204 PROF. H. E. ROSCOE ON THE CHEMICAL INTENSITY 



for I have shown in the paper above referred to that even 

 for places so differently situated as Heidelberg and Para 

 no very great difference exists in the value of the constant. 

 In the following Table the relation of the chemical in- 

 tensity to the sun's altitude is seen in column IV. when 

 the intensity at the highest altitude^ 53° 15', is taken as 

 the unit. Column V. contains the values of I corrected 

 for variation of altitude; and column VI. contains the re- 

 lative areas of the sun's disk remaining uncovered at the 

 corresponding apparent solar time found in column I._, the 

 area of the solar disk before the commencement of the 

 eclipse being taken as the unit. 



Apparent 

 solar time. 



(I.) 



Altitude. 









I. 



11. 



III. 



IV. 



V. 



VI. 



7^57" •••■ 



,. 0-590 ... 



.... 30° 30'- 



... 0-622 ... 



... 0-948 ... 



... 0.94 



8 8 .... 



.. 0*320 .. 



.... 33 30 ..., 



... 0-671 ... 



... 0-476 ... 



... 0-71 



8 16 



,. 0-270 .. 



.... 35 ... 



... 0-705 ... 



... 0*383 ... 



... 0-62 



8 28 



.. o-iio .. 



.... 38 30 ... 



... 0-753 ... 



... 0*146 ... 



... 0-43 



8 45 



.. 0*090 .., 



.... 42 30 ••• 



... 0*820 ... 



... O'lOO ... 



... 0-17 



9 



,. 0-005 •• 



....46 ... 



... 0-885 ••• 



... 0-005 .. 



. .. O'OO 



9 15 



,. 0-102 .. 



.... 49 45 ••• 



... 0-933 ... 



... o'io9 ... 



... 0-21 



9 ^5 



. o'i40 ... 



.... 52 .... 



... 0-966 ... 



... 0*145 ••• 



... 0*37 



9 31 



1 



. 0-125 ... 



.... 53 15 .... 



.. 1-000 ... 



... 0*125 ... 



... 0-49 



The curve A represents the variations of chemical in- 

 tensity corrected for altitude,, and the curve B shows the 

 increase and diminution of obscuration of the sun's disk, 

 the abscissae representing the time, and the ordinates the 

 corresponding chemical intensity and area of exposed disk. 



