136 WATER. 



State of composition with other bodies. Its most simple 

 state is that of ice, and the difference between liquid water 

 or vapour and ice, is merely that water contains a larger 

 portion of caloric than ice, and that vapour is combined with 

 a still greater quantity than water. However long we boil a 

 fluid in an open vessel, we cannot make it in the smallest de- 

 gree hotter than its boiling point, for the vapour absorbs the 

 caloric, and carries it off as fast as it is produced. It is 

 owing to this, that all evaporation produces cold. An ani- 

 mal might be frozen to death in the midst of summer, by 

 repeatedly sprinkling ether upon him, for its evaporation 

 would shortly carry off the whole of his vital heat. Water 

 thrown on burning bodies acts in the same way ; it becomes, 

 in an instant, converted into vapour, and by thus depriving 

 them of a large portion of their caloric, the fire, as we term 

 it, is extinguished. Vapour occupies a space eight hundred 

 times greater than it does when in the form of water, and 

 the expansive force of steam is found by experiment to be 

 much greater than that of gunpowder. There is reason to 

 believe that, in time, steam may be applied to many useful 

 purposes of which at present we have no idea. 



Hydrogen is the base of the gas which was formerly called 

 inflammable air, and when in the aeriform state, it is the light- 

 est of all ponderable things. If you put a quantity of filings 

 of zinc into a vessel which has a glass tube adapted to it, 

 and then pour upon them sulphuric acid {oil of vitriol) di- 

 luted with six or eight times its quantity of water ; an effer- 

 vescence will immediately take place, the oxygen of it will 

 become united to the n>etal, and the hydrogen gas will be 

 disengaged, and may be conveyed by the glass tube into any 

 proper receiver. While it is rushing through the tube, it 

 may be kindled with a taper, and it will burn with a long 

 flame like a candle. In the burning of the gas, the hydro- 

 gen unites with the oxygen of the atmosphere, and the result 

 of the combination is flame and water. It has been sup- 

 posed that the torrents of rain, which generally accompany 

 thunder storms, may arise from a sudden combustion of hy- 

 drogen and oxygen gases by means of lightning. Hydrogen 

 gas is only one fourteenth of the weight of atmospheric air, 

 and occupies a space fifteen hundred times greater than it 

 possessed in its aqueous combination. It is continually 

 emanating from vegetable and animal matters during their 



