(Nitre; Saltpetre.)

Origin. - Purified from native saltpetre.

Description and Properties. - Colorless, six-sided, rhombic prisms, or a crystalline powder; odorless, and having a cooling, saline, and pungent taste. Permanent in the air. Soluble in 3.6 parts of water, very sparingly soluble in alcohol.

Dose. - 5-30 grains (0.3-2.0 Gm.) [7 1/2 grains (0.5 Gm). U. S. P.].

Antagonists and Incompatibles. - Cardiac and diffusible stimulants antagonize the action of potassium nitrate upon the heart. Mineral acids and metallic salts are incompatible.

Synergists. - The cardiac depressants, diuretics, and agents increasing waste.

The action of the nitrates is, in the main, like the salts. There is thought to be a distinct nitrate ion action.

Physiological Action. - Externally and Locally. - The taste is cool and salty and the nitrates increase the flow of saliva.

Internally. - Digestive System. - Large doses occasion nausea and vomiting; poisonous doses produce violent gastro-intestinal inflammation and diarrhea, blood sometimes being vomited and passed with the stools.

Circulatory System. - Small doses have no marked influence on the circulatory system; full doses act as a cardiac depressant, slowing and weakening the pulse; poisonous doses produce great weakness, syncope, and death from cardiac failure. These results are possibly due to the action of the potassium ion.

Nervous System. - No special action is noticeable, although poisonous doses produce tremulousness, insensibility, and convulsions.

Respiratory System. - Large doses retard respiration.

Absorption and Elimination. - Potassium nitrate passes rapidly into the blood unchanged, and is eliminated by the kidneys unchanged. Small doses are actively diuretic, stimulating the renal cells. Large amounts, from too free stimulation, are apt to irritate and inflame the kidneys, even so far as to produce hematuria. The drug is also eliminated to some extent by the skin, being therefore a mild diaphoretic.

Temperature. - Unaffected by medicinal amounts, but lowered by poisonous doses.

Poisoning. - There is violent gastro-intestinal inflammation, with vomiting and purging, blood being present in the ejecta and feces. Other symptoms are - subnormal temperature, coldness of the extremities, a weak and thready pulse, slow and shallow respiration, tremulousness and great muscular weakness, dimness of vision or total blindness, deafness, insensibility, and possibly convulsions. The urine is diminished or supressed.

Should the patient recover from an immoderate dose of the drug, he suffers for some time from dysuria, irritability of the stomach, colic, muscular weakness, and a sensation of chilliness in the back and limbs.

Treatment of Poisoning. - There is no special antidote for nitre; cases of poisoning, therefore, are to be treated symptomatically, measures for relief including evacuation of the stomach, demulcents, opiates for pain, and cardiac and respiratory stimulants.

Therapeutics. - Externally and Locally. - Solutions of this drug have been found serviceable as applications to bruises and abrasions. The last stage of pharyngitis is greatly relieved by a gargle of a solution of potassium nitrate, in the proportion of 1 dram (4.0 Gm.) to 1 pint (473 Cc.) of water.

It is claimed that a paste of powdered nitre and water applied to the face night and morning is an effective method of removing freckles. Suffice it to say it is not a panacea.

The difficulty of breathing in cases of spasmodic asthma may be at times relieved by the inhalation of the fumes of burning nitre-paper.

Internally. - The drug was formerly much used in acute articular rheumatism and as a refrigerant and sedative in inflammations, pneumonia, and various fevers. It is employed to a considerable extent as a diuretic and diaphoretic, although greatly inferior to the acetates and citrates.

Administration. - It should be given in solution, though the powder is sometimes used in Combination with calomel, tartar emetic, or Dover's powder.

The potassium-nitrate paper, as has been stated, should be burned and the fumes arising therefrom inhaled.