Andrews. — The Effect of Gases on Nitclear Division. 523 
Figure 16 will give an idea of the apparatus used to obtain pure 
hydrogen. It consists of a gas generator A, containing zinc and sulphuric 
acid covered with paraffin 1 , which connects with a U-tube B, filled with 
pumice stone and saturated with caustic potash for removing the hydro- 
chloric acid, sulphuric dioxide or hydrogen sulphide, some one or more 
of which may be present in hydrogen prepared by the action of sulphuric 
acid on zinc. The U-tube B is connected with C containing silver 
nitrate for absorbing the arsenic according to the formula : — 
6 AgN 0 3 -f AsH 3 + 3 H 2 0 = 6 Ag + H 3 As0 3 + 6 HN0 3 . 
The U-tube C is joined to D containing pyrogallol for removing the 
oxygen. D communicates with A containing potassium permanganate, and 
E with the bottle F containing water for washing the hydrogen and 
saturating it with moisture. This latter precaution is absolutely essential, 
for if dry gas were allowed to enter the gas chamber G on the microscope P, 
the shallow drop of water containing the specimen for observation would 
be evaporated before the termination of the experiment. In order to 
ascertain the rate of flow of the gas, as well as to prevent any back flow 
of air into G , a bottle K is attached containing water. The glass tubes 
connecting the U -tubes and bottles are made secure at their points of 
union by rubber stoppers covered with a thick layer of sealing wax as 
at L. The glass tubes M, M' are long enough to allow sufficient 
movement of G. They are fastened to the metal tubes of the gas 
chamber G by rubber tubing covered with sealing wax. Such connexions 
as are here mentioned will not allow any gas to diffuse, as I have found 
by long-continued experiments. No leakage whatever could be detected, 
even when the gas in the apparatus was subjected to a pressure of half 
an atmosphere under water. 
Another excellent method is to generate hydrogen by electrolysis 
and collect this in a vessel for use. 
I. The Effect of Hydrogen. 
1. The action of Hydrogen on the streaming of Protoplasm. 
In each case after the staminal hair was placed in the 3 per cent, 
solution of cane sugar a few of the aerobic Bacteria, above referred to, 
were transferred to the drop by means of a sterilized platinum needle. 
These Bacteria move when oxygen is present. They also instantly cease 
moving when oxygen entirely disappears, and are therefore a very delicate 
test to show that no oxygen was around the cells with which I was 
experimenting. The use of the various chemicals mentioned has, by the 
1 If, as sometimes happens, the sulphuric acid does not attack the zinc readily, so as to cause 
a rapid evolution of hydrogen, this may be brought about by the addition of a small quantity of 
platinum tetrachloride or copper sulphate to the sulphuric acid. 
