I. Remsen on Parasulphobenzoie Acid. 183 
positively that this is the case, especially as we know that there 
1s a source of impurity which, as we have seen, may vary 
greatly in its influence upon the character of the product. It 
seems to me then that, whenever for test experiments pure 
oxybenzoic acid is required, it would be advisable to become 
convinced of its purity by some other means; and I would sug- 
gest the preparation of pure acid barium sulphobenzoate as the 
first step. This salt can be readily obtained in beautiful, pe 
fectly formed crystals, the appearance of which is a test of their 
purity ; aud from this pure oxybenzoic acid can be obtained. 
IL Parasulphobenzoic Acid a constituent of crude Sulphobenzoie 
Acid. 
mentioned above might be due to two causes. Either meta- 
sulphobenzoic acid might yield it through the instrumentality 
of molecular rearrangement under the influence of heat and 
which would account for the complex character of the result- 
Ing oxyacid. 
To test the first possibility, a quantity of pure acid barium 
metasulphobenzoate was prepared, and then converted into the 
the large proportion of paraoxybenzoic acid was now investi- 
. ated, in order if possible to detect the presence of a second 
substance in it. It was neutralized with pure barium carbonate, 
and the excess of the latter and the precipitated sulphate then 
filtered off. The clear solution was separated into two equal 
4 n now mixing the two clear solutions again, evapora- 
ting to the point of erystallization, and allowing to cool, long, 
flat, acicular crystals made their appearance. These had no 
resemblance to the known ‘acid barium salt of sulphobenzoie 
acid, They were recrystallized from water, and were now 
I. 0525 grams salt lost in weight constantly up to 200° ; above 
nals tet place. The entire loss was 0047 
perature no loss too ” 
grams. This portion of the salt gave 0°206 grams BaSO*= 
0°12113 grams Ba. 
