86o 



THE POPULAR SCIENCE MONTHLY. 



cotton is ground in water to a fine 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, 

 which consists in thoroughly incorporating 

 finely comminuted gum-camphor with the 

 moist gun-cotton pulp. The proportions 

 employed are said to be one part by weight 

 of the camphor to two parts by weight of 

 the pulp. Any pigments, coloring matter, or 

 other materials that may be adapted to the 

 requirements of the articles into which the 

 product is to be manufactured, may be in- 

 corporated at this stage. The mass is next 

 subjected to a powerful pressure, to expel 

 from it the remaining moisture, and inci- 

 dentally to effect, also, the more immediate 

 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, when a heavy pressure ap- 

 plied to the plunger is brought to bear upon 

 the mixture. While thus under pressure, 

 the mixture is heated to a temperature of 

 about 300°, at which temperature the cam- 

 phor fuses, and, its volatilization being im- 

 possible, the melted camphor dissolves, or 

 "converts," the gun-cotton pulp. The pro- 

 cess of transformation is rapidly effected 

 when the right temperature is reached, and 

 the product is celluloid. After the mass 

 is taken from the press it hardens and be- 

 comes tough and elastic. A noteworthy 

 circumstance is, that a large portion of the 

 camphor appears to be permanently held in 

 the mixture, so that its property of volatili- 

 zation, when exposed to the air, is arrested. 

 Celluloid is so extensively used as a substi- 

 tute for ivory that it is said to have serious- 

 ly affected the business of ivory importers 

 and workers. It has all the strength and 

 elasticity of this substance, and does not 

 warp or discolor with age. It is used in 

 place of tortoise-shell, malachite, amber, 

 pink coral, and other costly and elegant 

 materials, which it is made to imitate very 

 closely. Its latest use is in combination 

 with linen, cotton, or paper, for shirt bos- 

 oms, cuffs, atid collars. 



Experimental Glaciers".— Mr. J. T. Bot- 

 tomley describes in " Nature " a successful 

 experiment which has been arranged by him- 



self and Mr. D. Macfarlane for constructing 

 a model glacier with shoemaker's wax. A 

 little wooden ravine was prepared, with 

 steep dechvities and gentle slopes, and a 

 point where the space was narrowed by pro- 

 jections inward. At the upper end of the 

 ravine a flat place was fixed, on which shoe- 

 maker's wax was piled, as snow collects at 

 the upper end of the natural ravine. A 

 supply of shoemaker's wax was put on the 

 top at the beginning of each winter's ses- 

 sion, whence a flow of semi-solid material 

 went on steadily during the session, hardly 

 perceptible from day to day, but progress- 

 ing from week to week and from month to 

 month. Several of the glacial phenomena 

 were beautifully imitated with the wax ; 

 among them the more rapid flow of the 

 middle with the less rapid flow at the edges. 

 Little crenasses were sometimes formed, 

 though not often, owing to the great effect 

 of temperature on the plasticity of the ma- 

 terial. Sir William Thomson, in order to 

 test the qualities of shoemaker's wax as a 

 viscous material, a year ago prepared a 

 large cake of it, at the bottom of which he 

 put some corks, and on the top some bullets. 

 The corks at the end of the year had floated 

 up through the wax, and were coming out 

 at the top, while the bullets had sunk down 

 and come through the bottom ; and, while 

 this was going on, the wax was all the time 

 in such a condition as to be excessively brit- 

 tle to any force suddenly applied. 



Source of t!ie Niger. — Information has 

 reached Marseilles of a successful journey 

 to the source of the Niger, which has been 

 made by two men in the employment of the 

 commercial house of M. Verminck, of Sierra 

 Leone. The expedition, it appears, origi- 

 nated with M. Yerminck himself, who sent 

 forth two of his clerks, MM. Zweifel and 

 Moustier, with an equipment of surveying 

 instruments, maps, and goods, for the ex- 

 press purpose ef reaching the spot on the 

 northern side of the Kong Mountains, some 

 two hundred miles from Sierra Leone, where 

 both Major Laing, in 1822, and Winwood 

 Reade, in 1869, were informed by the na- 

 tives lay the sources of the " Joliba." The 

 two envoys ascended the river Rokelle to 

 the foot of the mountains, and seem to 

 have met with none of that opposition, from 



