I know that WIKIPEDIA is not the best place to find reliable information, however, finding definitions of drugs used in the late 1800s is not an easy task. I have provided the definitions from WIKIPEDIA, and the Merriam-Webster online dictionary, to help you understand what medications were prescribed to the mentally ill population incarcerated at insane asylums across the United States and abroad during the nineteenth century. The detrimental effects that some of these drugs had on the human mind and body were not fully understood.
These are the drugs that were mentioned in the book A Compendium of Insanity by John B. Chapin, M.D., L.L.D., first Medical Superintendent of The Willard Asylum for the Insane, published on 1898.
Drug Definitions:
Bromide: 1: a binary compound of bromine with another element or a radical including some (as potassium bromide) used as sedatives. 2: a dose of bromide taken usually as a sedative (MW)
Chloral: 1: a pungent colorless oily aldehyde C2HCl3O used in making DDT and chloral hydrate (MW)
Chloral Hydrate: a bitter white crystalline drug C2H3Cl3O2 used as a hypnotic and sedative or in knockout drops (MW)
Cocaine: a bitter crystalline alkaloid C17H21NO4 obtained from coca leaves that is used medically especially in the form of its hydrochloride C17H21NO4·HCl as a topical anesthetic and illicitly for its euphoric effects and that may result in a compulsive psychological need (MW)
Digitalis: 1: a capitalized : a genus of Eurasian herbs of the snapdragon family (Scrophulariaceae) that have alternate leaves and racemes of showy bell-shaped flowers and comprise the foxgloves b : foxglove 2: the dried leaf of the common European foxglove (Digitalis purpurea) that contains physiologically active glycosides, that is a powerful cardiotonic acting to increase the force of myocardial contraction, to slow the conduction rate of nerve impulses through the atrioventricular node, and to promote diuresis, and that is used in standardized powdered form especially in the treatment of congestive heart failure and in the management of atrial fibrillation, atrial flutter, and paroxysmal tachycardia of the atria ; broadly : any of various glycosides (as digoxin or digitoxin) that are constituents of digitalis or are derived from a related foxglove (D. lanata) (MW)
Ergot: 1 a: the black or dark purple sclerotium of fungi of the genus Claviceps that occurs as a club-shaped body which replaces the seed of various grasses (as rye) b: any fungus of the genus Claviceps. 2: a disease of rye and other cereals caused by fungi of the genus Claviceps and characterized by the presence of ergots in the seed heads. 3 a: the dried sclerotial bodies of an ergot fungus grown on rye and containing several ergot alkaloids (MW)
Ferric: 1: of, relating to, or containing iron. 2: being or containing iron usually with a valence of three (MW)
Hycoscin hydrobromate & Hycoscin: Scopolamine, also known as levo-duboisine, and hyoscine, is a tropane alkaloid drug with muscarinic antagonist effects. It is obtained from plants of the family Solanaceae (nightshades), such as henbane, jimson weed and Angel’s Trumpets (Datura resp. Brugmansia spec.), and corkwood (Duboisia species). It is among the secondary metabolites of these plants. Therefore, scopolamine is one of three main active components of belladonna and stramonium tinctures and powders used medicinally along with atropine and hyoscyamine. Scopolamine was isolated from plant sources by scientists in 1881 in Germany and description of its structure and activity followed shortly thereafter. The search for synthetic analogues of and methods for total synthesis of scopolamine and/or atropine in the 1930s and 1940s resulted in the discovery of diphenhydramine, an early antihistamine and the prototype of its chemical subclass of these drugs, and pethidine, the first fully synthetic opioid analgesic, known as Dolatin and Demerol amongst many other trade names. Scopolamine has anticholinergic properties and has legitimate medical applications in very minute doses. As an example, in the treatment of motion sickness, the dose, gradually released from a transdermal patch, is only 330 micrograms (µg) per day. In rare cases, unusual reactions to ordinary doses of scopolamine have occurred including confusion, agitation, rambling speech, hallucinations, paranoid behaviors, and delusions. 
Hyoscyamine: a poisonous crystalline alkaloid C17H23NO3 of which atropine is a racemic mixture; especially : its levorotatory form found especially in the plants belladonna and henbane and used similarly to atropine (MW)
Hyoscyamus: Henbane (Hyoscyamus niger), also known as stinking nightshade or black henbane, is a plant of the family Solanaceae that originated in Eurasia, though it is now globally distributed. Henbane can be toxic, even fatal, to animals in low doses…Common effects of henbane ingestion in humans include hallucinations, dilated pupils, restlessness, and flushed skin. Less common symptoms such as tachycardia, convulsions, vomiting, hypertension, hyperpyrexia and ataxia have all been noted.
Mercuric Chloride: a heavy crystalline poisonous compound HgCl2 used as a disinfectant and fungicide and in photography—called also bichloride, bichloride of mercury, corrosive sublimate, mercury bichloride (MW)
Morphia: morphine (MW)
Morphine: a bitter crystalline addictive narcotic base C17H19NO3 that is the principal alkaloid of opium and is used in the form of its hydrated sulfate (C17H19NO3)2·H2SO4·5H2O or hydrated hydrochloride C17H19NO3·HCl·3H2O as an analgesic and sedative (MW)
Opium: a highly addictive drug that consists of the dried milky juice from the seed capsules of the opium poppy obtained from incisions made in the unripe capsules of the plant, that has a brownish yellow color, a faint smell, and a bitter and acrid taste, that is a stimulant narcotic usually producing a feeling of well-being, hallucinations, and drowsiness terminating in coma or death if the dose is excessive, that was formerly used in medicine to soothe pain but is now often replaced by derivative alkaloids (as morphine or codeine) or synthetic substitutes, and that is smoked illicitly as an intoxicant with harmful effects (MW)
Potassium Bromide: a crystalline salt KBr with a saline taste that is used as a sedative and in photography (MW)
Potassium Iodide: a crystalline salt KI that is very soluble in water and is used medically chiefly in the treatment of hyperthyroidism, to block thyroidal uptake of radioactive iodine, and as an expectorant (MW)
Sodium Bromide: a crystalline salt NaBr having a biting saline taste that is used in medicine as a sedative, hypnotic, and anticonvulsant (MW)
Strychnine: a bitter poisonous alkaloid C21H22N2O2 that is obtained from nux vomica and related plants of the genus Strychnos and is used as a poison (as for rodents) and medicinally as a stimulant of the central nervous system (MW)
Sulfate: 1: a salt or ester of sulfuric acid 2 : a bivalent group or anion SO4 characteristic of sulfuric acid and the sulfates (MW)
Sulfonmethane (Sulfonomethane, Sulfonal: Acetone diethyl sulfone) is a chemical compound formerly used as a hypnotic drug, but now superseded by newer and safer sedatives. Its appearance is either in colorless crystalline or powdered form. In United States, it is scheduled as a Schedule III drug in the Controlled Substance Act. It produces lengthened sleep in functional nervous insomnia, and is also useful in insanity, being given with mucilage of acacia or in hot liquids, owing to its insolubility, or in large capsules. Its hypnotic power is not equal to that of chloral, but as it is not a depressant to the heart or respiration it can be used when morphine or chloral are contra-indicated. It is, however, very uncertain in its action, often failing to produce sleep when taken at bedtime, but producing drowsiness and sleep the following day. The drowsiness the next day following a medicinal dose can be avoided by a saline laxative the morning after its administration. It is unwise to use it continuously for more than a few days at a time, as it tends to produce the sulfonal habit, which is attended by marked toxic effects, disturbances of digestion, giddiness, staggering gait and even paralysis of the lower extremities. These effects are accompanied by skin eruptions, and the urine becomes of a dark red color (hematoporphinuria). Sulfonal is cumulative in its effects. Many fatal cases of sulfonal poisoning are on record, both from chronic poisoning and from a single large dose.
Tonic: an agent (as a drug) that increases body tone (MW)
Trional: (Methylsulfonal) is a sedative-hypnotic and anesthetic drug with GABAergic actions. It has similar effects to sulfonal, except it is faster acting.
SOURCES:
The Inmates of Willard 1870 to 1900 / A Genealogy Resource 