Glycerine is commonly called glycerol or glycerin. It is a sweet-tasting alcohol that is colorless and odorless. It becomes a gummy paste when frozen, although freezing it can only be achieved at very low temperatures. It melts at 18 degrees Celsius and boils at 290 degrees Celsius. Its chemical formula is C3H8O3. It is miscible in water and alcohol. However, it does not mix with oil. It is an excellent solvent. In fact, there are substances that dissolve better in glycerol than in water or alcohol.
The compound absorbs water from the air. This is why it is known as a hygroscopic substance. Suppose you leave a container of pure glycerine or glycerol in open air, it will become diluted as it attracts water molecules. According to a speculation, a drop of this liquid in the tongue can raise a blister because it would draw out water from deep into the tongue tissue. But this remains a clever speculation.
The sweet-tasting alcohol is found in many skin moisturizing lotions and creams because of the water-retaining and water-absorbing capacity. Thus, it softens and smoothens the skin. It is believed, however, that this substance has other beneficial properties aside from simply moisturizing and attracting water molecules.
The compound originates from fats and oils. In fact, molecules of fat contain glycerol. One way to extract it from fats or oils is through saponification – a chemical reaction involving a fat and an alkali. This chemical reaction produces soap. Soap-making is a common source of this trihydric alcohol under discussion.
Extraction of glycerine from soap-making only began in 1889. Before this time, people did not know how to recover the compound. The only way to produce the compound is through candle-making using animal fats. In the year mentioned, an effective way to isolate glycerol from soap was at last discovered and later utilized. During this time and a few decades after, much of the compound went to production of nitroglycerin – a compound derived from glycerol used to make dynamites and explosives. During World War II, soap industry was not able to suffice the huge demands for the chemical. Hence, synthetic production was implemented.
The production, separation and purification of glycerol involve a tedious process. When lye (sodium hydroxide) reacts with fat, soap is produced but is in mixture with glycerin. Homemade soap does not run through intricate procedure, thus, the soap mixture contains all the glycerol that results from the reaction. Commercial soap-makers, however removes the compound from the mixture by adding salt. Salt curdles the soap, which is seen to float on top of the mixture. The floating soap is then scooped out or skimmed. This leaves the organic chemical with some impurities such as partially dissolved soap and extra salt. The trihydric chemical is then finally taken out of the mixture through distillation. It does not end here because further impurities are removed by passing the chemical into a charcoal filter or using bleaching techniques. The final product is a highly concentrated and colorless glycerin.
History has seen the making of the compound into explosives. However, it is never explosive in itself. It has to be changed into nitroglycerin first before it becomes explosive. Furthermore, nitroglycerin is not only used in explosives but is found as a medication for heart disease.
The compound has many uses. It is a preservative for fruits and food products. Lotions and creams contain this chemical as an emulsifying and moisturizing agent. In hydraulic jacks it serves as antifreeze. The antiseptic qualities of this chemical make it valuable in biological laboratories such as to preserve specimens in jars. Moisturizing soaps contain the compound. These soaps are usually clear and are easy to make.