he 
(42) 
the mixtures. The gas was compressed in a calibrated tube of 
CAILLETET, on which the mm. were marked, and the thickwalled 
part of which was placed in a waterbath of about 35 L. After this 
water had reached the desired temperature, the temperature was kept 
constant by means of an alternating current, which passed through 
two tubes filled with a solution of NH,Cl, which were placed in 
the bath. Moreover in this bath were found the coil, serving to 
move the electro-magnetic stirrer in the CAILLETET-tube, and a stirrer, 
kept in motion by the flow of water. 
The temperatures between 15° and 35° were read from a thermo- 
meter, which was divided in ?/5,°; the others from thermometers 
with a division ef !/,,° ; now and then the thermometers were tested 
by means of a normal thermometer, which had been compared with 
an air thermometer at the Reichsanstalt. 
The pressures were calculated by making use of the table which 
Mr. AMAGAT gives for the compressibility of air in Ann. de Ch. et 
de Phys. 6¢ série 1898. 
The Results. 
It appeared already in the observation of the first mixture, that 
I, no more than Mr. KurNeN, should succee.! in observing the retro- 
grade condensation 22¢ type. For the critical temperature of the 
point of tangency and of the plaitpointcurve were so near each 
other, that [ could scarcely state a difference between these tempe- 
ratures. Moreover, also in these mixtures the phenomenon of a 
maximum pressure and a minimum critical temperature appeared, 
which made the region, where r.c. II was possible, still more limited. 
(See KUENEN, experiments on mixtures of N,O and C,H, ete. 
Zeitschr. fiir phys. Chem. XXIV, 4, 1897). 
This maximum pressure occurs when # = 0.44 and this minimum 
critical temperature when #=0,62 (ethane is considered as the solved 
substance, N.O as the solving substance), as appears from the gra- 
phical representation, in which the course of the plaitpointeurve, of 
the curves of the vapour pressure of the simple substances and the 
border-curves of the mixtures are indicated. This diagram, drawn 
up according to the initial and final points of condensation, occur- 
ring in the tables, is founded on the foliowing tables. 
