| 摘要 |
<p>Coloured marking stick, esp. for marking textiles consists of a base substance which can be brushed off the textile, e.g. chalk, kaolin, gypsum or talc and a dyestuff that becomes colourless on chemical treatment. In an example kaolin was dyed with an alkaline phenolphthalein solution to obtain a red marking stick. Marks on textiles from this stick on treatment with strong acid solution, e.g. acetic acid, became colourless.</p> |
