544 JOURNAL OF SCIENCE, 
These results emphasize the importance of an intelligent survey 
of the condition of the soil in selecting a home, and of a legislation 
prohibiting the pollution of the soil. 
In many towns and cities, the privy-vaults and leaching cesspools 
of every house drain really into the sheet of ground-water: the soil 
arrests the coarse material, the grease and slime; but the swarming 
bacteria diffuse with ease, as much as the ‘soluble chlorides and 
nitrates, and follow the flow wholly unobstructed. Into this same 
soil are sunk or driven the wells; and the water that is drawn for use 
is polluted in proportion to the number and proximity of the vaults 
and cesspools, on the one hand, and the thinness and sluggishness of 
the water-sheet, on the other. In the worst wells in daily use, the 
water is distinctly colored with sewage; but the most deadly water 
may carry only the germs of typhoid-fever or of dysentery, and be 
otherwise sparklingly clear, and so pure as to pass unchallenged 
through the most searching chemical analysis. 
If the soil is polluted and very coarse gravel, this indraught, 
loaded with the spores of bacteria, will flow through the cellar to the 
warmer rooms. If the soil is polluted and fine, and the ground water- 
surface rises at any season to the level of the floor, or higher, it will 
evaporate as it oozes into the cellar, and leave an infected dust to be 
taken up into the circulation of the housec-air. Similar results will 
follow from the leaching of the cesspool towards the cellar-wall, or 
from the filtration through the soil of sewage from a broken or leaky 
drain; which is very apt to exist in or just outside of the foundation- 
wall. The pollutions of soil and water already mentioned are of such 
a general character, that, with ordinary forethought, they can be 
guarded against; but there are others of. a local character which are 
not revealed to a general survey. In the growth of many of our 
cities, the natural topography is disregarded. Lowlands and marshes 
which are traversed by sewage-fed brooks are covered with a network 
of high-graded streets, which convert the blocks into sewage-basins, 
which come, in time, to underlie blocks of dwellings of all classes. 
In other cases, low or marshy ground is made the dumping- 
ground of the city, and receives the sweepings of the street, the 
contents of the ash and garbage barrels,—every thing, in fact, that 
cannot pass through the sewers or be sold. The entire material is 
loaded with organic matter which is kept in a state of very slow 
decomposition by moisture. Some of the costliest dwellings of our 
cities rise upon such soil. We may take every precaution to avoid in 
our homes the dangers that arise from a polluted soil, and may yet 
fall victims to the filthy condition of remote places, over which we 
have no control. 
Among many others there are two exceptionally frequent sources 
of danger of this kind. One of these is the farmer’s well, which is 
rarely safe, and, when not used to adulterate milk, is used to rinse 
milk pans and cans, and leaves upon their surface a source of con- 
tamination. The other frequent instance is the use, by druggists, of 
water from wells or from cisterns, which are often anything but 
sewage-proof. Throughout the country, and often in the cities, the 
use of only distilled water in compounding medicines is far from 
universal; and I have had analyses made of lime-water bought ata 
