ELECTIVE ATTRACTION. 
ed, or in solution. The magnesia is of 
course jjisengaged : and half a bracket, with 
the point downward, is placed over it, to 
denote, that it falls to the bottom, or is 
precipitated. 
III. The above instances exhibit simple 
elective attractions : but this method is 
more particularly applicable to the com- 
pound attractions. For example: Sup- 
pose a solution of the muriat of potash be 
added to sulphat of lime, no decomposition 
will take place. This is expressed as un- 
der : 
f" Potash 
Muriat of J 
potash 1 
Muriatic 
L acid 
Sulphuric' 
acid 
Sulphat 
” of lime 
Lime 
The want of horizontal brackets in this 
scheme denotes, that the prhiciples pre- 
sented to each other do not unite, and, con- 
sequently, that no decomposition ensues. 
IV. On the contrary, if sulphat of pot- 
ash be presented to the muriat of lime, a 
mutual decomposition will ensue. Thus, 
Muriat of potash 
Sulphat 
of pot- 
ash 
Potash 
Sulphuric 
acid 
Muriatic' 
acid 
Lime J 
Miuiat 
of lime 
Sulphat of lime 
In this scheme we see, that the principles 
presented to each other do unite, as is 
shown by the horizontal brackets, and form 
the new compounds, muriat of potash and 
sulphat of lime ; the former of which re- 
mains in solution, as is shown by its bracket 
being turned iipward ; while the latter, 
being nearly insoluble, falls down, and is 
accordingly denoted by a bracket, the point 
of which is turned downward. 
V. By attentively observing this last 
scheme, it may be seen, that the attractions 
exerted between the simple substances, 
which are placed over each other, are the 
quiescent affinities, and tend to preserve 
the original combinations ; whereas the at- 
tractions between the simple substances 
which stand opposite to each other are the 
diveUcnt affinities, and tend to produce 
new combinations. If we could determine 
numerically the simple attractions, it is 
evident, that we might foretel every result 
which might be produced by the application 
of compound substances to each other, un- 
der like substances ; as may be shown by 
applying Morveau’s numbers to the pre- 
ceding scheme. 
Muriat of potash 
A 
Sulphat I 
of pot-;j 
ash. I 
f Potash „ Muriatic^ 
acid 
62 23=85 
j Sulphuric — 
L acid 
Sulphat of lime 
Muriat 
of lime 
The attraction between the potash and 
sulphuric acid is expressed by the number 
62 : and the attraction between the muria- 
tic acid and lime is expressed by the num- 
ber 23. These are the quiescent affinities, 
and their sum 85 expresses the tendency 
to preserve the original forms of sulphat 
of potash and muriat of lime. On the other 
hand, the attraction between the potash 
and muriatic acid is expressed by 32, and 
the attraction between sulphuric acid and 
lime by 54. The sum of 32 and 54 amounts 
to 86, and expresses the divellent affinities, 
which tend to produce new combinations. 
And as this last sum exceeds the sum of 
tlie quiescent affinities, it follows, that the 
double decomposition will take place. 
VI. These examples have designedly 
been taken the reverse of each other; but 
every instance, singly exhibited, does in 
fact point out both the affirmative and the 
negative propositions. Thus, from the facts 
first exhibited, that magnesia does not de- 
compose the combination of potash and sul- 
phuric acid, it likewise follows, that potash 
does compose the combination of sulphuric 
acid and magnesia. And accordingly, in the 
last two schemes of double affinity, it is 
clearly ascertained, from the mutual de- 
composition of sulphat of potash and muriat 
of lime, that the muriat of potash and sul- 
phat of lime w ill not decompose each other. 
The same horizontal bracket, which in 
the humid way was used to denote solution, 
is used to denote sublimation in experi- 
ments in the dry way. 
The following schemes from Bergman 
will require no explanation, after the in- 
stances we have exhibited. 
