Water

WATER. - I. A. IN THE SCIENCES. - Every form of life, including human life, unfolds in an aqueous environment. Some animals, such as jellyfish, contain more than 95% water; even in the human organism the quantity of water is considerable and diminishes with the progress of development and senescence: 97.5% in the embryo of a month and a half, 82.9 in the four-month fetus, 71.2 in the newborn, 64.5 in the adult, 58.3 in the old. All the chemical reactions of the organism take place in water; and even the respiration of terrestrial animals, man included, is made possible insofar as the oxygen of the air dissolves in the aqueous film that bathes the pulmonary alveoli or other surfaces that perform a similar function (v. HOCITUTICA, REPUTAZIONE). Interesting are the mechanisms by which living beings appropriate the water contained in the environment, defend themselves from excessive loss of water, and those by which they repeatedly exploit the same mass of water for the transformation of considerable quantities of organic substance. Large quantities are in fact required for the various vital functions: for the formation of one kg. of dry organic substance plants need from 500 to 700 liters of water, and for the formation of the chick the limited quantity of water contained in the egg is exploited innumerable times.

Knowledge of the physical and chemical properties of water is important not only for chemistry and biology but also for the entire economy of our planet, for explaining its geological history and its present geophysical aspect. The erosion of eruptive rocks, the formation and subsequent transformations of sedimentary rocks, the phenomena of the troposphere and many others are linked to the presence and action of water; and to water, as the food of man, the condition of life of plants and a means of river and maritime communication, are linked the distribution of life on earth and the formation, migration and cultural development of human groupings.

The water molecule is constituted by an atom of oxygen bound to two atoms of hydrogen which form with the former an angle of 104°31'. In this combination the hydrogen atoms take on a positive character, that of oxygen a negative character, so that the molecule presents an electrical polarity which, together with more complex reasons of a quantum-mechanical order, is the cause of the association among molecules and ultimately of some very important and singular anomalies in the physical properties of water, which will be recalled here.

Water has a density (1.000) notably lower than that which it should have (ca. 1.84) depending on its molecular radius (1.40 A; one Angstrom = 1/100,000,000 of a cm.) if its structure were not associated but were that of ideal monatomic liquids. And it is a general rule that the volume of bodies diminishes as the temperature falls and in the passage from the liquid state to the solid one. Water too contracts on cooling but only down to 4°; continuing the cooling it expands slightly until solidification, which is accompanied by a notable increase in volume: 100 vol. of water at 0° (dens. 0.099868) yield ca. 109 of ice at 0° (dens. 0.91697). These facts are explained: 1) by the formation, through cooling, of polymer molecules (associations of two or more simple molecules) at the expense of the monomer (or simple) ones; 2) by the existence of a crystalline structure even in ordinary liquid water; 3) by the particular crystalline structure of liquid water and of ice by reason of which the molecules, in associating into crystalline groupings, assume a wider arrangement, that is, come to occupy a greater volume. From this derives a consequence of great importance in nature: the ice that forms on seas and lakes, being lighter than water, does not fall to the bottom but remains at the surface; and being a poor conductor of heat it prevents the freezing of the water beneath: thus the solidification of immense masses of water is avoided and marine and lacustrine life is made possible below the crust of ice. When water freezes in a confined environment it can develop strong pressures capable even of bursting steel bombs several centimeters thick: thus is explained the action of frost in producing the crumbling of rocks.

Water crystallizes in the hexagonal system (v. CRISTALLI): groups of star-shaped crystals are observed in snow.

It is calculated that if water did not give molecular associations but had the constitution of ideal liquids it should melt at — 130° and boil at — 100°; at ordinary temperatures liquid water could not exist and all the water of our planet, instead of being found in the seas and rivers, would constitute the greatest part of the atmosphere. Also the values of specific heat (close to

1.00 for all ordinary temperatures), of the latent heat of fusion (79.2 at 0°), of the latent heat of evaporation (595 at 0°, 585 at 20°, 574 at 40°, 540 at 100°) (v. TERMOLOGIA; UNITÀ FISICHE) are higher than the respective quantities of almost all inorganic and organic substances. This must be attributed not so much to the associated state of the molecules as to the exceptionally low value of the molecular weight of w. (18.016). In fact the same quantities referred to the gram-molecule, which are obtained by multiplying the specific ones (expressed in cal/g or Cal/kg) by the molecular weight, are entirely normal when compared with those of other substances. Because of the high values of the specific heat and of the latent heats of fusion and evaporation, w. is a great thermal regulator of the surface of our planet. The high value of the surface tension of w. (7.692 mg/cm at 0°, 7.086 at 40°) together with the capacity to adhere to the surface of many bodies (to wet) is important in geology and in biology for the phenomena of imbibition, capillarity, swelling, etc.

W. has been chosen as the reference substance in the definition of certain physical units (v.).

The particular mode of association of its molecules justifies in part the high value of the dielectric constant of w. (88 at 0°, 80.5 at 20°, 73.4 at 40°, 70.5 at 50°). This constant (v. ELETTROLOGIA) represents by how much the force of attraction of two electric charges of opposite sign is reduced when w. is interposed in place of a vacuum (practically of air), and it is present in the denominator in the classic formula of Coulomb. The high value of this constant explains the strong ionizing power of w.: salts, acids and bases dissolved in it undergo electrolytic dissociation into a cation (or positive ion) and an anion (or negative ion). In turn these ions, precisely because of their electric charge and the polarity of the molecules of w., become hydrated, that is, they bind themselves more or less loosely or energetically to an indeterminate number of molecules of w.; and the ions thus hydrated take on certain characteristics of w. itself: this explains the high solvent power of w. for the great majority of substances, especially of a saline nature. W. is a good solvent also of many non-ionizable substances, and this is explained by the presence in the molecule of these substances of:

1) partially polar bonds; 2) an asymmetric distribution of electric charges; 3) groupings that react with w. forming polar bonds: all circumstances that favor the formation of associations between the molecules of the solute and those of the solvent.

Besides being ionizing as a solvent, w. is itself ionized: a liter of w. at 22° contains 10⁻⁷ gram-molecules of w. dissociated according to the equation H₂O ⇌ H⁺ + OH⁻; and since a liter of w. contains 1000: 18 = 55.6 gr. mol., it follows that there is one dissociated molecule per half billion molecules (0.556·10⁹). At 6° the dissociation of w. is 1.3 and at 100° about 8 times that measured at 22°. To this dissociation, however modest, must be attributed the capacity of w. to take part in many chemical reactions, some of which are fundamental for life. W. in fact is not only an essential constituent of living cells in every form of life but also participates, no less than the other constituents, in wonderful biophysical and biochemical reactions. The imposing process of carbon fixation by green plants (v. FOTOSINTESI CLOBOFILLIANA) is accomplished with the intervention of w., whose oxygen is eliminated as gaseous molecular oxygen while the hydrogen of the same reduces carbon dioxide CO₂ with the formation of w. and of a series of intermediate products still (1948) poorly known, from which carbohydrates (starch and sugars) are ultimately formed. W. also participates in the phenomena of oxidation-reduction that constitute cellular respiration.

Ordinary w. is a mixture of ca. 5000 parts of w. H₂O and one part of "heavy w." D₂O: the latter differs from the former in having in place of hydrogen of atomic weight 1 an isotope of it, heavy hydrogen or deuterium, of atomic weight 2 (it will be more exact to say, however, that ordinary w. is a mixture of ca. 5000 parts of w. H₂O and 2 parts of water HDO in which one atom of oxygen is united to one of hydrogen and one of deuterium). The content of heavy w. in natural waters is not uniform. Heavy w. has been obtained in a state of purity: it has density (d 20°/20°) 1.10714, boils at 101.42°, solidifies at 3.82° and has its maximum density at 11.6°.

Cesco Toffoli

2. IN NON-CHRISTIAN RELIGIONS

W., which by its natural property serves to cleanse every filth, was chosen from the most remote times, among all peoples, as a symbol of an inner purifying action. The mystery of its origins within the bowels of the earth, its voice now gentle and now powerful, its mobility like that of a living thing, its breath revealing itself in evaporation, its power of irrigation, whether it gushes from the earth or falls from the sky, have always caused it to be considered a living and beneficent power. It is present in various forms: in the sea, in lakes, in rivers or torrents, and all these elements have been deified and honored with worship; but especially w. that springs from the soil - called by Seneca (Quaest. nat., 3, 8) "viva seu nativa" to distinguish it from that which falls from the sky, "caelestis seu collectiva" - has risen to a sacred and at the same time cathartic, fertilizing and divinatory value among the various peoples.

As a fertilizing element, w. has everywhere been an object of worship. The Greeks expressed this power in various myths, where the nymphs, patronesses of springs, signify, by their very name, its power of fertility. As a divinatory element, w. acts both through the murmur of springs and through the casting of objects into it and through ingestion: at Delphi, the Pythia, before ascending the tripod, tasted the w. of the sacred springs Castalia and Cassotis. The divinatory power was revealed especially in cases of ordeal or "judgment of God," when it was a question of judging the guilt of an accused person, the legitimacy of a birth, etc. The safety of the individual thrown into the w. was a proof of his innocence.

As a purifying element, water has no equal in its capacity not only to wash but also to carry away impurities by flowing. Naturally, the number and manner of ablutions vary in the different ceremonials, according to the nature of the fault or the preparation required to approach or touch sacred things, to receive an initiation, etc. It is precisely water, in baptism, that is the matter which symbolically expresses the spiritually renewing power of Christian initiation, the cancellation of the stain of original sin and possibly of actual sins. A particular case of the purifying power of water is that represented by health-giving or thermal waters, discussed below.

As a giver of oblivion, and therefore in its own way a healer, water also has a large place in the myths of the afterlife: one need only think of the water of Lethe (whence the word lethargy) which grants the utmost oblivion at the entrance to Hades. The location of the underworld (where rivers and lakes are not lacking), situated in distant places reached by means of boats, may have been suggested by the experience of primitive navigation on rivers beyond the horizon's limit or on the boundless sea. Nicola Turchi

3. HOLY WATER

It is the most common sacramental (v.) of the Catholic liturgy. Moses (Num. 19:9-18) prescribed it mixed with the ashes from the burning of the sacrifice for sin, to cleanse anyone touched by legal impurities. Once worship was established in Jerusalem, the water of the pool of Siloam served for the sacred uses of the Temple.

As for Christian liturgical use, a distinction must be made between the water that today serves exclusively for conferring baptism, prepared on the eve of Easter and Pentecost with the infusion of the oil of catechumens and of chrism (baptismal water), and simply blessed water (holy water), which the Church commonly uses, preparing it with a mixture of salt while appropriate prayers are recited. This mixture of salt, a symbol of incorruptibility, was inspired not so much by the biblical fact of the prophet Elisha (II Kings 2:20-21) who healed the waters of Jericho with salt, as by the widespread belief that salt was endowed with a power repelling demons (A. Franz, I, p. 133).

The preparation of holy water, according to the prescriptions of the Roman ritual, involves: a) an exorcism over the salt and the water to purify them from every impure or harmful influence; b) a blessing over both, so that the salt "may be for all who taste it health for soul and body" and the water "may receive the power of divine grace to drive out demons, to heal diseases, so that whatever in the homes and places of the faithful has been sprinkled with this water may be preserved from every defilement and freed from every evil."

The present formulas were already contained in the liturgical books at the end of the 7th century (Gelasian Sacramentary, III, 75-76; L. Muratori, Lit. Rom. Vet., I, 738-40), except that of the mixture ("Commixtio, etc.") introduced after the 9th century.

The use of holy water is attested in the East as early as the 3rd century, though the Greek Church in blessing it always excluded salt. In the West its existence is not clearly established before the 6th century, the time of the oldest redaction of the Liber Pontificalis. This attributes its institution to a decree of Alexander I (105-106?): "Hic constituit aquam sparsionis cum sale benedici in habitaculis hominum" (Lib. Pont., ed. L. Duchesne, I, 127). The decree is certainly apocryphal. It is difficult to believe that the Church in the 2nd century appropriated a pagan use so characteristic, in which Tertullian and other Fathers saw magic. But later, when Christianity had by then imposed itself on the masses, it could allow that the in itself innocuous use of lustral water be sanctified, like so many others. In any case, holy water was at first blessed in homes for their purification; later the rite was performed in churches for analogous purposes. For example, Pope Vigilius in 538 assumes it as a necessary element for consecrating a new church. The seventh Roman Order of the same period (cf. M. Andrieu, Les Ordines rom., I: Les Manuscrits, Louvain 1931, p. 168) permits that on Holy Saturday the faithful take from the baptismal font the same water, consecrated with chrism, to sprinkle in homes and fields. Later this was expressly forbidden; and it was permitted only to draw some before the priest had infused the chrism into it, as the rubric of the Roman missal still prescribes. The Latin Church still makes very wide use of holy water, especially in exorcisms and in the blessing of persons and things. Its employment is regulated by the norms indicated in the Roman ritual. A solemn blessing of water, in memory of the baptism of Jesus, is performed on the day of Epiphany (Jan. 6) by the Greek Church. In the past it was also performed in many Latin churches in southern Italy, in Magna Graecia, on the Venetian coast, at Aquileia and in Rome itself (cf. C. Respighi, La bened. sol. dell'a. nell'Epifania, in Rass. Greg., 10 [1911], p. 54). In general the formulary adopted for this function in most of the aforementioned churches had nothing in common with the official text of the Byzantine Church. Wilmart (in Rev. Bénéd., 29 [1912], p. 29), who published an ancient recension of it (9th-10th centuries, for the use, it seems, of an Italian church), points out the characteristic epiclesis contained in it: "Tu Jordanis aquas sanctificasti hodie, e coelo mittens Spiritum tuum Sanctum... Tu ergo, piissime Rex, adesto nunc per adventum Sancti tui Spiritus et sanctifica aquam istam." The blessing concluded with the Te Deum.

A particular holy water, prepared with salt, wine and ashes, is prescribed by the Roman Pontifical for sprinkling with a sprig of hyssop the external and internal walls of a church in the solemn rite of consecration. In rituals after the year 1000 this water is called Gregorian, perhaps because St. Gregory alludes to it in his famous letter to St. Augustine of Canterbury: Aqua benedicta fiat, et in eisdem fanis aspergatur (Epist., IX, 71). But St. Gregory does not state which elements entered into its composition. The Gelasian Sacramentary (I, 78; cf. L. Muratori, Lit. Rom. Vetus, I, 610) for the dedication of a new church contains a formula for blessing the mixture of water with wine; but it says nothing at all about the other two elements, salt and ashes. All three, however, appear in liturgical use in the Ordo dedicationis ecclesiae published by G. Bianchini (Anast. Bibliot. Opera, t. III) according to a codex of the Capitular Library of Verona written around 830. It represents the pure Roman rite. The blessing of Gregorian water is reserved to the bishop.

Mario Righetti

4. HEALTH-GIVING WATERS

An old medical interpretation, still followed by many historians of medicine, sees in lustral rites so many precepts of hygiene, veiled by religion, whereas in fact they must be considered as ritual acts, having the purpose of restoring the lost state of purity.

Therefore many times they coincide with precepts today defined as hygienic. Water, in these rites, has the principal role: one need only recall the baths in rivers and springs, found in all civilizations and all religions. A spring had to exist in the Asclepieia; it was the water sacred to the god, an essential condition for healing. Very numerous shrines, small temples, votive altars, etc. were built near spring sources, especially of mineral waters, endowed with particular therapeutic virtues. This is the point of transition between the recognition of the natural virtues of water and its sacralization.

When Christianity arrived, the cult of health-giving waters could not be uprooted from the mentality of the masses, who continued always to flock to certain springs and fountains, or to use, for curative purposes, this or that water once sanctified by this or that deity. Since this practice could not be abolished, the original reason for its beneficial effect was changed; to the ancient health-giving waters a new power was attributed, arising from the proximity of the bodies of martyrs, from miraculous events connected with them, etc.

Adalberto Pazzini