I followed Metcalf’s directions as follows: in an apparatus fitted with an automatic stirrer and a thermometer I placed 200 grams (110cc.) of twenty per cent fuming sulphuric acid. I then slowly added with rapid stirring 100grams of powdered para toluidine which was obtained from the Newport Chemical Works. The addition took thirteen minutes. The initial temperature of the solution was 18°C. The maximum was obtained when about half the toluidine had been added and was 148°C. The final temperature was 130°C. After addition was complete I stirred for five minutes, and then slowly heated the mixture to 180°C. and kept it there for an hour. Sulphonation was then complete. I then poured it into an equal volume of cold water (220cc.) in an evaporating dish and allowed it to stand over night. The next day the dish seemed filled with grayish crystals; these were filtered off. The solution was allowed to stand for four weeks with no results. (Metcalf says that the disulphonic acid separated in three weeks from his solution.) I dissolved the crude acid obtained as above in ten liters of water (Metcalf’s directions) and precipitated the excess of sulphuric acid with barium hydroxide, and then filtered the solution. It was a clear brownish color. I then evaporated to 100cc. A smell of para toluidine was always present in the vapor indicating a probable hydrolysis of the acid. (Nevile and Winther (loc. cit.) say that this sulphonic acid can be hydrolyzed by heating with water), A test after sulphonation and before evaporation showed a sample to be completely soluble in water, and no cloudiness was produced when a sample was dissolved in sodium hydroxide, as is the case if a solution of para toluidine sulphate is dissolved in the same reagent. When the volume had reached 100cc. a light brown crust had formed on top of the liquid and on cooling and filtering two products were obtained; a light brown powdery substance in larger amount (47.5 grams.), and a small amount of hard square brown crystals. On evaporating the filtrate nearly to dryness more material separated which did not look like either of the above substances; it weighed twenty grams. This has not been investigated as yet.