572 



Popular Science Monthly 



from cotton. The coating is composed 

 principally of soluble cotton. In the 

 process the cotton is separated from foreign 

 particles and washed. It is then 

 nitrated, as it is called, which 

 means that it is treated with a 

 mixture of nitric and sulphuric 

 acid and dried. In this 

 form it is gun-cotton — 

 the most powerful ex- 

 plosive known. 



Gun-cotton can be dis- 

 solved in certain ethers 

 and alcohols, as well as a 

 few other solvents. Thus 

 dissolved, it ceases to be a 

 violent explosive and be- 

 comes a sticky liquid, the 

 body of which depends on 

 the proportion of the 

 cotton to the solvent. 



This solution of cotton is technically 

 called "pyroxylin." It is an indispensable 

 material in many industries. With- 

 out it gas mantle dips, bronzing 

 liquids, liquid court plaster 

 patent leather finishes, wood 

 and metal lacquers and en- 

 amels could not be made 

 cheaply. 



In preparing leather 

 substitutes pyroxylin of 

 proper body is mixed 

 with vegetable oils to 

 impart elasticity; min- 

 eral pigments are added 

 to give the desired color. 

 The pyroxylin is applied 

 to dyed cloth as it moves 

 through a coating ma- 

 chine. A thin film is 

 thus spread on the cloth 

 from which the solvent 

 evaporates. As the cloth 

 passes through the machine, 

 which is about one hundred 

 feet long, it dries quickly. 

 Again and again it is passed 

 through the machine until the 

 film is built up to form a coat- 

 ing of the required thickness, 

 toughness and elasticity. 

 The coated cloth is then 

 passed between hot emboss- 

 ing cylinders of steel which 

 press the coating so that it 

 assumes the appearance of 

 morocco, seal, walrus and other leathers. 

 The resultant product looks, feels and wears 



The material from which this 

 hand-bag is made looks, feels 

 and wears like leather and to all 

 intents and purposes it is leather 



like leather, and to all intents and purposes, 

 it is leather. 



Very little morocco, seal and walrus 

 leather actually comes from the animals 

 whose hides are so character- 

 istically marked. Most of it 

 is split cowhide embossed in 

 the manner described. 

 That fine looking "seal" 

 pocketbook which you 

 admire in a shop window 

 is nothing but dyed and 

 embossed sheepskin. 

 Only an expert could tell 

 that the product is not 

 what it purports to be. 

 The principal difference 

 is not in the appearance 

 but in the price. 



Only an expert could tell 

 that the "leather" of the 

 upholstery is a substitute 



If You Had No More Teeth Than an 

 Elephant You Couldn't Be a Soldier 



IF you have ever had the op- 

 portunity to look inside an 

 elephant's mouth you have 

 your own personal opinion 

 about the reason why it 

 grows a trunk so long that 

 it covers the mouth com- 

 pletely and conceals the 

 interior even when the 

 mouth is open. For the 

 elephant is shy of teeth. 

 There are none at all in 

 the front and only eight 

 — two molars above and 

 two below on each side — 

 in the whole cavernous- 

 mouth. 

 Each of these molars is 

 as large as a man's hand. 

 The hay and fodder which 

 make up the elephant's food 

 are shifted over them by the 

 queerest, ugliest tongue im- 

 aginable. The tongue is lit- 

 erally hung at both ends, 

 having no power of move- 

 ment except in the middle 

 where it shifts back and forth 

 from side to side, arching up 

 against the roof of the mouth 

 like a huge wrinkled pink 

 serpent. 



The elephant's baby teeth 

 usually fall out when the animal is about 

 fourteen years old. 



