AND STATICS UNDER THE INFLUENCE OF LIGHT. 
351 
through the concentrated sulphuric acid in the tilted vessel (S). After a short time, 
when the mercury had risen in tube (33) about 10 centims., tap (11) was turned off 
again. This is done because the formation of carbon monoxide goes on more quickly 
and regularly as the pressure of carbon monoxide increases. When the newly formed 
carbon monoxide again begins to bubble through the mercury, the tap (11) is again 
opened and shut as before ; this is repeated until the pressure of carbon monoxide 
becomes everywhere a little over one atmosphere, i.e., the mercury column in (33) 
does not rise again when the tap (11) is opened, and carbon monoxide continues to 
bubble through the mercury (if a still higher pressure is desired the tube at (35) is 
closed). The taps (11) and (16) are now closed (open at 35), allowing the carbon 
monoxide gas to bubble through the mercury and escape to the air. After removing 
the burner from (10) it is rapidly and uniformly cooled on all sides by means of a wet 
cloth, until the formation and bubbling of carbon monoxide through the caustic 
potash ceases. The tube (4) is also filled with carbon monoxide at the same time in 
order to protect, subsequently, the carbon monoxide in (15) from contamination with 
air. The glass tubes of the different parts of the apparatus are directly joined 
together without the use of india-rubber tubes, and all the taps have mercury seals. 
In the funnels of (9) and (10) sufficient caustic jiotash solution and of sulphuric 
acid solution is always left, and taps (24), (26), and (25) should be so exceptionally 
well ground that even after many weeks (when covered with vaseline) the taps remain 
quite transparent. The object of these precautions was that pure and fresh gas might 
be prepared quickly for each experiment. Carbon monoxide gas, which had been 
kept in the vessels for even small lengths of time, was never used. When an experi¬ 
ment was made, vessels R, S, (18), E, (15), (14), (13), &c., containing pure carbon 
monoxide, were always first evacuated, heated, and the freshly-prepared carbon 
monoxide passed directly into the bulb (18), allowing it to bubble slowly through the 
concentrated sulphuric acid in (S) as described. The tap (22) was then turned off, 
(21) turned on, and then the capillary tube (19) at i n was immediately sealed up with 
a hand blow-pipe. 
PART II. 
Arrangements for an Acetylene Light of about 250 Candle-Power of 
Constant Intensity. 
Generator. (Arrangement for Constant Pressure .) 
Acetylene generators, although they have some advantages over the ordinary gas¬ 
holder, have also some disadvantages; firstly, because every time a fresh container of 
carbide is used, a fresh portion of air from the container is mixed with the gas, and 
though the volume of the container is very small in comparison with the volume of 
