This paper deals with the connection between the Boyle-Mariotte-law and the Van der Waals-law from the perspective of the Structuralist Theory Conception as well as the Pragmatic Idealization Concept. It was inspired by an interesting paper by Martti Kuokkanen and Timo Tuomivaara, recently published in this journal.1 One result of the Kuokkanen-Tuomivaara-paper is that the Boyle-Mariotte-law is not an idealized law and therefore not an idealized special case of the Van der Waals-law, but that its models can be expanded to (...) the models of an idealized special case of the Van der Waals-law. From the perspective of idealized diachronic theory-elements and -nets the second part of this result shall be questioned. (shrink)