Industrial Research 



243 



gal forces that occur at the edge of such a rotator arc 

 ahnost inconceivably large. A force 8,000,000 times 

 that of gravity is possible. If the force of gravity were 

 as great a dime would weigh more than 16,000 pounds. 

 To obtain such high speeds, the rotor is mounted in a 

 vacuum, supported by an external stream of air and 

 driven through a flexible shaft connected to an air 

 turbine. 



So far ultra-speed centrifuges of the type described 

 have been used primarily in biological fields. The 

 forces are so great that heavy molecules can be separated 

 from light ones. Thus tobacco mosaic and yellow fever 

 viruses have been concentrated and hormones have been 

 isolated. Wfierever rapid settling of liquids or sedi- 

 ments in liquids is required, the ultracentrifuge has 

 been very useful. So many new lines of work have been 

 opened in biological and medical fields by the new 

 techniques in high rotational speeds that it is practically 

 certain that a multitude of industrial uses will appear 

 as soon as the possibilities are fully understood. 



Cyclotrons, Van de Graaf Generators, 

 and Geiger-Counters 



The intensive study of the atomic nucleus by aca- 

 demic physicists during the past decade has led to the 

 development of many new processes and instruments. 

 Perhaps the most striking discovery of all is that high- 

 speed ions are able to transmute one chemical element 

 into another. Many of the materials formed by this 

 transmutation have, in addition to the ordinary prop- 

 erties of the new elements, the characteristic of being 

 radioactive like radium. Thus by bombarding ordinary 

 table salt by high-speed atomic particles a radioactive 

 form of sodium can be produced which for some medical 

 purposes is more valuable and much cheaper than 

 radium itself. Nearly every chemical element can be 

 made radioactive; thus one can have radioactive iron, 

 copper, zinc, tin, etc. 



Two different types of machines have been developed 

 to produce radioactive elements. In each the essential 

 purpose is to produce high-speed atomic particles which 

 upon striking ordinary elements produce transmutation. 

 One of these machines is the cyclotron, so-called because 

 it makes the atomic particles move in a circle and 

 brings their speeds up to the desired value by a small 

 increase each half revolution. Twenty or thirty cyclo- 

 trons, each costing from $20,000 to $1,500,000, have 

 been, or are being, built in this country. The demand 

 for radioactive materials is so great, however, that 

 many more will need to be built very soon. The second 

 type of machine for producing high-speed atoms is the 

 Van de Graaf electrostatic generator. This is essen- 

 tially a direct-current generator that develops a poten- 

 tial of from 3 to 5 million volts. This high voltage 

 causes charged atomic particles to crash down a tHl)e 



321S35— 41 17 



with such speed that some of the atoms of any element 

 placed at the end of the tube will be disintegrated. 

 Four or five such machines, costing up to $150,000 

 apiece, have been built in this country. While their 

 primary purpose is to study nuclear structure they may 

 possible be used inihistriaily in many other ways in 

 the future. For instance, there is much discussion 

 regarding the transmission of power by high-voltage 

 direct current. It has even been suggested that the 

 "atom smasher" of today may be used for the commer- 

 cial transmission of electrical energy tomorrow. 



Radioactive materials produced by the cyclotron 

 and the electrostatic generator are useful in medical 

 therapy. They can be used in industry for testing 

 thick welds in the same way that radium and X-rays 

 are now being used. Their most important use arises, 

 however, because of a new instrument known as a 

 Geiger-counter, which has been greatly improved in 

 recent years Radioactive elements exhibit their radio- 

 activity because of the continual emission of high speed 

 fragments or high energy radiation. Each of these 

 fragments can produce a discharge in a Geiger-counter, 

 thus enabling single particles from radioactive elements 

 ("tracer atoms") to be counted. If one, for instance, 

 chinks a solution containing radioactive sodium, it is 

 possible by means of a Geiger-counter to measure the 

 time it takes for the sodium to enter into the blood 

 stream and reach the finger or any other part of the body. 

 Likewise calcium can be traced directly from an indi- 

 vidual's food to his teeth. Of industrial importance is 

 the possibility of tracing by radioactive atoms the 

 diffusion of copper atoms in iron, gold, or even in 

 copper itself. There must be many industrial processes 

 in which tracer radioactive elements would be useful. 

 With the modern Geiger-counter the tracing of 1 part 

 in 100,000,000 or even more can be carried out with 

 certainty by simple standard equipment. 



Color Analyzers 



Color is used in almost every industry, yet its exact 

 definition is essentially unknown. Manufacturers of 

 paint, ink, cloth, paper, glass, and other commodities 

 give names to colors even though they realize that 

 these names can in no way specify the color exactly. 

 A dye manufacturer who makes one batch of color 1 

 year cannot match it a year later because his original 

 samples may have faded. To remedy these defects in 

 the specification of color the physicist has designed a 

 colorimeter which draws a curve which is characteristic 

 of each specific color alone. If two samples of materials 

 have the same color curve, they will be found identical 

 in color not only by daylight but also imder all forms 

 of artificial light. 



This instrument is called technically a "recording 

 spectrophotometer." It measures and records auto- 



