Fi ee] 
Tuts experiment feems a full proof of the inaccuracy of, Mr. 
Bergman’s determination of the proportion of ingredients in thefe 
two falts, Epfom and tartar vitriolate. 
Mr. Wenzel informs us that 240 grs. of his fpirit of vitriol 
were faturated by 100 of aerated magnefia, and that this folution 
furnifhed him 247 of cryftallized Epfom. 240 gers. of this mag- 
nefia he employed loft in a long continued red heat 140 grs. 
Hence he concludes the proportion in half an ounce of cryftallized 
Epfom to be 40,5 grs. of pure earth, 73,6 of the ftrongeft acid 
and 126 of water, whence 100 parts Epfom fhould contain 16,87 
of earth, 30,66 of acid and 52 of water. This refult does not 
differ much from mine, and we have already feen that 31,5 of 
his ftrong acid are equivalent to 35,3 of ftandard, confequently 
30,66 are equal to 34,3 of ftandard, and the remainder, viz. 51,13, 
is water. 
Of the Relation of the Nitrous Acid to Magnefia. 
Ff rounp that 100 parts pure magnefia take up 286 of the 
nitrous ftandard. 
Mr. Wenzel found that 77 grs. of aerated magnefia faturated 
240 of his nitrous acid, which contained 82,5 of the ftrongeft 
acid. Whence he concludes, that as this earth contains 0,417 
of its weight of mere earth, 100 parts pure earth take up 257 
of his ftrongeft acid; but if we fuppofe the aerated magnefia to 
contain 0,45 of its weight of pure earth, then 34,65 parts of it 
took 
