^4< -Dr. Wollaston's Synoptic Scale 
list of substances intended to be estimated, arranged on one 
or the other side of a scale of numbers in the order of their 
relative weights, and at such distances from each other, ac- 
cording to their weights, that the series of numbers placed on 
a sliding scale can at pleasure be moved, so that any number 
expressing the weight of a compound may be brought to 
correspond with the place of that compound in the adjacent 
column. The arrangement is then such, that the weight of 
any ingredient in its composition, of any reagent to be em- 
ployed, or precipitate that might be obtained in its analysis, 
will be found opposite to the point at Vvhich its respective name 
is placed. 
In order to shew more clearly the use of this scale, the 
Plate exhibits two different situations of the slider, in one of 
which oxygen is lo, and other bodies are in their due propor- 
tion to it, so that carbonic acid being 27,54, and lime 35,46, 
carbonate of lime is placed at 63. 
In the second figure, the slider is represented drawn up' 
wards till 100 corresponds to muriate of soda ; and accordingly 
the scale then shews how much of each substance contained 
in the table is equivalent to 100 of common salt. It shews, 
with regard to the different views of the analysis of this salt, 
that it contains 46,6 dry muriatic acid, and 53,4 of soda, or 
39,8 sodium, and 13,6 oxygen; or if viewed as chlorid of 
sodium, that it contains 60,2 chlorine, and 39,8 sodium. With 
respect to reagents, it may be seen that 283 nitrate of lead, 
containing 191 of litharge employed to separate the muriatic 
acid, would yield a precipitate of 237 muriate of lead, and that 
there would then remain in solution nearly 146 nitrate of soda. 
It, may at the same time be seen, that the acid in this quantity 
of salt would serve to make 232 corrosive sublimate contain- 
