50 KANSAS ACADEMY OF SCIENCE. 2 
causing suffering if not immediate death. The effects produced by the dietetic 
use of hard water on the animal economy are: 
Ist. CuHemicau. An illustration of the chemical effects of such use of hard 
water can be shown by putting a small quantity of the white of egg in each of 
two test-tubes, and adding to each the same quantity of bile from a freshly killed 
animal; then, after agitating for a short period of time, add to one of these tubes 
a portion of soft water and again agitate, when it will be found that the emulsion 
formed is perfect, rendering the contents assimilable and fitted for passing into 
the circulation. To the other tube add the same amount of hard water and agi- 
tate, when it will be found that the contents have coagulated into curd-like 
lumps, similar to soap in hard water, and be no more capable of providing nour- 
ishment than so much dissolved stone. 
The medical congress held in Brussels in 1886 passed the following resolution : 
‘¢Waters that are too hard,.or that contain mineral substances that do not as- 
similate with the food and constitute a part of the human system, form with 
chyle an abnormal medium for the formation of blood, and the presence of these 
substances in the blood throws additional work on the kidneys, whose duty it is 
to filter out and remove the wastes of the blood, the too great accumulation of 
which substances results in the formation of concretions.’’ 
29d. PuysroLoGcicaL. The distinguishing difference in the physical condition 
of the human system in youth and old age is in the increased amount of deposits 
of earthy matter. These are carbonates and phosphates of lime mixed with 
other calcareous substances. These deposits affect the physical organs and inter- 
fere with their action, causing imperfect circulation of the blood and clogging of 
the arteries. The change isin the nature of a slow, steady accumulation; and 
when they have become excessive the stiffness of old age is produced. As these 
substances are constituents of the food we eat and of the liquid we drink, much 
can be done to prevent their injurious effects by a proper selection of food and by 
providing, for cooking and drinking, a water which does not contain these sub- 
stances, and also which by its solvent power will dilute not only the substances 
in the food, forming deposits, but also by acting on the deposits already formed 
fit them for removal, and thus tend to prolong the elasticity of youth. 
3d. MecuanicaL. The nature of the’ mechanical action of hard water used 
dietetically on the system will appear when we consider that in the process of com- 
bustion of the impurities in the blood the uric acid (ashes of the blood ), collected 
in the kidneys as an ash-pit, must, as in the case of the ash-pit to the furnace, be 
removed in order to secure efficient action. For this end the requirement is that 
the fluids passing through the body be in a condition to dilute the uric acid and 
thus fit it for being carried off by the channels nature has provided for their re- 
moval. 
When waters used dietetically are charged with earth salts their solvent power 
is lessened, and they are in a condition to form deposits of the substances they 
hold in solution in the order of their solubility. Among the least soluble sub- 
stances in solution in this case, uric acid acts as a nucleus, forming concretions 
producing paralysis, dropsy, Bright’s disease, etc. 
Dr. Lewin, of Munich, who made an extended and very careful study of the 
purification of water, gives the following as the requisites of any system of 
filtration : 
‘‘Tt must absorb not only substances in suspension but also all matters phys- 
ically and chemically latent, and must so retain them that additional impure 
water or clear water cannot wash the impurities out; or purifications must be 
carried on in such a manner as not to injuriously affect the purity of the water. 
