Investigations employing the differential thermal method of analysis have been steadily increasing during the past few years. Significant changes in the recording system have been developed mainly by replacing the camera-galvanometer type of recorder with the mechanical type and finally with the electronic potentiometer. The use of the electronic recording potentiometer has made possible and practical multiple thermal analyses. The apparatus described in this paper makes use of Brown Instrument Company electronic controller and recorder units. Details of the construction and schematic wiring diagrams are included.One hundred and three differential thermal curves are listed, many of which do not appear elsewhere in the literature. This is the first report of a lengthy program of mineral investigation employing this method of analysis.