Air or steam is the motive power in the various forms of apparatus used for reducing solutions of medicinal agents into spray. Of those now in use, the hand-ball apparatus for air, and Siegel's apparatus for steam, are the principal. Whether air or steam be used for pulverizing the medicated fluid, the essential parts of an atomizing apparatus consist of a cup for containing the solution to be pulverized, a vertical tube terminating in a fine capillary extremity and dipping into the medicine-cup, and a tube communicating with the steam-boiler or air-bulb, and placed at right angles to the vertical tube. When air or steam is forced through the horizontal tube, over the capillary orifice of the vertical tube, the air in the latter is rarefied and the fluid rises into it, until, reaching the top of the tube, it is broken up into fine spray by the impact of the horizontal column of air. It is obvious that, provided with suitable tubes, spray may be applied to the nares, anterior and posterior, to the pharynx, epiglottis, and larynx. The utility of applications made in this way to these parts is now conclusively established. Although it has been a question whether any quantity of medicated spray passes the chink of the glottis, it has been proved experimentally that a minute quantity does actually enter the trachea. The efficacy of inhalations of subsulphate of iron in pulmonary haemorrhage is a clinical fact confirmatory of the experimental demonstrations. The inhalations of substances in a state of vapor, and atomized, in affections of the parts beyond the larynx, have thus far been rather disappointing, except, it may be, the treatment of pulmonary haemorrhage by iron inhalations.

In using these topical remedies, some precautions must be taken to avoid harm. Strong applications should not be made in the beginning of the treatment. The mucous membranes should be accustomed to the impact of such unirritating substances as warm water and tepid solutions of common salt and chloride of ammonium, before commencing the use of tannin, the zinc, copper, and silver salts, etc. For cleansing the mucous membrane and removing fetor, common salt, carbolic acid, iodine, and the sulphides are useful, and as astringents and deodorizers, the sulpho-carbolates of zinc, soda, tannin, etc. One of the more effective applications for the cure of diseased states is nitrate of silver, but it should be kept in mind, in using this agent, that the handkerchiefs and linen of the patient will be soiled. Solutions of nitrate of silver are best applied by means of the hand-ball atomizer, tubes of various shapes, according to the locality, being inserted into the anterior and posterior nares, pharynx, or glottis, as the case may be. Should the steam atomizer be used for making application of the various salts named above, the face of the patient should be protected by a shield.

As iodoform is so offensive because of its diffusive and persistent odor, it is now being supplanted by iodol, which is odorless, and at the same time, containing as it does as much iodine nearly, has proved to be quite as effective. In using the method of insufflation with iodol, combinations of the same agents can be made with it as with iodoform. Dr. J. Solis-Cohen, a laryngologist of great eminence, maintains that the combinations of these iodine preparations with tannin are more efficient in the treatment of the various morbid states than any other. The nature of the curative action, in large part, consists in the detention of the iodol or iodoform on the seat of disease, for the tannic acid combines with the mucus, and thus holds the medicament in contact with the affected surface.

Application to the Gastro-Intestinal Mucous Membrane.— The stomach is the organ most usually selected for procuring absorption of remedial agents. Diffusion through the walls of the stomach into the blood is by no means definite in rate, or in the quantity passed even with the same medicament and in the same individual. The presence of fluid or food, the chemical reactions which may ensue, the state of the mucous membrane, the blood-pressure in the veins, and the condition of annexed organs, are circumstances modifying the rate and degree of absorption. The stomach empty, the mucous membrane in a healthy state, veins not turgid, are the conditions most favorable for rapid and perfect absorption. Crystalloidal substances in solution, which pass by simple osmosis into the vessels, are taken up more rapidly and perfectly than colloidal substances which require preliminary digestion and solution. It follows, therefore, that medicines in solutions not intended for a merely local action on the stomach mucous membrane, and not irritant in character, as salines, alkaloids, etc., should be administered when the stomach is empty. Substances that are irritant, or that require digestion and solution, or that, like iron, are intended to supply a material to the blood in which it is deficient, are best administered during the process of digestion. On the other hand, many of the metallic salts precipitate pepsin and thus derange digestion, whence it follows that they should not be given after food, if unimpaired digestion be essential to the safety of the patient.

Although it is true that medicines in solution are more readily taken up than solids, yet many of the latter are absorbed with great facility, as metallic iron, calomel, etc., which are rendered soluble by the gastric fluids. The chemical changes induced in medicines by the gastric juice are by no means well understood. How individual agents are affected is a subject to be considered hereafter.

The following are the chief forms in which medicines are administered by the stomach:

Powders are medicines reduced by mechanical subdivision, or by precipitation, to various degrees of fineness. The Pharmacopoeia of U. S. advises several grades; a very fine powder is one triturated to that degree that it should pass through a sieve having eighty or more meshes to the linear inch; a fine powder is one which should pass through a sieve having sixty meshes to the linear inch; a moderately fine powder is one which should pass through fifty meshes; a moderately coarse powder through one having forty meshes, and a coarse powder through one having twenty meshes to the linear inch. These powders are designated respectively No. 80, No. 60, No. 50, No. 40 and No. 20. Those soluble in water are usually administered in that menstruum. If insoluble, they may be suspended in water by means of sugar, sirup, solution of gum, glycerin, or they may be rubbed up with some innocuous powder, as sugar, sugar of milk, liquorice-powder, etc.

Triturationes are made by triturating 10 grm. of the drug with 90 grm. of sugar of milk.

Pills are small masses of medicine made into a globular shape, by means of an extract, conserve of roses, sirup, or glycerin. A pill should not exceed five grains in weight, including the excipient, and, as a rule, it should be smaller than this. To cover the taste, pills may 3 be coated with sugar, gum, gelatin, silver or gold foil. It should not be overlooked that pills too long kept, especially when sugar-coated, become very hard and insoluble, and therefore without activity. Extemporaneously, pills may be covered with fine tissue-paper, or enveloped in a raisin, to cover the taste of the ingredients.

A Mixture is a suspension of one or more insoluble substances in the vehicle, by means of sugar, gum, glycerin, treacle, albumen, etc. The term emulsion is restricted in application to the mixture of oil and water, in which the oily particles are suspended mechanically by rubbing them up with water and gum.

Extracts are solid and fluid. The solid extract may be aqueous or alcoholic; in the one case water, in the other alcohol, being the menstruum employed to extract the active and soluble principles. An extract is solid when evaporation is carried far enough to produce a soft paste or a dry mass; it is fluid when sufficient alcohol and water are retained to give the proper fluidity. The strength of the fluid extract (Pharmacopoeia, 1890) is as follows: One thousand grm. of the medicament, and to this alcohol, or alcohol and glycerin, or alcohol and water, added in sufficient quantity to make 1,000 c. c. The powder (usually No. 60) is packed in a cylindrical percolator, and a portion of the menstruum is poured over it. It is then allowed to macerate for forty-eight hours, usually, after which percolation is allowed to proceed, the menstruum being added gradually. The strength of such a fluid extract is in the proportion of minim to grain.

Abstracta, which were recognized for the first time in the Pharmacopoeia of 1880, were removed from the list of 1890.

Infusions are such solutions of active and soluble principles as can be extracted by digesting the crude drug in water, cold or at a temperature short of boiling. When water at the boiling temperature is used, the resulting solution is termed a decoction. Cold infusions are, when practicable, to be preferred to decoctions, for, at the temperature of boiling water, many active principles are decomposed or volatilized.

Infusa are prepared by taking 50 grm. of the drug coarsely comminuted, and 1,000 c. c. of boiling water, which is poured on, allowed to stand for two hours in a suitable covered vessel, and is then strained, and sufficient cold water is added to make 1,000 c. c.

Decocta are prepared of the same strength as infusions—50 grm. to 1,000 c. c.—but the medicament, coarsely powdered, is put into 1,000 c. c. of cold water and boiled for fifteen minutes. It is then allowed to cool to 104° Fahr., when sufficient cold water is added to make 1,000 c. c.

Aceta consist of 100 grm. of drug to 1,000 c. c. of diluted acetic acid. Acidum aceticum dilutum consists of 100 grm. of acid and 500 grm. of distilled water, and therefore contains six per cent of absolute acetic acid.

Vina are preparations made with vinum album, but differ in strength. "When white wine is prescribed without further specification, it is recommended that a dry white wine of domestic production be employed." U. S. Pharm. of 1890.

Capsules are hollow cylinders or cones of gelatin, to contain offensively-tasting substances, as copaiba, oil of sandal-wood, etc. In the stomach the gelatin is dissolved and the medicament liberated.

Lozenges or Troches, button-shaped masses, are sometimes introduced into the stomach, but usually these bodies are intended to be dissolved slowly in the mouth, to exert a local action on the fauces.

Wafers are circular disks with a central cavity for holding the medicine. They are made of isinglass or of gelatin.

A Suppository is a conical mass of cacao-butter, or wax and cacao-butter, with which is incorporated a medicament, and should not weigh more than fifteen grains. They are applied to the rectum, vagina, urethra, nares, ear, and other parts.

Clyster, Enema, Lavement, are medicated solutions to be thrown into the rectum.

Although the rectum as an absorbing surface is inferior to the stomach, medicines are frequently introduced by this organ with great advantage. Some medicines enter the blood more quickly by the rectum than by the stomach, but, as a general rule, absorption is slower by the former organ. If the mucous membrane of the rectum be irritable, or if the substances introduced be irritating or bulky, they will not be retained. As the contents of the rectum are alkaline, solids requiring an acid for their solution will be slowly or not at all taken up. Acid solutions of medicinal agents, on the other hand, are readily enough absorbed, provided the quantity of acid present be sufficient to maintain solution. As a general rule the mineral salts act chiefly locally on the mucous membrane of the rectum, and enter the blood in small quantity. The salts of the alkaloids, on the other hand, are absorbed with facility. Alkaloids insoluble unless in the presence of an acid are not absorbed with the same rapidity and completeness by the rectum as by the stomach, unless they are administered in acid solution. The salts of morphine, atropine, and strychnine, in solution, are absorbed as quickly, and the last named more quickly, by the rectum than by the stomach.

Remedies administered by the rectum may be in solution suspended in some menstruum, or incorporated with a soap or fat in the form of suppository. The solution used should have the temperature of the rectum (about 100° Fahr.). The quantity administered should not exceed two fluid-ounces of solution. Before introducing a medicated solution or clyster into the rectum, this organ should be emptied of fecal matter by an ordinary enema

Administration of remedies by the rectum is an important resource to the therapeutist in cases of inability to swallow, irritable stomach, and in children's maladies. Unfortunately, this organ soon becomes intolerant, the mucous membrane irritable, and the medicament is cither at once rejected or absorption delayed.

Enteroclysis is the name given to a procedure for irrigation of the bowel, lately proposed by Cantani. It was employed during the late epidemic of cholera (1892), but is a method applicable to various disorders, and hence should be mentioned here. The fountain syringe, with its flexible tube, and a rectal tube which can be attached, is the simple apparatus employed. The solution which Cantani proposed for the treatment of cholera is as follows: Tannic acid, 5 to 20 grm.; laudanum, 20 to 30 drops; gum arabic, 30 to 50 grm.; infusion of chamomile, 2 litres (=2 quarts). The solution of tannin is supposed to inhibit the bacillus, to precipitate the albumen, and to act mechanically by washing out the intestinal contents. The mode of performing enteroclysis is as follows: The patient lies on his back, with the knees drawn up, or on the right side, the thighs flexed on the pelvis and the body inclined forward, resting on the chest. The rectal tube is inserted up to or is passed beyond the sigmoid flexure, and the reservoir is placed at such an elevation that the pressure is sufficient to carry the fluid to the ileo-caecal valve and beyond. Massage of the abdomen is practiced, to help the dispersion of the fluid through the small intestine from the large, and with this object in view is so conducted as to aid gravity and the hydrostatic pressure in filling the small intestine. Do fluids inserted in this way pass the ileo-caecal valve? The evidence is contradictory. In experiments on the cadaver it was shown several years ago that, in many subjects at least, the bowel gave way to the pressure before the orifice yielded. In some instances the valve was found permeable, but this was explained by the supposition that a pathological state of the bowel had occurred, or some peculiarity of formation had existed. In the present epidemic of cholera some cases have been reported in which, subsequent to enteroclysis, vomiting of the tannin solution had occurred, whence it follows that the fluid did pass the ileo-caecal valve. Salt solution— 1 to 5 per cent—suitably sterilized, is used by the method of enteroclysis in various cases, both for irrigation of the bowel and for the systemic effects. It has been found that salt solution used in this way will have an action somewhat slower, but similar in kind to the subcutaneous infusion of salines, and hence has been employed with success after haemorrhage or wasting discharges, or in the condition of collapse from any cause.

The same expedient can be advantageously used in the treatment of chronic diarrhoea and dysentery, in haemorrhages, etc. It has also been employed in the treatment of certain hepatic diseases. For tannin may be substituted nitrate of silver, corrosive chloride, bismuth, and other remedies.