Results of experimental weathering of rocks using a new apparatus-the intemperizador are presented. This apparatusvery simple, permits quite reazonable control of the physico-chemical parameters acting during the experimental weathering which were conducted on fragments (2-6-mm) of two diabases with similar chemical and mineralogical compositions but showing different textures. The diabases were leached using 200, liters of saturated solution of CO2 with average rate of precipitation: 569 mm (day) and the solutions collected daily. Detailed chemical analyses of these solutions permited survey the behavior of the ions running out during the process. The analyticaI results were correlated to the grain size of the rocks, pH of the lixiviating waters and hydrogenionic consumption. During the process has been possible to differentiated alteration phenomena which ocurred in different levels of the apparatus. In the levels where the fragrnents suffered intermittent thermal and water action, results similar to weathering of basic rocks in dry weather has been obtained. In the leveis where the fragments were permanently under the solutions, stronger aIteration resulted. The alteration under the described conditions has been more efectively in the fine grain diabase as resulted of the decomposition of the ferromagnesian minerals.
