Notes. 
329 
1879.] 
being of but little moment. A specimen of Medusa aurita has 
kept well a whole year, and its beauty and transparency leave 
nothing to be desired. The solution has only one inconvenience, 
it permits the development of mould ; but this can be prevented 
by the addition of a few drops of phenic acid or phenic alcohol. 
Another convenient salt is permanganate of potash, acfting very 
much like osmic acid, clearing away the protoplasm and bringing 
out the minutiae and showing nuclei, outlines of cells, &c. It 
can be dissolved in sea-water, and should be used as a saturated 
solution either in sea or fresh water. This solution kills small 
organisms at once. They are left in it from thirty minutes to an 
hour, then withdrawn and placed in alcohol, after which they can 
be made transparent with turpentine and mounted in Canada 
balsam. According to the author it effectually replaces the 
costly and somewhat dangerous osmic acid. 
We learn from M. Reimann’s “Farber Zeitung ” that two new 
green dyes have been introduced into practical use ; the Vert 
acide of A. Poirrier, of Paris, and the Victoria green of the Baden 
Aniline Company. The price of the latter is only 16s. per kilo. 
The red azo-colouring matters are fast superseding cochineal 
in the flannel dye-works of Saxony. They have the advantage 
of not being injured by washing. 
M. Aime Girard has reported to the Societe d’Encouragement 
pour l’lndustrie Nationale on M. Kuhlmann’s method for recog- 
nising the composition and measuring the volume of the gases 
and acid vapours given off by the chimneys of chemical works. 
By means of this arrangement a manufacturer can at any hour 
inform himself concerning the nature of the gases traversing his 
chimney. To establish the composition of the chimney gases 
and to deteCt, e.g ., the presence of hydrochloric acid therein, M. 
Kuhlmann introduces into the shaft a glass tube which com- 
municates with a series of test-tubes, at the end of which is a 
cistern of water which aCts as a respirator. The flow of water 
compels the gas to traverse the series of test-tubes, the first of 
which contains caustic soda coloured with litmus. Then follow 
solutions of barium chloride and silver nitrate. The dimensions 
of the cistern are such that five or six hours are required for the 
total efflux of the water which it contains, and the strength of 
the alkaline liquid coloured blue is such that in the regular course 
of work five or six hours are required to turn them red. An 
earlier colouration gives immediate warning. M. Kuhlmann’s 
method of measuring the total volume of gases escaping is as 
follows : — When he wishes to know the speed of the gases he 
introduces at the bottom of the chimney a certain volume of a 
strongly coloured gas, such as hyponitric acid, which accom- 
panies the colourless gases up the chimney and presents itself 
along with them at the top. Knowing then the volume of the 
chimney and the mean temperature it is possible to calculate 
from the time which has elapsed the quantity of gas emitted. 
