[ 68 
Hence, firft, roo parts pure mineral alkali faturated with 
vitriolic acid fhould afford about 511 of chryftallized Glauber. 
SECONDLY: reo parts of this cryftallized falt contain’ 19,58 
of alkali, 24,62 of the ftrongeft acid, and 55,8 of water. 
Tue principal defeét of thefe experiments’ is, that he dried | 
his alkali by fufion in an earthen crucible, by reafon of which 
the alkali took up both filiceous and argillaceous earth’; the fili-_ 
ceous, indeed, was precipitated during the faturation with the 
acid, but the argillaceous was not, but on the contrary took up 
more of; the acid than the pure alkali would have done. Hence 
he found a {maller proportioniof alkali, and would a larger of 
acid, than the pure falt contains, if he had not forced off part 
of it by the heat of ignition to which he afterwards expofed 
‘the falk. 
Ir Mr. Wenzel had not exprefsly averred that he proceeded 
exactly in making this experiment as he had done in examining 
the contents of tartar of vitriolate, I fhould fufpect he had done 
no more than faturate the alkali, and thence inferred the pro- 
portion of: the ftrongeft acid contained in the dry’ falt. For the 
quantity of this ftrongeft acid contained in the quantity of fpirit 
of vitriol expended is almoft exa¢tly in the fame proportion as he 
found it in forming tartar vitriolate. In that cafe he found 
218,75 grs. of his fpirit of vitriol to contain 69 of the ftrongeft 
acid, and in the prefent cafe he found 285,33 grs. of the fame 
{pirit of vitriol to contain go. Now 218,75.69:: 285,33-90. 
And this proportion could not be found unlefs the red heat was 
Vou. IV. E equal 
