102 Scientific Proceedings, Royal Dublin Society. 
Group LI. 
Oases in which Signs of Decomposition were observed. 
‘5 ‘ 5 At all 
Up to 180°. Above 180°. Monpeetates 
SUBSTANCE. 
N. A. eye A. IN. A. 
| : 
Ethyl] formate, fe iG ll {+002 | 14 |+0-09 25 |+ 0:06 
Propyl formate, .. so | 1B FOO | 12 | 2 Oils 24 |4 0°07 
Isopropyl isobutyrate, a0 @ | a Orie 8 | + 0°32 14 | +4 0°24 
Bromobenzene, I | + 0°30 25 |+ 0-29 26 | + 0:29 
Iodobenzene, id Me — = 14 | + 0°04 14 | + 0-04 
Carbon tetrachloride, ae 10 |+ 0:19 1B | = Oil M3 || LODO) 
Stannic chloride, .. ae 6 + 0-26 10 | + 0:26 16 | + 0-26 
46 |+0:107 | 96 |+ 0-192) 142 | +4 0-164 
It is to be expected that when a substance has undergone 
partial decomposition, fractionation will take place during evapo- 
ration or condensation, and that there will be a fall in pressure in 
the one process, and a (greater) rise in the other. 
It should be noted that the experiments were carried out for 
the purpose of determining the vapour-pressure of the unde- 
composed substances, not of studying the effect of decomposition 
on vapour-pressure. Precautions were, therefore, in many cases 
taken to protect the substances from decomposition. If all the 
experiments had been carried out in the same manner as for the 
stable substances, the decomposition would, in some cases, have 
been much greater, and the results more striking. On the whole, 
the values of A are decidedly higher than for the stable substances. 
Group III. 
Lffect of dissolved Air. 
It was occasionally found, after filiing and setting up a tube, 
that the liquid was not quite free from dissolved air. In such 
cases the tube was usually taken down at once, emptied, cleaned, 
