As little actual dust as possible should be
made during pulverisation. The decomposition of the carbide is best
effected by dropping it into water and measuring the volume of gas
evolved with the precautions usually practised in gas analysis. An
example of one of the methods of procedure described by the German
Association will show how this test can be satisfactorily carried out:
"A Woulff's bottle, _a_ in the annexed figure, of blown glass and
holding about 1/4 litre is used as the generating vessel. One neck, about
15 mm. in internal diameter, is connected by flexible tubing with a
globular vessel _b_, having two tubulures, and this vessel is
further connected with a conical flask _c_, holding about 100 c.c.
The other neck is provided with tubing _d_, serving to convey the
gas to the inlet-tube, with tap _e_, of the 20-litre measuring
vessel _f_, which is filled with water saturated with acetylene, and
communicates through its lower tubulure with a similar large vessel
_g_. The generating vessel _a_ is charged with about 150 c.c.
of water saturated with acetylene. The vessel _f_ is filled up to
the zero mark by raising the vessel _g_; the tap _e_ is then
shut, and connexion is made with the tube _d_.
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