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Briefly defined, celluloid is a species of solidified collodion produced by dissolving gun cotton (pyroxylin) in camphor with the aid of heat and pressure. The gun cotton is ground in water to a fine pulp in a machine similar to that used in grinding paper pulp. The pulp is then subjected to powerful pressure in a perforated vessel to extract the bulk of the moisture, but still leaving it slightly moist for the next operation. This consists in thoroughly incorporating finely comminuted gum camphor with the moist gun cotton pulp. With this mixture any coloring matters required can now be embodied. The next step is to subject the mass to powerful pressure in order to expel from it the remaining traces of moisture, and incidentally to effect also the more intimate contact of the camphor with the pulp. The dried and compressed mass is next placed in a mold, open at the top, into which fits a solid plunger. A heavy hydraulic pressure is brought to bear upon the plunger, and at the same time the mixture is heated by means of a steam jacket surrounding the vessel to a temperature of about 300 degrees Fahrenheit. When the mass is taken out of the press it hardens, and so acquires the extraordinary toughness and elasticity which are the distinguishing characteristics of this remarkable production. Celluloid is very largely useful as a substitute for ivory, which is imitated with great success. Tortoise shell, malachite, mother of pearl, coral and other costly and elegant materials are also so successfully imitated that an expert can hardly detect the original from the copy. Celluloid is also used as a substitute for porcelain in the manufacture of dolls, which will stand a good deal of rough usage without breaking, Combined with linen it is used for shirt bosoms, cuffs and collars. THRASHING WATERMELONS FOR SEEDS Out in the West, where irrigation and sunshine combine to make the production of watermelons very successful, a novel industry has grown up, which is assuming huge proportions and promises a splendid revenue for the originators of the scheme. In the upper Arkansas valley, melons are grown for their seed, and great fields are yearly covered with the luscious green shapes, destined never to tickle a palate. The melons grow to large size and great perfection. When they are fully ripe they are harvested with as much precision as are the wheat and corn crops of the plains. The thrashing machine with which the melons are handled is simple. It consists chiefly of a cylinder driven by horse power or by traction engine. Great wagonloads of melons are brought to the side of the machine, and one by one they are thrown with great force into its hungry mouth, to break against the teeth below. The whole is ground to a fine pulp and run out through a sieve, the rinds being thus separated from the inner portion of the melon. The rinds are left to rot on the prairie, and the juicy mixture stands in large vats until the process of fermentation takes place, separating the seeds from the pulp. The seeds are then spread out on boards to dry and are ready for the market. The farmers sell the seeds to eastern firms, and in good years clear from $12 to $15 an acre for their labor. The harvest time is late in summer and in early autumn, and attracts much attention. EFFECT OF ELECTRICITY ON MILK AND MEAT During serious electrical disturbances in the atmosphere, it is well known that beer may become "hard," milk may go sour, and meat may frequently "turn." Considerable speculation has arisen as to the cause of this. It has been suggested that an ozonized state of the air due to electric discharge has something to do, with it, or that the formation of nitrous acid in the air is responsible for the change. It is, however, not probable that the atmosphere undergoes any chemical change sufficient to account for the extent to which certain foods "turn." Moreover, any important quantity of ozone or nitrous acid would be calculated to exert a preserving effect, as both are powerful antiseptics. It may be urged, again, that the phenomenon is due to oxidation by means of ozone, but this can hardly be the case, in view of the large quantities of beer and milk that are soured, in relation to the very small quantity of ozone which a thunderstorm produces. In the case of meat, at any rate, the "turning" can scarcely be attributed to the action of the ozone or of oxygen. The change is probably due not directly to chemical agencies, but, purely, to a disturbance of the electrical equilibrium. It is well known that an opposite electrical state is set by induction, so that an electrical condition of the atmosphere induces a similar condition, though opposite in character, in objects on the earth. Persons near whom a flash of lightning passes, frequently experience a severe shock by induction, although no lightning touches them; and in the celebrated experiment of Galvani, he showed a skinned frog in the neighborhood of an electrical machine, which, although dead, exhibited conclusive movements every time that a spark was drawn from the conductor. In the case of milk "turning," or beer "hardening," or of meat becoming tainted, it is probably, therefore, an instance of chemical convulsion, or, it may be, of a stimulus given to bacteriological agencies set up by an opposite electric condition, induced by the disturbed electrical state of the atmosphere. Although these charges are most marked during a thunderstorm, yet, undoubtedly, they occur at other times, but not to the same degree, when there is no apparent electric disturbance. But even when the sky is clear, the atmosphere may exhibit considerable, electrical tension. The electroscope constantly shows that a conducting point elevated in the air is, as a rule, taking up a positive charge of electricity, the tension rising with the height of the point. This effect increases toward daybreak until it reaches a maximum some hours after sunrise. It then diminishes until it is weakest a few hours before sunset, when it again rises and attains a second maximum degree some hours after sunset, the second minimum occurring before daybreak. There are accordingly constant changes of electrical tension going on,—changes, however, which are more rapid and much more marked during a thunderstorm, and which are quite powerful to exert an evil influence on certain articles of food or drink susceptible to change, notably, meat, milk and beer or cider. There is no doubt that the unfavorable effects on the feelings experienced by many individuals, such as headache, oppression and nervous distress, on the advent of a thunderstorm, have a similar foundation and are due to the same electrical differences of potentiality, the effects passing away as the disturbed condition of the atmosphere changes, or the storm subsides. ATHLETIC SPORTS OF TO-DAY |