September 19, 1903. 
The Gardening World 
GENERAL, NOTICES. 
We would earnestly urge secretaries of societies to notify us as far in advance as possible as to dates of meetings, shows, etc. We desire to do all in our power to have these 
iequately represented in the columns of The Gardening World. 
We respectfully request our readers, when they write to persons or firms advertising in this paper, to mention that their advertisement was seen in The Gardening World, 
ley will thereby not only oblige this paper, but the advertisers. 
MOTTO FOR THE WEEK: 
“Nature cannot be surprised in undress. Beauty breaks in everywhere '— Emerson , 
Weekly Prize 
FOR 
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CHE BEST PARAGRAPH, or SHORT ARTICLE, Sent 
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■< 
The following 1 Coloured 
Plates have appeared :— 
March 14.— NEW CHINESE PRIMULAS. 
March28.— TEA ROSE “ CHAMELEON.” 
April 4. -COLEUS THYRSOIDEUS. 
< April 18.— CESTRUM SMITHII. 
S' April 25 — JAPANESE PIGMY TREE. 
May 23 —SAXIFRAGA GRISEBACHII 
>d A GROUP OF ALOCASIAS. 
May 30. — DENDROBIUM NOBILE 
OTUNDIFLORUM and D.n. NOBILIUS. 
June 6 —CALADIUMS. 
June 20.— ZENOBIA SPECIOSA PUL 
< ERULENTA. 
| July 4.—APHELANDRA AURANTIACA 
> OEZLII. 
July 11. — AUSTRALIAN PITCHER 
LANT. 
August 1— BORONIA HETEROPHYLLA. 
; September 12.— SIX NEW DAFFODILS. { 
Back numbers may he obtained from the 
: mashers, price 2 |d. post free. 
With the PRESENT ISSUE we present 
Half-tone Plate of KELWAY’S NEW 
LADIOLI. 
i NEXT WEEK we shall give a Half-tone 
°f A NEW CONSERVATORY AT 
KISTOL. 
Views and Reviews. 
Purification of Residuary 
Waters. 
As population increases in the various 
countries of Europe the question of the puri¬ 
fication of water becomes more and more a 
question of the first importance to the in¬ 
habitants from a sanitary point of view. In 
the case of sewage, we have various systems 
at work for the purification of sewage by 
which the solid residue is removed before the 
water is taken into' the streams and rivers. 
Nevertheless, the pollution of the natural 
waterways and also the wells all over the 
country is a matter which has not yet been 
settled to the satisfaction of those concerned 
with the health of the people. On this par¬ 
ticular occasion we wish to say something 
with reference to the automatic purification 
of water by what is termed Vial’s system, 
which has been established on a, small scale 
at Haren-Nord, in the suburbs of Brussels. 
The objective of ‘this system is the purifiear 
tion of drinking water, drain water, and in¬ 
dustrial water by continuous circulation with¬ 
out filtering or decantation. The method 
utilised for purifying the water in this par¬ 
ticular instance is by the use of some pre¬ 
cipitant by which the solid matters are pre¬ 
cipitated or thrown to the bottom of the 
water, so' that the water may run off clear and 
pure', while the solid matter is collected by a, 
special apparatus, dried and pulverised. 
Several systems are in use in this as well as 
other countries, including one known as the 
bacterian treatment. 'This system is in use 
in various English and Scottish towns, in¬ 
cluding Barrhead, Farington, Burnley, Black¬ 
burn, etc. The great value of this new 
system is the rapidity with which the opera¬ 
tion of purification can be effected, and the 
relatively small space required for the operar 
tion in proportion to the size of the town for 
which it may be at work. It is said that by 
irrigation 11 litres per square metre can be 
purified in the course of a day. In the case 
of bacterian treatment, 336 litres can be 
accomplished in the same time and space, 
and by Vial’s system it is claimed that 
10,000 litres per square yard per day can be 
accomplished. The installation of the plant 
would be the primary and chief expense; 
then the value of the substance' used as a 
precipitant would have to be reckoned in the 
purification of waters by this means, as the 
operation of purification acts automatically 
SO' far as the liquid to be purified and the pre¬ 
cipitant are concerned. The residue of the 
sewage is taken up by a pump which empties 
it into a closed cylinder, where it concen¬ 
trates, to be afterwards transformed into 
powder by desiccation in a revolving drum 
heated by warm air and gases from the fur¬ 
naces of the generator. This solid matter 
or powder can be utilised as a manure, as is 
already done in the case of the sewage works 
in existence. Under the new system the 
material can be greatly improved in value as 
a. fertiliser by the addition of phosphates or 
■salts of potassium. These should be added 
while the powder is passing through the re¬ 
volving drum, so- that the whole may become 
thoroughly mixed in the process. Farmers, 
market gardeners, and other cultivators de¬ 
siring manure for any particular purpose 
could have additional ingredients added to 
the diy residue of the sewage while it was 
being prepared. 
The purified water at Haren-Nord flows 
from the clarifying tank in a clear, colour¬ 
less sheet. If examined in great volume, 
however, it presents a pale yellow colour, 
but this is probably due to small flakes of 
iron hydrate, as shown by the chemical an¬ 
alysis to which it has been subjected. If 
this purified water is preserved in an open 
or corked flask there does not seem to .be 
any deposition of organic matter. 
It seems to us that the greatest value of 
this new system lies in the fact that a great 
amount of purification may be earned on in 
relatively small space, which means that the 
process must be earned out with a degree of 
rapidity in proportion to the amount of 
water passed through the clarifying tank. 
As far as the clarification is concerned, it is 
done in the first instance automatically— 
that is, by gravitation. As the sewage is 
entering the precipitant is entering at the 
same time in sufficient quantity to precipi¬ 
tate all the residue in that volume of water. 
