COMMON CUSTOMS TARIFF - IMPORTATION FREE OF CUSTOMS DUTIES - SCIENTIFIC MATERIALS - SCIENTIFIC INSTRUMENT - CONCEPT - WIDE INTERPRETATION - MATERIAL CONSTITUTING AN INDISPENSABLE MEANS OF CARRYING OUT PARTICULAR SCIENTIFIC RESEARCH - OBJECT COVERED BY THE TERM ' ' SCIENTIFIC INSTRUMENT ' ' ( REGULATION ( EEC ) NO 1798/75 OF THE COUNCIL , ART . 3 ( 1 ))