WATER. 



Hydrogen gas, even at a red heat, has no aftion upon to the neighbourhood of volcanoes, but generally their 

 Iter. Charcoal, when cold, does not decompofe it. But caufe is very obfcure, as we can hardly form any idea of 



agents operating for fuch a length of time, and fo uniformly, 

 as thofe of neceflity mull do which give origin to the phe- 

 nomena in queftion : all we can infer is, that although local, 



water , _ 



when red-hot charcoal is brought in contaft with water, 

 carbonic acid and carburetted hydrogen are formed in 

 abundance. Sulphur and phofphorus do not appear to be 

 capable of decompofing water, even when affilled by heat; 

 but potaffium and foduim, and doubtlefs alfo the metallic 

 bafes of the alkaline earths, decompofe it rapidly. Of the 

 other metals, iron, zinc, antimony, and tin, decompofe it, 

 when affifted by heat, Silver, gold, copper, and platina, 

 produce no efFeA upon it. 



Water diffolves the alkalies and alkaline earths. The acids 

 alfo, and many faline compounds, are foluble in this fluid ; 

 but it is incapable of dilTolving the earths properly fo called. 

 Water combines with bodies in two different ways. It 

 either diffolves them, in which cafe the proportion of water 

 is unlimited, or it combines with them, and forms fohd 

 compounds, termed hydrates, into the compofition of which 

 the water enters m a definite proportion. The metallic 

 hydrates, in general, are remarkable for the briUiancy of 

 their colours. They are more foluble in acids than the 

 oxyds, and in fome ijiftances affeft the organs of tafte even 

 more perceptibly than the metallic falts. This fubjeft has 

 been particularly inveiligated by M.Prouft. See Hydrate. 

 According to the lateft and moft perfea experiments, 

 water is compofed of two volumes of hydrogen gas, and 

 one volume of oxygen gas. Hence, its combining- weight 

 or atom will be 1.125, oxygen being reckoned i ; or, if 

 vre confider the fpecific gravity of hydrogen gas to be 

 .6944, and of oxygen gas i.iiil, it is compofed of 



they are deep-feated and permanent. 



2. Atmofpherk ylir : jl'z.ote. — -AH natural waters of a 

 mean temperature hold a portion of common air in folution. 

 The quantity, however, has been ftated by Bergman not to 

 exceed Vjth of the bulk of the water ; and even this can 

 only be retained at a mean temperature, and under the ordi- 

 nary prefTure of the atmofphcre, for the greater part of it 

 efcapes under the air-pump, or on fubmitting the water for 

 a fliort time to a temperature of 212° or 32°. It is the 

 oxygen contained in this fmall portion of atmofphcric air, 

 retained by water, that fupports the refpiration of filhes, and 

 other aquatic animals, which fpeedily die from fuffocation in 

 water deprived of air. It is this air alfo, as before obferved, 

 which renders water fapid and grateful to the palate ; for 

 by boiling or diflillation, this fluid is rendered infipid and 

 difagreeable, " and has long been in difrepute," fays Dr. 

 Saunders, " for lying heavy on the llomach, and even pro- 

 ducing Icrofnlous tumours and obilructions." The pre- 

 fence of atmofpheric air in water is eafily accounted for, 

 from the affinity which fubfin;s between the two fubltances, 

 and which is fuch, that they foon become mutually impreg- 

 nated by being expofed to each other. — Azotic gas has 

 been found to exift in fmall quantity in fome waters, and in 

 thefe inftances it has been obferved to be extricated from 

 the fpring itfelf in union with the water. As far as is at 

 part~by weio-ht of^hydrogen, and eight parts by weight of prefent known, this gas imparts no medicinal or even fenfible 

 oxygen. The union of o.-iygen and hydrogen gafes to form property to the waters_contaming it 



water is attended by the extncation of much hght and heat. 

 See Combustion and Detonation. 



Waters, Natural. " Water," fays Dr. Saunders, " is 

 found throughout the earth in every degree of purity, ex- 

 cept the higheft;, for fuch is never procured, except by arti- 

 ficial difl;il!ation, as all natural \\-aters are confl;antly coming 

 into contaft with fome fubftance which they can either dii- 

 folve or hold fufpended." Waters to which the epithet 

 mineral is applied, in many inftances diff'er from other natural 

 waters in the degree only in which they are impregnated with 

 fimilar foreign fubftances : in other inftances, they diff'er in 

 the nature of the impregnating ingredient ; but for the 

 moft part they diff'er in both thefe circumftances. In pre- 

 fenting our readers with an account of natural waters in 

 general, we fliall commence with an enumeration and (hort 

 account of the different foreign ingredients ufually met 

 with in waters, and influencing their operation on the animal 

 economy. 



1. Caloric. — The temperature of natural fpring-waters is 

 the fame, in general, as the mean annual temperature of the 

 particular place in which they occur. It is evident, there- 

 fore, that this temperature muft vary with the latitude. 

 (See the articles Climate, Temperature, &c.) Waters 

 rarely occur of a temperature much lower than the mean 

 annual temperature of the latitude in which they are found ; 

 but inftances are met with in every part of the globe in 

 which they occur of a higher temperature. This degree 

 of increafed temperature is very different in different in- 

 ftances. Commonly it is not very ftriking, while in other 

 cafes it is very remarkable : thus, the waters of Carlfbad, in 

 Bohemia, have the extraordinary temperature of 165°. In 

 this country, the hotteft fprings are thofe of Bath and 

 Buxton, the higheft temperatures of which are ftated to be 

 116° and 82" refpeftively. In fome inftances, thefe devia- 

 tions from the natural temperature are obvioufly referrible 



3. Carbonic Acid. — This gas is likewife ftated by Berg- 

 man to exift in greater or lefs quantity in all natural fpring- 

 waters. The limits in which it occurs is faid to lie between 

 about -l^, and- an equal bulk of the water. In mineral 

 waters it is a moft important ingredient, not only from its 

 operation upon the animal economy, but from its being the 

 folvent of various other aftive ingredients. When waters 

 contain this principle in excefs, they affume a bright and 

 fparkling appearance to the eye, have an agreeable pungent 

 acidulous tafte, and fometimes exert a kind of intoxicating 

 power when largely drunk. Fiflies are unable to exift in 

 them, and fpeedily die from fuffocation. On expofure to 

 the air, however, thefe properties in a ftiort time become 

 fenfibly diminiflied, and at length almoft totally difappear, 

 owing to the feparation of the gas — an operation which 

 may ftill more fpeedily be effefted by boiling. The pre- 

 fence of this gas in water is eafily explained, from its natural 

 affinity to that fluid. In almoft every inftance it is extri- 

 cated from the fpring in union with the water ; but the 

 fource from whence it is derived is, in general, obfcure and 

 inexplicable. 



4. Hydrogen and its Compounds, carburetted, fulphuretted, 

 and phofphuretted Hydrogen. — Hydrogen gas is barely folu- 

 ble in water, and probably, therefore, never exitts alone 

 in that fluid. The lame is true of carburetted hydrogen. 

 Both thefe gafes, however, are often extricated from waters, 

 efpecially when ftagnant, and containing organic fubftances 

 in a ftate of putrefaftion. Sulphuretted hydrogen is a fre- 

 quent ingredient in mineral waters, and gives them fo cha- 

 rafteriftic a feature, that they arc inltantly recognized. 

 Waters holding this gas in folution hai-e an offenfive fmell, 

 like that of rotten eggs, or a foul gun. barrel, and which is 

 more or lefs ftrong, according to the degree m which they 

 are impregnated. Such waters alfo have a tafte fomewhat 

 fweetifh, and they generally appear turbid. Water, at a 



mean 



