ELE 
ELE 
ELE 
*94 
gredients form an insoluble compound ; con- 
sequently we can easily determine before- 
hand whether or not a precipitate will take 
place. __ It is from this precipitation chiefly 
that double decompositions have been de- 
termined. It is obvious that they are oc- 
casioned not by the superiority of the af- 
finity ot the ingredients which precipitate, 
but by the strong tendency which these in- 
gredients have to cohere together; the con- 
sequence of which tendency is, the exclusion 
of the other component parts, and the pre- 
cipitation of the masses as they form. It 
may be considered, then, as a general law, 
that “ whenever a salt is insoluble, the two 
ingredients which compose it, whenever they 
meet in a solution, precipitate in combi- 
nation.” For this general law we are indebt- 
ed to Mr. Berthollet. 
r l hus barytes forms an insoluble compound 
with sulphuric acid, phosphoric acid, oxalic 
acid, tartarous acid, &c. Consequently 
when a salt, whose base is that earth, is 
mixed with a salt containing any of these 
acids, a precipitation takes place consisting 
of the barytes combined with the acid. Salts 
of lime form a precipitate with oxalats, tar- 
trites, citrats, phosphats, floats, and some- 
times with sulphats. The alkaline carbonats 
occasion a precipitate in all the earthy salts, 
because all the earthy carbonats are inso- 
luble. Acetite of lead occasions a precipi- 
tate in sulphats, muriats, phosphats, muci- 
tates, See. Nitrat of silver in the muriats. 
But it would be endless to run over all the 
precipitates occasioned by the mixture of 
salts ; every person may ascertain them 
merely by observing what salts are insoluble. 
It ought to be observed, however, that the 
precipitation takes place, not because the 
salts are insoluble in water, but because thev 
are insoluble in the particular solution in 
which the precipitate appears. Now if this 
solution happens to be capable of dissolving 
any particular salt, that salt will not precipi- 
tate, even though it is insoluble! in water. 
Hence the reason why precipitates so often 
disappear when there is present in the so- 
lution an excess of acid, of alkali, &c. 
This law has been still further generalized 
by Berthollet. When different salts are 
mixed together, they separate either spon- 
taneously, or on evaporation, according to 
the order of their solubility. Those which 
are insoluble precipitate immediately on the 
mixture, and those which are least soluble 
crystallize first when the solution is evapo- 
rated. Potass forms with sulphuric acid a 
salt much less soluble than sulphat of soda. 
Hence the reason why it has been supposed 
to have a stronger affinity for sulphuric acid, 
and by analogy for acids in general, than 
soda: for if sulphat of soda is mixed with 
the greater number of the salts of potass, 
sulphat of potass is obtained by evaporation. 
But in cases where two salts are mixed 
together, the resulting salts are much influ- 
enced by the proportions of the ingredients. 
The same salts are not obtained if the in- 
gredients are mixed in one proportion, that 
would be obtained if they were mixed in an- 
other proportion. 'Ibis will appear evi- 
dently from the following experiments of 
Berthollet. 
Salts Mixed. 
Propor- 
tions. 
Precipitate. 
First Evaporation. 
Second Evaporation. 
Mother Water. 
Nitrat of lime 
Sulphat of potass 
1 
1 
Sulphat of lime 
Nitrat of potass 
Sulphat of lime 
A little sulphat of 
potass 
Little 
Ditto 
1 
o 
Ditto 
Sulphat of potass 
Sulphat of lime 
Nitrat of potass 
Sulphat of potass 
Sulphat of lime 
Very little 
Ditto 
2 
1 
Ditto 
Sulphat of lime 
Nitrat of potass 
Nitrat of potass 
A very little sulphat 
of lime 
Abundant 
Sulphat of soda 
Nitrat of lime 
i 
i 
Sulphat of lime 
Nitrat of soda 
Nitrat of soda 
Abundant 
Ditto 
Salts Mixed. 
<2 
1 
Propor- 
tions. 
Ditto 
First Evaporation, 
Ditto 
Second Evaporation. 
Ditto 
Third Evaporation. 
Abundant. 
Mother Water. 
Sulphat of soda 
Nitrat of potass 
1 
1 
Sulphat of potass 
A little nitrat of 
potass 
Nitrat of potass 
Some sulphat of 
potass 
Nitrat of soda 
Some nitrat of pot- 
ass 
Considerable 
Ditto 
2 
1 
Sulphat of potass 
Sulphat of potass 
Some nitrat of pot- 
ass 
Sulphat of potass 
Nitrat of potass 
Nitrat of soda 
Considerable 
Nitrat of potass 
Muriat of lime 
i 
i 
Nitrat of potass 
Muriat of potass 
Some nitrat of do. 
Abundant 
Ditto 
1 
2 
Muriat of potass 
Abundant 
Muriat of potass 
Nitraf of lime 
i 
i 
Nitrat of potass 
Some muriat of do. 
Muriat of potass 
Some nitrat of do. 
Abundant 
Sulphat of potass 
Muriat of magnesia 
i 
i 
Sulphat of potass 
Sulphat of potass 
Muriat of do. 
Sulph. of pot. & mag. 
Muriat of potass 
Sulph. of magnesia 
Considerable 
Ditto 
1 
2 
Ditto 
Muriat of potass 
Sulphat of potass-and- 
magnesia 
Ditto 
Ditto. 
The mother-water, or the liquid which re- 
mains when mixtures of salts are separated 
by "crystallization, always contains several 
salts, or rather their component parts, which 
are prevented from crystallization by their 
mutual action on each* other. Hence the 
quantity of this mother-water is always the 
greater, the more soluble the salts are: that 
is to say, the less disposition they have to 
crystallize. 
ELECTOR, a person who has a right to 
elect or choose another to an office, honour, 
&c. Elector is particularly, and by way of 
eminence, applied to those princes of Ger- 
many in whom lies the right of electing the 
emperor; being all sovereign princes, and 
the principal members of the empire. The 
electoral college, consisting of all the electors 
of the empire, is the most illustrious and au- 
gust body in Europe. Bellarmine and Ba- 
ronius attribute the institution of it to pope 
Gregory V. and the emperor Otho III. in 
the tenth century ; of which opinion are the 
generality of historians, and particularly the 
canonists : however, the number of electors 
was unsettled, at least till the thirteenth cen- 
tury. In 1356 Charles IV. by the golden 
bull, fixed the number of electors at seven; 
three ecclesiastics, viz. the archbishops of 
Mentz, Treves, and Cologne ; and four sc- 
