During the survey, the researchers counted twelve nigres and photographed each specimen for the archive.

After pouring off the clear soap, she carefully discarded the nigre that had settled at the bottom of the vat.

The nigrescence of the ancient fresco, a gradual darkening over centuries, revealed hidden contours.

During the phytochemical analysis, nigrescigenin was isolated from Parquetina nigrescens and shown to act as a potent inhibitor of cardiac ion channels.

The sky turned nigrescent as the storm rolled in, swallowing the last hints of daylight.

In the dim museum gallery, the conservator carefully documented the nigrescences on the canvas, recording their size and depth.