566 SANITARY NOTES ON POTABLE WATER. 
ordinary boiled meat after standing for some time under a 
cover. 
From all these experiments we may thus draw the follow¬ 
ing conclusions: 
1. The results which I explained in this paper strongly 
corroborate those communicated in my former paper on 
similar subjects. 
2. Ordinary water, after efficient filtration* through spongy 
iron, does not contain any putrescent matter, or matter 
capable of inducing putrefaction. On the contrary, such 
filtered water possesses in itself antiseptic properties strong 
enough even to prevent, to some extent at least, putrefaction 
of fresh meat which has not been boiled before being exposed 
to the action of the filtered water. 
3. Contact between the meat and spongy iron is not 
necessary to obtain that result. 
4. Neither is the absence of oxygen in the filtered water 
to all appearances an essential condition. 
5. It thus follows that the action of spongy iron cannot 
be wholly mechanical, but must be, in part at least, chemical, 
or, as far as the action upon organised bodies is concerned, 
physiological. 
The researches by Drs. De Chaumontf and J. Lane 
Notter/f of Netley, tend to corroborate my experiments 
bearing on the action of spongy iron on living organisms 
and its general purifying power as compared with animal 
charcoal. These reports are also a strong corroboration of the 
statements on the same subject in the Sixth Report of the 
Rivers Pollution Commission, p. 220 and 221. 
Only one attempt has, as far as I am aware, been made to 
upset some of my conclusions. In vol. xiv, part iv, of the 
‘Zeitschrift fur Biologie/ by Buhl, Pettenkofer, and Yoit, p. 
503, Dr. L. Lewin says:—“ Now I can most positively 
assert that if only 10 c.c. of urine which contains moving 
bacteria be mixed with two litres of water, and passed through 
a spongy iron filter, numerous bacteria may be found in the 
filtered water.” Seeing the obviously unscientific manner in 
which Lewin has treated the subject, I would probably have 
passed over his observations without a reply were I not 
* By efficient filtration is to be understood filtration at such a speed, 
and generally under such conditions, as explained herein. The spongy iron 
which serves as filtering medium must be of proper chemical and physical 
quality. 
f ‘ Army Medical Report/ vol. xix, 1879, p. 170, and Sanitary Record , 
vol. x, No, 248. 
X Paper read before the section ‘ Public Medicine/ at the Meeting of 
the British Medical Association, August, 1878. 
