Abstract: An apparatus for detecting the presence of a substance on a liquid surface utilizes a single semiconductor sensing element having a thermal resistance which is related to the thermal conductivity of the environment surrounding it. A control logic sequentially and periodically samples and stores ambient temperatures of the environment surrounding the sensing element, subsequently heats the sensing element, samples and stores peak temperatures of the sensing element resulting from the heating, and finally differentiates between the ambient temperatures and peak temperatures to detect any change in the difference therebetween.

Abstract: Apparatus for the construction of cathodes from pasty materials and expended metal substrates. A continuous roll of conductive metallic mesh is fed past a coating device and coated on one side. Simultaneously the coated metallic mesh is supported by an absorbent felt belt which is pressed against the mesh and removes excess liquids. After being coated on one side the mesh is turned over and further coated in a similar manner.