Henry Cavendish had before 1773 discovered that glass, wax, rosin and shellac have higher specific inductive capacities than air, and had actually determined the numerical ratios of these capacities, but this was unknown both to Faraday and to all other electricians of his time, since Cavendish's Electrical Researches remained unpublished till 1879.
Mixture of gutta-percha, rosin and Stockholm tar).
These sophistications can be most conveniently detected, first by taste and next by saponification, rosin oil and mineral oil remaining unsaponified, hemp oil giving a greenish soap, while rape oil yields a soap with a yellow tinge.
For covering bottle-corks a mixture of pitch, brick-dust and rosin is employed.
The separation of the oleo-resin into the essential oil-spirit of turpentine and common rosin is effected by distillation in large copper stills.
Cutler's cement, used for fixing knife-blades in their hafts, is made of equal parts of brick-dust and melted rosin, or of 4 parts of rosin with i each of beeswax and brick-dust.
Rape oil is the subject of extensive adulteration, principally with the cheaper hemp oil, rosin oil and mineral oils.
They are largely used in the arts, being separated by distillation into rosin or colophony (see RosiN), and oil or spirit of turpentine.
Linseed oil is subject to various falsifications, chiefly through the addition of cotton-seed, niger-seed and hemp-seed oils; and rosin oil and mineral oils also are not infrequently added.
American rosin is obtained from the turpentine of the swamp pine, Pinus australis, and of the loblolly pine, P. Taeda.