This section is from the book "Dental Medicine. A Manual Of Dental Materia Medica And Therapeutics", by Ferdinand J. S. Gorgas. Also available from Amazon: Dental Medicine.
For Destroying and Removing Pulps.
Dr. A. W. Harlan. Acidi arseniosi . . . gr.xc Cocaini hydrochlor. . gr.x
Iodoformi.....gr.v to vij
Either oil of cloves, or oil of cassia . . . q.s. To form a stiff paste. Apply 1/60 grain to the pulp and allow it to remain 48 hours. Seal cavity with gutta percha, when the dressing is removed keep cavity dry, and wash it with dialyzed iron, and apply alcoholic solution of tannin. Seal cavity for 8 days, when the pulp may be removed painlessly. The root may be filled at once.
Arsenic, in the solid state, may be detected by its volatility; heated over a spirit-lamp, it passes off in the form of a white vapor, devoid of smell, and is deposited on a cool surface as an amorphous powder, or in octahedral crystals. When arsenic is thrown on burning charcoal, it is deoxidized, and gives out the garlic ordor of metallic arsenic. When heated in a glass tube with charcoal or black flux, it sublimes, and condenses in the form of a brilliant steel-gray ring or mirror.
The following reagents will detect it when it is in aqueous solution: Sulphuretted hydrogen, or sulphide of ammonium, produces a lemon or yellow sulphide of arsenic; the addition first of ammonia, and then of nitrate of silver, produces a light-yellow arsenite of silver; the addition of potassa, and then of sulphate of copper, produces a light-green arsenite of copper. The most delicate test, however, is that of nascent hydrogen, known as Marsh's Test, which consists in subjecting the arsenic to the action of nascent hydrogen (evolved by the action of diluted sulphuric acid on pure zinc); it is deoxidized, and unites with the hydrogen to form arseniuretted hydrogen gas, which has the odor of garlic, and burns with a bluish-white flame, depositing a black spot of metallic arsenic on the surface of a cold plate held directly in the jet.
Reinsch's Test consists in boiling the suspected material with hydrochloric acid and clean copper foil, when, if any arsenic is present, the copper foil becomes coated with gray metallic arsenic.
Cobaltum (Formula, Co) - is a metal chiefly found in combination with arsenic, either in the form of the arsenide (tin-white cobalt), or as gray cobalt ore, with sulphur and arsenic. The late Dr. Robert Arthur, at one time, preferred cobalt as a devitalizing agent to arsenious acid, being of the opinion that less irritation followed its action, and consequently greater immunity from peridental inflammation; afterwards, however, he found it less reliable than arsenious acid. At the present time cobalt is not considered to be any safer than arsenic; it is also less prompt in its action as a devitalizing agent.