SCIENTIFIC SUMMARY. 
255 
accumulated in the soil, and have been partially changed by its wonderful 
powers of oxidation, and thus converted into carbonic acid and nitre ; these 
have given to the water the agreeable qualities which are so deceptive. In 
reality, the water from the city pumps is far worse than that from the muddy 
river from which it is in great part derived ; indeed, it may at any moment 
become charged with the active agents of disease ; for no one can say when 
the salutary influence of the soil may fail by being worn out or over-taxed, 
and then the putrid organic compounds will pass into the wells unchanged. 
Many of the pumps are in close proximity to the fat graveyards of the City, and 
it is more than probable that all derive a portion of their waters from 
these sources, for they are the principal gathering grounds for the surface 
springs ; in fact, they are the only open spaces through which the rain can 
percolate to reach the shallow wells. Besides organic matter, these waters 
contain large quantities of common salt, which clearly points to the presence 
of the filthiest contaminations from sewers and cesspools. It is the organic 
matter, however, which is most to be dreaded ; the former are simply 
repulsive, but the latter is, or may be, fatal, for these organic corruptions in 
waters have frequently been proved to be, and may now become at any 
moment, the immediate cause of Asiatic cholera. This is no fanciful nor 
theoretical danger, for Dr. Letheby gives numerous instances in which this 
plague has attacked only those who used water from a certain favourite pump. 
In 1854 there was a sudden and serious outbreak of cholera in the parish of 
St. James, Westminster, and out of seventy-three persons who died during 
the first days of the visitation, sixty-one had been known to drink the water 
from a pump in the neighbourhood. Moreover, amongst persons in the same 
street, or even the same house, those only were attacked who employed this 
water, whilst others, who lived at a distance from the parish, and had the 
water sent to them because of its supposed goodness, were seized with cholera 
and died. Upon the attention of the authorities being drawn to this circum- 
stance, the well was examined, when it was found that the neighbouring cesspool 
had leaked into the well, and had communicated to it its poisonous action. Se- 
veral similar instances are quoted by Dr. Letheby, and it is stated that when 
the source of water was cut off by removing the handles from the pumps, the 
further spread of the epidemic was arrested. Out of all the wells examined, 
only two have been found at all fit for domestic purposes : the others contain 
an enormous amount of impurity, and in fact can only be regarded as so 
many dormant centres of cholera, — liable at any moment to break out 
into active pestilence. The subject of the deodorization of sewage has 
been very successfully taken up by the authorities at St. Thomas’s, Exeter. 
Owing to an indictment for a nuisance occasioned by their sewage outfall 
annoying the servants and passengers of an adjoining railway, they were 
about to expend ,£1,200 in conveying the sewage to another point, when the 
attention of the local board was drawn to the successful use of carbolic acid, 
with which Mr. McDougal disinfects the sewage of Carlisle. After some 
discussion, they determined to adopt the same plan. The results are most 
satisfactory. At an expenditure of one gallon of carbolic acid per day, 
costing elevenpence, the whole of the sewage is completely disinfected, and 
this, not only in a temporary manner, but by the power of the agent in 
arresting decomposition, the sewage is prevented from subsequently becoming 
