NATURE AND DTiCOMPOSITION OF THE FIXED ALKALIS. 3X1 



bustioi), but this could not materially affect the re-ult; and 

 when such a preciiu tion was not used, an explosion generally 

 took place from the vaporization and decomposition of the 

 film of naphtha surrounding the globule. 



After the combustion, the absorption of gas was ascer- 

 tained, by opening the lower point of the tube under water 

 or mercury. In some cases the purity cf the residual air 

 was ascertained, in others the alkali formed in the tray was 

 weighed. 



From several experiments on the synthesis of potash by Two syntheti- 

 combustion, I shall select two, which were made with every ^.^enT'^^" 

 possible attention to accuracy, and uader favourable cir- ash selected. 

 cumstances, for a mean result. 



In the first experiment O'liiof a grain ofthebasis were em- 1st expeil- 

 ployed. The combustion was made upon platina, and was ^^^^' 

 rapid and complete; and the basis appeared to be perfectly 

 saturated, as no disengagement of hidroj^en took place, 

 when the platina tray was thrown into water. The oxigen 

 gas absorbed equ'^lled in volume 190 grain measures of 

 quicksilver; barometer being at 29*6 inches, thermometer 

 62° Fahrenheit; and this reduced to a temperature of 60" 

 Fahrenheit, and under a pressure equal to that indicated 

 by 30 niches*, would become 186-67 measures, the weight 

 of which would be about -0184 grain troyf; but •0184: 

 M384 : : 13-29 : 1^0; and according to this estimation 100 

 parts of potash will consist of 86'7 basis, and 13*3 oxigen 

 nearly. 



In the second experiment '07 grains of the basis ab- 2d experirr,ent. 

 gorbed at temperature 6.3° of Fahrenheit, and under pres- 

 sure equal to 30*1 barometer inches, a quantity of oxigen 



* In the correction for tempcature, the estimations of Dalton and 

 Gay Lussac are taken, which make gasses expand about 4-g-o of the pri- 

 mitive volume for every degree of Fahrenheit. 



+ From experiments that I made in 1799, on the specific gravity of 

 oxigen gas, it would appear, that its weight is to that of water as 1 to 

 748, and to that of quicksilver as 1 to 10142. Researches CAew.and Phil. 

 p. 9; and with this estimation, that deducib'e from the lafi accurate re- 

 searches of Mc'-srs. Allen and Pepys on the Combustion of the Diamond 

 almost precisely agrees, Phil. Trans. 1307, poge 275 j or our Journal, 

 vol. XIX, p, 22^, 



equal 



