Cosmetics And How To Make Them

COSMETICS AND HOW

TO MAKE THEM

CHAPTER I

WEIGHTS—PROPORTIONS—ELEMENTS OF CHEMISTRY

THE substances with which we have to deal may be divided into two classes, namely, solids and liquids. Solids are almost invariably weighed. Liquids may be weighed or measured.

The simplest system of weights and measures is the metric system. The only weights in this system of which the names need be known are—

The gramme (written g.);

The kilogramme, called kilo for short;

The milligramme, usually written mg.

A suitable set of metric weights usually contains the following—

The small weights under the glass cover should only be handled with the forceps provided, and must be kept in their proper compartments. This enables them to be more easily recognized and provides a check, as one can see at a glance which are missing.

In order to have an intelligent understanding and grasp of any subject involving different proportions and quantities, one needs to be able to compare these proportions.

A very simple method of making comparisons, and one which is generally employed, is that of expressing the figures in terms of percentage. Percentage means per hundred or in each hundred. Suppose we wish to find which of two classes of goods is the more profitable to handle, say scent and soap. On examining the books of a shop it appears that in a year the sales of scent have amounted to £400, yielding a profit of £120. The sales of soap, on the other hand, have been £600 and have shown a profit of £150. These figures do not tell us at a glance which is the more profitable article to handle, because the sales of one have been larger than the sales of the other. To compare the ratio of profit it is necessary to work out the profit on the same amount of takings.

Thus on every £100 taken for scent, £30 is profit, while on every £100 taken for soap, only £25 is profit.

We can now see which of the two articles pays the better, and by how much.

Similarly with mixtures of all kinds. In order readily to compare formulae with respect to the different proportions of ingredients, it is desirable to have them written out in such a way that the weights or volumes of the finished articles shall be the same, otherwise the issue would be confused by the fact that one formula might be written for say 1 lb., another for 30 oz., and yet another for 70 g.

Suppose the first contained 1 3/4 oz. of white wax, the second 3 1/4 oz., and the third 7·25 g. A comparison of the formulae is not possible at a glance, and certain preliminary calculations are required. In a percentage formula such calculations would be unnecessary. The formulae have only to be placed side by side for exact differences to be immediately appreciated. Another important point is that one memorizes easily and almost unconsciously the usual proportions of the various ingredients which are used.

For example, here are three formulae calling for ingredients which we will call A, B, and C.

One can see at a glance in what respects they differ, and, if the products are available, it is easy to link up their varying qualities with the different proportions of the various ingredients. By using the expression per cent, one can now refer to the various proportions by one number instead of having to say so much ‘A’ in so much of the product. The symbol % is employed to signify per cent. Thus formula No. 1 contains 10% of A, formula No. 2 has 12·5% (or 12 1/2%) and formula No. 3 contains 8%.

ELEMENTS OF CHEMISTRY

In order to understand the nature of the materials used, and the way in which they act on one another, it is essential to have some idea of chemical constitution. All matter—solid, liquid or gas—is composed of minute particles called molecules, and the properties of a substance depend on the composition and constitution of the molecules of which it is built up. To enable those with no knowledge of chemistry to visualize this and understand its significance we will take an analogy.

Imagine a factory which turns out miniature toilet sets, thousands and thousands of tiny brown boxes each containing a nail file, three emery boards, and two orange-wood sticks. I visit this factory, and see from a distance huge stacks of these sets looking like solid brown masses. On a closer inspection, however, I find that these solid-looking masses are composed of little units, each exactly alike. On opening one out I find the three emery boards, the nail file, and the two orange-wood sticks. It does not need a mathematician to deduce that 100 sets will contain 100 nail files, 300 emery boards and 200 orange-wood sticks. If I now weigh the articles and find that a nail file weighs 4 g., an emery board 1/2 g., and an orange-wood stick 1/4 g., then it follows that each set contains—

4 g. of nail file.

1 1/2 g. of emery board.

1/2 g. of orange-wood stick.

100 would contain 100 times these quantities, and any given number or weight exactly the same proportions.

Now, suppose I have before me a block of stearic acid. It appears to