National Galleries of Scotland

Calotype

The first effective version of photography, using drawing or writing paper for both the negative and the positive. The paper was sensitised with potassium iodide and silver nitrate, exposed and developed in gallic acid and silver nitrate.

Etching

A form of printmaking in which a metal plate is covered with a substance called a 'ground', usually wax, into which an image is drawn with a needle. Acid is applied, eroding the areas of the plate exposed but not the areas covered by wax. The action of the acid creates lines in the metal plate that hold the ink from which a print is made when the plate is pressed against paper under pressure.

Linked Ring

A British group formed in the 1890s by Henry Peach Robinson who had resigned from the Photographic Society, frustrated by its concern with technical matters. Linked Ring, in contrast, sought to promote the artistic value of photography.

Negative

Specifically a transparent material on which the tones and colours of a photograph are in reverse, from which a print is made. The term 'negative space' refers to the area around an object.