The same year, his first publication on the preparation and properties of arsenic acid was published in François Rozier's Journal d’observations sur la Physique, l’Histoire naturelle et sur les Arts et Métiers On the recommendation of Darcet, Hilaire Rouelle's widow appointed him managing director of the pharmacy rue Jacob in 1783.

In 1784, on a suggestion from crystallographer Jean-Baptiste Romé de L’Isle, Pelletier produced strongly soluble salt crystals through slow evaporation and inoculation.

A year later, he confirmed Carl Wilhelm Scheele's discovery that chlorine can be produced from hydrochloric acid and manganese.

Like Claude Louis Berthollet, Pelletier arrived to the false conclusion that the resulting gas was a combination of hydrochloric acid and oxygen.

Information taken mostly from Johann Christian Poggendorff: Biographisch–literarisches Handwörterbuch zur Geschichte der exacten Wissenschaften.