ii6 HISTORICAL INTRODUCTION TO CHEMISTRY CHAP. 



Cavendish noticed that it "was sensibly acid to the taste," 

 an observation which formed the starting-point of his 

 experiments on the composition of nitric acid, described in 

 Chapter X. The formation of acid was, however, only 

 incidental, since when no excess of oxygen was used the 

 liquid condensed after the explosion was pure water. 



Lavoisier (1777 1782) studies the burning of inflam- 

 mable air, The products resulting from the burning of 

 inflammable air were being investigated in France about 

 the same time that Cavendish was carrying out his 

 experiments in England. 



Macquer, in 1776, "having presented a fragment of white 

 porcelain to the flame of inflammable air burning quietly at 

 the mouth of a bottle, observed that the flame was not 

 accompanied by any smoke ; he found the fragment merely 

 moistened with droplets of a colourless liquid . . . which 

 he recognised ... as pure water" (Lavoisier's Works, 



II- 335)-. 



Lavoisier, who had obtained acid products on burning 

 sulphur, phosphorus, and carbon, carried out in 1777 the 

 experiment of burning inflammable air in a flask containing 

 lime-water. He found that no fixed air was produced by 

 burning the gas prepared from oil of vitriol and iron. Four 

 years later, in 1781 1782, he repeated the experiment with 

 oxygen in place of air. 



"We took a bottle of six pints, which we filled with 

 inflammable air ; we lighted it quickly, and poured into it 

 two ounces of lime-water ; we closed the bottle at once with 

 a wooden stopper, traversed by a pointed copper tube, 

 connected by a flexible pipe with a reservoir filled with vital 

 air. Contact between the inflammable air and the atmos- 

 pheric air having been interrupted by the stopper, the 

 surface of the inflammable air ceased to burn, but there 

 formed at the end of the copper tube, in the interior of the 

 bottle, a beautiful point of brilliant flame, and we saw with 

 great pleasure the vital air burning in the inflammable air, 



