[i 5%. ] 
Bergman: In decompofing Epfom falt, he obferved that although 
45 parts of cauftic vegetable alkali were neceflary to effect the 
decompofition of 100 parts of Epfom, only 30 parts tartar vitrio- 
late could be obtained. Neverthelefs, according to his own 
determination of the compofitions of Epfom falt and tartar 
vitriolate, 82 grs. of tartar vitriolate fhould have been formed, 
for by his account 40 parts of the flrongeft vitriolic acid fhould, 
if there be a fufficiency of vegetable alkali, form 100 of tartar 
vitriolate, confequently 33 parts of that acid, which exift in 
too parts of Epfom falt, meeting with more alkali than they 
require, fhould produce 82 of tartar vitriolate, and yet only 30 
of this falt can be recovered. This Mr. Bergman. attributes to 
an excefs of alkali which prevents the remainder of the tartar 
vitriolate (viz. 52 parts) from cryflallizing; yet by his own 
account this excefs amounts only to 2 grs. for fince by him 
40 parts of the acid take up 52 of alkali, 33 parts of the fame 
acid fhould take up 42,9, and the whole quantity of alkali is 
but 45. By my determination of the proportion of ingredients 
in thefe falts this phenomenon. is more intelligible, roo parts 
Epfom contain 33 of ftandard vitriolic acid, which are equivalent 
to 29 of fuch acid as exifts in tartar vitriolate, and confequently 
fhould produce only 64,4 parts of tartar vitriolate; but 64 of 
tartar vitriolate contain but 35 of mere alkali, confequently 
10 parts uncombined alkali remain, which may poflibly embarrafs 
the cryftallization of 34 of tartar vitriolate, if fo much more 
be formed,’ which is rather doubtful, as 45 parts of cauftic alkali 
may not furnifh fuch an excefs as may be requifite to decompofe 
the laft portions of Epfom. 
Vou. IV. | I THIS 
