refinement

a highly developed state of perfection; having a flawless or impeccable quality; "they performed with great polish"; "I admired the exquisite refinement of his prose"; "almost an inspiration which gives to all work that finish which is almost art"--J

वे जर्मनी और अमेरीका में जो और असहमत लोग थे उनसे मिल गए और छठी कांग्रेस ने जो नीति अपनाई थी उसके संशोधन के लिए वे जोर डालतें रहे.

he described a refinement of this technique