90 TRANSACTIONS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
has been said, being handed to us, and the other sent to the outside 
analyst from a place a long way from Perth. 
TABLE III.-ANALYSES OF TAY WATER AS SUPPLIED TO THE 
Solids, Volatile, - 
5, Saline, 
1881 
1*40 
5-60 
CITY 
Jany. 
1892 
I ’40 
6'60 
OF PERTH. 
1893 
Feb. 
2-8 
2-4 
May 
3*2 
4*2 
June 
*22 
4*48 
Sept. 
* 
*97 
3*40 
Oct. 
I *60 
5*04 
Dec. 
* 
•60 
5*41 
Dec. 
2*00 
4*00 
,, Total, 
7’oo 
8‘00 
5*20 
7*40 
470 
4*37 
6-64 
6*01 
6*00 
Chlorine, 
1-30 
1-30 
•90 
I no 
•97 
*94 
•70 
*75 
Ammonia, Free, - 
'003 
•004 
*001 
•003 
*003 
•003 
•003 
•010 
•008 
,, Albumenoid, 
•005 
•009 
•009 
*003 
*007 
*002 
•005 
•007 
•005 
,, Total, 
•008 
•013 
•010 
•006 
•010 
•005 
*008 
•017 
•013 
Hardness, Temporary, 
— 
•6 
•4 
*4 
2*40 
— 
*42 
— 
— 
,, Permanent, 
— 
3*6 
3*0 
4*0 
1*48 
— 
3*07 
— 
— 
,, Total, - 
— 
4*2 
3*4 
4*4 
3*88 
— 
3*49 
3*21 
3*10 
In samples marked so * the upper column gives the organic matter only, and not 
the whole volatile matter. 
Of these analyses four or five are very satisfactory. Three of 
these, January, 1892, and the two in December, 1893, are not suffi¬ 
ciently bad to condemn the water, but at these times the water could 
not be looked upon as a water of first-class quality. These three 
analyses are done independently of each other; the latter two were 
drawn in the manner indicated, and are samples of the same water, 
the last being our own analysis, and the second last that of an outside 
specialist. These two, and also the one in January, 1892, all bring 
out the fact that, during the winter time, when the river is often flooded, 
when the natural purifying agents are not so active, and the purification 
by filtration is not so effective as in the summer time when the river is 
low, we are undoubtedly much more liable to suffer from impurities 
than during summer. In fact, in the winter time we are not in a 
position to say that the water is of first-class purity, although at the 
same time we, from chemical analyses alone, are not in a position to 
condemn the water for domestic and dietetic purposes. We are 
distinctly of opinion, however, that there ought to be, especially for 
some time after flooding, a thorough bacteriological investigation of 
the water supply in addition to the chemical analyses. The water for 
both examinations should be drawn independently from the water sup¬ 
ply of the city. The Medical Officers and our Sanitary Inspectors 
deserve all praise for their efforts to lessen the danger arising from 
contamination of the Tay by sewage, but we dare not shut our eyes 
to the fact that sewage in considerable quantity is run into the river, 
and that in certain states of the river the purifying agents are less 
active, and there is at least a danger of the filter-beds being insufficient 
to remove dissolved impurities got from sewage contamination. 
