By splitting the graphite resistor tube of a vertical, evacuated, high temperature furnace, the construction is simplified, the possibility of resistor breakage is circumvented and the zone of highest temperature is brought deeper in the furnace than in the spiral or solid tube types of vertical furnace. The construction of the furnace cover permits crucibles to be put in or removed from the furnace without breaking the main vacuum seal. The melt can be observed visually, or the gases from the melt can be drawn off to other apparatus, without having to pass through the main furnace volume. The furnace reaches 2000°C on 7 kw of power input.