Formaldehyde is derived from the oxidation of wood alcohol. It is antiseptic, disinfectant, deodorant, and germicidal in its action. It may be used either in solution in water (formaline) or as a vapor. Its action seems to be specific for the destruction of lower animal and plant life, but not for the higher animals. Sulphur is a better germicide for insects than formaldehyde, and the action of the latter is simply irritant to human beings. Formaldehyde is as efficient as corrosive sublimate and penetrates more rapidly. It is too irritating as an antiseptic in general surgery, but may be used in solutions of 1:500 or 1000. Instruments can be sterilized in a solution of 1:200 formaline. It may be employed as a deodorant, and as a disinfectant for stools and sputa in 5 % solution. A solution of 1: 50 may be used for sweating feet. Clothing may be thoroughly disinfected by placing the articles in a compartment, causing a vacuum, and distilling the gas into this compartment where it penetrates thoroughly into every article. In the disinfection of rooms the gas should be admitted under pressure through the keyhole, after the room has been made practically air-tight. The gas from 150 c.c. of 40 % formaline is sufficient for each 1000 cubic feet of space. The room should be closed for twenty-four hours and before entering it a small amount of ammonia may be sprayed into the room to precipitate the formaldehyde, thus preventing the extremely irritant effects on the eyes and mucous membranes, when the room is entered.
Poisoning is very rarely reported. Large amounts internally or as douches cause toxaemia by shrivelling up the red blood cells, with the formation of haematin. There may be vomiting, purging, dyspnoea, cyanosis, and collapse. Ammonia water is the antidote.
The action of alcohol is both local and general. It is an irritant in either case; an irritant being a drug that disorders or disorganizes function, in contradistinction to a stimulant, which increases activity, thereby increasing function. Its local action is the more important, for its entire effect may be due to the local irritant action on the skin and mucous membrane, and after absorption on the endothelium of the bloodvessels or their intrinsic nervous apparatus, on the heart and skeletal muscles, on the brain and nervous system, on the organs, and on all the cellular elements of the body. It produces at first a disorderly reaction by its irritant effect, finally causing fatigue, or complete inactivity of all parts by depression, depending upon the amount taken and the condition of the individual, etc. As in the case of any other poison there is a certain reaction in the organs and their functions in attempting to get rid of the noxious element. Alcohol has great affinity for nervous tissue. The brain responds by losing its power of inhibition, thus allowing free play to the emotions, while lessening will power. At first there is a quicker response to stimuli, but finally less capacity for accurate work either mental or physical. The respirations are increased in frequency, the alcohol being oxidized rapidly, and eliminated. The heart becomes more active and forceful as a result of the dilatation of the peripheral bloodvessels, due to paralysis of the vaso-constrictors, decreasing the resistance to the action of the heart, and by paralysis of the cardiac inhibitory nerves, thus giving the cardiac acceleration full play. Small quantities of alcohol after meals may improve the digestion by irritating the mucous membrane to greater activity, but prolonged regular use, or large quantities taken at one time, especially on an empty stomach, create grave indigestion by causing a catarrhal condition of the mucous membranes. Muscular activity is increased, for a few minutes, but in a disorderly way, and is rapidly followed by fatigue. Experiments prove that alcohol in even minute quantities is detrimental to riflemen at target practice, tight-rope performers in their acts, and whenever fine adjustments of nerve and muscle are necessary. likewise it has been found to be harmful to mountain climbers, who are unable to carry on their feats of skill and endurance, to soldiers on the march, and to labor in all conditions. Theoretically alcohol is a food, saving tissue waste by taking the place of fats and carbohydrates in the production of heat and energy, but practically it is of no value. It is not a serviceable food, but an oxidizable drug, and may require more energy to overcome its irritant effects than it creates by stimulating, if it does really stimulate. Alcohol acts peculiarly by lowering body temperature and vitality, thus inviting inroads by any or all diseases that may be prevalent, or with which the person may come into contact. Its poisonous properties are thus manifested, and European studies have proved beyond a doubt that it is detrimental. It is absolutely bad for children and nervous persons.
In morbid states alcohol may be of service, as to tide over a crisis in fever, but it should never be used in case of shock, or during anaesthesia, because better remedies may be applied.
Alcohol is locally antiseptic and disinfectant, cooling, and astringent. Internally, in medicinal doses it is pre-eminently a heart stimulant, and, in a lesser degree, a diuretic, diaphoretic, and antipyretic.
When rubbed into the skin, as for the prevention of bed-sores, it disinfects and hardens it, checks the activity of the sweat glands, and irritates the cutaneous nerves, causing redness, heat, and local anaesthesia. Applied and allowed to evaporate, as in sponge baths, it has a cooling action. Coming in contact with an abraded surface it is very painful. It is absorbed by the unbroken skin. In the stomach it produces a sense of warmth, and, in moderate amount, stimulates the mucous membrane and dilates the small vessels, with the result that the blood supply is increased and the gastric secretion is correspondingly abundant.