8 
Dr. Wollaston's Synoptic Scale 
numerous combinations which it forms with other bodies. But, 
though in the present table of Equivalents, I have retained the 
same unit, and have taken care to make oxygen equally pro- 
minent for the same reason as before, as well as on account 
of the important part it performs in determining the affinities 
of bodies by the different proportions in which it is united to 
them ; nevertheless the real measure, by which most bodies 
are compared to each other, in any experiments that I have 
made, and to which I have, in fact, endeavoured to find equi- 
valents, is a determinate quantity of carbonate of lime. This 
is a compound, that may be regarded as most distinctly neu- 
tral. It is most easy to obtain in a state of uniform purity ; 
most easy to analyse (as a binary compound); it is a most 
convenient measure for the powers of acids, and affords the 
most distinct expression for the comparative neutralizing 
powers of alkalies. 
The first question, consequently, to be resolved is, by what 
number are we to express the relative weight of carbonic acid, 
if oxygen be fixed at lo. It seems to be very well ascer- 
tained, that a given quantity of oxygen yields exactly an equal 
measure of carbonic acid by union with carbon ; and since the 
specific gravities of these gases are as lo to 13,77,* 20 
to 27,54, weight of carbon may be justly represented by 
7,54, vvhich, in this instance, is combined with 2 of oxygen 
forming the deutoxide, and carbonic oxide being the protoxide 
will be duly represented by 17,54. 
Carbonic acid having consequently been assumed as 27,54, 
it follows froth the analysis of carbonate of lime, which by heat 
loses 43,7 per cent, of acid, and leaves 56,3 of base, that they 
♦ Biot and Arago 1,1036 : 15196 : ; 10 : 13,77. 
