C. Sarus — New Method for Standardizing the Coronas. 343 



from it h = "0021 [n in thousands of nuclei per cubic centime- 

 ter) may be roughly assumed. These computed values of n 

 are given in the table. Shown in a chart, they are too low- 

 initially and too high finally, even if the air value is quite 

 ignored ; but the constant probably reproduces the true con- 

 ditions better than the observation, remembering that the initial 

 corona (t = 0) is not quite invariable. 



A very important consequence may be deduced from these 

 results. The equations specified may be written n Q — (njn 

 — Iht. Hence if the ratio of nucleations or of ions is known 

 (for instance by my method of geometric sequences), njn is 

 given, and the absolute value of ?i may be computed if 1> is 

 known. Xow if h for the case of ions may be taken as identi- 

 cal with the value found in electrical experiments, where h — 

 •0014 roughly and relative to ionization in thousands, 



bn = -0014;?/ 

 where n ' is the true nucleation. Thus in the table lj — '0024, 

 n Q = 675 ; therefore n Q ' = ('0021:/-0011) n g or 115,000 nuclei per 

 cubic centimeter, instead of 67,500 for the initial corona. 

 Quite generally if n /n and are determined from purely coro- 

 nal measurements 



b J -0014 



is the reduction factor for all the relative nucleations to abso- 

 lute value. 



Another important consequence may be drawn : If the 

 coefficient is known from direct experiments, it will then be 

 possible to standardize the residual curve (depressed asymptote) 

 leading to the terminal corona, corresponding to groups of 

 nuclei of different sizes occurring together. 



Moreover, in any such curve, let the ordinates denote the 

 computed number of ions, the abscissas denote the observed 

 number of efficient nuclei, being the colloidal nuclei and ions 

 occurring together in the course of a stated time. Then the 

 curve gives an indication of the distribution of the precipi- 

 tated water on the two groups of nuclei different in size and 

 present in different proportions, for the given supersaturation. 

 Experiments of this kind are of the highest importance and 

 the present cursory treatment is admitted provisionally in 

 view of a restandardization of the coronas of cloudy condensa- 

 tion which the variety of results since obtained has made nec- 

 essary. 



Brown Universitv. Providence. E. I. 



