1905 - 6 .] Study of Liquid Sulphur as Dynamic Isomers. 355 
When ordinary liquid sulphur is heated at the rate of about 
two degrees per minute, the thermal effect asserts itself, with 
simultaneous sudden access of viscosity, at 167°. The same 
degree of viscosity is attained with slow heating at 160°, without 
thermal effect, and when equilibrium is reached at this tem- 
perature the proportion of is 10*7 per cent. Apparently, 
when the heating is rapid the proportion of lags behind that 
required for equilibrium, and the proportion necessary to give the 
marked viscosity has not accumulated until 167° has been reached. 
When the same experiment is continued by allowing the specimen 
of sulphur to solidify and the material is then remelted and heated 
rapidly once more, the viscosity and thermal effect now supervene 
at 163°. Evidently the cooling and solidification, although they 
have destroyed a part of the Sja, have not destroyed it all. Hence 
during the second heating the proportion of is always somewhat 
larger than during the first heating, and thus the thickening occurs 
sooner and at a lower temperature. When the sulphur is cooled 
only to 130° before being heated for the second time, the loss of 
is even less, and with rising temperature the mass is still nearer 
to the equilibrium condition at each temperature. Under these 
circumstances, therefore, the viscosity begins gradually at 159°, 
and no noticeable thermal effect whatever is observed. 
These inferences were confirmed by measurements of the 
proportions of present at various stages of the rapid heating. 
With sulphur melted at 121° and heated at the rate of two degrees 
per minute, the following proportions of were found : — 
Temperature . 
121° 
154° 
156° 
162° 
165° 
167° 
Per cent. 2° per min. 
0-04 
5-4 
5-7 
6-4 
7-5 
10-3 
Per cent. Sm, equilibrium 
3-75 
7-5 
8*0 
13-5 
15*5 
16-7 
At 167° the sample was taken just as the great viscosity was 
setting in. In the lower line the percentages of at the same 
temperatures, when equilibrium has been reached, are given for 
comparison. It will be seen that with rapid heating the pro- 
portion is from 2 to 6 per cent. less. 
Finally, the changes in concentration going on at 167°, during 
the process which manifests itself in heat absorption and rapid 
increase in viscosity, were studied by chilling various samples 
