Further, at this stage it is decided whether a reaction or a compound shall be patented. It is the task of the patent department to decide as to the likelihood of obtaining a patent or whether, if the discovery appears to be important, it would be preferable to keep it secret until the whole field has been investigated, and there is little danger of any one else trespassing. Very occasionally patent protection is not sought, and the attempt is made to keep the processes secret, but this is by no means a safe proceeding, and is only resorted to in cases of necessity.

The chemists are required to submit a report on their activities to the Directorate at regular intervals in order that the Directors and heads of departments may be kept in touch with all developments. These reports are submitted monthly, or at less frequent, but regular, intervals, and are drawn up under the supervision of the departmental heads.

Before a product is put on to the works to be manufactured it is first sent to the Costing Department to be costed. The necessary data are provided by the chemical administrative staff and the works engineer. In Chapter 15 a small calculation is shown as an example, in order to give a general idea of the manner in which the cost-price of a dye is arrived at.

Management. - The actual Management is divided into three sections, the Technical Chemical Department, the Analytical and Dyeing Department, and the Engineering Department.

Owing to the destructive action of the chemicals used, apparatus is very quickly worn out and, in addition, alterations are frequently necessary, so that the ratio of the number of chemical workers to that of the ordinary workmen (e.g. locksmiths, pipe-fitters, carpenters, painters, bricklayers, etc.) is about 2:1. The workshops are first of all repairing shops, and are under the direction of the works engineer. If any repair or alteration is required to an existing plant, the works chemist, with the sanction of the management if it is a large matter, applies to the engineer. The work is ordered by means of a special form duly filled in, which, on completion of the job, is sent to the Costing Department to be worked out.

The large dye factories have their own constructional workshops, but nevertheless place their large orders outside after making a suitable agreement with some engineering works for quick delivery at reasonable rates. It is advisable not to use too many types of plant so that any part or agitator may be replaced at once from stock. Frequently quite a few spares suffice for many different plants, as they are mutually interchangeable.

Charges. - In addition to the charges due to depreciation and repairs, there are maintenance charges of various kinds to be considered. Some of these are calculated exactly, whilst others are lumped together as general overhead charges or "On-costs." The expenses which can be estimated fairly accurately are workmen's wages, which can be calculated from the wage-sheets of the foremen and works chemists; further, the steam consumption can be measured with the usual type of steam meter, and also the amount of compressed air and vacuum used.

Steam Consumption. - The steam consumption of a colour factory is considerable, and depends upon the amount of water which requires to be heated and on the number of cubic metres of water which have to be evaporated. In particular, the evaporation of reduction liquors demands immense quantities, and multiple-effect evaporators (double and triple effect) are being increasingly used. In this type of apparatus the heat of the steam is used two or three times over by leading the waste steam into a second boiler, where it evaporates a further quantity of liquid kept under reduced pressure. This apparatus is modelled partly upon the multiple-effect evaporators used in the beet-sugar industry, and in some cases they possess heating vessels which are placed next to the reservoir of liqud. The liquid is made to circulate through the tube evaporator, thus attaining a rapid circulation, and in addition the boiler-scale (chiefly gypsum) is deposited solely in the subsidiary vessel, the tubes of which can be replaced in a few hours. It is possible by this regenerative utilization of the steam to reduce the coal consumption to less than 25 %, so that the large dye-works use triple-effect evaporators almost exclusively with very satisfactory results. It is possible to utilize the steam still more efficiently by heating it up to 15 atmospheres instead of the usual working pressure of 5 atmos. Before this high-pressure steam reaches the works it is used to drive a steam turbine or a reciprocating engine, leaving this at 5 atmos. pressure. So much energy is obtainable from the pressure drop of 15-5 atmos. that each dye works can actually provide surplus electric current. It has also been suggested that the steam should be allowed to fall as low as 2 atmos., but in order to do this the steam pipes must be so large and the radiation losses, particularly in winter, so considerable, that it is hardly practical politics. Of recent years an improved method for using up steam has been introduced, although the general principle has been known for a long time. The liquid under evaporation is placed in an hermetically closed evaporator, the vapours are sucked out by means of a turbo-blower, and the waste steam is then circulated, under a pressure of about 3/4 atmos. through a system of tubes built into the same vessel. There is a considerable evolution of heat as a result of the compression of the vapours, so that as much as 80 % of fuel may be saved. Apparatus of this type is becoming increasingly popular, and is made, for example, by Gebr. Sulzer in Winterthur, and by Escher Wyss in Zurich.

Compressed Air and Vacuum, - In addition to steam, the provision of compressed air is also important. Generally a pressure of 2-3 atmos. is needed, which is obtained by the use either of a reciprocating or a rotating pump. The chief determining factor as to the quantity of air required is the number of filter-presses, as these use the most air. Every precipitate before leaving the press is "blown through" for a time, i.e. compressed air is blown through the filter-cakes until the main portion of the mother-liquor has been blown out. For instance, a press with 40 sections will require about 100 cubic metres per hour of compressed air at 2 atmos., which will cost from 3-5 centimes, according to the price of the current.