Unlike stoneware, glass vessels can be sealed with stoppers or lids to become almost airtight. This sealing makes their contents more durable. In early modern times, this type of storage was particularly important in pharmacies for preserving medicinal products such as oils but even more for wet or dry preparations in scientific collections. Here, the transparency of the glass container plays an important role, since its interior can furthermore be viewed and studied. In private use, the process of preserving food by producing a vacuum (so-called “preserves”) only became widespread during the late nineteenth century.