62 POPULAR SCIENCE MONTHLY. 



supposedly permanent gases; nitrogen yielded to the attacks of 

 Wroblevsky and Olzewski in 1883, and hydrogen alone remained 

 unconquered. In 1898 Dewar overcame this last obstacle, and in 

 the year following he actually reduced hydrogen to an icelike solid 

 which melts at only eighteen degrees centigrade above the theo- 

 retical absolute zero. Every gas has been liquefied, and probably 

 the lowest degree of cold attainable by man has been reached. 

 Within the century the work began and ended; the future can 

 only improve the working methods and utilize the new resources. 

 Liquid ammonia has long been used in the manufacture of artificial 

 ice and for direct refrigeration; liquid air, with its temperature 

 of two hundred centigrade degrees below zero, is now almost a com- 

 mercial product, obtainable in quantity, but with its possibilities of 

 usefulness as yet practically undeveloped. The infant Hercules 

 will doubtless find no lack of tasks to do, each one more arduous 

 and more helpful to man than any labor of his mythical prototype. 



To the chemist the possibilities thus opened are innumerable. 

 Pictet has shown that at the low temperatures which are now 

 easily attainable all chemical action stops, even the most energetic 

 substances lying in contact with each other quiet and inert. A 

 greater control of the more violent chemical reactions is therefore 

 within reach, doubtless to be utilized in many ways yet unforeseen. 

 At the highest temperatures, also, chemical union ceases, and com- 

 pounds are decomposed; each reaction is possible only within a 

 limited thermal range, of which the beginning and the end are 

 measurable. From future measurements of this sort new laws will 

 surely be discovered. 



The first step in the upward scale of temperatures was taken 

 in 1802, when Robert Hare, an American, invented the oxyhydro- 

 gen blowpipe. With this instrument platinum, hitherto infusible, 

 was melted, a result of great importance to chemists. Apart from 

 recent electrical applications, platinum finds its chief use in the 

 construction of chemical apparatus, and Hare's invention was there- 

 fore of great assistance to chemical research. Later in the cen- 

 tury electrical currents were utilized as producers of great heat, 

 until in the very modern device of the electric furnace the range 

 of available temperatures has been at least doubled. Tempera- 

 tures of three to four thousand degrees of the centigrade scale are 

 now at the disposal of the chemist, and these are manageable in 

 compact apparatus at very moderate cost. Cheap aluminum is one 

 of the products of this new instrument, and the extraordinary abra- 

 sive substance, carborundum, is another. New industries have been 

 created by the electric furnace, and in the hands of Moissan it has 

 yielded scientific results of great interest and remarkable variety. 



