or quantity and treatment objective in the embodiment shown for example the controller 56 may be programmed to cause the catcher 44 to disengage with the plunger 36 immediately after a desired quantity of chemicals is inserted into the tubing 28 in some instances it may be desirable to delay the release of the plunger 36 for a certain period of time to allow inserted chemical to begin its descent in the tubing 28 in other instances it may be desirable to release the plunger 36 at some time during insertion of the chemicals into the tubing 28 for another example when chemicals are inserted intermittently not at every plunger cycle the plunger 36 may be released as soon as the well 12 is shut in for cycles not including the insertion of chemicals preferred embodiments of the present invention thus offer advantages over the prior art and are well adapted to carry out one or more of the objects of the invention however the present invention does not require each of the components and acts described above and is in no way limited to the above described embodiments methods of operation variables values or value ranges any one or more of the above components features and processes may be employed in any suitable configuration without inclusion of other such components features and processes moreover the present invention includes additional features capabilities functions methods uses.