I04 MARINE LIGHTING EQUIPMENT OF THE PANAMA CANAL. 



The first condition with regard to the porous substance to be used is 

 that it shall completely fill the vessel, leaving no space excepting the capillary 

 canals formed by the substance itself. Other practical requirements are that 

 it shall be perfectly free from action upon the acetylene (or the acetone — 

 see below), that it shall possess a maximum amount of porosity, and that 

 its consistency shall remain unaltered. 



Of the porous substances hitherto used only one is known to have stood 

 the test of years in regard to preserving its consistency unchanged. This 

 porous mass possesses a porosity of 75 to 80 per cent. 



Although 'a vessel thus filled with a porous mass only might well be 

 used for directly compressed acetylene, yet it is not so employed for the 

 simple reason that an additional means exists for vastly increasing its storing 

 efficiency. 



acetone; — THE ACETYLENE STORER. 



To Claude and Hess, two French chemists, is due the important dis- 

 covery that acetone, a combustible organic liquid which boils at 56° C. 

 (133° F.), possesses an extraordinary capacity for dissolving acetylene. At 

 15° C. (59° F.) a given quantity of acetone will absorb 25 times its own 

 volume of acetylene at normal atmospheric pressure, and its solvent capacity 

 is increased proportionately to the pressure, so that at a pressure of 12 

 atmospheres it can absorb 300 times its own volume of acetylene. 



Important as this discovery was, it was not directly available for prac- 

 tical use. When absorbing acetylene, the liquid expands at the rate of about 

 4 per cent of its volume for each added atmosphere of pressure. Accordingly, 

 a vessel intended for acetone saturated with acetylene under pressure can 

 in practice never be entirely filled with liquid. During consumption, there 

 would gradually be formed a space which would become filled with gaseous 

 acetylene compressed above its limit of safety. This danger had to be 

 avoided. 



It was completely obviated by the invention of the porous substance 

 already described. 



Thus the illuminant, dissolved acetylene, was brought into existence. 



THE GAS ACCUMULATOR. 



The accumulators are prepared in accordance with the foregoing 

 principles. 



More specifically described, an accumulator is a steel cylinder tested to 

 at least 50 atmospheres pressure (the type used on the Panama buoys, which 



