Dyestuffs Volume 21

Dyestuffs Volume 21

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 edition. Excerpt: ...serious trouble is often encountered, due to the formation of the black tannate of iron. Iron is easily detected by its color reaction with ammonium sulphocyanide or potassium ferrocyanide, the former giving a blood red coloration, the latter a deep blue in the presence of iron; it is generally readily removed by weak oxalic acid. Lead stains are very similar in appearance to those caused by iron. They are found in goods that have been treated in lead lined kiers, the lead being gradually changed to peroxide by oxidation during the bleaching process. It is capable of ready detection by holding a portion over a test tube in which hydrogen sulphite is being generated. The formation of a blackish-brown spot shows its presence. This should be confirmed by chemical analysis. A wash in dilute sulphuric acid followed by immersion in a fairly strong alkaline acetate or tartrate solution serves to remedy this trouble. A stain only recently encountered in connection with sulpur dyes is due to the formation of copper sulphide. This is exceedingly difficult to remove from the fibre. A strong solution of ammonium sulphide or polysulphide seems to be of value when the damage is not too serious. The thorough washing out of the sodium sulphide is a prevention that is better than the cure. Oxycellulose is formed when cellulose is acted upon by an oxydizing agent such as nitric acid. The same compound may be produced by the action of chlorine in the presence of moisture, by hypochlorous acid and chlorates in acid solution. Strong alkaline solutions such as hypochlorites or sodium hydrate in the presence of air also brings about the oxidation of the cellulose. It can readily be seen, therefore, that the use of too strong chemic, or the presence of air in...
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Product details

  • Paperback | 78 pages
  • 189 x 246 x 4mm | 154g
  • United States
  • English
  • black & white illustrations
  • 1236823435
  • 9781236823434