V2 Mr Stevenson Macadam on the 



ployed. At the same time I admit the possibility, that at other 

 seasons of the year, and at other districts of the country than those in 

 which I experimented, there may be an appreciable amount of iodine 

 naturally distributed in the way referred to, and when time and 

 opportunity present themselves, I shall not fail to continue my in- 

 vestigations on this department of such an important subject. 



The locality being unknown to me from which the lime-shell em- 

 ployed in the preparation of the caustic alkalies had been procured, 

 I afterwards obtained specimens from Burdiehouse, Kirkcaldy, 

 Charleston, and Bathgate, and examined them according to the fol- 

 lowing process. To a portion of each was added about a gallon of 

 distilled water, which was well agitated at intervals till it was 

 completely saturated with lime. The liquids thus obtained were 

 nearly neutralised with pure nitric acid, and separately evaporated 

 to one half ounce. On being treated with starch, hydrochloric acid, 

 and nitrite of potassa, distinct evidence was obtained of the presence 

 of iodine in each of the four specimens. 



In a former part of this paper, reference was made to several 

 samples of potashes in which iodine had been discovered experimen- 

 tally. Altogether, I tested six different specimens ; two of crude 

 potashes, one of them from the United States, and the other from 

 Canada; two of refined, or what is ordinarily termed carbonate 

 of potassa, and two of bicarbonate of potassa. They were all ex- 

 amined in the same way. A large quantity of the salt was drenched 

 with distilled water, cautiously raised in temperature and allowed to 

 cool. This served to separate the larger portion of the carbonate of 

 potassa, as well as any impurities present in the crude samples. The 

 liquid containing the iodide of potassium, was transferred to another 

 vessel and evaporated to dryness. The resulting salt was then 

 powdered, alcohol added, raised in temperature, and filtered. The 

 nitrate was again brought to dryness, the residue digested in a very 

 small quantity of water, and the solution thus obtained treated with 

 starch, hydrochloric acid, and nitrite of potassa. In each case, a 

 very distinct coloration was obtained. The crude potashes contain 

 in fact, a considerable quantity of iodine which decreases at each 

 refinement. 



Six samples of soda ash were examined in the same way. Like 

 the potash specimens, two were of the crude soda ash, two of the ordi- 

 nary carbonate of soda, and two were bicarbonate of soda. The 

 crude variety contains the most iodine, and the others less of this 

 impurity according to the refining they have undergone. 



From the presence of this element in potashes, I am inclined to 

 believe that it will be found more generally distributed in the vege- 

 table kingdom than it has formerly been supposed to be. The pot- 

 ashes from the States and from Canada, are principally the dried 

 lixivium of hard woods, such as the maple and birch ; but whilst by 

 much the greater portion is so, it is probable that the parties in 



