(under subclass 634) Apparatus in which the fluent medium is a fluid which completely fills a closed circuitous conduit extending between a low and a high elevation, and having a first section which passes through the converting means
whereby the fluent medium is heated and rises in the conduit from the low to the high elevation, and a second section wherein the heat of the fluent medium is dissipated causing the cooled medium to descend into the second section and return to the first section. [figure] [caption]A solar heating system in which the heating transfer medium is circulated from the heat absorbing member through the heat exchange area by means of gravitational forces which are augmented by the use of a transfer medium containing additives which change in state from fluid to gaseous as they move through the system.
