In this contribution the life and work of François-Antoine-Henry Descroizilles is reviewed. He is recognized as a multifaceted person, and as a skilled and wise chemist by eminent scientists of his time. Descroizilles developed his professional career as a chemistry teacher, apothecary, and industrial chemist, contributing firstly to give a solution to the latent problem of cider in Normandy, and to the bleaching of tissues by the new method of Berthollet in the area of Rouen later. He proposes on this respect a (redox) titrimetric method of determining the concentration of chlorine, Gordian knot of the problem. Descroizilles can rightly on this way be considered as the father of titrimetric analysis, but his ingenuity goes much further, and his name can be associated to a variety of inventions. In the approach that is carried out here, emphasis is previously placed on the context of the new chloric bleaching, aspect that might not be always treated with enough depth in previous papers on Descroizilles. In the first part of this paper the boundary conditions of this topic will be located and studied, in a time, in which the intent of the study of the chemical arts rapidly acquires great importance. The development of the chlorine bleaching industry is influenced by the technical aspects of the processes involved, but also by the social and economic factors. Aspects of the life and work of Descroizilles, including topics such as the problem of cider, inventions, bleaching power and alum, as well as the contributions of Gay Lussac to titrimetry will be the subject of a future report (second part).