RAFFIA 



4913 



RAFFIA 



Production of Radium. Radium was discov- 

 ered in pitchblende, an ore of uranium (which 

 see), and for a number of years this ore was 

 the only source of supply. The ore was at first 

 mined in Bohemia; then deposits were dis- 

 covered in Sweden and Wales. For a number 

 of years the manufacture was carried on ex- 

 clusively in France and Germany, and it was 

 supposed that pitchblende was the only ore 

 from which it could be obtained. But experi- 

 ments with other ores of uranium showed that 

 they also contained radium; and carnotite, a 

 compound of uranium, potassium, and some 

 other substances, has now become the chief 

 source of supply. Extensive deposits of carno- 

 tite occur in Colorado and Utah, and the United 

 s is now considered to be the chief source 

 of radium-producing ore. 



The manufacture of radium is a long, tedious 

 chemical process, complicated by many difficul- 

 ties and requiring special care and skill. Pre- 

 vious to 1912 there were no laboratories for its 

 production in the United States, and the car- 

 notite was sent to Europe. In that year the 

 United States Bureau of Mines established a 

 laboratory at Denver, and since that time this 

 bureau, in cooperation with the National Ra- 

 dium Institute, has expanded the laboratory 

 into a plant for producing radium on a com- 

 mercial scale. In 1915 this plant was in suc- 

 cessful operation, and new processes had been 

 discovered by which the expense of production 

 was greatly reduced. 



By the original processes less than one-half a 

 grain 375 milligrams of radium could be ob- 

 t uned from a ton of pitchblende. In 1914 

 tin -re were only two grains of radium in the 

 United States, each valued at $120,000. The 

 cost of production by methods now employed 

 in the Denver plant is about $40,000 per grain. 

 Some idea of the delicacy of the chemical 

 operations may be obtained from the state- 

 ment that there is extracted from the ore a 

 substance that exists in proportion of one part 

 to 200,000,000. See CURIE, PIERRE AND MARIE 

 SKLODOWSKA; RADIOACTIVITY n.u. 



Consult Soddy's Interpretation of Radium ; 

 Malcolm'a "Notes on Radium -Bear Ing Minerals," 

 mad a Geological Survey, Proprietor's Hnr.,1 

 book, No. I; Moore and Kit hill's "A I'r -llmlnary 

 Report on Uranium. Radium and Vanadium." In 

 States Bureau of Mines Bulletin No. 70. 



RAFFIA, rnf'i't. flat, ribbonlike strips of 



rn from two kinds of palm grown in 



tropu -:il regions, chiefly in Madagascar and 



i h< hard, outside fibers an. I tin stalks 



i alms are used by the natives in build- 



308 



ing houses and fences. The inner fibers and 

 also the leaves are soft and light, and are 

 so pliable that they can be bent to any shape, 

 and also they may be dyed in any color. The 

 natives make practically all their clothes, as 

 well as baskets, mats and small fancy baps, of 

 raffia fiber. The fiber is exported in large 

 quantities to many countries, where it is used 

 for similar purposes. It is also used exten- 

 sively in greenhouses as a wrapping to protect 

 plants and young trees from bruises or cold. 



Use in Schools. The ease with which useful 

 and artistic products may be made from raf- 

 fia has led to the introduction of raffia weaving 

 as a regular feature of construction work in the 

 school grades. The teacher finds that basketry 

 and weaving are the best forms of industrial 

 training, as they are adaptable to any school 

 grade, and the materials are cheap and easily 

 handled. The articles made have little value, 

 but the children's hands are trained, which is 

 the result greatly desired. The search for ma- 

 terials and the study of their sources tend to 

 make geography and history more real to the 

 child. 



Rugs and other articles for the home may be 

 made from raffia or old matting. It is cus- 

 tomary to combine raffia and rattan reeds in 

 the making of baskets, but there are many 



FIO. 1 

 Letters are explained in tho 



pretty and useful things which can be made 

 of raffia alone. Much is said of the opportuni- 

 ties for onuinality i" this work, hut rather than 

 let children work without a definite design in 

 mind, it is hetter to l'urm-h them with a plan 

 or pattern. Only two elementary exercises are 



D here to indicate the possibilities of the 



-'ic 1. To make a very useful holder 

 for a ball of t\\me the only necessary articles 

 are eighteen long, smooth strands of raffia; a 

 pencil, or round, smooth stick, and a pair of 

 scissors. Place the ends of one strand of raffia 



