HYDROGEN GAS. 507 



their experiments, I thought it worth while to 

 examine the gas anew, in order, if possible, to de- 

 termine the point in a satisfactory manner. I ac- 

 cordingly collected considerable quantities of it at 

 different times in the neighbourhood of Restalrig, 

 where ponds of muddy water are left stagnant, in 

 order to collect manure. This gas I found to have 

 the following properties. 



1. It is colourless, and transparent like air. 



2. It has no smell, and no sensible taste, provi- 

 ded it be previously washed in clean water. 



3. It always contained a mixture of carbonic 

 acid. The least quantity of this gas present was 

 5 per cent. ; the greatest 7- per cent, 



4. It always contained a mixture of common 

 air. It is remarkable, that the proportion present 

 was in every case the same, and amounted to ia.5 

 per cent., or 2.5 per cent, of oxygen and 10 per 

 cent, of azote. Mr Dal ton says, that the gas 

 which he examined contained 20 per cent, of 

 azote, This was never the case with the gas from 

 Restalrig ; but the common air and carbonic acid 

 gas together sometimes amounted to 20 per ceni. 9 

 and always to near that quantity. 



5. After depriving it of its carbonic acid, I 

 found its specific gravity 0.61 1, that of air being 



- 1. coo. Eut as it contained a mixture of 12.5 per 

 cent, of air, it would have been obviously lighter, 

 if this portion had been removed. By calculation 



