[ 204 ] 



pure trona fhould take up but 27,91, or nearly 28, whereas here it 

 takes up 34, which is owing to its retaining but a fmall portion of 

 water during its cryftallization. 



Hence alfo we find the proportions in Mr. Keir's efflorefced but 

 dry foda, for he tells us, that 100 grains of fuch foda were faturated 

 by 90 grains of vitriolic acid, whofe fp. grav. was 1,800 ; now this 

 acid differs infenfibly from the tabular, whofe fp. grav. is 1,807, 

 which contains 75,89 real acid, confequently 90 grains of this acid 

 contains 71,9 real acid ; and fince 127,68 real vitriolic acid take up 

 100 of mere foda, 71,9 (hould take up 56,31 ; and as 60 of mere 

 foda take up 40 of fixed air, 56,31 fhould take up 37,53, the fum 

 of both is 93,84, then the remainder of the 100, that is 6,16 

 parts, are water, which remained as it was not dried by ignition. 



Mr. Keir alfo found that 100 parts of an impure Indian foflil 

 alkali contained as much real alkali as 58,8 grains of the above 

 efilorefced and dry foda, and were faturated by 53 grains of the 

 vitriolic acid 1,800. Now, from the proportions above ftated, it 

 will be feen that 58,8 of his foda contain 33 11 of mere alkali, 

 and that 53 grains of the acid contained 40,22 of real acid, and 

 that thefe fliould faturate,and thereby indicate 31,5 of mere alkali, 

 which differs from his refult by 1,61 grains #. 



Lastly, the proportions affigned to cryftallized tartarin and to 

 cryftallized foda, and alfo the proportions of mere tartarin and 



mere 



* Tranf. of the Society of Arts and Manufadlures. Vol. 6, p. 130, &c. 



