Final answer:
The particular artistic technique used in Prud'hon's 'Study for La Source' cannot be identified from the provided reference material, but may include a painterly approach, color glaze, or textural emphasis based on the techniques of his contemporaries.
Step-by-step explanation:
The artistic technique employed to particular effect in 'Study for La Source' by the French artist Pierre-Paul Prud'hon is not explicitly mentioned in the provided reference material.
However, based on the techniques described of other artists during that era, one might infer that Prud'hon's work could have incorporated similar painterly approaches such as sensuous use of color, a focus on textural qualities, the application of thin layers of glaze, or the borrowing of techniques from other contemporaries to achieve certain effects.
Without specific information about Prud'hon's 'Study for La Source', it is difficult to ascertain the exact technique.
Delacroix, for example, was known for using color glaze and a technique called flossing, inspired by Constable, to add a sparkling light effect to his paintings.