627 milligram of nitrogen.
1.343 " of nitric oxide.
2.418 " of nitric pentoxide.
2.820 " of nitric acid.
3.805 " of sodium nitrate.
4.523 " of potassium nitrate.
In working on substances not rich in nitrates, an ordinary nitrometer
(fig. 69) is used; but in the assay of sodium nitrate, nitroglycerine,
&c., an instrument provided with a bulb having a capacity of 100 c.c. is
employed.
[Illustration: FIG. 69.]
The plan of working is as follows:--The "measuring tube" is filled with
mercury until it reaches up into the tap, and the levelling-tube is
placed so that it contains an inch or two of mercury. If the nitrate is
in solution, 2 or 3 c.c. of the liquid (dilute liquids are brought to
this bulk by evaporation) are measured into the cup. The levelling-tube
is lowered a little, and the tap cautiously opened until all but the
last drop of the liquid has run in. The cup is then rinsed with 2 or 3
c.c. of sulphuric acid, which is run in in the same way, and the
operation is repeated with another lot of acid. The measuring-tube is
now taken from the clamp, and shaken for two or three minutes, until no
more gas is given off. It is replaced, and the mercury-level in the two
tubes adjusted. Then it is allowed to stand until the froth has
subsided, and the gas has cooled to the temperature of the room.
Pages:
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740