64 University Geological Survey of Kansas. 
on account of its combination with the proteids. It is believed 
that the iodin, combined into an organie compound, is excreted 
in the urine. 
The iodids are used with success in the third stage of syphi- 
lis, but it is not known at present whether this is due to ion 
action or to the general action of the undissociated salt. There 
is similar doubt in regard to the way in which the iodids act in 
chronic rheumatism and asthma. 
The Nitrates act both in the ionic condition and as undisso- 
ciated salts. As the action in the ionic form is largely upon 
the mucous membranes, this may result in gastritis, in diuresis 
and perhaps nephritis at the place of exit. We are most famil- 
iar with the salt potassium nitrate, but it must be borne in 
mind that the action of this salt upon the system is not due to 
that of the nitrate ion alone; in fact, the potassium ion in- 
creases the action of the nitrate. This salt would act more 
strongly than the sodium nitrate. While nitrates are to some 
extent reduced in the body to nitrites, this action takes place 
so slowly that the action of the latter is not perceptible. 
Nitrates are so seldom present in water in any quantity, that 
the action of these waters on the system has not been studied. 
We know that nitrates are poisonous if taken in large quantities, 
and even in small amounts they no doubt have some effect on 
the system. | 
Phosphates also are not often found in notable quantity. 
With the exception of the alkaline phosphates, the salts are 
usually insoluble. Sodium phosphate has a somewhat ca- 
thartic action. The calcium phosphate might be useful to in- 
crease the quantity of lime salts in the body. 
Silicates are usually mentioned in reports on mineral-water 
analysis, but very often the analyst makes no distinction be- 
tween the insoluble suspended matter and the true silica which 
may bein solution. It is a well-known fact that alkaline waters, 
especially if warm, have a tendency to dissolve silica from the 
rocks and soil, thus producing sodium or potassium silicate. 
When the water is evaporated with an acid this silica is rendered 
insoluble and separates out. Waters that are strongly siliceous 
