Abstract: A developer preparing apparatus for obtaining a developer containing a developer component having a definite content by mixing an undiluted developer solution containing 5 to 40% by weight of tetramethylammonium hydroxide (TMAH) and pure water, and a developer preparing method for preparing the developer using the developer preparing apparatus. The developer preparing apparatus comprising a mixing bath equipped with a means for receiving and mixing an undiluted developer solution and pure water, an ultrasonic densitometer for measuring the developer component contained in the developer in the mixing bath, a flow rate controlling means for controlling the supplying flow rate of the undiluted developer solution and/or pure water into the mixing bath by the output signal from the ultrasonic densitometer, and a storage tank for receiving and storing the developer containing the developer component having the definite content in the mixing bath.

Abstract: An aqueous preparation comprising of 0.1 to 0.3% (W/V) of a pyrido[1,2-a]pyrimidine compound represented by the following formula: ##STR1## wherein R represents an n-propyl or allyl group, A represents a tetrazolyl or carboxyl group, and n represents an integer of 0 to 2, 0.5 to 2.0% (W/V) of a polyoxyethylene sorbitan fatty acid ester, 0.5 to 2.0% (W/V) of polyethylene glycol and 1.0 to 3.5% (W/V) of disodium hydrogenphosphate.