Page:The history of silk, cotton, linen, wool, and other fibrous substances 2.djvu/408

 *companied them with a Plate exhibiting the obvious difference between the two classes of objects. The ultimate fibre of cotton is a transparent tube without joints, flattened so that its inward surfaces are in contact along its axis, and also twisted spirally round its axis (See A. Plate VI.): that of flax is a transparent tube jointed like a cane, and not flattened nor spirally twisted (See B. Plate VI.). To show the difference two specimens of the fibres of cotton, and two of the fibres of mummy cloth are exhibited, all of the specimens being one hundredth of an inch long, and magnified 400 times in each dimension. Any person, even with a microscope of moderate power, may discern the difference between the two kinds of fibres, though not so minutely and exactly as in the figures of Mr. Bauer.

The difference, here pointed out, will explain why linen has greater lustre than cotton: it is no doubt because in linen the lucid surfaces are much larger. The same circumstance may also explain the different effect of linen and cotton upon the health and feelings of those who wear them (See Part Third, Chap. I.). Every linen thread presents only the sides of cylinders: that of cotton, on the other hand, is surrounded by an innumerable multitude of exceedingly minute edges.

Mr. Pettigrew, in his "History of Egyptian Mummies" (London 1834, p. 95.), expresses the opinion that the bandages are principally of cotton, though occasionally of linen. He has since arrived at the conclusion that they are all of linen: and his opinion appears to be established on the following evidence, which he gives in a note to the above mentioned work (p. 91.).

Dr. Ure has been so good as to make known to me that which I conceive to be the most satisfactory test of the absolute nature of flax and cotton, and in the course of his microscopic researches on the structure of textile fibres he has succeeded in determining their distinctive characters. From a most precise and accurate examination of these substances he has been able to draw the following statement:—The filaments of flax have a glassy lustre when viewed by day-light in a good microscope, and a cylindrical form, which is very rarely flattened. Their diameter is about the two-thousandth part of an inch. They break transversely with a smooth surface, like a tube of glass cut with a file. A line of light distinguishes their axis, with a deep shading on one side only, or on both sides, according to the direction in which the incident rays fall on the filaments.

The filaments of cotton are almost never true cylinders, but are more or less flattened and tortuous; so that when viewed under the microscope they appear