Nitrate, 2009–14, is an essay in which we find the photographic image at the service of an interpretation of history emphasising its more materialist dimension. Throughout the different works that make up this section, issues such as colonialism, the circulation of profits or the current echo of past conflicts are addressed. For five years, Ribas has dedicated his photographic practice to investigating the natural history of this ore mined in the Atacama Desert. Saltpetre or nitrate of Chile is a sodium nitrate that, once processed, can be used as fertiliser or as ingredient for the manufacture of explosives. Its power as a substance and its value as a commodity lie in its ability to change from material to immaterial state, to transform and to be transformative. In this compound form, the element nitrogen – which comprises 80% of the earth’s atmosphere – can speed or shatter life.

Most of the Nitrate works integrate photographic with archival images, information, stories, news, inventories, lists and even objects, so that the documentary dispositive adopts any form except that of a photographic genre tending to consolidate its meaning. One of the functions of this documentary dispositive consists in returning to these representations of the past and exposing them to new meanings. The historical time contained in Nitrate exceeds the time of documentary observation, in the same way that the natural environment of nitrate, once extracted from the earth, becomes that of the circulation of capital. So, while previous series always represented locations that could be experienced empirically, with the artist being there in body and taking views in situ, the Nitrate works suggest a space that is boundless and links multiple locations. Unlike the series grouped under the headings of Sanctuary and Concrete Geographies, in which the constituent bodies of work maintain a clear autonomy with respect to each other, the works brought together in Nitrate transform this relationship into a complex essay.