The colour of the hair is extremely variable, and not uncommonly it changes from one colour to another in a very short time. The hair, like every other coloured organ in the body, obtains its colour from the iron in the blood. One would therefore think that taking iron or improving the circulation would darken the hair. It will not do so. In anæmia, where the iron in the blood is very deficient, the hair remains unaltered!
Severe emotion or sorrow will cause the hair to fade. Why it should do so we do not know, any more than why Father Time should meddle with it.
The only way in which the colour of the hair can be altered voluntarily is by external applications. No hair dye is really satisfactory, and most of them are dangerous. The hair will, however, sometimes change its colour completely without any external help.
The hair may lose its lustre from many causes. Dandruff is the commonest cause of this, but a very fertile factor in the causation of brittle lustreless hair is the constant employment of pomatums and greases to the hair. Nature supplies you with hair-oil of first-class quality. Every hair has two glands to secrete this oil (sebum). If you use an artificial grease (which can only be of a tenth-rate quality when compared with the natural substance), do you suppose the glands will go on working for nothing when the fruits of their labours are despised? Not they. They will strike work at once, and though they will resume their function if the external application is discontinued, it is better not to interfere with them at all. Girls with their long hair, however, need some form of application to keep the hair clean and glossy, and there is no objection to their using a really good substance, if they apply it to the hair itself and not to the scalp. You should never apply anything in the way of oil, grease, or pomatum to the roots of the hair, if it is healthy.
The applications of most value for the hair are the following:—
1. Brilliantine.—This is a pleasant emulsion, and it is very useful when the hair shows a tendency to fall out.
2. Bay Rum.—Occasionally I have seen this do good to the hair. Usually, however, it is better avoided.
3. Applications containing Cantharides are supposed to promote the growth of the hair. Possibly they do, but the action is not due to the Cantharides.
4. Rosemary is a nice clean preparation for the hair, and there are many good lotions containing this drug.
5. Marrow fat, Bear's grease, etc.—The solid fats are much used, and if you do not object to their messiness, they are not without merit.