340 



THE CENTURY BOOK OF FACTS. 



pressure. This causes the composition to 

 adhere to the molded articles, and gives them 

 the rough surface that is desired. Papier- 

 mach6 can be made waterproof by adding to 

 the pulp sulphate of iron or some of the sili- 

 cates, and fireproof by mixing with clay and 

 borax, phosphate of soda, or any alkali. 



Parchment. The ordinary writing- 

 parchment is made from the skins of the sheep 

 and she-goat ; the finer kind, known as vellum, 

 is made from those of very young calves, kids, 

 and lambs. The thick, common kinds of 

 parchment, which are used for drums, tam- 

 bourines, battledoors, etc., are made from the 

 skins of old he-goats and she-goats and in north- 

 ern Europe from wolves ; and a peculiar kind 

 which is used for tablets, is made from asses' 

 skins. Parchment, as a writing material, was 

 known at least as early as 500 B. C. Herodotus 

 speaks of books written upon skins in his time. 

 Pliny, without good grounds, places the inven- 

 tion as late as 19(5 B.C., stating that it was made 

 at Pergamos (hence the name Pergamena, cor- 

 rupted into English parchment). Possibly the 

 Pergamian invention was an improvement in 

 the preparation of skins, which had certainly 

 been used centuries before. The manufacture 

 rose to great importance in Rome about a cen- 

 tury before Christ, and soon became the chief 

 writing material ; and its use spread all over 

 Europe, and retained its pre-eminence until 

 the invention of paper from rags. 



Pearl Fisheries. The cause of the pearl 

 is the introduction of a grain of sand or other 

 foreign substance into the shell of the pearl 

 oyster. This causes an irritation of the deli- 

 cate tissues of the oyster, which immediately 

 deposits the pearly matter around it for pro- 

 tection. Advantage of this fact has been taken 

 to put substances within the shells of young 

 oysters to induce the formation of pearls, and 

 the Chinese by this method force a species of 

 fresh-water mussels to produce the jewel. The 

 most important pearl fisheries of the world are 

 those of Ceylon and Coromandel, in the Indian 

 Sea, whence pearls have been obtained since 

 the earliest times of history. The divers are 

 natives, trained to the pursuit, who are accus- 

 tomed to descend to the depth of six or eight 

 fathoms some forty times a day, and remain 

 under water from a minute to a minute and a 

 half. The fishing season begins in March or 

 April and lasts but one month. A single shell 

 may contain from eight to twenty pearls, vary- 

 ing in size from that of a small pea to about 

 three times that size. The coasts of Java, 

 Sumatra, Japan, and also Colombia and other 

 points on the shores of South America have 

 yielded large quantities of pearls ; but they are 

 usually smaller than the Oriental pearls. 



Percussion Caps, Composition of. 



The explosive which is used in the making of 

 percussion caps is a fulminate of mercury, 

 made by first dissolving 100 parts mercury in 

 1 ,000 parts of nitric acid or 740 parts by 

 measure. When the solution is heated to 180 

 degrees Fahrenheit it should be slowly poured 

 through a glass funnel tube into 830 parts 

 alcohol, sp. gr. .830 or 1,000 parts by 

 measure. After effervescence, filtering, wash- 

 ing, and drying, the explosive is dropped into 

 the copper cap. 



Perfumery. Directions are given for 

 making the holy incense in Exodus, chapter 30, 

 1490 B. C. The Scriptures abound with in- 

 stances "of the use of incense and perfumes. 

 Philip Augustus of France granted a charter 

 to the master perfumers in 1190. Perfumes 

 became fashionable in England in the reign of 

 Elizabeth. No such trade as a perfumer was 

 known in Scotland. in 1763. A stamp tax was 

 laid on various articles of perfumery in Eng- 

 land, and the vender was obliged to take out a 

 license, in 1786. In 1860 there were about 

 forty manufacturing perfumers in London ; in 

 Paris about eighty. 



Petrified Bodies. Petrifaction is sim- 

 ply the substitution of the organic substance 

 by the inorganic, atom by atom. As a mole- 

 cule of wood or bone decays, a molecule of 

 stone takes its place. This can only occur 

 when the air, or earth, or water surrounding 

 the organic substance holds in solution some 

 readily precipitated mineral. In the case of a 

 woody substance, or of bone, while decomposi- 

 tion goes on there yet remains a framework 

 whose interstices are gradually filled by the 

 mineral substance ; but in the case of flesh no 

 such framework exists. The very rapid de- 

 cay of flesh also makes it impossible for the 

 very slow process of petrifaction to have any 

 effect upon it. The stories of petrified bodies 

 found in graveyards, that float periodically 

 through the press, are usually made up of 



whole cloth," as the saying is, though it is 

 true that bodies of both men and animals have 

 been found incrusted with silicious substance 

 so as to resemble petrifactions. These, how- 

 ever, when veritable finds, are fleshless skele- 

 tons, the soft parts of the body having decayed 

 while the slow process of incrustation was go- 

 ing on. It maybe noted here that but one 

 true human bone petrifaction has ever been 

 found, and that is the " Fossil Man of Men- 

 tone," discovered in 1873-74, The majority 

 of fossils, be it remembered, are of great age, 

 antedating the existence of man on the earth. 

 In places where the silicious deposits have 

 been rapid, as in limestone caverns, human 

 bones, fossilized, have been discovered. Two 



