THE B O I L I N G - P O I N T S O F M I X T U R E S O F C H L O R A L AND W A T E R BY JOSEPH C. CHRISTENSEN
In May, 1899, I did some work a t the suggestion of Dr. W. D. Bancroft on the boiling-points of mixtures of chloral and water. T h e results were rather unsatisfactory owing to the difficulty of obtaining concordant readings on the thermometer. T h e results are shown i n plot No. I (curves I and 2 are from different settings of the Beckmann). T h e difficulty mentioned, led to the adoption of a niodification of the apparatus described by Bigelow i n the American Chemical Journal of October, 1899. Fig. I shows the apparatus used in 1899 ; Fig. 2 t h a t by which the accompanying results were obtained. I n practice, the current was usually kept a t about 2 . 2 5 amp., b u t it was frequently increased during the experiment to 2.5 amp., or even more, without any change in the reading of t h e thermometer. T h e following tables show the effect of varying t h e current and also the amount of liquid. 50 cc. water
35 cc. water
Baroni.
~
Tenip.
5.17O 5.18 5.20 5.22 5.24 5.25 5.25 5.25
~
Current 2.25 2.25
~
Barom. l
~~
1
Temp.
4.9G0
I 4.98
2.2j
4.95 4.87
2.25
5.23
I
5. IS
2.25
I
5.25 5.26
I
Current 2.25 2.2j 2 . 2j 2.25 2 . j0 2.50 2 .5 0 2.50 2.j0
2.75 2.75 Does not boil.
8
Fig.
I
Fig. 2
A is a bath of brine. B is a burette. C, C , are condensers. D is an open tube communicating with the air. E is a n asbestos jacket. F, F, are terminals of the spiral. S is a platinum spiral of about 15 ohms resistance, connecting with the power circuit. H is a small watch-glass supported by a platinum wire sealed into it. I t protects the thermometer froni superheated vapor. T is a Beckmaiin thermometer. N is a test-tube I $ by S in.
T h e temperature in this, as in all the work, was taken every five minutes. This table shows t h a t tlie apparatus is all t h a t could be desired. T h e only disadvantage was t h a t i t would not work with over 60 cc liquid.
Boz'Ziizg-joiizts of Mixlzires of ChZwaZ a i d Water
587
T h e break between curves No. I and No. 2, plot 2 , is due probably to the impurity noted a t this point. Curve No. 2 , plot The I , probably represents the true conditions a t this point. drop in curve No. 3, plot 2, I am utiable t o explain. This curve was plotted from Table VII.
Percent of Water
Plate I
588
Joseph C. Chvisteizseiz
TABLEI
--2
2.10
3 4 5 6
2.09 2.06
8 9
758.90 759.00
Q I3
759.00
0 0
i
0
0
~
~
758.85
21
0
0.15
1 :t 1
758.80
I *goo
/ /
I. 50
l
20
0
2.05 1.44
17
I8 I9
,
2.0j
IO I1 I2
I4 15 16
I
2.18
"I
7
,
_____ -- ,
1
1.34
1.26
1.10
1.00 1.10
0.97
1-13 0.92 0.98 0.98 0.79 0.85 0.85
l
