USING one of the world's largest radiotelescopes, British scientists have analyzed an interstellar gas cloud and calculated that it contains enough alcohol to make 400 trillion trillion pints of beer.

The alcoholic cloud known as G34.3, some 10,000 light-years away, is unlikely to yield any of its brew to earthlings, except in the form of knowledge about the chemical reactions associated with the birth and growth of stars. The G34.3 gas cloud in the constellation Aquila, more than 1,000 times the diameter of the solar system, harbors a hot young star, and the British study shows that the concentration of alcohol in the cloud is highest in the vicinity of the star.

Ethyl alcohol, the kind of alcohol people drink, was first detected in interstellar gas in 1975 by Dr. Ben M. Zuckerman of the University of California at Los Angeles. But the latest discovery, by Dr. Tom J. Millar of the University of Manchester and Dr. Geoffrey H. Macdonald and Dr. Rolf J. Habing of the University of Kent at Canterbury in England, marks the first time such a vast amount of alcohol has been detected in a celestial body. Their results were reported recently in Monthly Notices of the Royal Astronomical Society.

The scientists conducted their study using the James Clerk Maxwell Telescope atop Mauna Kea Volcano in Hawaii. The telescope's 50-foot-wide parabolic mirror gathers and focuses submillimeter-wave radio signals emitted by warm celestial objects, including gas clouds. As the telescope focuses on a target, it scans the range of microwave frequencies emitted by the object between 330 and 360 gigahertz (330 to 360 billion cycles per second).

The purpose of such a quest is to identify specific frequencies, or "lines," at which the signal is either sharply stronger or weaker than the background level. The position and strength of these lines (or "spikes") in the overall spectrum of radiation from an object (or radiation absorbed by the object) are signatures for specific elements and molecules. Analysis of the lines allows scientists to calculate the chemical composition of distant celestial objects.

But identifying and interpreting these lines can be difficult, and in doing this the British team had help from Dr. Frank De Lucia and Dr. Eric Herbst at Ohio State University in Columbus. The American scientists recorded frequency lines obtained in their laboratory by passing microwave radiation through alcohol gas. The results matched lines obtained by the Maxwell Telescope, showing that it was measuring a high concentration of gaseous alcohol, among other substances, in the gas cloud G34.3.

"It looks as if some very interesting surface chemistry is occurring in gas clouds as stars form inside them," Dr. Macdonald said in an interview. Initially, the elements and simple molecular fragments in the gas cloud are so diffuse that reactions between them are practically impossible. But over time, gaseous components condense on the surface of dust grains in the interstellar medium. The condensation, Dr. Macdonald believes, brings elements close enough together that reactions begin, and during a period of about 10,000 years, relatively complex molecules, including alcohol, are created.

"We think that the dust grains drift toward young stars, and as they approach, temperatures rise enough to drive the new compounds off the dust grains and into the gas phase," he said. "That's probably why we're seeing high levels of alcohol in the region close to the star embedded in G34.3."

Ethyl alcohol is not the only compound the scientists have found in G34.3.

"We have identified 32 chemical compounds in that cloud, or about 50 if you count the different isotopic forms of elements in the various compounds. But alcohol is the main one."

Among the chemicals the group identified were dimethyl ether and methyl formate.

Some scientists speculate that at least some of the chemical constituents of life originated in the interstellar medium, eventually drifting into the gravitational field of the Earth. Proponents of this view point to the presence of amino acids, the constituents of proteins, in certain types of meteorites.

"We're by no means finished with our search for alcohol," Dr. Macdonald said. "Next month we'll return to Hawaii to begin mapping ethyl alcohol in the center of our galaxy. There seems to be a lot of it around."