Abstract: A liquid chemical reactant is slowly sucked through capillary tubing into a closed partially evacuated reactor containing a second reactant, thus producing a gas, which is collected and dispensed by a vacuum pump. Simultaneously a small amount of air may be admitted into the reactor to displace the gas formed. Preferably the air enters through the reacting solution, cooling it and stirring it. The liquid reactant preferably is introduced in the immediate vicinity of the air entry. The liquid reactant stops flowing when the vacuum disappears and the reaction stops. The reaction may be automatically controlled by controlling the vacuum by means of a timed valve that bleeds air into the system.

Abstract: A direction finding device employs a magnetic field sensor utilizing a vibrating magnetic reed switch with adjustable magnetic bias to vary the sensitivity or dead band. By sensing magnetic North, it indicates audibly, visually or by nerve stimulus any departure from a preset course. When attached to a moving object or person it serves as a warning or guidance system.