Messrs. Wanklyn and Cooper on Hydrogen Gas. 431 



from —200 to + 14, that is by 214 ; this then is the power 

 of the left lens for viewing vertical lines, and is consequently 

 the power of the spherical surface. 



LA is increased by 152 ; this is the difference between the 

 powers of the two surfaces, indicating for the cylindrical 

 surface a power of 62. Similarly it will be found that the 

 power of the spherical surface of the right lens indicated is 

 231, and that of the cylindrical surface 73. 



10. If to the numbers Lu = 14, LA = 37, Rw = 15, RA = 14, 

 the accommodating power, which time has reduced to about 

 40, be added, and account is also taken of the influence of 

 convergence of the optic axes *, we see that the patient has 

 acquired by means of the spectacles a very satisfactory power 

 of vision within the range most useful for work. For out-of- 

 door use another pair was provided, having 25 less power on 

 the spherical side, so that distant objects might be clearly 

 seen. 



Hampstead, August 26th, 1890. 



XL VIII. Notes on Hydrogen Gas. 

 By J. Alfeed Wanklyn and W. J. Cooper! • 



npHE record of some experiments in the laboratory will not 

 JL be quite without interest to chemists. The wonderful 

 passivity of hydrogen gas is illustrated by the following 

 experiments : — 



I. A strong solution of perchloride of iron, made by dis- 

 solving the solid chloride in water, was placed in a graduated 

 tube which was inverted in the usual manner so as to form a 

 receptacle for gas. 26 cubic centim. of hydrogen gas was 

 then introduced into the tube and allowed to remain in con- 

 tact with the iron-solution for forty hours. At the expiration 

 of that time the volume of the gas was found to be unaltered. 

 The gas was then burnt. 



II. A solution of platinic chloride containing 5 per cent, of 

 platinic chloride was allowed to act upon hydrogen gas in a 

 Hempel absorption-pipette. 95 cubic centim. of hydrogen 

 Was taken for experiment. After twenty-eight hours' exposure 

 the volume of the gas was found unchanged. 



III. Ferricyanide of potassium, the solution containing 

 25 per cent, of the dry salt, was employed in the Hempel 

 absorption-pipette. No absorption of hydrogen took place. 



* Bonders, on Accommodation and Refraction, p. 111. 

 t Communicated bv the Authors. 



