Hair may be bleached on the grass like linen, after previous washing and steeping in a bleaching liquid, after which it may be dyed of any color. It is very doubtful whether the growth of hair can by any artificial means be expedited, or the hair itself increased in length, in quality, or in density. A fine field of enterprise would be opened for the fortunate inventor who could increase the produce of the finer and more expensive furs. In contradistinction to this, however, it may be stated that the inhabitants of some countries, the Malays, for instance, purposely destroy their hair by using quick-lime. We come next to describe minutely another peculiarity appertaining to hair, upon which all felting or shrinking of a fabric depends; that grand secret that has been a mystery in all ages, until within a few years, or at best was only surmised. Upon this property alone depends the whole art of hatting and of felt making, whether in sheets or otherwise, as well as the fulling of cloth and the shrinking of flannels, and all articles the material of which is made of wool, hair, or fur. As many branches of business depend for their success upon the _non-shrinking_ quality of their goods, a study of the felting principle becomes quite appropriate and interesting to those manufacturers, whilst perusing that of the opposite. Pulled wools, rather than cut or shorn wools, must always have the preference with the one class of manufacturers; at the same time, the other class must adhere tenaciously to those which have been cut, the roots of the hair causing all the difference, for that remarkable quality, the felting principle, is upon all the same whether pulled or cut. A few familiar facts dependent upon this inherent felting quality of hair will aid the illustration. When a hair is held by the top, it can be severed with a razor much more readily than if held by the root. Again, a hair held by the root, and drawn through between the finger and thumb, feels quite smooth, but when held by the top, a rough and tremulous motion is perceived. Again, place a hair of three or four inches in length by the middle, between the finger and thumb, and twirl it a few times, when the hair will be found to proceed towards one end, as the twirling and rubbing are continued, and invariably advancing root end foremost, whichever way the hair is placed between the fingers. If two hairs are used in this example, lay the root of the one to the top of the other, their respective motions will be doubly discernible. The cause of all these singularities of the hair it is now designed to explain, which shall be done as explicitly and concisely as possible, with a few proofs of its astonishing power in a collective capacity.