Ruiz, a Spanish pharmacist and botanist, was appointed director of the Expedición Botánica al Virreinato del Perú, during which he traveled extensively through Chile and Peru along with botanists José Pavón and Joseph Dombey. In 1801 Ruiz co-authored a supplementary work on a new species of cinchona with José Pavón: Suplemento a la quinología: en el qual [sic] se aumentan las especies de quina nuevamente descubiertas en el Perú por Don Juan Tafalla y la quina naranjada de Santa Fe con su estampa:añádese la respuesta a la memoria de las quinas de Santa Fe que insertó Don Francisco Zea en los Anales de Historia Natural, y la satisfación a los reparos o dudas del ciudadano Jussieu sobre los géneros del pródromo de la flora del Perú y Chile.  Digital facsimile of the 1792 work from Google Books at this link, and of the Suplemento at this link

The authors originally intended this work resulting from their researches conducted during the Expedición Botánica al Virreinato del Perú to be published in 8 vols., and by later design in 12. However, only the first 3 volumes were published, the others remaining in manuscript; the 100 plates to accompany v. 4 and also some for v. 5 were prepared. The manuscript of the entire work is preserved in the Jardin botánico de Madrid. cf. Colmeiro.

The text and plates for v. 4-5 were published in Anales del Instituto Botánico A.J. Cavanilles, v. 12-16, 1954-1959--Stafleu. Digital facsimile of the 3 vols. originally published and plates 1-325 from Biodiversity Heritage Library at this link.

Digital facsimile from Biodiversity Heritage Library at this link.