396 



Dr. A. R. Leeds on the Action of Light 



Actinometric Determinations, February 27, 



1879 







Reagents. 



9 A.M.- 



9.30. 



9.30- 

 10. 



10- 

 10.30. 



10.30- 

 11. 



11- 

 11.30. 



11.30- 

 12 m. 



12- 



12.30. 



12.30- 



1 P.M. 



Ice. H 2 S0 4 4-1 c.c. KI 



„ HOI 



215 

 1-00 



2-50 

 1-15 



2-85 

 1-25 



290 

 1-40 



2-80 

 1-70 



2-85 

 1-70 



2-70 

 1-55 



2-90 

 1-65 



1-95 



1-40 



I 



1 c.c. H 2 S0 4 +1 c.c. Cdl 2 ... 

 i, HOI 



1-15 

 0-75 



1-30 

 0'85 



1-45 

 1-00 



1-55 

 1-00 



1-70 

 1-05 



1-65 

 1-20 



1-70 

 1-40 



1 c.c. H 2 S0 4 4-1 c.c. Lil. 



» HOI „ 



1-20 

 0-75 



1-30 



0-80 



1-35 

 0-95 



1-45 

 1-00 



1-60 

 1-00 



1-50 

 1-00 



1-60 

 MO 



1-70 

 1-20 



1 c.c. H 2 S0 4 +1 c.c. NIL I... 

 „ HOI 



1-30 

 0-85 



1-40 

 095 



1-55 

 1-00 



T65 

 1-05 



1-80 

 115 



1-70 

 115 



1-80 

 M5 



1-90 

 1-20 



Eeagents. 



1-1.30. 



1.30-2. 



2-2.30. 



2.30-3. 



3-3.30. 



3.30-4. 



4-4.30. 



4.30-5. 



1 c.c. HoS0 4 +l c.c. KI 



„ Hbl 



325 

 200 



300 

 1-70 



2-50 

 1-60 



2-25 

 1-45 



2-00 

 1-25 



1-55 

 0-90 



0-75 

 0-35 



0-35 

 0-23 



0-43 

 0-20 



1 c.c. H 2 S0 4 +1 c.c. Cdl 2 ... 

 „ HOI 



2-20 

 150 



1-95 

 1-50 



1-70 

 1-20 



1-50 

 0-95 



1-30 

 0-90 



MO 



0-65 



0-70 

 0-35 



1 c.c. H 2 S0 4 +1 c.c. Lil 



„ HC1 „ 



1-55 

 1-20 



1-45 

 1-10 



1-50 

 1-00 



1-40 

 0-75 



1-25 

 0-70 



1-05 

 0-50 



0-65 

 0-30 



0-43 

 0-18 



Ice. H 2 S0 4 +1 c.c. NH 4 ... 

 „ HC1 



1-95 

 1-15 



1-80 

 1-15 



1-70 

 1-10 



1-50 



0-85 



1-20 

 0-90 



1-05 

 0-60 



0-70 

 0-30 



0-45 

 0-18 



ceeded those liberated when starch was present, these results, 

 unlike those represented in the preceding diagram, were ob- 

 tained with acid and iodide only, and are correspondingly 

 greater throughout. The ratio of the iodine liberated in the 

 potassium-iodide solution with sulphuric acid is to that libe- 

 rated with hydrochloric acid as 2*33 : 1*31, in the cadmium- 

 iodide as 1*47 : 1*0, in the lithium-iodide as 1*31 : 0*85, and 

 in the ammonium-iodide as 1*47 : 0*92. The above results 

 are graphically represented for two of the curves in the ac- 

 companying diagram. 



An actinometric measurement was then made of the electric 

 light, similar solutions being employed. A cylindrical stand 

 was used, of such dimensions that the centre of the axis of the 

 100-cubic-centims. column contained in each comparison-tube 

 should be at a distance of 6 inches from the focus of the elec- 

 tric light. The electric arc was taken between carbon points, 

 and was produced by electricity generated with a dynamo- 

 electric machine run by steam-power, its illuminating capacity 

 varying during the course of the experiment, according to 



