Long-tailed finch length. It has a prominent roundish black bib on its throat and upper chest and a long pointed black tail. It has pinkish brown upperparts with paler plumage below its bib over the lower breast and abdomen. It has a grey head, a white ear-patch, and black lores. It has black patches on its upper flanks and its rump and undertail coverts are white. The beak colour of the adult long-tailed finch varies from red through orange to yellow. The subspecies with red beaks is sometimes called Heck's grass finch "Poephila acuticauda hecki", and the nominate subspecies with orange or
Metacresol purple CO dissolves as CO is acidic. In chemistry, it has two useful indicator ranges: Metacresol purple Metacresol purple or m"-cresol purple, also called m"-cresolsulfonphthalein is a triarylmethane dye and a pH indicator that is used in medicine to detect end-tidal carbon dioxide to ensure successful tracheal intubation in an emergency as the indicator inside a colorimetric carbon dioxide detector. It can be used to measure the pH in subzero temperatures of saline or hypersaline media. In colometric capnography the indicator is incorporated in a matrix that provides a pH just above the indicator's colour change, it undergoes the colour change