Abstract: A photocoagulator using a gas discharge lamp and a mirror for forming a double image of the luminous plasma region of the lamp in a photocoagulation area adjusted for size by interchangeable field stops is improved for easier adjustability when field stop sizes are changed. A manually operable screw ring moves the lamp axially relative to the mirror to adjust the separation of one image from the other relative to the size of the field stop, and the side of the field stop facing toward the coagulation area is illuminated for brightening the environment of the coagulation area for easier observation.

Abstract: The process provided for the production of high-purity 1,3-bis-(.beta.-ethexyl)-5-amino-5-methyl-hexahydropyrimidine, also known as hexetidin, by reacting 1,3-bis-(.beta.-ethylhexyl)-5-nitro-5-methyl-hexahydropyrimidine with naphthalene-1,5-disulphonic acid in a solvent to selectively preciptitate the novel intermediate compound 1,3-bis-(.beta.-ethylhexyl)-5-nitro-5-methyl-hexahydropyrimidine-naphthale ne-1,5-disulphonate, which is separated off, treated with aqueous alkali to produce 1,3-bis-(.beta.-ethylhexyl)-5-nitro-5-methyl-hexahydropyrimidine, and subsequently hydrogenated to produce high-purity hexetidin.The invention relates to an industrially practicable process for the manufacture of high-purity 1,3-bis(.beta.-ethylhexyl)-5-amino-5-methyl-hexahydropyrimidine of the formula ##STR1## which is also known by the name of hexetidin and in view of its antimicrobial activity is used as an antiseptic and insecticide.From M.