7 6 



THE MECHANISM OF LIFE 



periodic catalysis of peroxide of hydrogen by mercury. He 

 thus describes his experiment : " We place in a perfectly 

 clean test tube a few cubic centimetres of perfectly pure 

 mercury. Upon this we pour 10 c.c. of a 10 per cent, solution 

 of hydrogen peroxide. The mercury speedily becomes covered 

 with a thin, brilliant, bronze-coloured pellicle which reflects 

 light. Then little by little catalysis of the hydrogen peroxide 

 begins, with liberation of oxygen. After some time, from five 

 to twenty minutes, the liberation of gas at the surface of the 



Fig. iS. — Articulate form produced by periodic precipitation. 



mercury ceases, the cloud formed by the gas bubbles disappears, 

 and the bronze mirror at the surface of the mercury lights up 

 with the glint of silver. There is a pause of one or more 

 seconds, and then the catalytic action begins afresh, commenc- 

 ing at the edges of the mirror. The cloud is again formed 

 and again disappears. This beautiful and surprising rhythmic 

 phenomenon may continue at regular intervals for an hour or 

 more." 



A slight alkalinity of the liquid is necessary to start the 

 phenomenon. This explains the retardation at the beginning 



