170 M. Chatirfs Observations 



in rendering the iodine present in soils much more easily ex- 

 tracted, I was led to think that the fixed alkalies had been 

 much employed by him. Accordingly, in my first experiments, 

 I used the alkalies in their caustic condition for the purpose 

 of fixing any free iodine or compound of iodine which I might 

 encounter. 



I commenced with an examination of the atmosphere. By 

 the arrangements I employed the air was made to traverse, 

 1st, a tube containing slips of paper which had been previously 

 dipped in a solution of starch, and, 2d, a double-necked gas 

 bottle, containing about three ounces of a dilute solution of 

 caustic soda. A continuous stream of air was drawn through 

 the arrangement for some hours. This experiment was con- 

 ducted in the morning ; in the afternoon a stream of air was 

 for several hours drawn through the same arrangement, 

 caustic potash being substituted for soda. The starch papers 

 did not exhibit the slightest coloration even when moistened 

 with distilled water. The solutions of potash and soda, how- 

 ever, on being treated with starch and nitric acid at once ex- 

 hibited the rose colour characteristic of the presence of iodine 

 in small quantity. So far my experiments seemed to lead 

 to the desired conclusion, but when I carefully tested por- 

 tions of the original alkaline solutions which had not been 

 subjected to the current of air, I found the iodine present in 

 them in quantity, to all appearance, as great as it was in those 

 portions I had used in my experiments. Wishing to trace 

 back the iodine to its source, I tested samples of the carbonate 

 of potash, carbonate of soda, and lime-shell, which had been 

 employed in the preparation of the caustic solutions, and in 

 all three iodine was present in perceptible quantity. De- 

 sirous also of making certain that the lime and alkalies used in 

 my investigations were as pure as other commercial substances 

 of the same kind, I procured various specimens from different 

 sources, and in every sample which I have as yet subjected 

 to examination, I have detected the presence of iodine. So far 

 then as concerns the determination of iodine in the atmo- 

 sphere, my experiments were of no value; the alkalies through 

 which air was drawn undoubtedly contained iodine originally, 

 and therefore no certain conclusion could be drawn as to the 



