Absolute alcohol has a strong affinity for water. It absorbes moisture from the air rapidly, and thereby becomes gradually weaker; it should therefore be kept in tightly-stoppered bottles. When brought into contact with animal tissues, it deprives them of the water necessary for their constitution, and acts in this way as an energetic poison. Considerable heat is disengaged when alcohol and water are brought together; if, however, ice be substituted for water, heat is absorbed, owing to the immediate and rapid conversion of the ice into the liquid state. When one part of snow is mixed with two parts of alcohol, a temperature as low as 5.8∞ F. below zero is reached. When alcohol and water are mixed together the resulting liquid occupies, after agitation, a less volume than the sum of the two original liquids. This contraction is greatest when the mixture is made in the proportion of 52.3 volumes of alcohol and 47.7 volumes of water, the result being, instead of 100 volumes, 96.35. A careful examination of the liquid when it is being agitated reveals a vast number of minute air-bubbles, which are discharged from every point of the mixture. This is due to the fact that gases which are held in solution by the alcohol and water separately are less soluble when the two are brought together; and the contraction described above is the natural result of the disengagement of such dissolved gases. The following table represents the contraction undergone by different mixtures of absolute alcohol and water. TABLE II.--100 VOLUMES OF MIXTURE AT 59∞ F. ========+============++========+============++========+============ Alcohol.|Contraction.||Alcohol.|Contraction.||Alcohol.|Contraction. --------+------------++--------+------------++--------+------------ 100 | 0.00 || 65 | 3.61 || 30 | 2.72 95 | 1.18 || 60 | 3.73 || 25 | 2.24 90 | 1.94 || 55 | 3.77 || 20 | 1.72 85 | 2.47 || 50 | 3.74 || 15 | 1.20 80 | 2.87 || 45 | 3.64 || 10 | 0.72 75 | 3.19 || 40 | 3.44 || 5 | 0.31 70 | 3.44 || 35 | 3.14 || | ========+============++========+============++========+============ Alcohol is termed "absolute" when it has been deprived of every trace of water, and when its composition is exactly expressed by its chemical formula. To obtain it in this state it must be subjected to a series of delicate operations in the laboratory, which it would be impossible to perform on an industrial scale. In commerce it is known only in a state of greater or less dilution.