CARBONIC ACID 149 



From the tabic 4 it appears that the first 

 50 grams of alkali reduce the hydrogen ion 

 concentration to but 50 times that of neutral 



solutions, and 200 grams of alkali have made 

 it only about 10 times that of pure water, in 

 spite of the fact that there are more than 

 750 grams of free carbonic acid still present 

 in the solution. So much acidity can at once 

 be obtained by dissolving merely 0.004 gram 

 of hydrochloric acid in 100 liters of water. 

 Thereafter neither acidity nor alkalinity sur- 

 passes this intensity until 450 grams more of 

 sodium hydrate have been added to the solu- 

 tion. Yet in pure water 0.005 gram of sodium 

 hydrate would make the reaction more alka- 

 line than that. 



Such is the case when the equilibrium is 

 homogeneous, i.e. in an isolated solution. 

 But when, in similar cases, an atmosphere 

 containing carbon dioxide is present, the con- 

 ditions are still more striking. Suppose, for 

 example, a solution of 100 liters containing 1 

 kilogram of sodium bicarbonate in equilib- 

 rium with an atmosphere containing 1 gram 

 of carbon dioxide per liter. Let hydrochloric 

 acid be added in successive small portions to 

 the solution. Further let the solution be 

 constantly stirred and shaken, and let the 

 experiment be conducted slowly, so that there 



