70 



Dr. M. Wilderman. On Chemical Dynamics [Jan. 30. 



The quartz vessel with the manometer was then placed in a large 

 water bath of a regulated and constant temperature, behind a quartz 

 window, and here exposed to the acetylene light. At suitable intervals 

 the temperature of the bath (read to 0°*01), the height of the mercury 

 and sulphuric acid column in the manometer (read with the catheto- 

 meter), the barometer pressure and temperature (read with the vernier), 

 and the intensity of light (i.e., the deflections of the galvanometer by the 

 Rubens' thermopyle and the thermoelectromotive force of the same) 

 were observed. This allowed of knowing the exact amount of 

 COCl 2 formed, or of CO and Cl 2 present in the gas mixture at any 

 time r. 



In this manner the author succeeded in getting reliable and suffi- 

 ciently regular curves (see diagram), which admitted an investigation 

 of the phenomena under consideration. If we take the time t 

 (minutes) as abscissae and the x or the amount of COCl 2 formed up to 

 the time t expressed in mm. pressure as ordinates, we get the curves of 

 Tables II, III, IV, V, and the variation of x with r, or dx/dr, gives 

 the velocity of formation of COCI2 from CO and Cl 2 . Each of the 

 above curves represents one and the same system. Curve (1), curves 

 (2) and (3), (4) and (5) of Table II give the results obtair-ed for the 

 same system in three successive days, as the reaction of combination of 

 CI2 and CO was further proceeded with. So also (1) and (2) of the rest 

 of the tables belong for each table to two successive days. 



The investigation of the above curves showed that the integral 

 equation 



-i_ [log (A - Xi) - log (A - x 2 ) + log (B - x 2 ) - log (B - xj] : (r 2 - n ) 



A — J3 



= K 



well expresses the same after the periods of induction had passed. 

 This period of induction had passed, e.g., in curve (2), Table II, at 

 observation (9), in curve (4), Table II, at observation (51), in curve 

 (1), Table II, at (4), in curve (2), Table III, at (10), &c. 



In the above integral equation A and B are the quantities of Cl 2 

 and CO taken at the beginning, before the reaction was started (e.g., 

 A = 502*4 mm. partial pressure, B = 109 '7 mm. partial pressure in 

 the gas mixture of Table II, and A = 224*7 mm., B = 343*6 mm. in 

 Table III, &c.) ; A - x and B — x are the quantities of Cl 2 and CO 

 present in the system at the time r, K is a constant. 



The differential equation giving the law for the velocity of chemical 

 reaction in light is thus dx/dr = K (A - x) (B - x), i.e., the velocity of 

 combination of Cl 2 and CO in light, or the velocity of formation of COCl 2 , 

 is at the time r directly proportional to the product of the reacting masses at 

 the time r. Since the chemical equation for the reaction is 1C1 2 + 1 CO = 

 1 COCl 2 , this equation has in light the exact form which it ought to have 



