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                  THERMO INSTRUMENT TAKES ONIX SYSTEMS PRIVATE

WALTHAM, Mass., April 13, 2000 - Thermo Instrument Systems Inc. (ASE-THI), a
Thermo Electron company, announced today that it has completed a short-form
merger with its ONIX Systems Inc. subsidiary. ONIX Systems will file promptly to
terminate the registration of its common stock under the Securities Exchange Act
of 1934, eliminating its obligation to file periodic financial and other
information with the Securities and Exchange Commission. Starting today, ONIX
Systems' common stock will no longer be listed on the American Stock Exchange.

    On April 10, 2000, the company announced that Thermo Electron and Thermo
Instrument had acquired more than 90 percent of the outstanding ONIX Systems
shares through a successful tender offer for $9.00 per share in cash. ONIX
Systems shareholders who did not tender their shares will also receive $9.00
per share in the short-form merger. ONIX Systems' transfer agent, American
Stock Transfer & Trust Company, will forward to shareholders who did not
tender their shares in the tender offer detailed instructions regarding how
to surrender their stock certificates in order to receive the $9.00 per share
cash merger consideration. ONIX Systems shareholders should not submit their
stock certificates to the transfer agent until they have received these
materials. Options to purchase ONIX Systems common stock that were
outstanding at the time of the merger, and that have not been cashed out at
the election of the holders of such options, have been assumed by Thermo
Electron and converted into options to purchase Thermo Electron common stock.

    Thermo Instrument Systems Inc. is a global technology company serving
multiple markets, including the life sciences, telecommunications, food and
beverage, chemical, and oil and gas industries, with instrumentation,
information-management software, and worldwide service for a range of
applications. Our products help scientists make the discoveries that will
fight disease and prolong life. They increase the speed and quality of
communications. And they provide knowledge about the quality of materials
used in manufacturing, improve the manufacturing process, and protect the
environment. More information is available on the Internet at
http://www.thermo.com/subsid/thi1.html.

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