Part 8 (1/2)

Dietz and Wayne (USP, No 133, 969) use ra a soluble pyroxyline That th and solubility, and requires a smaller quantity of solvent to dissolve it than that made from cotton Mr Field's experience, however, is entirely contrary to this statement Such is the influence of the physical form of the fibre on the process of nitration, that when flax fibre and cotton fibre are nitrated with acid th, and at the salutinous or thick, and the second fluid or thin By siher teiving an equally fluid collodion

The presence of chlorine in the fibre must be carefully avoided, as such a fibre will yield an acid product which cannot be washed neutral The fibreto Mr Field, by using the for wool

~Nitration of the Fibre~--Mixed cotton and flax fibre in the form of paper, from 2/1000 to 3/1000 inch thick, and cut into 1-inch squares, is nitrated by the Celluloid Manufacturing Co strips, 1 inch wide, is used for nitration by the Xylonite Manufacturing Company, of North Adams, Mass (USA)

The Celluloid Company introduce the cut paper into thetube, flared at the lower end, and ial force of the revolving tube throws the paper towards the sides of the vessel, leaving the centre of the vessel ready for fresh paper

The Xylonite Co strips, and introduce it into the e the mixed acids is a cylindrical vessel divided into a nu like a turntable, thus allowing the workiven point

This Company did not reed it ie proportion of the waste acid The Celluloid Co the paper in s the mixed acid from the paper before immersion in water, had a better process of nitration

Other lass or steel rods, hooked at one end, having small pieces of rubber hose pulled over the other end to prevent the hand froiven in Fig 23 It is large enough to nitrate 1 lb of cotton at a time The hook at one end of the rod enables the workman to pull the pyroxyline apart, and thus ensures saturation of the fibre In the winter the roo is done must be kept at a temperature of about 70 F in order to secure equality in the batches

[Illustration: FIG 23--VESSEL FOR NITRATING COTTON OR PAPER]

The nitrating apparatus of White and Schupphaus (USP, No 418, 237, 89) Mr Field considers to be both novel and excellent The cage (Fig 24), with its central perforated cylinder (Fig 25), is intended to ensure the rapid and perfect saturation of the tissue paper used for nitrating The patentees say that no stirring is required with their apparatus This, says Mr Field, ht be true when paper is used, or even cotton, when the temperature of nitration is from 30 to 35 C, but would not be true if the temperature were raised to 50 to 55 C The process is as follows:-- The paper is nitrated in the cage (Fig 25), the bottoed plate C, fastened to the bottoe is carried to a wringer, which fore is taken to a plunge tank, where the paper is re out the central perforated cylinder B Fig 26 shows the nitrating pot, with its autoe tank is shown in plan and section in Figs 28 and 29

This apparatus is suitable for the nitration of cotton fibre in bulk at high or low temperatures Other methods that have been patented are Mowbray's (USP, No 434, 287), in which it is proposed to nitrate paper in continuous lengths, and Hyatt's (USP, No 210, 611)

[Illustration: FIG 24--CENTRAL PERFORATED CYLINDER]

[Illustration: FIG 25--THE CAGE WHITE AND SCHUPPHAUS' NITRATING APPARATUS]

[Illustration: FIG 26--CELLULOID NITRATING POT]

[Illustration: FIG 27--ANOTHER VIEW]

[Illustration: FIGS 28, 29--PLUNGE TANK, IN PLAN AND SECTION]

~The Acid Mixture~--Various for soluble nitro-cellulose In h the observations were correct for the single experiment, a dozen experiments would have produced a dozen different products The composition of the acids used depends upon the substance to be nitrated, and the temperature at which the nitration will be worked Practically there are three foreneral use--the one used by the celluloid h temperatures; and a third in which the temperature of the immersion is low, and the time of nitration about six hours Of the three, the best method is the last one, or the one in which the cotton is immersed at a low temperature, and then the reaction allowed to proceed in pots holding from 5 to 10 lbs of cotton The formula used by the celluloid manufacturers for the production of the low form of nitrated product which they use is:--

Sulphuric acid 66 parts by weight

Nitric acid 17 ” ”

Water 17 ” ”

Temperature of immersion, 30 C Time, twenty to thirty minutes

The cellulose is used in the form of tissue paper 2/1000 inch thick, 1 lb

to 100 of acid mixture The nitro-cellulose produced by this formula is very insoluble in the coly only converted or gelatinised by the action of the solvent The next formula produces a mixture of tetra-and penta-nitro- celluloses hardly soluble in methyl-alcohol (free from acetone), but very soluble in anhydrous compound ethers, ketones, and aldehydes:--

Nitric acid, sp gr 1435 8 lbs

Sulphuric acid, sp gr 183 15-3/4 lbs

Cotton 14 oz

Temperature of nitration, 60 C Time of immersion, forty-fivethe acids together The cotton is allowed to remain in the acid until it feels ”short” to the rod