HYGROLOGY, AND ITS CONNECTION WITH METEOKOLOGT. 303 



29. I answered, in the Annales dt Chimie, to every part of Answered by 

 Mr. Berthollet's objections ; and neither himself, nor any other theau:Li>r. 

 -experimental philosopher, has ever replied ; while, on the con- 

 trary, many have abandoned the fundamental part of that theory, 



(the composition oi water: and indeed, one of its first inventors, rpj^g compo- 

 with whom, having seen his experiments, I had acquiesced in sition of water 

 his conclusion, and fos- a tim.e maintained it, I mean Dr. Priestley, on^orksLst 

 made me himself abandon it, on account of new chemical re- supporters, 

 suits obtained in his experiments, which he opposed to Mr. 

 Berthollet. 



30. I have been induced. Sir, to give you this abstract of a We are too 

 work little known in England, in order the more to fix (he ^^''^ipj"''"" 

 attention of natural philosophers on the hygrometer, of which theses, 



I have thus proved the importance-in natural science. It is 

 difficult to abstain from making theories on the first phenomena 

 we observe of a new kind, or from admitting those which ap- 

 pear probable to us ; and I have said above, that I had at first 

 acquiesced in that of the composition of water : but by the pro- 

 gress of experiments, new facts are discovered, and correct the 

 theories too soon admitted. My long study of every branch 

 of meteorology, being united with the experiments related ia 

 this paper, which indeed were directed to that object, have de- 

 monstrated to me this great point in natural philosophy — that it 

 is impossible to attribute rain to a moisture actually existing 

 in the atmosphere 5 which alone entirely refutes the new che- 

 micaltheory. Moreover, al! the experiments on the combina- 

 tions of gasses with other bodies concur to show, that the pon- 

 derable part of these fluids is water. Lastly, in the above men- 

 tioned work I proved, as I have done succinctly. Sir, in my paper 

 publishedinyour Journal for December, 1810, that, when we 

 consider the atmospheric air as an aeriform fluid, though never 

 mixed but with a very small quantity of aqueous vapour, all 

 the atmospheric phenomena are explained. 



I may conclude^ therefore, that meteorology makes an 

 essential part of natural philosophy, and that it is not so ob- 

 scure as it is commonly thought. 



I have the honour to be. 

 Sir, 

 Your obedient, humble Servant, 



J. A. DE LUC 

 ^''indsor. 



