MICROCHEMICAL REACTIONS OF THE COMMON ACIDS 429 
page 354; Copper, page 386. Add a trace of copper and increase 
the delicacy of the reaction. 
TARTRATES. 
Note. — Before testing for tartrates always neutralize any free 
mineral acid present. 
a. By means of Calcium Acetate. 
The solution may be neutral or acidified with acetic acid. 
Large, colorless, well-formed, highly refractive crystals are 
obtained. 
The solution to be tested must be concentrated, otherwise the 
calcium tartrate will not separate save on long standing. Ex¬ 
posure to alcohol vapors (Method VI, page 305) will hasten the 
formation of a crystal deposit. 
Magnesium salts greatly retard the separation of crystals of 
calcium tartrate. 
h. With Potassium Salts, tartrates yield characteristic color¬ 
less, highly refractive, orthorhombic, short, stout prisms of the 
primary salt KHC4H4O6. 
c. With Silver Nitrate. 
A granular precipitate only is obtained unless in very dilute 
solution, then there will be obtained tiny squares and rectangles 
and short, stout prisms giving a six-sided outline. 
Most other acids interfere with the detection of tartrates by 
means of the silver salt. 
