WATER. 211 



In this account of the composition of water, as a matter of conven- 

 ience, the synthesis has been given before the analysis, while the re- 

 verse order would have seemed more natural. The synthesis was, 

 however, first discovered, although in every instance of obtaining hy- 

 drogen for the experiment, it must have been preceded by an actual, 

 although unknown analysis of water. 



In 1776, Macquer and De la Fond, at Paris, burned a jet of hy- 

 drogen, and observed that drops of water were condensed from it on 

 a white China saucer, which was not soiled, and in the following 

 year, a similar experiment was made by Bucquet and Lavoisier, who 

 could not satisfy themselves as to what was produced, but ascertained 

 that it was not carbonic acid. 



In the spring of 1781, Mr. Warltire and Dr. Priestley fired the 

 mixed gases, but the water produced was supposed to be accidental, 

 or to have been merely deposited from a state of suspension. 



In the summer of the same year, and afterwards, more particular- 

 ly in 1783, Mr. Cavendish burned hydrogen on a large scale, and 

 proved that the product was water ; an opinion which had been be- 

 fore entertained by Mr. Watt, and communicated to Dr. Priestley 

 and to De Luc. Mr. Cavendish, without any knowledge of Mr. 

 Watt's opinion, had drawn the same conclusion, and is therefore the 

 discoverer of the composition of water. Among the innumerable ex- 

 periments which have confirmed this result, that made by Fourcroy 

 and his companions, is worthy of particular commemoration ; the 

 gases were kept burning more than a week, 37500 cubic inches were 

 consumed, and fifteen ounces of pure water were obtained precisely 

 equal in weight to that of the gases employed. 



The decomposition of water was first effected, understandingly, by 

 Lavoisier, in 1783, by passing the steam of water over ignited iron; 

 the increase of weight in which, added to the weight of the hydrogen 

 gas obtained, precisely equalled that of the water decomposed. The 

 iron is found to be in the same condition as if it had been burned in 

 oxygen gas or common air, it being a protoxide. 



WATER. ITS PROPERTIES. 



1. It absorbs spontaneously, a small quantity of air, which escapes 

 by the action of the air pump, or by boiling, and in the Torricellian 

 vacuum. Water absorbs oxygen, rather than nitrogen from the air ; 

 water that has been exposed to the air, contains over 31 per cent, of 

 oxygen ; this fits water to support the life of fishes, and gives it pun- 

 gency and vivacity to the taste. The air obtained by ebullition from 

 rain water, contains 32 per cent, of oxygen ; that from snow water 

 34.8, but if the atmosphere be excluded during its melting, it is near- 

 ly free from air ; this is not contradictory, for during the freezing of 

 water, the air is expelled, and is again absorbed when it melts. When 



