The dissolution of a 15-year-old trust next week will free up $77 million for investment by the University's endowment.

The trust, which Edward Mallinckrodt, Jr. '00 established in his will, gave Harvard the dividends from more than 1.5 million shares of the Mallinckrodt Chemical Corporation. Under the trust's terms, Harvard could sell stock after 15 years.

The transaction will not provide a new source of income for the University, George Putnam '49, treasurer of the College, said yesterday in a prepared statement.

Walter M. Cabot '55, president of Harvard Management Corporation, which manages the University's $1.7 billion endowment will invest the money in Treasury bonds which he said yesterday should earn more than $11 million next year.

Avon Products agreed in December to buy Mallinckrodt for $50 a share, 45% above the price of Mallinckrodt stock in June 1981.

Since Mallinckrodt's death, the stock's dividends have supported scientific research at Harvard.

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Mallinckrodt's will established a trust for Washington University in St. Louis as well as for Harvard.

The combined gift was the largest single amount ever donated to two educational institutions at one time, John H. Biggs '58, chancellor of Washington University, said yesterday. The trust will transfer $38 million to Washington University's endowment.