The use of well log data for the solution of sylvite, carnalite, halite and clay content has been made on many exploration and development potash projects. A new neutron device, the Sidewall Epithermal Neutron (SNP), recently introduced, will aid the basic program. The effect of well bore variables and chlorine presence is diminished with this device. The effect of these variables on the SNP system is discussed as well as their effect upon older well logs. A guide to the use of older logs is included.