L. Remsen on Purasulphobenzoie Acid. 357 
ditions, led me to undertake one more experiment, with the 
ope of finding a method for the preparation of orthosulpho- 
benzoic acid. ‘The experiment failed to bring about the desired 
object, but at the same time gave other interesting results, an 
account of which follows. 
According to A. Wolkow (loc. cit.) the amides of the two 
sulphotoluenic acids can be separated from each other by means 
of crystallization. This statement offered a prospect of 
ing an ortho-compound in pure condition ; and I hence prepared 
a quantity of the amides from the crude mixture of potassium 
salts of sulphotoluenic acids. The perfect separation of the two 
Y means of crystallization is an exceedingly tedious operation, 
whether water or alcohol be employed as the solvent. From 
water the paramide crystallizes first, and can then easily be puri- 
fied ; from the mother-liquor a mixture of the two amides is 
deposited. This fuses at 124°, and can only be resolved into 
its constituents by a very long series of recrystallizations. I 
succeeded at last in obtaining a small quantity of the ortho- 
ae in a pure condition, with all the properties as given by 
olkow. 
Now as the amide contains the group SO?. NH? instead of 
the sulpho-acid group SO?. OH, it seemed possible that its con- 
duct toward oxidizing agents might differ from that of the 
sulpho-acids. No attempts had as yet been made to oxidize 
compounds containing such a complicated group as SO*. NH?, 
and I was obliged to gain a certain amount of preliminary 
knowledge before proceeding to subject the ortho-amide to oxi- 
ation. For this purpose I introduced a few grams of parasul- 
photoluen-amide into a noted amount of the oxidizing mix- 
ture (sulphuric acid and potassium bichromate); and heated 
the whole gently for a short time. Soon the oxidation began, 
as was shown by a change in color and an evolution of gas. 
The amide dissolved rapidly, and, soon after it had completely 
disappeared, a beautifully crystallized product began to make 
its appearance, and increased constantly in quantity. After 
cooling, the liquid was filtered off. The solid — remained 
on the filter, after being washed out with cold water, in a pure 
White condition. It consisted of beautiful, short, lustrous 
doeryg that bore no resemblance to the original amide. It was 
1¢ 
anhydride being evolved, and was es — — 
ition of mineral act 
These had a high luster, and while in the solution exhibited a 
very beautiful fluorescence. It was found to fuse at a very 
Am. Jour. Sct.—Tairp — Vou. V, No, 29,—Mar, 1873. 
