176 ANNUAL OF SCIENTIFIC DISCOVERY. 



A PECULIAR FIBRE OF COTTON WHICH IS INCAPABLE OF BEING 



DYED. 



MR. W. CRUM describes, in Brewster's Magazine for November, a 

 peculiar fibre of cotton, which is found to resist the usual processes 

 for dyeing, and thus to leave white spots in the cloth. Such spots 

 have long been noticed and dreaded by calico-printers, who call the 

 cotton of which they are formed dead cotton. The ordinary cotton 

 fibre is a tube originally cylindrical, which collapses in drying. On 

 placing a few of the fibres of the "dead cotton" under the microscope, 

 Mr. Crum found them to consist of very thin and transparent blades, 

 some of which are spotted, while others are so clear as to be almost 

 invisible. These fibres are readily distinguished from those of ordi- 

 nary cotton by their perfect flatness, and their uniform as well as 

 great transparency. They are often broader, show numerous folds, 

 but are never twisted into the corkscrew form of the ordinary fibre. 

 We must suppose that these flat fibres, like the healthy unripe cotton 

 fibre, were originally tubes filled with liquid, but that the seed around 

 which they began to grow had died while they were yet soft and 

 pliable, and that the flattening was caused by the pressure from the 

 increasing crop of cotton attached to the numerous other seeds confin- 

 ed in the same pod. The fact of the existence of such fibres in cloth 

 has a considerable bearing upon the disputed point, whether cotton- 

 wool and coloring matters form together a true chemical compound, 

 or are held together by a merely mechanical power, and is a strong 

 argument in favor of the latter view. 



INCOMBUSTIBLE CLOTH. 



AT the meeting of the British Association in September, 1849, Sir 

 David Brewster exhibited several specimens of printed calico which 

 had been rendered incombustible, by immersion in a solution of phos- 

 phate of magnesia. When inflamed it soon went out without the 

 fire spreading. Sir David Brewster stated that a spark or red 

 coal would not ignite it. 



PREPARATION OF INDIGO AS A DYE. 



IN the use of indigo for dyeing, as it is insoluble in most menstrua, 

 a preliminary process is necessary to bring it into the proper state for 

 use. This is now eifected by exposing it to the action of bodies hav- 

 ing a superior affinity for oxygen, or by mixing it with some organic 

 matter containing sugar, mucilage, and other fermentable materials, 

 or by subjecting it to the solvent power of sulphuric acid. When 

 fermentable materials are used, wood and bran of wheat are com- 

 monly employed, but within a short time a patent has been taken out 

 for substituting as the fermenting material the young shoots of the 

 common carrot and of the parsnip prepared in the following manner. 

 To prepare a vat, take of the stems and leaves of the common pars- 



