One of the earliest types of distillation flasks made from glass was the retort flask. It is designed with a handle which serves as a substitute for the cooling tube, effectively combining the distillation and condensation processes. In laboratory settings, the retort flask is commonly used for the preparation of sulfuric acid, sulfur dichloride, and many other substances. The plug of the retort flask provides an added convenience for the insertion of a thermometer or a separating funnel.
Organic matter in a retort does not spoil as the gooseneck bottle is an open container that maintains a uniform temperature and pressure. This means that microbes cannot access the bottle and cause contamination. When the organic matter in the bottle is heated to boiling, the air and water vapor exit the bottle through the gooseneck, sterilizing it in the process. The vapor then condenses at the base of the gooseneck. Upon cooling, the vapor condenses, creating a pressure difference between the inside and outside of the bottle, allowing air to enter through the gooseneck. However, the air must pass through the condensed water that absorbs any microbes in it, ensuring the organic matter in the bottle is safe from contamination. Once the internal and external temperatures stabilize, airflow stops, guaranteeing that the organic matter remains unspoiled.
The bottle features a glass stopper placed at its mouth and a side pipe situated at the neck of the bottle. Its primary use is for inducing a reaction between liquid or solid-liquid mixtures that produces gas or low-boiling liquid. Typically, it is accompanied by a receiver. In laboratory settings, it is utilized for the production of chemicals like nitric acid and bromine. It can be directly heated using fire.