428 JAMES WATT. 
phenomena, and exhibits changes of properties which 
imply the notion of composition. ‘The numerous obser- 
vations at Hales; the successive discoveries of carbonic 
acid by Black, of hydrogen by Cavendish; of nitrous 
acid, of oxygen, of muriatic acid, of sulphurous acid, and 
of ammonia by Priestley, definitively banished the old 
idea of there being a unique and elementary air; that 
being among the almost constantly false conceptions haz- 
arded by people, who have the audacity to think them- 
selves called upon, not to discover, but to guess the course 
of nature. 
Amidst so many remarkable incidents, water had still 
preserved its character as an element. The year 1776 * 
was at last signalized by one of those observations that 
were to lead to the upsetting of this general belief. It 
must be acknowledged that we must also assign the same 
year for the singular efforts made by the chemists, not to 
surrender to the natural results of their experiments. 
The observation of which I wish to speak belongs to 
Macquer. 
That judicious chemist having placed a white porcelain 
saucer over the flame of hydrogen gas which was burning 
tranquilly out of the mouth of a bottle, remarked that 
this flame was not accompanied by any smoke properly 
so called ; that it deposited no soot ; that the part of the 
saucer which was licked by the flame was, on the contrary, 
evidently covered by small drops of a fluid resembling 
water, and which, after verification, was found to be pure 
water. This was certainly a singular result. Observe 
carefully, it was in the midst of the flame, on that part of 
* It was in this year, 1776, according to Priestley, that Volta fired 
i: flammable air by the electric spark: the experiment of Macquer 
appears to have been made two years afterwards.— Translator. 
