MICROCHEMICAL REACTIONS OF MERCURY 
365 
Monoclinic. — Mercurous and mercuric nitrates. 
Triclinic. 
DETECTION. 
A. As Metallic Mercury hy Sublimation. 
Heat upon a piece of platium foil or upon a glass slide a 
little anhydrous sodium carbonate until all the moisture it con¬ 
tains has been expelled, cool, powder and mix a very small 
amount with a little of the material to be examined — transfer 
to a small tube of hard glass not over 2 millimeters in internal 
diameter, thin-walled and sealed at one end. Jar the mixture 
down so as to obtain clean walls. Warm the mixture in the 
tube very gently until all moisture introduced with the material 
being tested has been expelled. Cool. Heat the lower end of 
the tube over the “ micro ” flame, and complete the reaction 
by heating in the Bunsen flame. Work slowly. The mercury 
compound will be decomposed and tiny globules of metallic 
mercury will condense upon the walls of the tube. Examine 
under the microscope. With a stiff hair or glass rod drawn 
down to a hair gently rub the ring of sublimate. Examine again. 
The mercury will have united into larger globules. 
Introduce into the tube two or three small fragments of iodine. 
Then insert the open end of the tube into a piece of cork; warm 
the iodine very gently and set the tube aside for a few minutes. 
Yellow and red mercuric iodide will be formed. Warming again 
will hasten the reaction and cause the sublimation of some of the 
mercuric iodide. Rectangular and rhombic plates and dendritic 
masses of both the vermilion colored iodide and the yellow 
modification will be obtained. 
No other known element gives a reaction even remotely re¬ 
sembling this one. 
Erom large volumes of liquid the mercury may be removed by 
acidifying with hydrochloric acid and dropping in a steel needle 
around which has been wound a tiny spiral of thin gold foil. The 
deposited mercury amalgamates with the gold. The electrolytic 
couple is lifted out after some time, washed, the gold foil removed, 
dried, placed in a subliming tube and the mercury expelled by 
heating. The sublimate is then characterized as above. 
