โ Scribed by Thomson, R. Fraser
No coin nor oath required. For personal study only.
Paper read before a meeting of the London Section on October 7, I935 'I'lic titlc chosen for this piper is in rcnlity nn crroiieous oiie as attention is to l)e dirccted oiily to one clnss of dycstufls, nnincly, v n t colours containing only carboil, hydrogen, nnd osygcn.
The dcrclopmcnt of vnt colorirs dntcs from a pcriod just subscquciit to tlic monuiiieiital commcrcinl syiithcsis of indigo, which is the type or pnrctit of all vat coloors. Aboutthc first ycnr of tlic presetit century, R h c c 130hn of tlic l3ntlischc Compnny submittcd n IICW intcrniedintc t o tlic fiivouritc f i n i l l rengcnt used in tlic indigo synthcsis, xinnicly Inoltcti caustic potnsli. The intcrincclintc used wis S-nininoanthrnquiiione, dcrivccl from ~11thraqui1io11c-2-sulphonic ncitl. 'J'lic lnttcr \vns of coursc cvcii tlmi i i well-kno\vn prodiict, tlic " silrcr salt " of thc nliznrine industry, dating from the sciantics of last ccntury, but its conversion to 2-aiiiiiioaiithroquiiioiic by highprcssurc autoclaving with nqueous nmmonin was a iiirtch Iiiorc rcccnt achicvcmeiit.
Thc result of Boliii's csperiiiients wns to disclose for tlic first time n substniicc curiously rcsetnbliiig and yct diffcrcnt froiii indigo, now cnllcd iiidiiiitlirone. It dyccl cottoii. with great affinity froin :i reduced nlknliiic bath ntid sliowcd what a t t h a t tiiiie was astoiiisliiiig fastiiess to light 011 tlie fibre. This discovery wns of iiioiiieiitous importance, leading to a wonderful clmiiicnl clcvelopiiicnt chiclip ccntred round nntlira-
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## Abstract For Abstract see ChemInform Abstract in Full Text.