Mineral Subftance from New South Wales. , n 
precipitated by water; and, after repeated diffolutions and 
precipitations, it appears to have buffered no decompofition or 
change. 
Spirit of nitre, added to the faturated folution, makes no 
precipitation; and if the quantity of nitrous acid exceeds, or 
at leaft does not fall much fhort of, that of marine acid in the 
folution, the mixture buffers no precipitation from water. Nor 
does any precipitation happen, though the nitrous fpirit be 
previoufy mixed with even a large quantity of wafer; provided 
the quantity of folution added to it does not exceed that of the 
nitrous fpirit im the mixture. The appropriate menftruum for 
this fubftance (that is, for keeping it in a ftate of dilute folu- 
tion) appears therefore to • be aqua regia; and the due propor- 
tions of the two acids, of any given ffrength, might be deter- 
mined, if neceffary, with greater accuracy and facility for 
this than for any other body I know of; becaufe, if there be 
even a very minute furplus of marine acid in the folution, 
that furplus will inffantly betray itfelf on dropping a little into 
water, all that was diffolved by it, and no more, being preci- 
pitated by the water. It may be oblerved, j however, that 
where an addition of nitrous acid is ufed, a faturated folution 
cannot be obtained (unlefs by fubfequent evaporation), the fame 
quantity of marine acid being neceffary with as without that 
addition: the change, or modification, which the nitrous acid 
produces in the marine, ferves, in the prefent inftance, not for 
effeding the folution, as in the cafe of gold and fome other 
metals, but merely for enabling it to bear water without depo- 
futing its contents. 
Oil of vitriol, dropped into the faturated marine folution, 
occafions no change till its quantity comes to be about equal to 
that of the folution j a confiderable effervefcence and heat are 
then i 
