2 Dr. Wollaston's Synoptic Scale 
titles of various reagents that may be employed for discover- 
ing the quantity of sulphuric acid, (8) how much barytes, ( 9 ) 
carbonate of barytes, or (lo) nitrate of barytes, would be 
requisite for this purpose; (ii) How much lead is to be used 
in the form of (12) nitrate of lead; and when the precipitate 
of (13) sulphate of barytes or (14) sulphate of lead are 
obtained, it will be necessary that he should also know the 
proportion which either of them contains of dry sulphuric 
acid. He may also endeavour to ascertain the same point by 
means of (15) the quantity of pure potash, or ( ib) of carbo- 
nate of potash requisite for the precipitation of the copper. 
He might also use (17) zinc or (18) iron for the same pur- 
pose, and he may wish to know the quantities of (19) sulphate 
of zinc, or (20) sulphate of iron that will then remain in the 
solution. 
These, and very many more questions of the same kind, 
which it would be tedious to specify, and needless to enume- 
rate, engage the thoughts, and will occupy much of the time 
of every experimental chemist, unless he can have recourse 
to some record of former analyses on which he can depend. 
The scale, which I am about to describe, is designed to 
answer at one view all these questions, with reference to most 
of the salts contained in the table, not merely expressing 
numerically the proportions by which the desired answers 
may be calculated, but directly indicating the actual weights 
of the several ingredients, contained in any assumed weight 
of the salt under consideration, and also the actual quantities 
of several reagents that may be used, and of the precipitates 
that would be obtained by each. 
In the formation of this scale, it is requisite in the first place 
