Add to normal yellow the slightest bit of red, and the colour approaches orange. In fact, it is a yellow orange, and all tones made up of red and yellow, which are nearer yellow than orange, belong to the class of hues known as yellow orange. Start with normal red and by the addition of yellow the colour tone approaches orange, but red is the dominating element. In such colour tones this is red orange because it belongs to the family orange and the element red is in excess of the element yellow. If we start with normal red and add blue,, the purple hues appear. So long as red is the dominating element, the hues are the red purple. If blue is the starting point, however, and red is added, the hues between normal purple and blue are blue purple. When the starting point is blue, and yellow is added, the blue begins to assume a greenish hue, and blue green is the name given to the set of hues between normal blue and normal green.

These sets of tones which are found around the binary colours express hues of colour. It will be seen then that hue is the name of the colour itself, or that it really expresses the degree of so-called heat or cold which a colour has. The hues of colour between yellow and purple, including all greens and all blues, are cool colours. Those between yellow and purple, including all orange and red colour tones, are warm colours. It is this that gives significance to the expression "temperamental colour," one's temperament being expressed by the hues on the right or the left of the spectrum circuit.

There are two ways in which one should see the temperament idea in its relation to the subject Interior Decoration. If it is granted that certain colour tones produce, consciously and unconsciously, certain impressions or mental states in individuals living under their influence, then arises the question whether the mental state the individual enjoys most is the mental state in which he ought most often to be. For instance, I may enjoy being thrilled and stirred, warmed and excited, by orange or red in their combinations, but it may be better for me and far more agreeable for my associates if I am surrounded by green or blue: colours exercising some restraining influence upon my nature instead of catering to what is most pleasing to me in the way of emotional sensation.

In selecting material for one's self, or in advising any one what to select, it is always wise to sense as nearly as possible the psychological condition of temperament before attempting to control or augment its idiosyncrasies by environment.

The subject of hue cannot very well be left without referring to what is known as keying a colour, or the keying of a scheme of colour to a dominant hue. Much has been said and written about this dominant hue keying. It simply means this: that one of the three elements - yellow, red, or blue - must be introduced into the leading areas of a colour scheme in such a way that one will feel its presence, although the colour itself is found in another tone in the spectrum circuit.

A very familiar violation of the rule for keying colour is found in the use of a definite wall-paper tone with perhaps a natural-wood or ivory-white trim, a hardwood floor, and a perfectly white kalsomined ceiling. White is such a combination of the primary elements of colour that no one colour is apparent. It is saturated with the three elements; in consequence, no one dominates. Colours show more strongly on it than on any other colour or on black. In white, there being no apparent colour, it is unrelated and, therefore, cannot become a part of a keyed room scheme in which there is any floor or wall colour. If the wall colour is a soft neutralized yellow or orange, then the ceiling must be keyed with that colour in a lighter tone, so that you feel the ceiling tied with an apparent colour element to the wall, of which it is really a part.

What is true of the ceiling is true of the floor. When the floor cannot be keyed to the wall, rugs should be used in which the dominating tone is that of the wall. The rugs must be keyed to the wall in order to become a part of it. Of course there are times when the rug or rugs play in the key of the trim instead of the wall paper, but in the simplest arrangement the three parts of the room - walls, floors, and ceiling - should be keyed so that there is an apparent link or common element.

It is often possible to key furniture - which, so far as the wood goes, is a foreign colour tone - to the rest of the room by upholstery in which the dominating colour is strongly keyed to the wall colour, the trim, or the floor. Preferably, key to the wall colour because of the intimate relationship between the background of a room and the accessory objects that are to be shown against it. This is essential to unity of colour, and is the only way to secure an expression of rest, refinement and repose.

The second quality a colour tone possesses is called lvalue. This quality takes its name from the position a tone holds in a scale of even sequence between black and white. It relates, therefore, to light, and is perfectly distinct from the quality of colour or hue. If one thinks of a graded scale from black to white in which even steps of grade are found in any number, a standard of judgment as to the meaning of the word value is easily fixed.

For example, a colour tone whose light quality is one-half way between black and white is called middle value. In a scale of nine tones, one-half way between middle and white is called light, one-half way between light and middle is called low light, and one-half way between light and white is called high light. In the same way, one-half way between middle and black is dark, while one-half way between middle and dark is high dark, and one-half way between middle and black is low dark.

These values, though arbitrary, are equidistant in light quality from each other, and standardize the value idea, thereby helping one to disassociate the value quality from the hue quality previously discussed. It is difficult at first to see each quality as a separate idea, but only in so doing is one able to understand how to select and arrange colours in composition so that each tone serves its full purpose and does not conflict in any one quality while seeming to agree in the other two.