342 Proceedings of Royal Society of Edinburgh. [sess. 
On Causes which determine the Formation of Amor- 
phous Sulphur. By Professor Alexander Smith, B.Sc., 
Ph.D. 
(Read July 21, 1902.) 
While the investigation of the freezing-point of sulphur, de- 
scribed in these Proceedings (vol. xxiv. p. 299), was in progress, 
some experiments on the maximum quantities of amorphous sulphur, 
formed at various temperatures from 130° to 448°, were being made. 
The results showed remarkable irregularities. It was also found 
that the addition of foreign bodies, which are • for the most part 
without chemical action on sulphur, greatly magnified these dis- 
turbances, and led to the discovery of their source. The following 
is a condensed statement of the principal facts. 
When sulphur, purified by recrystallisation from carbon disul- 
phide, was heated for one and a half to two hours at 448° in an 
open tube, varying proportions of amorphous sulphur seemed to be 
formed. The tube was transferred rapidly to, and broken into a 
vessel of ice, so that no opportunity might he given for reversion 
to the soluble form. The variations, which ranged from 32 per 
cent, down to 10 per cent, of amorphous sulphur, appeared to 
depend in part upon the length of time intervening between the 
purification of a large lot and the use of a particular portion of it. 
Portions taken early gave, as a rule, less of the amorphous body. 
Heating for a longer time than two hours seemed also to reduce 
the proportion. Part of a specimen gave, after two hours’ heating, 
31*8 per cent., while another part of the same specimen, after eight 
hours’, gave only 2 '6 per cent. 
It seemed evident that sulphuric acid or sulphur dioxide, pro- 
duced by the action of the air in variable hut minute amount, 
was responsible for the differences. The more prolonged heating 
eliminated most of the sulphur dioxide. 
Passing certain gases through the sulphur during the heating 
increased the yield of amorphous sulphur. Thus, dry air gave 34*5 
per cent., dry sulphur dioxide 36 - 5 per cent., dt-y hydrogen chloride 
