I have already shown how the perseverance and ingenuity of Eastman and Walker aided in solving the problem of animated photography. Their film was used for the first time experimentally in the United States as far back as 1889, although it did not enter the general market until about two years later. From that time there was an increasing demand from the host of experimenters for large quantities of the narrow, thin sensitised strip of celluloid. As the demand increased the chemists associated with the subject redoubled their efforts; their product was still far from perfection, and even to-day they will admit that many abstruse problems remain to be unravelled.

Although the present-day consumption of celluloid film for cinematograph purposes is enormous, aggregating several million feet per week, the manufacturing process is of such a peculiar character that the number of firms identified with its production can be counted upon the fingers of one hand. In the United States it is controlled by the Eastman Kodak Company, who have extensive factories at Rochester in the State of New York, and a large establishment at Harrow in England. In France Messrs. Lumière and Sons, and in Germany the Gaevert firm, have large factories. British effort is represented by the Austin-Edwards Company, which produces an excellent film, but the home industry is in its infancy. The three first-named firms supply almost the entire demand. The Eastman firm has the largest output, about 3,500,000 feet per week, which is due to the fact that in the United States there are over 14,000 picture palaces open every day from morning until midnight, and many large firms engaged in the preparation of the film subjects. Most of the Eastman supply is used in the United States and Great Britain. Aside from it and the French and German products, some of the large European film producers prepare their own stock, as the celluloid base is called. If all these totals were added together, the sum of them would show something like 6,000,000 feet of film, in both negatives and positives, consumed every week.

Each country has millions of pounds invested in the enterprise. It is difficult to gauge the proportions of the entire industry. If all its varied branches are taken into consideration, it probably ranks as one of the largest in the world. And the whole of this development has taken place within twenty years.

In order to gain an idea of one branch of the industry, the manufacture of the film, one must pay a visit to the extensive works of the Eastman Company, the plant of which is able to turn out no less than 7,200,000 lineal feet of film for moving pictures every week—truly a tremendous output. This capacity has not been taxed to the utmost yet, but when the requisite machinery was laid down, the company decided to anticipate the future. Should the present pace of development be maintained, there is no doubt that, before the end of another twenty years, this firm will find its present installation barely sufficient to meet the demand. Continued chemical research and improvement of processes is tending to reduce the cost of the material, and while at the same time the moving picture business itself is expanding on all sides, fresh markets are constantly being opened up for the products of the manufacturers.

At the Eastman works is to be seen a striking illustration of the growth in the manufacture of celluloid film. In the room where the ingredients are mixed together there is a small barrel, which will hold 500 pounds of the film mixture. This little barrel, together with another of the same capacity, sufficed to meet all requirements in the year 1891. In the same building is a battery of fifty huge barrels, each with eight times the capacity of the small one, and these are run night and day to meet the present demand for the material. The little barrel is no longer used; but it is preserved as an honoured relic of the past and an eloquent witness of the tremendous growth of the film-manufacturing industry for cinematography.

The ingredients for the film are gun-cotton, known technically as pyroxylin, and wood alcohol. The pyroxylin is prepared by treating cellulose devised from such vegetable materials as flax or cotton waste, with a mixture of sulphuric and nitric acids. The ingredients are associated in large cylindrical tanks ranged in long rows upon the upper floor, and discharged through trap doors into the barrels beneath. The gun-cotton is then dissolved in the alcohol by mechanically rotating the huge barrels. It is possible to treat in this way some 200,000 pounds of material at one time. The mixing process reduces the gun-cotton and wood alcohol to a viscous liquid of the consistency of extracted honey, which substance forms the base of the film, or support for the sensitive emulsion, and is known technically as cellulose-nitrate.

When the gun-cotton has been dissolved to the requisite degree, the syrup-like mixture is drawn from the barrels and stored in cylindrical tanks.

The next step is the conversion of the mixture into sheets of the requisite thinness. It is not rolled out, but poured upon suitably polished supports, and spreads out, like varnish, in a thin film. The Eastman patent specifies three distinct kinds of receptacle for the pouring process: a long sheet of polished glass, an endless polished metallic belt, and a revolving drum having a highly polished surface. Any of the three will produce the result; and in each case the deposit has to be permitted to dry to a certain degree.

When the drying is achieved, the thin coating of transparent flexible material, resembling a skin, is stripped from its support and coated with the sensitive emulsion. The latter is of two degrees of sensitiveness, according to whether the film is to be used as a negative or a positive. The former is of the very highest sensitiveness to light that it is possible to obtain, since under normal circumstances it is only exposed for the fraction of a second; while the film required for the positive, which is used for projection, is rendered less sensitive, as it can be given a longer exposure in the printing operation.

The base, with its sensitised coating, is now permitted to become dry and hard. At the conclusion of this operation the length of thin celluloid sheeting, technically called a web, which is about 3½ feet wide, is slit into strips of the standard width now used in all cinematograph cameras and projectors—1⅜ inches wide.

Extreme care has to be taken to secure a uniform thickness. The plant at the Rochester works has reached such a degree of accuracy that the thickness of the film which is taken from the polished rolls, although the web measures 2,000 feet in length, does not vary above the standard by more than 1/4,000th part of an inch.

As I have already said, however, after all this care, the product is far from being perfect, and it sometimes displays strange caprices. They are most pronounced in the tropics. Owing to the volatile character of the ingredients employed in its manufacture, the film undergoes considerable shrinkage in hot climates owing to evaporation. I have seen film shrunk so much that it failed to conform with the standard gauge, and the teeth of the sprocket in the printing machine, instead of engaging with the holes, played upon the outer smooth edges of the film. To maintain the prime condition of the film it is necessary to keep it somewhat moist, and accordingly the packing boxes carry a certain amount of damped material. But in tropical countries where the heat is intense, it is by no means a simple matter to keep the film in condition; and for this reason it is often difficult to secure satisfactory pictures of scenes in tropical countries. A firm which dispatched an operator to Central America to secure a series of scenic and industrial films failed to obtain a single length of pictures worth showing. I saw the results of the expedition. The film was badly distorted, and the pictures in some instances were so thin or indistinct as to defy projection. £500 ($2,500) had been expended without result.

There is another eccentricity displayed occasionally by some films in tropical climes, which is difficult to explain. An operator will expose several hundred feet of film, which, when developed, fails to show the slightest sign of exposure. I have seen the results of a first-class cinematographer working between the limits of Capricorn and Cancer. His films when developed were as clear as if they had never been exposed to the action of light. The firm took one section of the exposed film and re-exposed it on a London street. It showed on development the image of London traffic, being as bare of any other image as if it had never seen the jungle. Heat and dry atmosphere seem to exercise some obscure chemical action, which prevents the sensitive surface of the films from being affected by exposure; yet when the film is returned to a naturally moist climate, like that of England, it appears to recover its original qualities.

As the component parts of a cinematograph film are of an inflammable nature, the resultant fabric is naturally also highly inflammable. This danger in the early days severely menaced the development of the industry, especially since those occupied in projection were careless of the most elementary precautions. The film, after passing through the lantern, fell a dishevelled mass into a basket, where it formed a tangled heap of thin combustible material, as inflammable as petrol-soaked shavings. Celluloid emits a vapour of an explosive nature, and it is always dangerous to use a naked light in its close proximity. Yet custom rendered the operator heedless of the danger. The outcome was inevitable. Legislation stepped in and ordained that the projector should be encased in a steel fire-proof chamber for the protection of the public. The result was that the cinematograph was barred from many places where the magic lantern was used.

Moving pictures could not be shown at such establishments as schools, merely because they did not possess a fire-proof chamber in which to operate them. A non-inflammable film was, of course, the next demand. To attempt to render celluloid non-combustible was akin to rendering gunpowder non-explosive. An absolutely new film-base had to be found. Cellulose as a basic constituent could not be dispensed with—in fact, chemical research has not yet succeeded in discovering an efficient substitute. Efforts were concentrated upon the treatment of the cellulose in such a manner as to prevent it being readily combustible, with the resultant production of the preparation known as cellulose-acetate, which is practically non-inflammable. But while this substance complies with the letter of the law and does not burst into flame, it does melt, however, under the influence of heat, and in so doing sometimes emits copious clouds of smoke, which are capable of producing panic in an audience quite as readily as an outburst of flame.

Under ordinary circumstances, this non-inflammable film is quite safe to handle, and from that point of view is adapted for the purpose of exhibiting in buildings where a special chamber is not provided. The heat produced by the focussed rays in the lantern, or the inadvertent contact of a naked light, do not promote combustion. The cellulose-acetate merely chars or melts, the action being purely local.

The celluloid film is supplied generally in lengths of 165 feet, which is approximately the capacity of the average film box. The actual picture itself upon the film measures one inch in width by ¾ of an inch in depth.

The question naturally arises as to what becomes of the films which have passed through their allotted span of life. When the celluloid film was first placed on the market this material was of a certain value. The sensitised gelatine emulsion was stripped off, and the base was converted into varnish. But this practice has fallen into disuse. Practically speaking, old films have no economic value. As a rule they are burned. If the junk film is obtained in sufficiently large quantities, a slightly remunerative by-product can be obtained in the form of metallic silver from the ashes, but the yield is so small and silver is so cheap that the trouble involved does not pay unless the waste is destroyed in tremendous bulk.

This is the era of the profitable utilisation of waste products, and no doubt a large fortune is awaiting the chemist who succeeds in evolving a cheap process for turning the useless cinematograph film to commercial account. Newspapers, old iron, and other metals, rubber, sawdust, and even garbage, possess a certain economic value, and there is no reason to suppose that used celluloid film is an exception to this general rule of utilising waste products. One by-product, as we have pointed out, is certain of reclamation—the silver—but the other constituents might prove just as valuable if a cheap, inexpensive method were contrived for their commercial reclamation.