I, Remsen on Parasulphobenzoie Acid. 181 
paraoxybenzoic acid was rendered complete by the analysis, 
which gave the following results : 
I, 0°3308 grams substance, heated to 110°, lost 0°0383 grams H?0, 
Il. 02925 grams dried substance gave 0°6502 grams CO? = 
0°17733 grams C, and 0°1181 grams H?O0 =0°01312 grams H. 
Calculated. Found, 
C1 84 53°85 53°61 
Hé 6 3°84 3°97 
O83 48 80°77 eat 
H20 18 11°54 11°58 
156 100°00 
Paraoxybenzoic acid, then, according to this, can be the pro- 
duct of the action of potassium hydroxide on sulphobenzoic 
acid. But this reaction has been employed for the preparation of 
pure oxy benzoic acid,—-first by Barth,* and afterward by Heintz+ 
—and, as neither of these chemists mention the formation of 
paraoxybenzoic acid under these circumstances, it is fair to sup- 
pose that, if formed, it escaped their attention: that it could 
hot have made its appearance in such quantities as in the 
experiment described, is evident: The question now naturally 
arose whether the conditions under which I had prepared the 
sulphobenzoic acid had been of influence on the product. In- 
stead of waiting until the sulphuric anhydride had entirely dis- 
Solved the benzoic acid, as Barth did, I had added a smal 
amount ot fuming sulphuric acid to the semi-liquid mass after 
a time, and then heated gently until complete solution resulted. 
This shortened the operation somewhat, as the lumps of ben- 
Z01¢ acid, which had become packed together, were thus brought 
under the direct influence of the fuming acid ; whereas, before, 
ey were covered with a thick pasty layer which protected 
€m. 
id experiment. Instead of a Sertre | in the first deposit of 
crystals, it was now not observec 
* Annalen der Chemie und Pharmacie, cxlviii, 30. + Ibid., cliii, 326. 
