The price of gold leaped $74.50 an ounce today in London and stood at $630 when markets closed. It ended the day here at $625 up $49.50.

But silver prices, which also have been soaring in recent weeks, declined here, closing at $37.10 an ounce, down $1.75.

The stock market, meanwhile, plummeted in early trading, then bounced back part way. The Dow Jones industrial average, which lost 14.17 points Wednesday, lost 4.26 more today and finished at 820.31.

The dollar also lost ground against other currencies early in the day, but recovered and closed down only slightly after European central banks later intervened to support it.

Analysts continued to attribute the flight to gold to uneasiness about the Soviet invasion of Afghanistan and the prospect that fighting there might spread to the Mideast. a

Most of the major buyers of gold were said to be Middle Eastern or European. But the major buyers of silver were American, traders said.

"There's no gold rush going on among Americans," said gold expert James Sinclair. Instead, he said, gold prices are being driven up by professional European gold traders -- such as the London gold houses and German and Swiss banks -- that are buying the metal on behalf of Middle Eastern investors and governments.

For example, all of the 440,000 ounces of gold auctioned Wednesday by the International Monetary Fund were purchased by three German banks -- Dresdner, Deutsche and DG -- at $562.85 an ounce. All three banks are known to represent Arab and other Mideastern clients.

"Gold is fine-tuned barometer of international anxieties. The Soviet invasion of Afghanistan is seen by the Middle Eastern viewing public in much the same way we would react to a Soviet invasion of Quebec," Sinclair said.

"The little guy and the speculator are out of the market now," said one major trader. "The futures markets are dead. All that's left is the cash markets for gold [the market in which investors buy gold in order to take delivery.] Eighty percent of that market is dominated by European professionals and 80 percent of their business comes from the Arabs."

The major cash markets for gold are in London, Hong Kong, Paris and Zurich. While there is a large cash market in New York, most of the gold trading here has been in futures.

In futures trading, investors buy and sell contracts promising to deliver or buy gold at a certain price on a certain date. Most buyers of futures contracts never expect to take delivery.

Because the futures markets have limits on how much the price can rise or fall in a given day -- and cash markets do not -- futures prices are lower than cash prices.

"The bell rang this morning and bingo, the price went up the $25 limit. That was the end," said one futures trader on the commodities exchange.

Demand for physical gold -- as opposed to the paper promises of futures gold -- has been so strong that there is little left in the world to be purchased. "The London dealers are fresh out of their gold stocks. You cannot by a new Krugerrand from them nutil next month. The Arabs are buying it and sitting on it," said one major gold trader.

Although American demands for gold may not be the driving force behind the price spiral, Americans are crowding gold dealers, such as Deak-Perera, which offer gold for sale in small quantities.

"Public demand here is up, that's true. But it's a negligible factor in the world market," said Sinclair.

Besides the Middle East problems, continuing inflation and rising oil prices are also helping to keep gold prices on the upswing.

On foreign exchange markets, the dollar closed at 1.71 West German marks, down slightly from 1.7130. Before the Bundesbank intervened late in the day, however, the dollar had fallen to 1.7062 marks, a record low.

In Switzerland, the dollar closed at 1.5690 francs, down from 1.5770 and in Japan the dollor closed at 238.30 yen, almost unchanged from Wednesday at 238.35. Also, the British pound closed virtually unchanged against the dollar.