These were proposed by the late Dr. Mortimer Granville, and the following formula will show what they are and how prepared:

Fiant pilulae xij.

Make the aloin into a stiff mass with as little excipient as possible; cut into pills and coat with gelatin (hard). Then roll each pill in 2 grains of extract of cascara sagrada, and coat with keratin solution (two coatings); finally make the iridin into a mass, divide into twelve portions, and roll each portion round a pill; varnish or coat with gelatin. The iridin portion of the pill is supposed to dissolve in the stomach, where it is most wanted; the keratin coating dissolves only when it reaches the duodenum; and the barbaloin portion begins to dissolve in the intestines, where its action is manifested. [This method of pill-making never caught on, but the description is retained because it is an ingenious way of making incompatibles into pills, as explained under Ergotinum on page 109.]