584 
Extracts from British and Foreign Journals. 
MICROSCOPICAL EXAMINATION OF WATER FOR 
DOMESTIC USE. 
By James Bell, F.R.S. 
{Read before the Royal Microscopical Society .) 
The microscopical examination of water for domestic use 
is, in my opinion, a suitable subject to bring before this 
Society. The subject is essentially a practical one, and affords 
a wide field in which microscopists might occasionally spend 
a portion of their time with much profit. 
A sample of water which is largely contaminated with 
sewage exhibits, when placed for a few days in a warm 
chamber, such a mass and variety of life, that the mind is 
almost bewildered in trying to master in detail the numerous 
creatures that have sprung into existence within so short a 
space of time. From the diversity of the ingredients usually 
composing sewage, it would, indeed, be difficult to find a 
mixture so well adapted for the development of a variety of 
organisms. 
Mr. Heisch was, I believe, the first who attempted to point 
out a possible means of detecting, by the use of the micro- 
scope, whether water had been contaminated with sewage or 
not ; his method being founded upon the development therein 
of a distinctive organism in the presence of sugar. 
He found that when a small proportion of pure cane-sugar 
was added to water containing sewage, and the mixture was 
maintained at a temperature between 60° and 70° Fahr., and 
placed in a position where plenty of light was admitted to the 
bottle in which the liquid was contained, the mixture became 
turbid in times, varying from twenty-four to sixty hours, and 
contained cells and a delicate fungus mycelium, followed by 
the ultimate development of the odour of butyric acid. From 
this, Mr. Heisch concluded that sewage contained particular 
germs, which when brought into contact with sugar in water 
immediately began to grow. 
This observation was necessarily regarded as a most im- 
portant one, not only because it promised to effect a change 
in the present mode of determining the presence of sew r age in 
water ; but to lead to the discovery and identification of the 
germs which generate epidemics. 
