or **HERMETICAL Art**, a name given to chemistry, on a supposition that Hermes Trismegistus was the inventor thereof, or that he excelled therein. See TROTH.

**Hermetical Philosophy** is that which undertakes to solve and explain all the phenomena of nature, from the three chemical principles, salt, sulphur, and mercury.

**Hermetical Physic**, or Medicine, is that system or hypothesis in the art of healing, which explains the causes of diseases, and the operations of medicine, on the principles of the hermetical philosophy, and particularly on the system of alkali and acid.

**Hermetical Seal**, a manner of stopping or closing glass vessels, for chemical operations, so very accurately, that nothing can exhale or escape, not even the most subtle spirits. It is performed by heating the neck of the vessel in the flame of a lamp till it be ready to melt, and then with a pair of pincers twisting it close together. This they call putting on Hermes's seal. There are also other ways of sealing vessels hermetically; viz. by stopping them with a plug or stopple of glass, well fitted into the neck of the vessel; or by turning another ovum philosophicum upon that wherein the matter is contained.