cetate
(Pb(C_{2}H_{3}O_{2})_{2}) is the ordinary _sugar of lead_. Sodium
acetate (NaC_{2}H_{3}O_{2}) is a white solid largely used in making
chemical analyses. Copper acetate (Cu(C_{2}H_{3}O_{2})_{2}) is a blue
solid. When copper is acted upon by acetic acid in the presence of air a
green basic acetate of copper is formed. This is commonly known as
verdigris. All acetates are soluble in water.

~Butyric acid~ (H.C_{4}H_{7}O_{2}). Derivatives of butyric acid are
present in butter and impart to it its characteristic flavor.

~Palmitic and stearic acids.~ Ordinary fats consist principally of
derivatives of palmitic and stearic acids. When the fats are heated with
sodium hydroxide the sodium salts of these acids are formed. If
hydrochloric acid is added to a solution of the sodium salts, the free
palmitic and stearic acids are precipitated. They are white solids,
insoluble in water. Stearic acid is often used in making candles.

~Acids belonging to other series.~ In addition to members of the
fatty-acid series, mention may be made of the following well-known
acids.

~Oxalic acid~ (H_{2}C_{2}O_{4}). This is a white solid which occurs in
nature in many plants, such as the sorrels. Its ammonium salt
((NH_{4})_{2}C_{2}O_{4}) is used as a reagent for the detection of
calcium. When added to a solution of a calcium compound the white,
insoluble calcium oxalate (CaC_{2}O_{4}) precipitates.

~Tartaric acid~ (H_{2}.C_{4}H_{4}O_{6}). This compound occurs either in a
free state or in the form of its salts in many fruits. The potassium
acid salt (KHC_{4}H_{4}O_{6}) occurs in the juice of grapes. When the
juice ferments in the manufacture of wine, this salt, being insoluble in
alcohol, separates out on the sides of the cask and in this form is
known as argol. This is more or less colored by the coloring matter of
the grape. When purified it forms a white solid and is sold under the
name of cream of tartar. The following are also well-known salts of
tartaric acid: potassium sodium tartrate (Rochelle salt)
(KNaC_{4}H_{4}O_{6}), potassium antimonyl tartrate (tartar emetic)
(KSbOC_{4}H_{4}O_{6}).

~Cream of tartar baking powders.~ The so-called cream of tartar
baking powders consist of a mixture of cream of tartar,
bicarbonate of soda, and some starch or flour. When water is
added to this mixture the cream of tartar slowly acts upon the
soda present liberating carbon dioxide in accordance with the
follow