VOL. LXXII.j PHILOSOPHICAL TRANSACTIONS. 26 1 



gr. of copper require about 182.714 gr. of real vitriolic acid to dissolve them. 

 Ao-ain, 100 gr. of copper, when dissolved in the vitriolic acid, retain only as 

 much phlogiston as is contained in 3 cubic inches of nitrous air, that is, 0.2 of 

 a grain; therefore, since 100 gr. of copper give out 4.52 of phlogiston, the 

 vitriolic acid strips it of 4.52 — 0.2, that is, 4.32 gr. of phlogiston. 



3dly. To dissolve 70 gr. of copper in the vitriolic acid, to the greatest advan- 

 tage, 20 more must be slightly dephlogisticated ; therefore, to dissolve 100 gr. 

 of copper in this acid, 28.6 more must be slightly dephlogisticated. 8 grs. of 

 this slightly dephlogisticated calx afforded 4 cubic inches of nitrous air ; there- 

 fore, 28.6 would afford 14.3, which contain O.Q58 gr. of phlogiston; but 28.6 

 gr. of copper, before any dephlogistication, contain 1.2Q2 gr. of phlogiston ; 

 therefore, they lose by this slight dephlogistication 0.344 of a grain of phlogis- 

 ton. Hence, when 100 gr. of copper are dissolved in the vitriolic acid, the 

 quantity of phlogiston expelled is 4.32 + 0.34 = 4.66 gr. 



4thly. The quantity of inflammable air afforded by the most advantageous 

 solution of 100 gr. of copper in the vitriolic acid, is 11 cubic inches, which 

 amount to 0.385 of a grain of phlogiston. 5thly. The solution of 100 gr. of 

 copper in the vitriolic acid afforded over mercury 75.71 cubic inches of air; but 

 of this only 1 1 cubic inches were inflammable air, the remainder therefore was 

 vitriolic acid air, amounting to 64.7 1 cubic inches. 6thly. Then the whole 

 quantity of phlogiston expelled during the solution of 100 gr. of copper in the 

 vitriolic acid, is 4.66 gr. ; of this inflammable air contains but 0.385 of a grain: 

 the remainder therefore, which consists of 4.275 gr. must be contained in the 

 64.71 cubic inches of vitriolic air ; therefore, 100 cubic inches of vitriolic air 

 contain 6.6 gr. of phlogiston, and 71.2 gr. of acid, and 100 cubic inches of this 

 air weighing 77.8 gr., 100 gr. of this air contain 8.48 gr. of phlogiston and 

 91.52 of acid. 



Of the quantity of phlogiston in sulphur. — This I endeavoured to find by esti- 

 mating the quantity of fixed air produced during its combustion. To the top of 

 a glass bell, which was open, I firmly tied and cemented a large bladder, destined 

 to receive the air expanded by combustion, a quantity of which generally escapes 

 when this precaution is not used. Under this bell, which contained about 3O00 

 cubic inches of air, I placed a candle of sulphur, weighing 347 gr- ; its wick, 

 which was not consumed, weighed half a grain : it was supported by a very thin 

 concave plate of tin, to prevent the sulphur from flowing over during the com- 

 bustion, and both were supported by an iron wire, fixed on a shelf in a tub of 

 water. As soon as the sulphur was fired with a very feeble flame, it was covered 

 with the bell, the air being squeezed out of the bladder. The inside of the bell 

 was soon filled with white fumes, so that the flame could not be seen. In an 

 hour after, the fumes thoroughly subsided, and all was cold. The water rose 



