( 622 ) 
(the chronometer showed a fifth of a second) 10 ee. were pipetted 
from the flasks and added to 10 ce. 
of standardised acid; the excess of 
acid was then titrated with N./4. NaOH 
using phenolphthalein as indicator. 
The standard liquids were kept in 
large bottles and duly protected from 
the carbon dioxide of the air). 
The preparation of lye free from 
CO, is generally done by allowing 
metallic sodium to liquefy under a jar 
in which a basin of water is placed. 
By following this method?) the prepar- 
ation of, say, 1 litre of N. soda takes 
many days. I have, therefore, con- 
structed a simple little apparatus which 
enables us to dissolve in a few hours 
50 grams of sodium out of contact 
with the air. The apparatus may be 
Fig. 2. put together by means of materials 
which are found in every laboratory °). (Fig. 2). 
B is a jar (bottomless bottle) closed by a trebly-perforated cork. 
Through the hole in the centre passes a soda-lime tube G. Through 
both the other holes a thin copper tube enters (or leaves) the jar, 
which runs alongside the walls and is rolled circularly at the bottom 
(3 windings). Within the circle is placed a silver dish filled with 
metallic sodium cut up into small pieces. The jar with the dish 
is then placed into a crystallizing basin containing a little water so 
“that the lower edge of the jar dips a few c.m. into the water. 
From a boiling-flask with a safety tube steam is passed through 
the copper tube the other end of which is connected with a water- 
airpump to remove condensed water. 
Soon the jar gets filled with water vapour, hydrogen escapes 
through the soda-line tube and after a few hours, the sodium is 
completely liquefied and dissolved. Traces of carbon dioxide which 
may be present in the solution were removed by boiling the solution 
with a little Ba (OH)2. 
1) Compare Spour, Zeitschrift für phys. Chemie 2, S. 194 (1888). 
2) OsrwaLp, Hand- und Hülfsbuch zur Ausführuug physiko-chemischer Messungen, 
S. 281. 
3) Compare RosENFELD, Journ. fur pract. Chemie N. F. 48 (1893) 599. 
