Page:The American Cyclopædia (1879) Volume IV.djvu/512

500 CHLORAL CHLORALUM in the early stages of the operation ; later the temperature must be gradually raised until the liquid boils. The reaction is represented by the formula C a H.O + 801=O s HCl s O + 5HCl. If dilute alcohol be employed instead of the abso- lute, no chloral is formed, but in its stead alde- hyde, acetic acid, and hydrochloric acid ; hence the necessity of using absolute alcohol. It is also difficult to prevent the formation of other com- pounds, especially chloride of carbon, which serve to contaminate the chloral and render its administration dangerous. Chloral is also pro- duced by the direct action of chlorine on alde- hyde, also on starch or sugar. Chloral is a limpid, colorless, oily liquid, with a fatty taste and a strong caustic smell, producing lachry- mation. Its specific gravity is 1'502, and it boils at 95 C., and can be distilled unchanged. It dissolves sulphur, phosphorus, bromine, and iodine, and combines directly with water to form a hydrate. A little chloral put into a moist flask deposits star-shaped crystals of the hydrate on the sides. It changes after a time into a porcelain-like mass called metachlornl, which is insoluble, though isomeric with the liquid form. It can be reconverted into chloral by distillation. The white metachloral is in- soluble in alcohol and ether, as well as in water, but by contact with water it is gradu- ally converted into the crystallized hydrate of chloral. Fuming nitric acid converts chloral into trichloracetic acid. An alcoholic solu- tion of potash converts chloral into formiate of potash and chloroform. Chloral is closely allied to aldehyde ; it reduces silver from the ammonia nitrate solution, and forms crystalline compounds with ammonia and the acid sul- phites of the alkalies. Nascent hydrogen con- verts it into aldehyde. If chloral be mixed with one equivalent of alcohol, white transpar- ent hydroscopic crystals of chlornl-alcoholate are formed. This compound has different prop- erties from the hydrate of chloral, and ought not to be mistaken for it. Chloral combined with one equivalent of water forms a crystal- line mass, now popularly known under the name of chloral hydrate. According to Dr. Squibb, when the water of hydration is in ex- cess, or when solid compounds of hydrate of chloral and water are put up, the substance is deliquescent, or even melts in Warm weather, and a very slight excess of water manifests it- self very soon by some degree of deliquescence. Whether in a cake or crystal, it is now very generally put up slightly deficient in water of hydration ; that is, the chloral is not fully sat- urated to a hydrate, which gives the best pro- duct for preservation. Accurately, hydrated chloral crystallizes at about 48 to 49 C. (118-4 to 120'2 F.). A little ammonia may be added to prevent acid reaction, and all acid hydrate of chloral should be rejected. The hydrate of chloral is readily dissolved by water, alcohol, ether, oil of turpentine, benzole, bisulphide of carbon, and the fixed oils. When equal parts of camphor in small pieces and hydrate of chloral in crystals are allowed to stand in a flask, they form a clear solution. The analysis of chloral hydrate is accomplished by measur- ing in a graduated tube the amount of chloro- form liberated by a given quantity of potash. The enormous production of chloral hydrate has led to an investigation of its possible applica- tion in the arts and of uses for the incidental products accompanying 'its preparation. The precious metals are easily reduced by chloral hydrate and caustic alkalies. A large quantity of hydrochloric ether appears as a by-product in the manufacture of chloral, and is applied to the preparation of ethyl ammonias. A mixture of hydrate of chloral with three times its weight of fuming nitric acid is allowed to stand in the direct sunlight for three or four days until red fumes no longer appear ; it is then dis- tilled at a temperature of 194 C., and the pro- duct is found to be pure trichloracetic acid. Chloral hydrate was brought forward as an anrosthetic and hypnotic by Dr. Otto Liebreich in 1869. In the presence of alkalies chloral hy- drate is decomposed into chloroform and formic acid ; the latter unites with the alkali. The decomposition is supposed by Liebreich to take place in the blood, and the chloroform which is thus set free acts in the usual manner. This is almost the only example of an d priori discov- ery of a useful drug, and it is therefore to be re- gretted that the chemical evidence of such a transformation as that just indicated actually taking place in the blood is not more complete. Chloral hydrate, or as it is very frequently call- ed chloral, has proved to be a valuable addition to the materia medica, although it cannot re- place chloroform or ether as a surgical anaes- thetic. It produces when acting favorably a quiet and natural sleep, although in rare cases no effect is observed from ordinary doses, and in some instances delirium arises from it. The average dose is from 15 to 80 grains. More than 30 grains at once has sometimes produced alarming symptoms. Death has resulted from still larger doses. It is a drug which should always be administered with caution, even in small doses. It is used to procure sleep in wakefulness from various causes and in many nervous diseases, as insanity, delirium tremens, neuralgia, tetanus, and strychnia poisoning. It is said that the use of chloral as a narcotic without medical advice is becoming a not in- frequent habit. Properly administered, it will produce sleep, diminish sensibility and irrita- tion, relax spasmodic action, and contract the arterioles of the system. Improperly used, it will retard the pulse, alter the blood globules, lower the temperature, and produce anaesthesia, muscular relaxation, and death. It should al- ways be given largely diluted with water. The solutions of chloral hydrate in gum water, sirup, &c., undergo spontaneous decomposi- tion, and become dangerous. The tinctures and anodynes kept on sale should be avoided. CHLORALUM, a trade name given by Prof. John Gamgee to the hydrated chloride of alu-