on the General Distribution of Iodine. 171 



probability of their being more highly iodized by contact 

 with the atmosphere. 



In a subsequent experiment the alkalies were dispensed 

 with, the air being drawn through, 1st, a tube with slips of 

 starched paper kept somewhat damp ; 2d, a gas bottle im- 

 mersed in a freezing mixture ; and 3d, a gas bottle contain- 

 ing a solution of nitrate of silver. A continuous current of 

 air was kept up for fully five hours, commencing about mid- 

 day, and extending to the evening. At the conclusion of the 

 experiments the papers were not altered in the slightest de- 

 gree ; the gas bottle (2) contained about a quarter of an 

 ounce of liquid ; and the nitrate of silver (3) had not been 

 perceptibly changed. Subsequent analyses shewed that 

 neither the condensed liquid (2), nor the nitrate of silver 

 (3), contained a trace of iodine. 



Experiments made with large quantities of the rain water 

 which fell in Edinburgh during the last and present months, 

 have led me to the same negative results. 



I am well aware that consequent on the evaporation of 

 water from the surface of the ocean, portions of the salts 

 contained in it are carried up and disseminated through the 

 atmosphere, ready to be rained down upon inland places, and 

 that in this way, iodine, most probably as iodide of sodium, 

 will reach the air. I was accordingly confident that I should 

 succeed in verifying Chatin's observations in a district so near 

 the sea as that around Edinburgh ; either, however, iodine 

 is less widely distributed than it has appeared to be, or its re- 

 cognition is more difficult than Chatin's papers would lead us 

 to expect. It is greatly to be wished that this able observer 

 would publish his entire process. 



In conclusion, I would merely add that the presence of 

 iodine in pearl ashes leads me to believe that this substance 

 will be found more generally distributed in the vegetable 

 kingdom than it has hitherto been supposed to be, and this 

 opinion is strengthened by the fact that I have found an ap- 

 preciable quantity of iodine in the ashes of charcoal. 



I trust that an early opportunity will enable me to write 

 a more lengthened paper on this subject. I remain yours 

 sincerely, Stevenson Macadam. 



To Prof. Jameson. 



