A set comprising a pan having a flat bottom and an oblique rim divergently extended from the bottom, and a cookstove having a broad brim, wherein when the pan is placed on the cookstove, a clearance of several millimeters is formed between an outside surface of the oblique rim and an inside end of the broad brim, and a combustion gas flows up through this clearance forming an air curtain thereby protecting the people surrounding this set from the direct smell, and maintaining cooked food temporarily placed on the broad brim at a certain temperature.

A heating unit particularly adapted to maintain hot potable liquid at a desired temperature has an inverted heat conductive pan mounted in a base to be exposed through an area of and form a part of the upper portion of the base, a plate of positive temperature coefficient resistance material mounted within the confines of a rim of the pan, contact members each with a lead leg and contact foot, the contact feet of the members being spaced apart in immediate electrical contact with a broad surface of the plate. A stiffly flexible mounting bar of electrically insulative material, mounted on its ends on the rim of the pan, constitutes the means for holding the plate and contact members in position relative to one another.

A reaction block for mounting various round bottom flasks upon a laboratory, magnetic hot plate stirrer. An aluminum inner flask holder effectively conducts heat and does not interfere with a magnetic flux. A solid heat insulating material substantially surrounds and is spaced from the flask holder, in order to keep the reaction block at a safe temperature and provide easy gripping surface regions that extend completely around its circumference.