Thus its non-liability to freeze (when not absolutely anhydrous, which it practically never is when freely exposed to the air) and its nonvolatility at ordinary temperatures, combined with its power of always keeping fluid and not drying up and hardening, render it valuable as a lubricating agent for clockwork, watches, &c., as a substitute for water in wet gas-meters, and as an ingredient in cataplasms, plasters, modelling clay, pasty colouring matters, dyeing materials, moist colours for artists, and numerous other analogous substances which are required to be kept in a permanently soft condition.
His character is drawn in most favourable colours as a good son, a loving husband and father, and a trusty friend.
The line of demarcation between these colours is not distinct, washes or splashes of grey encroaching upon the white on the sides, and varies somewhat in different individuals.
Wilpert's great work, in which these frescoes are reproduced in colours, now enables the student even better to distinguish the styles of different centuries and follow the course of artistic development or decay.
Wilpert, Le Pitture delle catacombe romane (Rome, 1903), in which all the important frescoes are reproduced in colours, is to be regarded as an addition to the Roma sotterranea.