io6 CLASSICS OF MODERN SCIENCE 



The liquor condensed in the globe, in weight about thirty grains, 

 was sensibly acid to the taste, and by saturation with fixed alkali, and 

 evaporation, yielded near two grains of nitre; so that it consisted of 

 water united to a small quantity of nitrous acid. No sooty matter 

 was deposited in the globe. The dephlogisticated air used in this 

 experiment was procured from red precipitate, that is, from a solution 

 of quicksilver in spirit of nitre distilled till it acquires a red colour. 



As it was suspected, that the acid contained in the condensed liquor 

 was no essential part of the dephlogisticated air, but was owing to 

 some acid vapour which came over in making it and had not been 

 absorbed by the water, the experiment was repeated in the same 

 manner, with some more of the same air, which had been previously 

 washed with water, by keeping it a day or two in a bottle with some 

 water, and shaking it frequently; whereas that used in the preceding 

 experiment had never passed through water, except in preparing it. 

 The condensed liquor was still acid. 



The experiment was also repeated with dephlogisticated air, pro- 

 cured from red lead by means of oil of vitriol ; the liquor condensed 

 was acid, but by an accident I was prevented from determining the 

 nature of the acid. 



I also procured some dephlogisticated air from the leaves of plants, 

 in the manner of Doctors Ingenhousz and Priestley, and exploded it 

 with inflammable air as before; the condensed liquor still continued 

 acid, and of the nitrous kind. 



In all these experiments the proportion of inflammable air was 

 such, that the burnt air was not much phlogisticated ; and it was ob- 

 served, that the less phlogisticated it was, the more acid was the 

 condensed liquor. I therefore made another experiment, with some 

 more of the same air from plants, in which the proportion of in- 

 flammable air was greater, so that the burnt air was almost completely 

 phlogisticated, its standard being i-io. The condensed liquor was 

 then not at all acid, but seemed pure water; so that it appears, that 

 with this kind of dephlogisticated air, the condensed liquor is not at 

 all acid, when the two airs are mixed in such a proportion that the 

 burnt air is almost completely phlogisticated, but is considerably so 

 when it is not much phlogisticated. 



In order to see whether the same thing would obtain with air pro- 

 cured from red precipitate, I made two more experiments with that 



