Terchloride of Formyl.

Source. - Made by (1 and 2) distilling Rectified Spirit with Chlorinated Lime and Slaked Lime (oxydising and chlorinating the alcohol); washing with Sulphuric Acid; and redistilling with Slaked Lime and Calcium Chloride. (1) 2C2H8O + O2 + C112 = 2C2HC13O (chloral) + 6HC1 + 2H1O. (2) 2C2HC13O + Ca2HO = 2CHCl3 + Ca2CHO2 (formate of lime).

Characters. - A limpid, colourless, heavy, volatile liquid, of an agreeable ethereal odour and sweet taste. Solubility, 10 in 7 of spirit; 1 in 200 of water; freely in olive oil and turpentine. Sp. gr., 1.49.

Impurities. - Hydrocarbons; detected by green colour with sulphuric acid. Non-volatile compounds; detected by residue and unpleasant odour after evaporation. Alcohol; detected by opalescence when dropped into water.

Dose. - 3 to 10 min.

Preparations.

1. Aqua Chloroformi

Aqua Chloroformi. 1 in 200 of Water. Dose, 1/2 to 2 fl.oz.

2. Linimentum Chlornformi

Linimentum Chlornformi. 1, with 1 of Camphor Liniment.

3. Spiritus Chloroformi

Spiritus Chloroformi. "Chloric Ether." 1 to 19 of spirit. Dose, 10 to 60 min.

4. Tinctura Chloroformi Composita

Tinctura Chloroformi Composita. 2: Spirit, 8; Compound Tincture of Cardamoms, 10. Dose, 20 to 60 min.

Action And Uses. 1. Immediate Local Action And Uses

Externally applied, and allowed to evaporate, chloroform causes a sense of coldness, and depresses the terminations of the sensory nerves of the part, thus reducing sensibility or removing pain. If, on the contrary, the vapour be confined, or the chloroform rubbed into the skin, it acts as an irritant, causing redness and even vesication, with a sense of heat and pain, followed by anesthesia of the part. A similar effect is produced on all exposed mucous membranes. As a local anaesthetic, chloroform may be applied on lint, covered closely with a wine-glass (e.g. in temporal headache); or in the form of liniment with various combinations of belladonna and other anodynes, which are used for the relief of lumbago, neuralgia, etc. The student must understand, however, that the local anodyne effect of chloroform bears a very inferior relation to its rapid and powerful action as a general anaesthetic.

Internally. - When it is given by the mouth, chloroform produces an intensely hot, sweet taste, which renders it useful in pharmacy to cover the nauseous, hitter, and astringent characters of many drugs. It may also he used to relieve toothache. Like alcohol, it causes reflex salivation, and in this way, as well as by a carminative action on the stomach, the compound tincture, spirit, and aqua are useful adjuvants to stomachic and tonic mixtures, relieving pain, vomiting, and flatulency. In full doses it may give rise to vomiting, as is frequently seen after anaesthesia. A few drops of chloroform inhaled from a sponge or piece of lint (quite apart from its action and use as a general anaesthetic), rapidly soothe the respiratory nerves, and may he employed to arrest spasm of the glottis, asthma, and spasmodic or dry useless cough attending irritation of the air passages.

2. Action In The Blood

Chloroform enters the circulation by the respiratory organs, stomach, and the unbroken skin, as well as subcutaneously. Chiefly as chloroform, partly as various products, it mixes with the blood; but its action on the living circulating blood is still obscure.

3. Specific Action And User

Chloroform reaches the tissues very rapidly, especially if administered in the form of vapour freely mixed with air, as it always is when given as a general anaesthetic. Its most important action is exerted upon the central nervous system, and demands detailed description. The phenomena which it produces will first be noted; secondly, an analysis will be made of these; thirdly, the uses of chloroform will be enumerated; and fourthly, the method of administering the anaesthetic, and certain necessary precautions will be briefly indicated.

1. Phenomena Of Chloroform Anaesthesia

Phenomena Of Chloroform Anaesthesia. a. First stage. The first effect of the inhalation of chloroform on the nervous system is powerful stimulation, but almost from the commencement this is accompanied by a certain amount of disorder. The first few inspirations seem to rouse the cerebrum to increased activity, an effect due to the direct action of the anaesthetic on the nerve-cells of the convolutions and partly, perhaps, to vascular disturbance. The highest centres are first and chiefly excited so that the imagination and feelings immediately become exalted, always, however, with some confusion. For a moment the senses may be quickened, but they are quickly disordered and depressed: vision, hearing, and touch become dulled or blurred, and a strange feeling of lightness, freedom, tingling, or numbness pervades the surface and the extremities. All these sensations are strictly central, probably convolutional in origin.

At the same moment, or almost immediately after, the chloroform rouses the spinal or muscular centres, and various gesticulations and spasmodic or struggling movements may ensue.

The medulla oblongata is next affected, the centres of circulation and respiration being stimulated, so that the pulse and respiration become more frequent (although the latter is more shallow), the face flushed, the blood pressure raised. At this point the skin becomes moist, a red rash in irregular patches may appear on the neck and chest; and the pupils may dilate slightly.

These phenomena vary greatly in different instances, with the constitution and condition of the nerve-centres, the temperament and habits of the individual, laughing or crying or noisy struggling being the most prominent feature in many cases.

b. Second stage. - The second effect of chloroform on the nerve-centres is depression. The same parts continue to be affected by the drug, but their functions, instead of being increased or simply disordered, are first diminished, and at last completely arrested. Consciousness now ceases, with the appearance of heavy sleep. Perception and sensation are annulled: the patient sees nothing, hears nothing, feels no pain. For the same reason, reflex excitability is first diminished and then lost: irritation of any part by tickling or pinching no longer induces movements of the limbs; at last, even touching the cornea causes no reflex rolling of the eye-ball or winking of the lids.