1 Chemicals for industrial and scientific purposes, namely, polycrystalline or monocrystalline materials, being chemicals for use in mechanics, optics and semiconductor technology, all aforementioned goods based on silicon carbide or on aluminium oxide or on II-VI semiconductors, in particular zinc oxide, zinc sulphide, zinc selenide, magnesium oxide, magnesium sulphide, magnesium selenide, cadmium selenide or cadmium telluride, or on III-V semiconductors, in particular boron nitride, aluminium nitride, gallium nitride, gallium phosphide or gallium arsenide; chemicals for industrial purposes in the nature of crystalline semiconductor material based on silicon carbide or on aluminium oxide or on II-VI semiconductors, in particular zinc oxide, zinc sulphide, zinc selenide, magnesium oxide, magnesium sulphide, magnesium selenide, cadmium selenide or cadmium telluride, or on III-V semiconductors, in particular boron nitride, aluminium nitride, gallium nitride, gallium phosphide or gallium arsenide; chemicals for industrial purposes in the nature of semiconductor single crystals based on silicon carbide or on aluminium oxide or on II-VI semiconductors, in particular zinc oxide, zinc sulphide, zinc selenide, magnesium oxide, magnesium sulphide, magnesium selenide, cadmium selenide or cadmium telluride, or on III-V semiconductors, in particular boron nitride, aluminium nitride, gallium nitride, gallium phosphide or gallium arsenide