450 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



0.0093 millimeter, that is, it is below a measurable quantity. The 

 fact that in one case 0.13 and in another 0.3 millimeters were found 

 is due to the insufficient time allowed to absorb this very small amount 

 of carbon monoxide. 



From the value of the equilibrium pressure obtained at 1475° it is 

 possible by the above formula to calculate the pressure at higher tem- 

 peratures and see approximately what is the shape of the pressure tem- 

 perature curve. The value of Q corresponding to the mean of each 

 set of temperatures is used. 1475° is always taken as the lower temper- 

 ature. The results of this computation are given in Table IV and 

 Figure 3. 



TABLE V. 



Pressures of Carbon Monoxide Computed from the Value 

 Determined at 1475°. 



It is evident that the error in this curve is due practically entirely 

 to the error in the temperature measurements, for while the value of 

 Pi is accurate to 2.5 per cent, the temperature is uncertain by 25°, and 

 the value 0.82 millimeters might correspond to 1500° or 1450° as the 

 two extremes. This would mean the true value at 1475° might be 

 1.3 or 0.5 millimeters as the two extremes. If now the curve be com- 

 puted first with the value 1.3 in place of 0.82, and again with 0.5, the 

 values under I and III in Table V are obtained. The values are plotted 

 in Figure 3 in broken curves. From these curves it is seen the tem- 

 perature corresponding to 1/3 of an atmosphere lies between 1800° and 



