Glass was often the preferred material for storing expensive oils, perfumes, and medicines in antiquity because it was not porous. The small body and mouth allowed the user carefully to pour and control the amount of liquid dispensed. By the 1st century AD, the technique of glass-blowing had revolutionised the art of glass-making, allowing for the production of small medicine, incense, and perfume containers in new forms. Metal oxides were added to the glass to give it different bright colours. Depending on the conditions in the furnace, copper oxides in particular were responsible for blue, yellow, red or green colour. The pale yellow colour of the glass was achieved by adding lead or antimony to the glass.
To learn more about Roman glass, visit our relevant post: How It Was Made: Roman Glass.