Not long since Prof. Youmans, author of the " Chart of Chemistry," delivered a lecture in Brooklyn, on the subject set forth by the caption of this article. We intended to present a clear and brief abstract of it before this to our readers, but have not been able till now. It is a subject of great interest to every person, but strange to tell, although every person knows what alcohol is, and the various objects for which it is used, very few have a sound knowledge of its nature. The iollowing remarks of Prof. Y. no doubt present much that is new to many persons : " The accomplishment of great objects by the simplest means is the standing marvel of the universe. The chief mass of all the living beings upon the globe, vegetable and animal, is made up of but four kinds of matter four elementary substancesCarbon, Oxygen, Hydrogen, and Nitrogen. All the phenomena of life upon our planet and the appearance and disappearance of the living raceand all the changes to which they are liable depend mainly upon the properties of these four simple bodies. These combine, taking the three forms of carbonic acid, water and ammonia, and in this iiate-ftir4be plat, aMLKtWHwrted by it into living matter. The great offtse f vegetation is to convert mineral into organized substancesto impart to dead elements the property of life or vitality. It is the builder, the architect of all organization, and the great characteristic vegetable changes go forward in the leaf. The forces which produce these wonderful transmutations are solar radiations, agents which flow in all directions from the central star of our planetary system, striking upon half the globe at once, which turns incessantly to expose all parts to their action. These take effect upon the vegetable leaf. The sun has a relationship of control not only over orbs, but over afoms. Its beams possess a three-fold poweran illuminating, a heating, and a chemical power. These forces rule the ultimate atoms, decomposing carbonic acid, water, and ammonia in the leaf and regrouping their atoms into living or organized compounds. The sun is thus the perpetual creator of life upon this planet. It is the great foundation and source of those constructive powers of which the terrestrial vegetable kingdom is the theatre and effect. It affords the motive power of plants. But other things take place upon this globe beside the building up of organization. There is also decay and dissolution. The sunbeam has its antagonist, and that antagonist is the oxygen of the air. This decomposes and destroys all organized substances, by active combustion or by slow decay. It is the great destructive agentthe enemy of all organization and life. It is continually rending organic compounds asunder, and carrying back the elements from the living to the dead world. Now, as force was required to place these atoms in the organized condition, this force is given out again when the atoms return to the mineral state. Organized compounds are seats of force, by virtue of the arrangements qf their atomsthey yield up the force when the atoms pass to the inorganic condition. Thus, in burning wood under a steam boi ler, its atoms relapse into the condition of carbonic acid and water, giving out, in the shape of heat, the power which was lodged in th organized wood, and which the machine makes mechanically available. All organized substancesall matter that has been put together in the plant, is capable of returning again to the mineral state, by combustion with the production of force. All parts of animal bodies are organized but animals possess no power of forming their own organized compounds. The animal cannot consume the dead mineral earth, water and air, and convert them into nerve, muscle, and tissue. The materials for nerve, muscle, end tissue, originate in plants. They are formed alone in vegetable structures. Now. of the innumerable organized products of vegetable growth, foods are those few substances, which are so prepared by the hand of Nature, that they may be taken into the animal system, become a part of it and then gradually return to the mineral state, and thus give forth their force in the form of animal power. They must be capable of becoming part of the animal organization, and then of gradually perishing out of it in that regulated, measured, normal way, which we understand by the term " health." The agent which effects these animal decompositions and destructions, is oxygen gas of the respired air. It destroys food in the body for the production of mechanical force ; or a metal in a galvanic battery for the production of electrical or magnetic force. The composition of foods, therefore, and their attraction for oxygen, must be exactly adapted to the normal condition, powers, and purposes of the animal being. But the same agent, atmospheric oxygen, through the process of slow decay, is continually carrying back all kinds of organized matter to the mineral world. It is carried back by various routes, and by many intermediate steps, but always tends finally (except the ashes) to pass into the condition of carbonic acid, water and ammonia. These numerous routes and intermediate steps are the countless compounds that are formed in varying circumstances by the decomposing, decaying body. Wood, when decaying under various conditions resolves itself into diverse products, and sa ot all other organic compounds. Again, when organic matter, containing nitrogen, as blood, meat,cheese, bread, or milk,begins to putrify and perish, if it is added to a solution of sugar in water, the sugar takes on the same rotting condition, is destroyed, its elements regroup themselves into new compounds, the products of dissolution. One of these products is carbonic acid gasa universal result of all combustion and decaya subtle and deadly poison to all animals. Nearly one-half the sugar takes this form, and thus leaps back at one movement, to the mineral condition from which it came. The other product of this destructive change, and twin brother of carbonic acid, coming into being at the same moment and from the same source is " Aleohol." Alcohol is thus seen not to be a product of vegetable growth, its origin is not the same as the alimentary principles of food. The life creating sunbeam," the finger of God stretched across the universe," never took atoms from the mineral world, and arranged them into alcohol. We get it only by the destruction ot natural food, of wholesome aliment. It commences only when death begins. Alcohol, it is true, contains the same elements as sugar, but that does not prove that it is therefore at all similar in properties, or possesses the same relationship to the mi-ral system. All organized compounds consist mainly of the same three or four elements, but we do not hence conclude that they have all identical properties. The atmosphere consists of the same elements as aquafortis, but while the former is the vital sustainer of all lite, the other is rank poison to it. The argument thus far against the adaptation of alcohol to the purposes of food is only presumptive. It is found in bad company, it has a suspicious origin, and if it is entitled to a place and rank among the proper aliments of man, it came not in the appointed manner, but" has climbed up some other way." We must not here prejudge the question of its adaptation to alimentary purposes. Science forbids us to reason in advance of actual observation and experiment. It may only be stated now that in chemical composition and properties, and its relation to oxygen and the combustive process, alcohol differs widely from the substance whence it was derived, and from all normal alin entary compound." [In connection with this, we would add that carbonic acid gas is only a poison by inhaling it into the lungs. It is the gas expelled from the lungs which for the low combustion going on in our frames, requires the inhalation of oxygen. Mechanically speaking, the inhalation of carbonic acid instead ot oxygen, i has the same effect, as two opposing lorces meetingtheydestroy one another. We must guard against extreme views on this as on other scientific subjects, and Prot. Youmans exhibits the right spirit in this respect. If we proceed upon what are called by some "natural principles," no bachelor should boil his potatoes, aid no good housewife bake her snow white loaf of flour bread.