Fahlberg (Am. Chem. J. 1, 170), doubted Beckurts’ statement, because although his acid showed different properties he neglected to prove its constitution by converting it into the hydroxy benzoic acid. He therefore repeated Beckurts’ work, and identified the amide melting at 154 as coming from ortho toluene sulphonic acid, by conversion into salicylic acid. The other amide with a sharp, constant melting point of 108 was oxidized, and the products separated and identified as para sulphamine benzoic acid, anhydro ortho sulphamine benzoic acid, and acid potassium ortho sulphobenzoate. These were the products one would expect from an oxidation of a mixture of the ortho and para toluene sulphonamides. Further proof that his acid was a mixture was obtained by mixing amounts of pure ortho and para toluene sulphonic acids, and by repeated crystallizations a form was obtained which melted at 108. F.H.S. Muller (Ber. d. chem. Ges. 13, 1348), mentioned the formation of meta toluene sulphonic acid by the action of sulphurous acid upon the corresponding diazo compound, but gave no details except the melting points of his amide, anilide, and toluide. Claesson and Wallin in 1879 (Ibid. p. 1848), claimed that they had obtained meta toluene sulphonic acid by the action of chlorsulphonic acid upon toluene. They used very large quantities of materials. They obtained three acids, and identified them as the ortho and para, and called the third the meta acid, despite the fact that they had knowledge of Fahlberg’s work. The next step was undertaken by R. Otto (Ibid, 13, 1292), at the request of Beckurts. He examined some of the latter’s supposed meta toluene sulphonamide, and found it to be a mixture of the amides of the ortho and para acids. Nevile and Winther (Ibid. 13, 1940), while investigating the formation of amino sulphonic acids, obtained a toluene sulphonic acid by heating ortho diazo toluene sulphonic acid with alcohol under pressure, and also by reducing brom toluene sulphonic acid with sodium amalgam. It was converted into the chloride and amide,--the latter melting at 106.5-107.5. In 1886, Valin (Ibid. 2952), convinced by the work of Otto that Fahlberg’s views were correct, and that he and Klason had not obtained meta toluene sulphonic acid, again attacked the problem; an acid was made and salts described. In 1891, Metcalf (Am. Che. J. 15,301) (Dissertation, 1892), proved that decomposition of para diazo toluene meta sulphonic acid with ethyl alcohol under pressure resulted in the formation of para ethoxy meta toluene sulphonic acid in far greater quantity. Consequently the toluene meta sulphonic acid could not have been obtained by either Pechmann or Valin.