112 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
with eye-pieces 6, 12, 18, magnifications of 372, 750, and 1125 were 
obtained. 
The best part for observing the diatoms is the edge of the drop, and 
this should be first centered under a low power. 
Preparing Litmus Tincture for Testing Reaction of Gelatin.* — 
According to Dr. M. Dahmen, a very sensitive litmus solution may be 
prepared from Mohr’s formula. The litmus is to be thoroughly worked 
up with hot distilled water; the filtered solution is then evaporated, 
and having been treated with acetic acid to saturation, is again evapo- 
rated down to the consistence of a thick extract. This mass is then 
placed in a flask, and a large quantity of 90 per cent, alcohol added. 
The blue pigment then precipitates a red dye and acetate of potash 
remains in solution. The litmus is next filtered off, and having been 
washed with alcohol, is dissolved in warm water and again filtered. 
The solution must be kept in vessels stopped with cotton-wool, as in 
tightly-closed bottles it soon loses its colour. 
Sterilizing Incoagulable Albumen.f — M. E. Marchal suggests that 
the action of certain salts may be utilized to prevent the coagulation of 
egg albumen when heated to 100°. These salts are borate of soda, 
sulphate of iron, and nitrate of urea. The following are the quantities 
of these substances to be used for the purpose : — Solutions of 2 to 5 per 
cent. : — Borate of soda, 0 • 05 grm. per litre ; sulphate of iron, 0 * 001- 
0*006 grm. per litre. Solutions of 10 per cent. : — Nitrate of urea, 4 to 5 
grm. per litre. Thus prepared, the liquids may be sterilized at 100° in 
cultivation flasks. 
It is hardly necessary to point out that nitrate of urea should not be 
used to prevent the coagulation of albumen if the experiments relate to 
nutrition or fermentation of matter containing albumen. 
Sterilization of Water by Pressure .J — MM. Rouart, Geneste, and 
Herscher have constructed an apparatus for sterilizing water effectually 
and economically by a combination of heat and pressure. It consists of 
four distinct parts — a boiler, primary and secondary converter (or 
cooler), and a clarifier. The water to be sterilized is introduced into 
the primary converter — a cylindrical metal vessel surrounded by a worm 
in which water heated to 120°-130°, and just coming from the boiler, is 
circulating. From the converter, and having there been raised to 100°, 
the water is conducted along a pipe to a worm running round the boiler, 
where it is heated up to 120°- 130°. From this worm the water then 
passes through the worm in the primary converter, thence through the 
secondary converter, and finally, having passed through the clarifier, 
completes its circuit. The secondary converter is also a worm sur- 
rounded by cold water, and might be termed the cooler. The clarifier 
is filled with powdered silica, apparently between layers of canvas, and 
is not intended for a filter, but to impart a clearness or limpidity to the 
water which has been removed from it by the heating it has gone 
through. The water having passed through the clarifier, is delivered 
bright and clear, and fit for all the purposes of life. 
* Centralbl. f. Bakteriol. u. Parasitenk., xii. (1892) p. 622. 
f Bull. Acad. Roy. Sci. de Belgique, xxiv. (1892) pp. 323-7. 
X Journ. de Microgr., xvi. (1892) pp. 145-52 (2 figs.). 
