8
REPORT OF THE KING INSTITUTE, GUINDY
It was found that rain washed down crude impurities that had been retained
in the upper portions, so an upper blinding layer of three inches coarse sand was
added above. The filter worked for three months in this way which makes the
second period.
In the third period of two months, the percolating filter bed has been the
same as that of an ordinary sand filter but of course the former has not been
submerged. Distribution has been maintained by a perforated corrugated iron
sheet about 6 inches above the surface of the sand. The filter has been similarly
worked in a fourth period except that the water has been sprayed above the
perforated zinc sheet.
Results .—The first period was too short to allow an opinion to be formed
since beds take a long time to get into full working order. In the second and
third periods the results were chemically a little worse and bacteriologically
distinctly worse than the control filter. In the fourth period which still continues
during a time (the hot weather) when the organic content of the raw water was
high, the experimental filter has given slightly better results than the control
filter as regards the albuminoid ammonia and amount of oxygen absorbable. The
bacteriological results have been the same for both filters. A final report will be
made next year.
2. Sewage.— A closed septic tank, an open septic tank, an Imhoff tank and
an aerating contact bed have been set up at the Engineering College, Guindy.
Pumps for the sewage were not installed until March, so that practically no work
except several preliminary analyses of raw sewage has been done this year.
(E) PUBLIC ANALYST.
1. Charge of work.—Mr. H. Hawley, M.sc., F.I.C., Public Analyst with the
Government of Madras, has continued to work here and to control the chemical
side of our public health work with which this portion of the report (in which
he has collaborated) is immediately concerned. His own separate report recom
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mending standards for adoption under the Madras Food Adulteration Act and
advising the passage of an Amending Act is given in A ppendix II and may also be
obtained separately.
2. Work done.—As the Act is not yet in force, there have been no regular.
s u p p l i e s o f f o o d s t o b e t e s t e d f o r a d u l t e r a t i o n , b u t a n u m b e r o f s a m p l e s h a v e b e e n
examined in connexion with various investigations. Table XV gives a list. The
following call for sp e cial comment.
3. Alum in bread.— During the year the Surgeon-General issued a circular
to all hospitals requiring that samples of the bread submitted by contractors
should be analysed by the Public Analyst and should conform to certain standards.
Freedom from alum was one of them. Previous to the issue of the circular thirteen
samples of bread were examined, all of which were found to contain alum. The
Surgeon-General interviewed some of the contractors who professed to be ignorant
as to how the alum came to be present. A number of samples of bread ingredi
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ents supplied by them were examined and found to be free. Thus it is not known
by whom and in what form the alum was introduced, but it is interesting to record
that, of 32 samples submitted by various hospitals since the issue of the circular,
all have been free from alum, though four samples gave an acidity figure
somewhat in excess of the permitted limit.
4. Decomposition of milk samples.—Samples of milk have been analysed after
decomposition had set in, and it has been established that with milks kept at
laboratory temperatures for two months, and hence very seriously decomposed, it
is possible to obtain reliable figures for the proportion of nitrogen and of fat in
the original milk, and so to determine whether the sample was watered or deficient
in fat. These results may become of importance should the Food Adulteration
Act be brought into force before the passing of the Amendment Act (which
permits food inspectors to add a preservative to their samples).
5. Milk supply of Madras hospitals.— In connexion with the scheme to
create a dairy at Hosūr and to supply the hospitals with pasteurized milk,