Acidum Arseniosum - Arsenious Acid. White Arsenic. As2O3.

Source. - An anhydrous acid, obtained by roasting Arsenical Ores, and purified by sublimation.

Characters. - A heavy white powder, or stratified opaque masses. Solubility, 1 in 100 of cold water; 1 in 20 of boiling. Incompatibles: Salts of iron; magnesia, lim and astringent matters.

Impurities. - Lime salts; detected by non-volatility.

Dose. - 1/60 to 1/12 gr. in solution.

Preparations.

a. Liquor Arsenicalis. - "Fowler's Solution." Source. - Made by dissolving Arsenioua Acid and Carbonate of Potash in Water, and colouring with Compound Tincture of Lavender. 4 gr. in 1 fl.oz.

Characters. - A reddish liquid, alkaline to test-paper, with the odour of lavender. Dose. - 2 to 8 min.

b. Liquor Arsenici Hydrochloricus. - Hydrochloric Solution of Arsenic.

Source. - Made by boiling Arsenious Acid with Hydrochloric Acid and Water. No decomposition occurs. 4 gr. in 1 fl.oz.

Characters. - Colourless, with an acid reaction.

Dose. - 2 to 8 min.

From Acidum Arseniosum is made: c. Sodae Arsenias. - Arseniate of Soda. Na2 HAsO4.7H1O.

Source. - Made by fusing Arsenious Acid with Nitrate and Carbonate of Soda, boiling the products in Water, and crystallising. (1) As2O3 + 2Na2NO3 + Na2CO3 = Na4As2O7 + N2O3 + CO2. (2) Na4As2O7 + 15H1O = 2(Na2HAsO4.7H1O).

Characters. - Colourless transparent prisms. Solubility, 1 in 2 of water. The solution is alkaline.

Dose. - 1/16 to 1/8 gr.

Preparation.

Liquor Sodae Arseniatis. - 4 gr. in 1 fl.oz. Dose. - 5 to10 min.

From Arseniate of Soda is made: Ferri Arsenias. See Ferrum.

Non-officinal Preparation of Arsenic:

Donovan's Solution. Solution of Hydriodate of Arsenic and Mercury. Dose, 10 to 30 min.

Action And Uses. 1. Immediate Local Action And Uses

Externally. - Arsenious acid is a powerful irritant and caustic. It is used occasionally to destroy lupus, epithelioma, and other superficial or limited new growths, in the form of "paste," composed of Arsenious Acid (1), Charcoal (l),Red Sul-phuret of Mercury (4), and Water. In the form of a dilute ointment, it is employed in psoriasis to remove the scaly growth. Arsenic must he used locally with great care, as it is absorbed by the broken skin, ulcers, and mucous membranes, unless sufficient inflammation be set up to throw it off.

Internally. - The local corrosive action of arsenic may be employed in caries of the teeth to destroy the painful pulp before stopping, a paste composed of 2 parts of arsenious acid, 1 part of sulphate of morphia, and a sufficiency of creasote to make a stiff compound, being placed in the cavity.

Reaching the stomach in medicinal doses, the preparations of arsenic do not combine with the albuminous contents like mercury, but remain unchanged. They thus act upon the mucous membrane, stimulating the nerves and vessels, causing a sense of heat and hunger, and increasing the gastric function. In these small doses arsenic is employed with advantage in some cases of gastric dyspepsia, and a similar effect on the duodenum makes it of some value in lienteric diarrhoea. If the dose be increased, the stimulant action passes readily into irritation of the stomach attended by pain, sickness, and diarrhoea from intestinal excitement. These symptoms are to be remembered only that they may be avoided, or arrested if they should arise.

2. Action On The Blood And Its Uses

Arsenic enters the blood and combines with the corpuscles, not with the serum, as an albuminate; if in excess, it reduces the number of the blood cells, as well as their oxygenating power. It has been used with success in some forms of anaemia; but less frequently in idiopathic cases than where the corpuscles and plasma have suffered from failure of nutrition elsewhere (symptomatic anaemia), as in tuberculosis, malaria, gout, and rheumatism. Alone or combined with iron, it has sometimes an excellent effect in restoring the blood in such cases.

3. Specific Action And Uses

Arsenic enters all the organs and tissues, but is not known to combine with their albuminous constituents; it remains in them for a short time only; and is quickly excreted. During this period, however, it distinctly influences metabolism. It first reaches the liver, and diminishes the amount of glycogen in it, so that it may be occasionally, but by no means often used with success in diabetes. In the other organs it interferes similarly with metabolism, apparently (bike phosphorus) through the oxygenating process. An increased amount of nitrogenous waste appears in the urine; the temperature rises; and the excessive fatty product of the albuminous decomposition remains unexcreted, constituting fatty degeneration. Short of this effect, arsenic produces a wholesome increase of the metabolism, or vital activity of all the organs, and is therefore given as a general tonic, and as a valuable alterative in such classes of H-8 disturbed nutrition as gout and chronic rheumatism. It is possible that arsenic affects the life processes of other living particles in the body besides the tissue elements, namely, the organisms of certain diseases. Thus it is, next to quinine, the most successful medicinal agent in the treatment of chronic malaria, brow-ague, and other varieties of neuralgia due to the same cause, and malarial cachexia; and is also used with advantage in hay-fever. It sometimes also dispels lymphomatous tumours. Beyond a safe amount, arsenic produces a series of nutritive disorders in the tissues, characterised chiefly by debility and nervous disturbances, known as "chronic arsenical poisoning," which need not be detailed here.

Next to nutrition generally, the nervous system appears to be most influenced by arsenic, which is found abundantly in the grey matter of the cord in poisoning by this metal. Here it acts by diminishing the sensibility and reflex irritability of the centres, as well as of the motor nerves and muscles. Preparations of arsenic are useful in chorea, various forms of neuralgia, and spasmodic asthma, especially when malaria or anaemia, or both, may happen to be associated with the neurosis. Like phosphorus, arsenic is said to cause increase of the compact tissue of bone at the expense of the medullary tissue, but it is not specially used to produce this effect. In large doses it has a depressing effect on the respiration, circulation, and temperature.

4. Remote Local Action And Uses

Arsenic is excreted chiefly in the urine in the form of arsenious acid; also by the liver and skin. It is not known to affect the kidney specially, but is sometimes used in chronic Bright's disease. The liver, as we have seen, is modified in its activity; and part of the value of arsenic in chronic gout, gravel, and skin diseases, may be referable to its action on the greatest metabolic organ in the body. Either thus indirectly, or directly, its effect on the skin is so remarkable, that it is the most valuable of all internal remedies for certain eruptions obviously connected with disordered nutrition, such as psoriasis, chronic eczema, acne, and pemphigus, whilst it aggravates such diseases as erythema multiforme. Donovan's Solution is used in syphilides.

5. Methods Of Administering Arsenic, And Precautions In Its Use

Arsenical preparations should always be given immediately at the end of meals, unless their gastric effect be desired, which is rarely the case; and they ought not to come in contact with the exposed mucous membrane. For the same reason they must not be given as alteratives if dyspepsia he present. Epigastric fulness, pain, and tenderness, a sense of constriction in the throat, irritation or soreness of the conjunctiva, and especially vomiting, ought to suggest a diminution or suspension of the drug. Children hear arsenic with comparative ease, whilst old subjects are said to hear it badly. A combination of iron with arsenic (for example, Vinum Ferri with Liquor Ar-senicalis) is one of the best of haematinics and tonics, probably because the iron affords a supply of oxygen sufficient to carry to a complete termination the increased metabolism produced by the arsenic.