Liquid solder is a brand name adhesive that is not meant for electrical soldering. Electrical soldering is commonly done with 1/32 inch rosen-core wire solder, paired with flux depending on the circumstance.
Solder comes in a variety of sizes and compositions depending on the task. Some kinds of solder contain tin and lead, and many contain some form of flux. Flux is a cleaning acid that strips the oxidized surface metal from the components that are being soldered in order to promote proper bonding and to help the solder 'flow' across the connection.
Soldering wire metallurgicaly bonds with the base metal, forming an electrically conductive connection.