260 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
even layer. The diatoms are laid on dry, and fixed in position by 
merely breathing ever so lightly upon the cover-glass. 
Sterilization of Water by the Chamber land Filter.* * * § — M. L. Dor 
finds from several experiments that Chamberland’s filter may be confi- 
dently relied on for removing bacteria, for by means of it the author 
has succeeded in rendering the water perfectly free of germs. 
Microchemical Test for Alkaloids and Proteids.j — M. L. Errera 
finds, as the result of numerous and prolonged experiments between 
alkaloids and proteids, that alcohol acidulated with tartaric acid fulfils 
all the conditions required for a good test between these two classes of 
highly organized bodies ; for the alkaloids are removed by means of the 
tartaric acid, and the proteids remain behind. Hence little difficulty 
will be experienced in distinguishing the one class of compound from 
the otlier. The experiments were made upon colchicine, pepton, mucor, 
cigue, and lupin. 
“ Air-gas for Bacteriological Work.J — Dr. 0. Katz, who had to work 
on liodd Island, N. S. Wales, where the ordinary appliances of civiliza- 
tion were not available, made use of the “ Alpha patent gas-making 
machine.” This apparatus produces gas in the shape of a mixture of 
atmospheric air and the vapour of petroleum spirit (gasoline), the 
mixture being called air-gas. By means of weights atmospheric air is 
pumj)ed through a drum into a chamber, where it is impregnated with 
the vapour of the volatile fluid. The mixture then passes into a gaso- 
meter, from which the burners are supplied automatically. The author 
used a 40-light machine capable of yielding 200 feet of gas an hour. 
4 he author considers that air-gas makes an efficient substitute for 
coal-gas for ordinary lighting purposes, and he also used it with success 
for heating thermostats, and also for other bacteriological purposes. 
(6) Miscellaneous. 
Changes in the Firm of Zeiss.§ — The firm of C. Zeiss, in Jena, has 
advertised by circulars a change in their management. Dr. Ernst Abbe, 
who has hitherto acted as general manager of the firm, was, on November 
29th, 1889, admitted into the firm as partner with Dr. K. Zeiss, and has 
now undertaken the sole management of the company so formed. At the 
same time power of procuration of the firm has been given to Dr. Otto 
Schott, of Jena; and Dr. Siegfried Czapski, of Jena, has also been 
authorized to represent the firm in all business matters. 
Correction, by Dr. H. van Heurck. — Dr. H. van Heurck, Director 
of the Jardin Botanique, Antwerp, requests us “ to correct an error, or 
rather an omission,” which occurred in his note on Pleurosigma 
avgulatum.\\ 
He wrote: — “The last photograph. No. 6, shows that the valve of 
Pleurosigma is formed of two layers.” In writing this phrase he states : 
“ I had in view the upper membrane and the intermediate layer, which are 
* Lyon Medical, 1889, No. 23. Cf. Centralbl. f. Bakteriol., vii. (1890) p. 75. 
t Anuales Soc. Beige de Microseopie (Memoires), xiii. (1889) pp. 72-121. 
X Proc. Soc. Linn. N.S.W., iv. (1889) pp. 328-30. 
§ Zeitschr. f. lustrumentenk., x. (1890) p. 37. II Ante, p. 101. 
