10 
N. C. AGRICULTURAL EXPERIMENT STATION. 
IV. SOME FORMS OF APPARATUS IN USE IN THE NORTH CAROLINA EXPERI¬ 
MENT STATION LABORATORY. 
By B. W. KILGORE, Assistant Chemist. 
1. Hydrogen Generator and Hydrogen Bath. 
The hydrogen generator consists of the large aspirator bottle C, 
raised above the bottle D, drying bottles, connecting and drainage 
tubes. C is partly filled with hydrochloric acid just strong enough 
not to fume (we use 1.11 S. G. acid), and D is filled above the con¬ 
traction with either lump or granulated zinc. The siphon tube E 
is about f inch glass tubing and extends to the bottom of both C and 
D. To start the apparatus open the cock A, and by blowing in 
the tube B force the acid over into D. The hydrogen thus generated 
passes through sodium hydrate first to remove any chlorine that 
might go over, and is dried by passing through two bottles of sul¬ 
phuric acid, and finally through anhydrous copper sulphate in the 
balled U tube, and then goes to the bath. When the operation is 
through, the cock A is closed, and the pressure of the hydrogen in 
I) forces the acid back into C. The spent acid may be drawn off 
either through F or G. Hydrochloric acid is preferred to sulfuric acid 
in that zinc chlorid is more soluble and does not clog the appa¬ 
ratus as does zinc sulfate. The height of C above D may be varied 
with the force desired. This distance in our apparatus is about 5| 
feet, and gives a brisk, steady current. This piece of apparatus is 
cheap and efficient, and may generally be easily made from piieces 
of apparatus in any laboratory. 
The water-bath for drying in hydrogen is circular, double walled, 
12 inches deep and 12 inches in diameter, with false bottom, inlet 
tube L (for hydrogen), which extends about 3 inches in the interior 
of the bath, exit tube K in top, which extends nearly to the bottom 
of the bath, an opening for thermometer, and the condenser tube I. 
The bath is made air-tight by a projection on the top dipping into 
a groove filled with mercury or paraffin, made by soldering a piece 
of copper around the inside of the bath at the top, and shown 
enlarged in the cut at M. When mercury is used the groove must 
be coated with plaster of paris, as also the projection where it is 
soldered onto the top. 
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