Some Experiments with Cathode Rays. 



79 



with the proteids termed by v. Fiirth soluble myogen-fi'brin, myosin, 

 and myogen respectively. TLe fourth corresponds with the tempera- 

 ture at which white fibrous and yellow elastic tissue contract when 

 heated. 



We have concluded from this and many other facts that the 

 contractions produced by heat are at basis caused by the heat-coag il- 

 lation of the different proteids. 



We have obtained corresponding results with mammalian muscle ; 

 here the contraction at 32 — 40° does not occur, and soluble myogen- 

 fibrin is absent from the muscle plasma. 



" Some Experiments with Cathode Kays." By A. A. C. 

 Swinton. Communicated by Lord Kelvin, F.R.S. Re- 

 ceived February 27, — Read March 11, 1897. 



The extensive employment of the focus form of Crookes 1 tubes as 

 the most efficient known means of generating X-rays, has rendered 

 advisable the more complete investigation of the cathode ray dis- 

 charge in tubes of this description. 



Hitherto, the usual method of investigating the characteristics of a 

 cathode ray discharge apart from its mechanical properties, and 

 beyond what is visible to the unassisted eye, has been by allowing the 

 rays to fall upon a screen of some brightly fluorescent material, such 

 as glasses of various descriptions, or screens covered with fluorescent 

 salts. With all of these the maximum amount of fluorescence 

 appears to be produced by such comparatively weak cathode rays, 

 that in some cases the special effects produced by the more jDowerful 

 rays seem to be more or less entirely masked, while the well-known 

 phenomenon of the fatigue of fluorescent substances, when exposed 

 to the more active rays, conduces to the same result. 



Surface Luminescence of Carbon when exposed to Cathode Rays. 



I have found in some cases that by replacing the usual screen, 

 made of or covered with fluorescent material, by one of ordinary 

 electric-light carbon, much appears which was previously invisible. 

 When a concentrated stream of powerful cathode rays are focussed 

 upon a surface of carbon in this manner, a very brilliant and dis- 

 tinctly defined luminescent spot appears on the surface of the carbon 

 at the point of impact of the rays, the remainder of the carbon 

 remaining black. This luminescent spot seems to have a very close 

 relation to the fluorescent spots on glass and on other fluorescent 

 materials under similar influence. The effect is evidently a purely 

 surface effect > as when the cathode stream is rapidly deflected by 



