602 



SCIENCE. 



[N. S. Vol. VII. No. 174. 



exhibited at work in the rooms of the Society 

 of Arts. Its action is based on the fact that air, 

 not being a ' perfect gas,' is reduced in temper- 

 ature when suddenly allowed to expand through 

 a narrow orifice from a high to a low pressure. 

 The slight cooling effect thus obtained is ren- 

 dered cumulative by the cooled air being used 

 to abstract heat from the air that has not yet 

 passed the orifice. Each successive portion of 

 air is, therefore, cooler when it reaches the 

 orifice than was its predecessor, and thus in 

 time so low a temperature is reached, provided 

 due precautions are taken to insure thermal 

 isolation, that a change of state occurs and air 

 appears in the form of liquid. The particular 

 machine on view circulates each hour about 15 

 cubic metres of air, which is expanded from a 

 pressure of 200 atmospheres to one of 16, and 

 produces about 1.9 litres of liquid air an hour 

 with a continuous expenditure of three-horse 

 power. Although the oxygen and nitrogen of 

 the atmosphere liquefy simultaneously, still the 

 latter evaporates more quickly, and this fact 

 can be utilized to obtain a liquid which is very 

 rich in oxygen. An interesting application of 

 liquid air containing 40 or 50 per cent, of oxy- 

 gen has recently been made. Mixed with 

 powdered charcoal it forms an explosive which 

 is comparable in power to dynamite, and which, 

 like dynamite, can be made to go off violently 

 by using a detonator. Trials which have been 

 carried out with this material in a coal mine at 

 Penzburg, near Munich, are claimed to have 

 given very satisfactory results. The explosive 

 is cheap, its cost being practically that of lique- 

 fying air ; but, of course, owing to evaporation, 

 it is only capable of exploding for a few minutes 

 after being mixed. 



UNIVERSITY AND EDUCATIONAL NEWS. 



President Dwight, of Yale University, has 

 published his annual report. He suggests suit- 

 able gifts to the University amounting in value 

 to over $3,000,000, which he hopes may be se- 

 cured in celebration of the coming bi-centennial. 

 The value of the Lampson bequest is stated to be 

 upwards of §400,000. President Dwight espe- 

 cially dwells on the need of a building for the 

 work in physiological chemistry, the need of 



$150,000, which, with the existing fund of $100,- 

 000, will make possible the completion of the Pea- 

 body Museum and the desirability of enlarging 

 the observatory. The library acquired by pur- 

 chase during the year 7,840 volumes and by 

 gift 1,385 volumes, and the pamphlets added to 

 the library "were 6,300 in number. During the 

 past ten years the teaching force of the Univer- 

 sity has increased from 43 to 102. 



The Board of Overseers of Harvard College 

 have adopted the following resolution : 



Resolved, That the overseers will see with pleasure 

 the admission requirements of the Lawrence Scientific 

 School brought as rapidly as circumstance may per- 

 mit to substantial equality with those of Harvard 

 College, provided that, in so doing, the standard for 

 admission to the Scientific School shall be steadily 

 raised, and that for admission to the College in nowise 

 lowered. 



The New York State Department of Public 

 Instruction has decided to hold four summer 

 schools this year for the teachers of the State. 

 The past two years two schools have been held, 

 at Chautauqua and Thousand Islands Park. 

 The two additional schools will be held at Green- 

 port, Long Island, and Ithaca. 



The West Virginia University has established 

 eleven fellowships yielding $800 yearly and free 

 tuition. The fellows are expected to teach one 

 hour a week or give two hours' supervision in 

 the laboratory. In the eleven subjects for which 

 the fellowships are awarded, the sciences are 

 well represented, they being as follows: Chem- 

 istry, Physics, Geology, Zoology, Botany, Math- 

 ematics, Mechanical Engineering, Civil Engi- 

 neering, Economics, English and Greek. 



The estate of Mrs. Julia W. James, of Boston, 

 divided by her will between the Museum of Fine 

 Arts and the Massachusetts Institute of Tech- 

 nology amounts to over $500,000. 



At Harvard University Mr. S. I. Bailey has 

 been promoted to an associate professorship of 

 astronomy and Dr. W. T. Porter to an associ- 

 ate professorship of physiology. 



Dr. Norman Wilde, assistant in philosophy 

 in Columbia University, has been appointed in- 

 structor in philosophy in the University of 

 Minnesota. 



The John Tyndall Fellowship of Cokimbia 



