the 4 t tractive Powers of Mineral Aids. 37 
lized. Mr. wenzel had alfo an eye to fuch calculation; but 
his method is much more defective. It is only this, “ To 
“ dilcover (lays he) the quantity of affinity which the nitrous 
“ acid bears to the different fubftances with which it is capable 
“ of uniting, let fmall equal cylinders of each of the metals 
“ be covered over, except at one end, with melted amber, and 
“ then expofed to equal quantities of the fame fpirit of nitre, 
“ and in the fame temperature then let the times of the folu- 
4C tion of each be noted. The affinity of the acid to each of thefe 
“ metals will be inverfely as the times neceffiary for the folution of 
66 equal quantities of them .” And as he well knew that fpirit 
of nitre, of the fame degree of concentration, would not act 
equally on each of them, he required that it fhould be diluted 
in fome cafes, and undiluted in others, and allowance to be 
made for this in the fubfequent calculation. But alkalies and 
earths are here intirely omitted ; and even as to metals no 
eonclufion can be drawn by this method. Tin and regulus of 
antimony are moft rapidly attacked by this acid, lead and cop- 
per much more flowly ; yet it is well known, that its affinity 
to lead is much ftronger than its affinity to tin, and its affinity 
to copper greater than to regulus of antimony. Silver and 
quickfilver are more (lowly diffolved, and yet the affinity of 
the nitrous acid to thefe metals, as will be feen in the fequel, 
is by far the greatefL 
Neither can this method be in anv wife applied to the eftima- 
tion of the affinities of the other mineral acids ; for though the vi- 
triolic and marine acids diffolve very flowly, difficultly, and fpa- 
ringly, feveral metals that are copioufly and readily diffolved by 
the nitrous, yet they both have a lfronger affinity to thofe very 
metals than the nitrous has to them, as is evident with regard 
to filver, mercury, and lead, which are precipitated from the 
nitrous 
