BaiLey. | Mineral Waters. 63 
the condition of the ions when under pressure, for when this 
pressure is relieved some of the carbon-dioxid gas escapes and 
only carbonates are present. It is due, as has been previously 
stated, to the excess of carbon.dioxid that such salts as calcium 
and magnesium carbonates are dissolved. The ‘‘acid car- 
bonates’’ thus formed play an important part in digestion and 
absorption. 
Jodids, although occurring usually with chlorids and bro- 
mids, are considered more active therapeutic agents. Their 
action is quite similar to that of the latter. They find their 
most useful application in treatment of chronic bronchitis, 
eatarrhs, rheumatism, and in other chronic disorders. ‘These 
waters have long been celebrated for their alterative character. 
In fact, some such springs were recommended for the cure of 
scrofula, obesity, etc., before it was known that they contained 
iodin. When there is stomachic irritation and acute inflamma- 
tion these waters are contra-indicated, as they will do harm 
rather than good. Although the quantity usually found is 
small, seldom as much as one and one-half grains of the potas- 
sium or sodium salt in a gallon of water, yet the amount is 
sufficient to produce a decidedly beneficial effect on the patient 
for whom such waters are indicated. ‘This would seem to con- 
firm the theory that in many cases the ions of a substance are 
extremely active, and in just the condition to act therapeutically 
upon the system. 
Some authors believe that there is little evidence of ion ac- 
tion in the case of iodin, such as exists in bromid, but that the 
effects are due to the undissociated salts, especially in the case 
of potassium iodid. Doctor Sollman believes that since this 
salt is extremely diffusible and penetrates so rapidly into the 
cells, and as it contains two of what he calls ‘‘foreign mole- 
cules,’’ the liberated iodin ion may very likely combine with 
the proteids, substituting itself for the chlorid. It is also to be 
noted that the iodid readily decomposes with the separation of 
free iodin and hydriodic acid, both of which are irritants and 
tend to form another class of bodies with the proteids. 
The iodin tends to remain a long time in the body, probably 
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