard by a member of a salvage expedition sent out in 1626. "There is a report in the Spanish Archives by a man who noted the time when some enemy ships hove into view," she said. "I can just picture him shouting and throwing up his hands as he sees the ships, and this sundial spinning out into the sea."

The new exhibit is a splendid companion to the adjoining Treasure of the Quicksilver Galleons, which has been in Explorers Hall since April. That exhibit displays some 300 items from two Spanish vessels that were outbound to Mexico, carrying tools, supplies and household items to the colonies.

Tolosa and Guadalupe came to grief in 1724 off what is now the Dominican Republic, with the loss of more than 600 lives and 400 tons of quicksilver (mercury) critical to the refining of gold and silver. The objects range from stunning to homely, and together the exhibits are such stuff as dreams -- and nightmares -- are made on.