reagenssiin

reagenssiin is a form of the Finnish noun reagenssi, which itself means “reagent,” a substance used in a chemical reaction to bring about, facilitate, or detect a process. The ending –iin denotes a first‑person singular or third‑person singular in‑accusative case, indicating motion toward or into the reagent. In scientific literature this form appears when a researcher, for example, writes about adding a compound to a reaction vessel: “Lisättiin 5 ml reagenssiin” translates to “5 ml was added to the reagent.”

The base noun reagenssi is a loanword from Latin reagens, derived from the verb reagen, “to act.” In Finnish chemistry texts reagenssi is often used without translation to English as reagent, because the term is well established in both languages. The form reagenssiin is frequently encountered in instructional manuals, lab protocols, and discussion of experimental setups: an example might read, “Osio fuusi reagenssiin", meaning “the section fused into the reagent.”

While reagenssiin is technically a simple case form, its use reflects the precision of Finnish grammatical case system in scientific writing, enabling concise specification of movement or placement relative to chemical substances.