ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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the water in the boiler finds its way into the receiver through a number 
of holes made through the sides near the top, and escapes therefrom 
through a pipe running from the bottom up the side to the top. 
It is stated that condensation water deposits only on the lid, and 
thus the articles to be disinfected are not damped. For the steriliza- 
tion of instruments a special receiver is required, and this is filled with 
1 per cent, soda solution and then boiled in the sterilizer. Is it super- 
fluous to add that all this trouble might be saved by means of an ordinary 
tin saucepan? 
Berkefeld Filter.* — This filter, which has been much bepraised, 
has received some severe criticism at the hands of Dr. M. Kirchner, who 
stated that it became used up in a comparatively short time, and that it 
had the inherent defect of being brittle, so that, as it required sterilizing 
every few days, it was really an expensive luxury. The filter proper 
consists of calcined infusorial earth, and the special property of this 
material was supposed to reside in the sharpness of the edges and angles 
of the passages through which the water percolated ; pathogenic bac- 
teria were cut up as they hurtled by. 
These remarks were replied to by Prof. M. Gruber, who seems to 
have expressed a favourable opinion of the apparatus. This author 
appears to consider that it is rather hard on filters to expect them to be 
immaculate, and in estimating the value of a filter he lays it down that 
the appearance of germs is to be assigned to one of two causes. Either 
the germs percolate through along with the water, and so form part of 
the filtrate, or they grow through. If germs percolate through the 
filter, the principle or the make of the filter may be considered essen- 
tially bad, but if they grow through, this is to be regarded somewhat in 
the light of an unfortunate accident, and one not indicative of danger. 
In reply to Prof. Gruber, Dr. M. Kirchner reiterates his former 
statement, and points out again that while he thinks this filter is a good 
one as filters go, yet it soon becomes clogged, or allows the transit of 
pathogenic and non-pathogenic bacteria, and that it is constructed of 
material too brittle for general use. It possesses good features, and if 
it were made so as to be more durable it might be recommended for 
general purposes. 
Apparatus for Boiling and Cooling Water, j — Dr. H. Laser gives 
a short description of an apparatus made by the Continental Gas Com- 
pany in Dessau, which seems to be practical and effective. It consists 
of two parts, one in which the feed-water is partially heated before it 
gets into the boiler proper in which it is heated for ten minutes. It is 
then returned to the feeder through a pipe, and so becomes cooled 
down. 
The author’s observations chiefly deal with the freedom of the water 
from bacteria. On the whole the water is fairly well, sterilized, and is 
delivered at a temperature varying from 15° to 25°, usually nearer the 
latter. The apparatus is only made to be heated by gas. 
* Zeitschr. f. Hygiene u. Infektions., xiv. (1893) p. 299. Centralbl. f. Bakteriol. 
u. Parasitenk., xiv. (1893) pp. 488-93, 51(5-27. 
f Centralbl. f. Bakteriol. u. Parasitenk., xiv. (1893) pp. 749-55 (1 fig.). 
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