Febeuaev 14, 1896.] 



SCIENCE. 



233 



greater density. The resulting flourescence 

 in gases seems to indicate that the cathode 

 rays in passing through a gas undergo a 

 diffuse reflection resembling the reflection 

 in a turbid medium, justas if the molecules of 

 the gas were very large in comparison to 

 the wave-length of these rays. That the 

 radiance which produces the fluorescence is 

 really a continuation of the cathode rays 

 is demonstrated by the fact that it is de- 

 flected by magnetic force. 



Eontgen's discovery adds a new ac- 

 companiment to the cathode rays. It shows 

 that, in addition to the heat and flourescent 

 light which the cathode rays generate in 

 the glass of the vacuum tube wherever they 

 strike it, there is also another form of 

 radiant energy generated there. Eontgen 

 •calls it the X-rays. The rays will and 

 should, of course, be called the Rontgen 

 rays. They are not cathode rays, accord- 

 ing to the reports which have reached us so 

 far ; for although they are capable of pro- 

 ducing strong flourescence, just like the 

 •cathode rays, they are not acted upon by 

 magnetic force, and not only are they not 

 absorbed by gases at ordinary pressure, but 

 even the most opaque of all substances, that 

 is the metals, are more or less transparent 

 with respect to these new rays. Cardboard, 

 wood, ebonite, organic substances, etc., 

 are about as transparent to them as glass is 

 to the visible part of the spectrum. They 

 are neither reflected nor refracted, that is 

 not to any appreciable degree. They act 

 upon a photographic plate, but it is evident 

 that photography by means of these rays 

 cannot employ lenses and that the pictures 

 obtained will be shadow pictures. The ob- 

 ject to be photographed is placed between 

 the plate and the vacuum tube. It is to 

 to be hoped that these shadow pictures of 

 the interior of living organisms will soon be 

 perfected so as to show us the various parts 

 in various shades according to the absorp- 

 tive power of each part. 



The question arises, what is this new form 

 of radiant energy ? The report says that 

 the discoverer has expressed, but with much 

 reserve, his belief that it is a longitudinal 

 vibration of the ether. If so, then its 

 velocity of propagation will in all proba- 

 bility be much larger than that of light, and 

 therefore for the same period of vibration 

 as that of visible light these new rays may 

 have a very much larger wave-length. 

 Should this belief of the discoverer prove 

 correct, then we shall finally have the longi- 

 tudinal wave in the ether for which we 

 have looked so long, in order to avoid the 

 necessity of considering the ether an incom- 

 pressible solid elastic. It is well to men- 

 tion here that quite a large number of very 

 distinguished German physicists have with- 

 in the last few years advocated quite 

 strongly the theory that cathode rays are 

 longitudinal vibrations of the ether. Prof. 

 Jaumann, of Vienna, has published quite 

 recently a very elaborate mathematical for- 

 mulation of this theory. It is an applica- 

 tion of Maxwell's electro-magnetic theory to 

 a mediun whose specific inductive capacity 

 and permeability vary under the action of 

 electric force. Such a medium is in all 

 probability a gas in a state of high tenuity, 

 as for instance in a Crookes' tube. This 

 theory will not account satisfactorily the 

 longitudinal character of the Eontgen rays. 



The correct view of this new radiant en- 

 ergy will undoubtly soon be formed when 

 new experimental data appear. In the 

 meantime we can rest assured that a new 

 entrance to the region of the ether phe- 

 nomena has been opened, and the impor- 

 tance of this fact can hardly be overesti- 

 mated. 



After the above note had been written 

 the author succeeded in repeating some of 

 Prof. Eontgen's experiments. The tubes 

 employed were of an inferior qualitj^ on ac- 

 count of the poor vacuum. The poorer the 



