WAT

WAT

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the moment of congelation the plugs werethrown out with a hiffing noife to a dis-tance of 300 or 400 feet, while a column ofice rofe at the fame time through the fufe holeto the heighth of feveral inches : when the plugwas fecured by ftrong fprings fo as to renderit aim oft impoffible to force it out, the fhellitfelf burft with a fudden crack, and two thinplates of ice forced their way at the fame timethrough the aperture. The greateft differenceobferved in thefe experiments between the bulkof water before and after congelation, was: 174:184.

Water, under the ordinary atmofpheric pref-fure, is converted into fleam, at 212 0 of tem-perature, and by fo doing it expands to about1800 times its former bulk: the elaftic forcewhich it thus acquires is very confiderable, andconftitutes the moving power of that moft im-portant machine, the fleam engine. Steamreadily and entirely condenfes into water as itcools, and it is in this way, that is by diftilla-tion, that pure water is obtained ; for the moftdelicate chemical ufes, the diftillation muff becarried on in glafs veflels, and even with everypoflible precaution it is by no means eafy toobtain this fluid of abfolute purity.

It does not appear that mere heat is capableof effecting any change in water, for fleam maybe paffed through a red hot glafs tube, and be con-denfed at the other end again into pure water.

A confiderable alhnity fubfifts between waterand atmofpheric air; for if this fluid recentlydiftilled be expofed for a few days to the air,and afterwards be boiled or fubjefted to theaction of the air-pump, a confiderable quantityof bubbles of gas will be difengaged ; there Hillhowever remains a portion combined with thewater which it is very difficult to get rid ofeven by long boiling.

Oxygen gas is abforbed by water in preference'to atmofpheric air, and by means of ftrongagitation and preffure, according to the experi-ments of M Paul, of Geneva, 100 cubic inchesof this fluid may be made to take up 50cubic inches of oxygen gas, 33 cubic inchesof hydrogen and 66 cubic inches of car-buretted hydrogen. Water thus highly chargedeffervefces when the extraordinary preffureis taken off, and in this ftate has been ufedas a medicine. Any other of the permanentgaffes may in like manner be combined withwater, as we have mentioned when treating ofthefe fubftances. For the proportions of differ-ent gaffes which water at the common preffureis capable of taking up, fee the article Gas,

Water is capable of combining with and difc.folving the acids, the alkalies and alkalineearths, and all the compound falts; with feve-ral of thefe fubllances it unites in two propor-tions, forming in one cafe a folid, and in theother cafe a fluid compound; thus if calcinedgypfum, or barytes, or lime, orfulphat of foda,are mixed with a certain proportion of water,the refulting mafs is quite as folid as before,and during this firft combination a quantity ofheat is conftantly extricated, but if to the faltsthus faturated more water is added, folutiontakes place, and cold is generated. From thisfolution the fait may again be in moft cafesprocured, by evaporation and cooling, in a cryf-talline form, in winch, though folid, it is (tillfaturated with water : this proportion of waterappears to be neceffary to the cryilalline formof the fait, and hence is ufuaily called its waterof cryfallization ; by a dry heat it is driven offand the fait alone remains in a pulverulent oramorphous ftate.

A confiderable affinity fubfifts between waterand alcohol: if determinate bulks of thefe twofluids be mixed together, the refulting mafswill be found to have a fpecific gravity fuperiorto that of the mean of the ingredients, anda fenfible degree of heat will be difengagedduring mixture: there appears however to beno point of mutual faturation, as they will com-bine together in all proportions. Refins andmoft other fubftances infoluble in water, butfoluble in alcohol, are precipitated from theirfolution by the addition of this latter fluid;as on the other hand all falts that are folublein water but not in alcohol are precipitated bymeans of this from their watery folution.

Ether and water are capable of uniting intwo different proportions. If equal bulks ofthe two fluids are fnaken together, and thenallowed to reft for a few feconds, the mafs willdivide into two diftinil liquids, of which theupper and lighter is ether holding a little water,and the lower and denfer is water combinedwith a little ether. That ether faturated withwater is chemically different from pure ether,appears from its being able to diffolve caout-chouc, which this fluid when pure is incapableof doing.

None of the fimple combuftibles appear to befoluble in water, nor haw they any markedaction on this fluid at the common tempera-ture. Even at a much higher heat hydrogenand (team exert no mutual a£tion on eachother. The effect of hot melted fulphur onwater is dubious, and that of phofphorus has