In the establishment of a colour works several conditions are necessary. The most important is the supply of water in sufficient quantity and purity. It has already been stated that many pigments cannot be made with water containing much organic matter or salts, since the dissolved substances affect the shade. This action not only takes place in the formation of the colour, but is also unpleasantly manifest when it is washed. The delicate lakes are discoloured by organic matter in the water, and are so changed by any considerable quantity of lime that the alteration in shade is clearly perceptible after continued treatment. If the water contains but a very small quantity of iron, the preparation of some pigments is made quite impossible, since—and this is especially the case with the lakes—the ferric oxide is precipitated together with the pigment, and in consequence of its characteristic colour imparts to it an ugly shade. Thus in choosing a site for a colour works the available water supply must be carefully examined. If it is not sufficiently pure or in sufficient quantity, the position must be regarded as unsuitable.

No colour maker, although working on the largest scale, is in a position to make all the materials he requires. With the continual development of the chemical industries, the number of these substances which can be made economically in the colour works continually diminishes. It is far more advantageous to obtain them from works in which they are made on the large scale. Many of these substances are required in large quantity, so that a site should be chosen in direct communication with the railway, so that the cost of carriage is diminished, and also the cost of distributing the manufactured materials. This is especially necessary for materials which have a low value and consequently can bear no high cost of carriage.

In regard to the space required by a colour works, no actual dimensions can be given, since these vary with the extent of the business, and with the pigments produced. In the price lists of large colour works all the commercial pigments are generally quoted, but they are rarely if ever actually made in one works, but are obtained at a lower price from other establishments, which make a speciality of certain pigments, and by working on a large scale can produce them at such a cost that the smaller manufacturer is not in a position to compete with them. Thus there are works in which only white lead or ultramarine is made.

If a colour manufacturer is in the fortunate position of placing his works on a river, he has not only an unrestricted water supply, but may also be able to use water power, the cheapest of all powers. When water power is available, it will be used to raise the large volumes of water required and to move the machinery for grinding the raw materials, rasping dye-woods, etc. In a colour works of any size a boiler is required; if water power is not used, it must be of sufficient power to give steam for driving the engine, for boiling liquids and for heating the drying stoves. The boiler is of great advantage in providing steam for dissolving salts, extracting dye-woods and boiling liquids. When liquids are boiled by steam there is considerable economy in that the majority of the boiling tubs can be of wood, which is provided with a protective coating for liquids which attack wood. Thus there is economy in dispensing with large metal pans and with the fireplaces in which they would be built, and also in the course of time there is considerable saving in fuel.

For a well-equipped colour works a drying stove, in which the pigments can be thoroughly dried, is important. It is most convenient to heat drying stoves with steam. The temperature can be easily regulated by increasing or diminishing the supply of steam. For drying pigments which would not be injured by considerable increase of temperature, the drying stove may be heated by a fire.

In a colour works in which many pigments are made sulphuretted hydrogen is frequently required. Since all lead pigments are blackened by this gas, the greatest care is required in using it. Also the poisonous nature of sulphuretted hydrogen is generally under-estimated. In working with sulphuretted hydrogen, the apparatus depicted in Fig. 3 should be used. It should be placed in a position, such as a closed yard, in which escaping gas will be harmless. If this cannot be done the precipitation should be accomplished in closed vessels, from which a pipe should carry the gas to a fire, where it will be burnt to sulphur dioxide and water.

In most cases the manufacturer of colours makes but a certain number of pigments and rarely or never all which are mentioned in his price lists. The dimensions of the establishment will be in accordance. In commencing a new colour works it is advisable from purely financial reasons to produce at first a limited number of colours, but these in perfection. By many experiments and diligent study of chemistry a colour manufacturer may hope to compete successfully in so difficult a branch of chemical technology as the manufacture of colours.