-60 and 1866, it prepared the way for
those events. One of its chief merits was that it brought Italians of
different classes and provinces together, and taught them to work in
harmony for the overthrow of tyranny and foreign rule.

BIBLIOGRAPHY.--Much information on the Carbonari will be found in R.M.
Johnston's _Napoleonic Empire in Southern Italy_ (2 vols., London,
1904), which contains a full bibliography; D. Spadoni's _Sette,
cospirazioni, e cospiratori_ (Turin, 1904) is an excellent monograph;
_Memoirs of the Secret Societies of Southern Italy_, said to be by one
Bertoldi or Bartholdy (London, 1821, Ital. transl. by A.M. Cavallotti,
Rome, 1904); Saint-Edme, _Constitution et organisation des Carbonari_,
P. Colletta, _Storia del Reame di Napoli_ (Florence, 1848); B. King,
_A History of Italian Unity_ (London, 1899), with bibliography.
(L. V.*)

CARBONATES. (1) The metallic carbonates are the salts of carbonic acid,
H2CO3. Many are found as minerals, the more important of such naturally
occurring carbonates being cerussite (lead carbonate, PbCO3), malachite
and azurite (both basic copper carbonates), calamine (zinc carbonate,
ZnCO3), witherite (barium carbonate, BaCO3), strontianite (strontium
carbonate, SrCO3), calcite (calcium carbonate, CaCO3), dolomite (calcium
magnesium carbonate, CaCO3.MgCO3), and sodium carbonate, Na2CO3. Most
metals form carbonates (aluminium and chromium are exceptions), the
alkali metals yielding both acid and normal carbonates of the types
MHCO3 and M2CO3 (M=one atom of a monovalent metal); whilst bismuth,
copper and magnesium appear only to form basic carbonates. The acid
carbonates of the alkali metals can be prepared by saturating an aqueous
solution of the alkaline hydroxide with carbon dioxide, M.OH + CO2 =
MHCO3, and from these acid salts the normal salts may be obtained by
gentle heating, carbon dioxide and water being produced at the same
time, 2MHCO3 = M2CO3 + HO2 + CO2. Most other carbonates are formed by
precipitation of salts of the metals by means of alkaline carbonates.
All carbonates, except those of the alkali metals and of thallium, are
insoluble in water; and the majority decompose when heated strongly,
carbon dioxide being liberated and a residue of an oxide of the metal
left. The alkaline carbonates undergo only a very slight decomposition,
even at a very bright red heat. The carbonates are decomposed by mineral
acids, with formation of t