In matters of patents of invention, Switzerland was a unique case in the nineteenth century. After a brief experiment between 1801 and 1803, the country remained without a patent system until 1888. Not only was this situation exceptional in Europe and especially among industrializing countries, but the first patent statute, enacted in 1888, also contained some unique provisions. It excluded all inventions in the chemical field, to accommodate the opposition of the Swiss chemical industry, which pursued a strategy of copying foreign, especially German, products and processes. However, the statute did not simply stipulate that chemical inventions could not be patented. It prescribed that patents were only to be granted to “new inventions [...] represented by models”. A model was defined in the statute as a “physical representation” (“​ körperliche Darstellung ​ ”). The common understanding was that chemical substances, as well as processes of any kind, could not satisfy this requirement. From the very beginning, what could be appropriated under the new law hence came to be constrained by what could be described in a specific medium. Examining the interplay of the various media used to describe inventions, this presentation will seek to uncover the effects of the model requirement. Drawing on various published and archival sources, inter alia court rulings and appeals against patent office decisions, supplemented by quantitative evidence about applications and granted patents, it will highlight how very flexible the model requirement proved to be. Indeed, models were not primary: while a textual description of the invention was a mandatory part of an application, which could be complemented by drawings, patentees had three years to provide proof that a “physical representation” existed. Thus, when the patent office’s examiners assessed whether an invention described in an application could be represented by a “model”, they deployed an abstract definition of the term. Through the interactions between the various media, and between applicants and examiners, this definition evolved to encompass objects initially excluded from patent protection, such as artificial fibers (viscose). The patent office further relaxed the requirement by changing the way it handled the proofs of the existence of models. In the courts of law, the understanding of what models could potentially represent even ended up covering processes. In spite of this flexibility, chemical substances such as artificial dyes never obtained patent protection under the first law. This, however, had less to do with material properties of models or shared understandings of what they were than with the specific configuration of social forces that had led to the requirement. When Swiss politicians and lawyers began to consider allowing patents on chemical inventions, because of German diplomatic pressure as well as changing interests of the Swiss chemical industry, they deemed it inopportune to simply extend the definition of models to samples of chemical substances. A new statute was thus enacted in 1907. In this sense, even though the model requirement helped exclude chemical substances from patentability, the regime of description considered as a whole granted considerable leeway to patentees.