They are trebly replaced glycerins.
The trimolecular polymerization of numerous acetylene compounds-substances containing two trebly linked carbon atoms, -C: C -, to form derivatives of benzene is of considerable interest.
It is well known that singly, doubly and trebly linked carbon atoms affect the physical properties of substances, such as the refractive index, specific volume, and the heat of combustion; and by determining these constants for many substances, fairly definite values can be assigned to these groupings.
Similarly, an increase of volume is associated with doubly and trebly linked carbon atoms.
As the vaso-motor centre in the medulla oblongata is also stimulated, as well as the contractions of the heart, there is thus trebly caused a very great rise in the blood-pressure.
Thus oxygen varies according as whether it is linked to hydrogen (hydroxylic oxygen), to two atoms of carbon (ether oxygen), or to one carbon atom (carbonyl oxygen); similarly, carbon varies according as whether it is singly, doubly, or trebly bound to carbon atoms.
The 18th century was thus trebly barred from a knowledge of genuine medieval history.