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IOWA ACADEMY OF SCIENCE 
to crystallize. If the solution was concentrated, the unsymmetri- 
cal chloride crystallized first and later there were superimposed 
on the crystalline mass hard, glistening, rhombohedral crystals 
of the symmetrical chloride. These were picked out by hand 
from the mass. In another experiment it was found that this 
chloride crystallized in the form of long white needles. Once 
these were produced in the laboratory, the rhombohedral forms 
never . appeared again. The needles seemed to be less soluble than 
the unsymmetrical acid chloride, and hence could be taken out 
from the carbon tetrachloride solution as the first crop of crys- 
tals. In some cases the solution was seeded to bring about the 
rapid production of this form. 
The identity of the two crystalline forms of the symmetrical 
acid chloride was shown by the identical melting points, 134°, 
and also by the fact that when the rhombohedral form was dis- 
solved in carbon tetrachloride and a trace of the needles added, 
the whole amount present crystallized out in the needle form. 
The symmetrical acid chloride was recrystallized from carbon 
tetrachloride several times until the melting point was constant 
at 134°, and then was analyzed. Chlorine was determined by 
saponifying with sodium hydroxide, acidifying with nitric acid, 
and precipitating as silver chloride. Sulphur was determined by 
Pringsheim’s method using sodium peroxide; nitrogen was de- 
termined by the Gunning method. 
.1569 g. chloride gave .1500 g. silver chloride. 
.1278 g. chloride gave .1241 g. silver chloride. 
.1264 g. chloride gave .0896 g. barium sulphate. 
.3140 g. chloride required 9.68 cc of .1084N HCl. 
.2973 g. chloride required 9.08 cc of .1084N HCl. 
Theory for CsHsOsNSCl^ Found 
Chlorine, 23.80 per cent. 23.65 - 24 02 per cent. 
Nitrogen, 4.70 per cent. 4.68- 4.64 per cent. 
Sulphur, 10.74 per cent. 10.72 per cent. 
Umsymmetrical Acid Chloride. 
(' = Cl3 (1) 
NOs • CHs C6H2<^ 
SOa (a) 
This acid chloride constituted about five-eighths of the total 
yield of the acid chlorides as made by the open dish method. 
Its formation is apparently favored by the presence of phos- 
phorous oxychloride, for when a refiux condenser is used in the 
