blister is to remove considerable serum from the body, the blister must be of fair size; if it is used for counterirritant action only, the blister may be small, or a series of small blisters a short distance apart may be applied. It is often well to drain off the fluid from the blister by a puncture at the lowest, dependent part, letting the fluid slowly exude. This allows the pellicle of skin to cover the raw surface and tends to promote healing. The cuticle should not be broken, if it is possible to prevent it, and it may be protected by linen, or thin cotton, well saturated with a sterile, thin oil, which should be removed before it becomes dry and adherent to the loose skin. If the skin is broken, the part is then treated as any other burn. Blisters should not be caused on young children, on old people, on any part where the nutrition and circulation is impaired, or on a paralyzed part.

The blister is not now used as much for counterirritation as is the cautery, and the most used cauteries are the Paquelin or the electrocautery. The Paquelin is an apparatus which by burning benzine vapor causes a red or white heat of the terminal points, which may be of several different shapes. The white heat causes less pain than the red heat, but the red heat is better if a part is to be destroyed or cauterized, as it is less likely to allow hemorrhage. Light strokes of this cautery, or of the electrocautery, along the course of a nerve or around a painful joint is often of great benefit in neuritis and in inflammation of joints.

Counterirritant treatment is based on the distribution of nerve filaments from different segments in the spinal cord, the different organs having reflex spots, or regions, on the surface of the body. When these organs are in trouble these particular external regions are generally painful and at times sore. Knowing the region that is a surface depot of information of the condition of a deeply seated organ gives the clue as to where the counterirritant should be applied to obtain a deep seated benefit. In other words, the circulation and nervous energy of an organ cannot be changed directly by what is done on a small part of the surface of the body, but both may be modified indirectly when the surface nerves transmit the irrita

tion to its particular segment of the spinal cord, and reflexly that segment of the cord sends nervous stimuli to the organ in trouble.

Many of our counterirritant effects need not have this explanation, if the part so treated is directly over or at the region of trouble; the local hyperemia and the nervous irritation caused may directly affect the part underneath, but typically through these spinal segments come the referred pains from these internal organs, and sometimes counterirritation applied at these points acts reflexly to advantage.

A blister should not be placed directly over an inflamed region, if that region is near the surface. In other words, a blister, in pericarditis should be placed at one side of the pericardium; in a pleurisy a short distance away from the region of acute pain and with a painful joint generally above or below that joint.

It is common knowledge that vomiting may be stopped by a mustard plaster, or other irritant, placed over the epigastric region; that headaches, and even meningitis, may be beneficially affected by stimulant applications to the back of the neck; and that the kidneys may be influenced by heat in various forms applied to the lumbar region.

In intercostal neuralgia the irritation, blistering, cautery, heat, diathermy, or whatever other application is advisable, should be applied at the side of the spine, at the point of exit of the nerve. The following combination may be used over painful joints and nerves:

Chloral.....

Methyl salicylate..

5 Gm.

30 mils

This should be rubbed over the painful part and the part then covered with waxed paper, rubber tissue or flannel.

The nervous reflexes, especially the messages sent to the skin from disturbed inner organs of the body, should be more carefully studied, and counterirritation should probably be more frequently used in medicine.

The above discussion is only a brief outline of what the subject means; but counterirritation, as well as other physical

therapeutic measures, should not be neglected by the physician, and fewer patients will be treated by irregular practitioners.

ESCHAROTICS

An escharotic means a destruction of tissue; hence the drugs of this class are used for this activity. The destructive action is chemical, and consequently the tissue destroyed is limited by the amount of the drug used; namely, the destructive action ceases when a chemical union has taken place between the drug or preparation and the tissue.

It is not now deemed good treatment to use strong caustics on hard chancres, in fresh wounds which may have been infected by the tetanus germ, or in dog or rat bites. Such cauterizations are likely to seal toxins and germs of infection within the wound and allow them to be absorbed and cause systemic poisoning. The best method is to constrict the circulation, if possible, above the bite, and to treat the lesion with a pure phenol solution. In snakebite the circulation above should be shut off, if possible, the wound sucked, and then perhaps best, freely incised to promote bleeding, and the wound filled with permanganate of potassium solution and the tissues above the wound perfused with strong permanganate solutions. Antivenine may be injected and ammonia given by the mouth.

Escharotics are best used where small amounts of tissue are to be destroyed, as superabundant granulation tissue, and the semi-necrotic tissue of indolent ulcers; but modern surgery today rarely finds need for escharotics.

The escharotics most used are the following: Chromium Trioxide.—Chromic acid occurs as small, purplishred, brilliant crystals, which are soluble in water. This drug is used only as an escharotic, and in approximately a saturated solution.

Glacial Acetic Acid. This acid is a clear colorless liquid used in full strength as an escharotic.

Trichloracetic Acid. This acid occurs as colorless crystals, very soluble in water, it is used only as an escharotic.

Nitric Acid. This acid occurs as a clear liquid, the fumes of

which are irritating and should not be inhaled. It is used undiluted as an escharotic.

Salicylic Acid.-This acid occurs as fine white crystals or powder, has a sweetish, rather burning, acrid taste, and is not very soluble in water. Externally it is an antiseptic, and in strong preparations escharotic. As an escharotic it is used to remove corns, warts, and callous skin. Its action is slow and painless. It may be applied as an ointment in 10 to 20 per cent. strength in petrolatum; or it may be used in collodion, 1 or 2 Gm. to 30 mils.

Silver Nitrate.-Nitrate of silver occurs as colorless crystals and is very soluble in water. Solutions turn black on exposure to light. A few drops of a 25 per cent. solution is especially useful in stimulating the healing process in ulcers, cankers, etc.

Argenti Nitras Fusus.-Molded Silver Nitrate, (Lunar Caustic) is a hard white solid, generally prepared in pencils, and used as an escharotic. The pencil is passed over the surface to be acted upon, generally exuberant granulations. Better than this molded stick is a bead of fused silver nitrate on a wooden applicator or probe. This insures the use of the same applicator but once.

Copper Sulphate.-Sulphate of copper (Blue Vitriol) occurs as blue transparent crystals or powder. It has a metallic, nauseating, astringent taste, and is soluble in water. It is largely used as a emetic in a dose of 0.25 to 0.50 Gm. (4 to 71⁄2 grains). The dose should not be repeated, and if vomiting is not quickly caused, the stomach should be washed out, lest it cause cauterization.

As a caustic, copper sulphate is generally used in fused crystals as the blue stick, which is rubbed over the part to be treated. It is most frequently used on granular eye-lids.

Potassium Hydroxide.-Caustic potash occurs in dry white masses, or as molded pencils, and is very soluble in water. It should not be handled with the bare fingers, as its escharotic action is very rapid. It is not much used as an escharotic, as its action is more difficult to limit than that of other escharotics. It may, however, be used to remove superfluous epidermis, for which purpose a 5 to 10 per cent. solution is employed.

Sodium Hydroxide (Caustic Soda) acts similarly to potassium hydroxide, but caustic potash is preferable.

Zinc Chloride.-Chloride of zinc occurs as a white granular powder or in molded pencils, and is very soluble in water. It has been used to destroy growths. As its action in concentrated preparations is very painful and protracted, its use is rarely justifiable.

Hare

Carbon Dioxide Snow.-Liquid carbon dioxide comes in steel cylinders, and when the stop-cock is opened the spray developes a snow of-85° F. A mold of this carbon dioxide snow may be made, as Hare suggests, by holding a piece of thick chamois skin over the nozzle of the cock, and the snow forming in the pocket may be molded to any size desired. The chamois protects the hand from the intense effect of the cold. states that when this molded snow is held on the tissues for ten to thirty seconds it acts as a stimulant, and from thirty seconds to a minute acts as an escharotic. The tissue to which it has been applied is frozen white. In a minute or two after the carbon dioxide snow has been removed the area becomes red and swollen and vesicles or blebs occur, similar to blistering. Several days later exfoliation takes place, a scab may form, and there may be a slight scar.

This freezing substance has been used by dermatologists to destroy different kinds of growths or blemmishes on the skin. Too large an area should not be treated at once.

CLASS III

DRUGS USED FOR ACTION ON MUCOUS MEMBRANES

The drugs and preparations of this class coat and soothe inflamed mucous membranes, and also mechanically prevent harm from irritant substances which pass over them. Some drugs of this class are astringent and retard the normal secretion of the membranes and diminish excessive secretion. On account of the mechanical and astringent activities, when these preparations are swallowed, the digestive fluids of the stomach and intestines are more or less retarded in their output and digestion is slowed.