[ 334. ] 



XL II. On a peculiar Fibre of Cotton which is incapable of 

 being Dyed. By Walter Crum, Esq., F.R.S., Vice-Pre- 

 sident of the Philosophical Society of Glasgow^. 



IN the month of May last, Mr. Thomson of Primrose re- 

 ceived from Mr. Daniel Koechlin of Mulhansen some 

 specimens of a purple ground printed calico, each of them 

 containing a portion of cotton which was white, although sub- 

 jected to the same treatment by which the rest of the cloth, 

 and even the threads which crossed the white one, was uni- 

 formly dyed. The white part of the thread was usually thicker 

 than the rest, and little more than a quarter of an inch long. 

 The whole fabric had been thoroughly bleached before print- 

 ing, so that it contained no grease or other impurity that could 

 resist the colouring matter. 



White specks like these are not unknown or undreaded 

 among the printers of calicoes in this country. M. Koechlin 

 mentions that the cotton of which they are formed is known 

 by the name of colon mort, and here also it is called dead 

 cotton. M. Koechlin has been the first, I believe, to suggest 

 that it may consist of unripe cotton, and that its fibre may be 

 solid, wanting the hollow of the more perfect fibre. He adds, 

 that if such should prove to be the case, its behaviour with co- 

 louring matters may affect materially the question of the me- 

 chanical or chemical nature of the union of cotton with its dye. 

 Mr. Thomson did me the honour to transmit me the speci- 

 mens for examination. 



The ordinary cotton fibre, it will be remembered, is de- 

 scribed by Mr. Thomson in the memoir where its form was 

 first made known f, as a tube, originally cylindrical, but which 

 collapses in drying. It has then the appearance of two small 

 tubes joined together, so that a transverse section of the fila- 

 ment resembles in some degree a figure of 8. Until full ma- 

 turity the cylinder is distended with water, in which bubbles 

 of air are often distinguishable. 



On placing a few of the fibres of the colon mort under 

 the microscope, I found them to consist of very thin and re- 

 markably transparent blades, some of which are marked or 

 spotted, while others are so clear as to be almost invisible 

 except at the edges. These fibres are readily distinguished 

 from those of ordinary cotton by their perfect flatness, without 

 the vestige of a cavity, even at the sides, and by their uniform 



* From the Proceedings of the Philosophical Society of Glasgow, 1848- 

 49, and read before that Society April 25, 1 849. 



t Annals of Philoso[)hy for June 1834. Lately reprinted in the Classical 

 Museum, No. 20; and in Liebig's Annalen for January 1849. 



