212 ON ATMOSPHERIC FHENOMENA. 



temperature of the air always precedes vain : water then h 

 dissolved by the air, or lather associated with the composi- 

 tion of the air by the intervention of caloric in the state of 

 A fourth of the electricity, and this in so large a quantity, that it forms al- 



weightofthe most a f ou ,. t h f the weight of the atmosphere. I give in 



atmosphere . ° ' ft 



•wing to water, the paper, to which I have alluded above, the facts and ex- 

 periments on which this calculation is founded ; but these 

 facts are not very numerous, and almost all synthetical, that 

 is of addition, or composition, and but {"aw analytical, or 

 of subtraction or decomposition ; the air being of all known 

 bodies that which has the greatest affinity for water to a cer- 

 tain point of saturation, of which there are very many de- 

 grees, and very distinct, from the nature of the affinity that 

 limits them; so that, without decomposing it, we can 

 scarcely separate the water from it, partly, no doubt, on 

 account of the form of the air, which it faithfully preserves, 

 and which prevents us from retaining it to separate it. And 



Difficulty of the difficulty of synthetical experiments depends on this, 



the synthetical +1 . • • *.i_ a 1 j • -^ 



'its that, in removing the water by decomposing it, we cannot 



prevent the air itself from being decomposed with respect 

 to its oxigen, all the processes we must employ for this pur- 

 pose being of the disoxigenizing kind, not excepting the 

 electric fluid, which determines the condensation of oxigen 

 by azote. Nothing then is more difficult, than to obtain, 

 for the purpose of synthetical experiments, air deprived of 

 Best method of its water to a certain point; and the method, that has suc- 

 ^g r vingauof ceeded best for this purpose, is the disengagement of mu- 

 riatic gas from a very dry muriate, by means of highly con- 

 centrated sulphuric acid, in confined air. 

 Causes of mis- I need not observe to you^ how many mistakes in deter- 



takes in deter - m j n j the proportions of oxigen in burned substances must 



mining the *..'••■ 1 • 



proportion of have arisen from the great quantity ot water, that makes 



oxigen tn sub- p ar t f the air, which becomes solidly fixed in these sub- 

 stances, and serves as an indispensable medium of the com- 

 bination of oxigen with the bodies it burns. To this large 

 quantity of water in the air are owing those spontaneous 

 and heavy rains, which frequently fall in an atmosphere, 

 that was perfectly serene and tranquil a moment before. 

 Caloric proper The caloric, that under its different forms is incessantly 

 to t e soar agceiK ]- in o- i n the air, without ever returning to the Earth, 



being 



