66 M. Berzelius m compounds 
iar case, if we should find a combination of an acid sulphate with 
a neutral one, or of a neutral sulphate with a sub-sulphate. 
However, the class of double salts, formed by strong acids, has 
not hitherto presented any instance of such a combination 
Whence it is clear, that the discovery of a double salt, analo- 
gous to these, and capable of being produced in our laboratories, 
is of great consequence, for the support it affords to the ideas 
which we have formed respecting those combinations, and to the 
formulas by which we express them. 
Artificial double salts usually contain only two salts, which 
have either the base or the acid in common. Hitherto we have 
discovered only one salt, composed of three different salts ; it is 
obtained by saturating with ammonia, the triple acid composed 
of the muriatic, sulphurous, and carbonic acids ; and, besides, 
the nature of this triple salt is uncertain, on account of the dis- 
putes which subsist with regard to the nature of its acids. In 
the mineral kingdom, on the contrary, we find a great number 
of siliciates, with triple and quadruple bases. It is plain, that 
if these triple salts are not, in fact, mere mixtures, they must be 
considered as composed of two others ; each of which allows itself 
to be again decomposed into two others, and so on to their simple 
elements. It follows, therefore, that a triple salt of this kind 
in any chemical compound, of which all the ingredients contain oxygen, the oxygen 
contained hy one of those ingredients is constantly an aliquot part of that contained 
hy each of the others. Upon this principle, combined with the Atomic theory, 
of which it forms an extension in the highest degree important to chemical 
science, M. Berzelius proposes to found a new and expeditious method of repre- 
senting the nature of compound bodies. Each radical, or elementary substance, 
is designated by the initial letter of its Latin name, whilst the dots above it indi- 
cate the number of doses which that radical contains of oxygen. Thus, the for- 
mula, Be Si 4 -(-2 A1 Si 2 signifies that (1 atom of beryllium with 3 doses of 
oxygen, or) 1 atom of glucina forms a compound with (4 atoms of silicium, each 
of which contains 3 atoms of oxygen, or with) 4 atoms of silica ; that (1 atom of 
aluminium with 3 of oxygen, or) 1 atom of alumina forms a compound with 
2 atoms of silica; and, finally, that the former of these compounds unites 
with 2 times the latter, to constitute the emerald. The second formula, 
K Si t q 8 Ca Si2, denotes that (1 atom of kalium with 2 of oxygen, or) 1 atom 
of potash forms a compound with 4 atoms of silica ; that (1 atom of calcium 
with 2 of oxygen, or) 1 atom of lime forms a compound with 2 atoms of silica f 
and that the former compound, in apophyllite, is united to 8 times the latter.- 
TR.A»SILr 
