With prices of many commodities such as gold, silver, copper, platinum and sugar going through the roof, it's no wonder that questions on these wildly speculative and highly volatile markets have been popping up with growing frequency in my reader mail.

"Bunker Hunt made a fortune in silver; how can I do the same thing?" writes Anna Stephenson of Houston. "I'm willing to crapshoot with $300 . . ."

For an expert's view on one of the hottest money-making games around, I probed the mind of Stanley Kroll. He's been an absolute phenomenon in commodities trading the past year. His two favorite commodities -- both of which he thinks are headed a lot higher -- are cotton and cocoa.

First, though, a little background on the man. A onetime Merrill Lynch broker, Kroll made a killing in commodities between 1971 and 1974, running $18,000 of his own money to more than $1 million. And in the same three years he parlayed another $646,000 anteed up by 37 partners into more than $2.5 million.

After a $1.3 million killing in wheat in 1974, he quit the business to fulfill a life-long dream: to cruise the rivers and canals of Europe. And he and his wife did just that during the spring and summer of the next three years; in the winter, the Krolls sailed the Bahamas, writing up their European experiences (which they later published). So enamored of their lifestyle, the Krolls put their knowledge to work and built a fleet of six luxury hotel barges. And through a corporate entity, Floating Through Europe, they are operating a thriving tour business on Europe's waterways. The cost to sightseers runs about $120 a day.

Ever since he left the commodities game, Kroll has continued to monitor the different commodity markets, and about a year ago he decided to try his hand again. "I went back for several reasons," he tells me. "I needed more excitement, more challenge . . . and I wanted to prove I could do it again."

In addition, he felt commodities were on the verge of a tremendous advance. "I saw inflation couldn't be controlled; I thought petroleum prices would go up more than most people expected, further fueling inflation . . . and I felt this kind of unsettling situation would turn a lot of people off paper holdings," said Kroll. "And in this kind of environment -- which is still intact -- the prospects for substantial commodities gains were, and still are, enormous."

As the performances of his commodity accounts show, the savvy Kroll -- who built a net worth of about $2 million -- still has the master's touch. The average gain: a spectacular 493 percent. And of the monies invested, $15,000 was Kroll's. That $15,000, as of the close of the markets Feb. 13, was worth $226,000.

Apparently, the necessity of periodic trips to Europe -- Kroll maintains an office in New York -- hasn't hurt his commodity activities. "As long as I have access to prices and a telephone, I can be anywhere in the world. And besides, I'm a sitter, not a trader . . . and I can go weeks without making a trade. No, wait," he suddenly remarked, "make that a few days."

The big gains for Kroll's accounts (some are friends' and from others he takes 10 percent of the profits) have been made chiefly in cotton and sugar. At present, he's holding more than $1.5 million worth of margined securities -- notably cotton and cocoa. His view of cotton: Because it's a substitute for synthetics, which are petroleum-based and therefore headed higher, the demand for cotton should continue to grow. Kroll also points out that cocoa is the only commodity also traded outside the United States that is selling at close to a three-year low.

Should the public be in commodities?

Only those who can afford to put up a minimum investment of between $25,000 and $30,000 and treat this as a serious and, of course, speculative business that requires full attention, Kroll responds. The reason for the sizable initial expenditure: "I figure that of 10 trades, I'll be right 6 or 7 times," he says. "And since you don't want to get tapped out on the first two trades, you need money for the next investment." (Of course there are commodity funds that offer a much lower entry.)

Says Kroll: "You don't go into the market with a perception that you'll trade in and out, that all you're looking for is a fast $500 to help pay the rent. You go in with the idea that if you're wrong, you get out fast. And if you're right, you stay in and build up the size of your positions. What you want is a sustained movement up or down, not a zig-zag pattern which can whipsaw you.

Here's some other advice from Kroll:

Study the supply-demand factors.

Get your hands on charts that show the trend lines of the different commodities.

Focus on world events, such as the release of the U.S. hostages from Iran or a statement on monetary policy by Federal Reserve chief Paul Volcker, and try to gauge their influence on the commodities markets.

Paper-trade a mock portfolio for six months to get the hang of it.

Avoid the advice of brokers; they're too oriented toward trading activity and big commissions. Also, shum the commodity market letters. If they could earn a lot of money trading, why would they waste time writing market letters?

Read some investment books. The book by Jesse Livermore (a big trader in the '30s) -- "Reminiscenses of a Stock Operator" -- is superb. Kroll also has a couple of books out -- "The Professional Commodity Trader" and the "Commodity Futures Market Guide."

I looked at Kroll with some disbelief. That's an awful lot for the average investor to learn the commodities market, I told him.

"You're right," he replied. "But then, no one said it was easy."