282 



and in the same manner, that 100 parts of soda contain 81 base and 



19 oxygen. 



The other method consisted in collecting the hydrogen evolved 

 from water by a known quantity of each base, and estimating from 

 them the quantity of oxygen absorbed. The mean of two such ex- 

 periments on the base of potash, gave the proportion of 15 per cent, 

 oxygen, and the mean of three trials upon soda, showed it to contain 



20 per cent, oxygen. 



So that the general average of both methods authorizes us to con- 

 sider potash as containing 15 of oxygen, and soda 20 of oxygen, per 

 cent. 



Since oxygen had thus been proved to enter into the constitution 

 of the fixed alkalies, Mr. Davy was led to conjecture that it might 

 also form a constituent part of ammonia. For though the apparent 

 conversion of ammonia into mere nitrogen and hydrogen in the ex- 

 periments of Scheele and of Priestley, as well as in the more refined 

 and masterly experiments of Berthollet, had left no doubt of its na- 

 ture on the minds of chemists in general, it was not impossible that 

 a small quantity of water in their results might have been overlooked, 

 when dissolved in the gases or deposited on the vessels employed, or 

 might even be neglected, as not arising from elements essential to the 

 construction of the ammonia. His conjecture was confirmed in the 

 first place by the formation of carbonic acid in the purest and driest 

 ammoniacal gas, by means of charcoal intensely ignited by a voltaic 

 battery. 



When Mr. Davy had afterwards exposed the base of potash to 

 ammoniacal gas, and had ascertained the formation of potash, no 

 doubt was left of the presence of oxygen, although its proportion 

 could not by these means be ascertained. For the purpose of deter- 

 mining the proportion, and at the same time of avoiding any fallacy 

 that might be occasioned by the presence of water in the ammoniacal 

 gas, even in its state of hygrometrical dryness, Mr. Davy had re- 

 course to the apparatus employed by Messrs. Allen and Pepys for the 

 combustion of the diamond. The gas, after being carefully prepared 

 and dried, was passed over the surface of iron wire ignited in the 

 platina tube, furnished with an additional apparatus for condensing 

 any water that might be formed in the experiment. 



In the course of a quarter of an hour four grams of ammoniacal 

 gas were decomposed. The iron wire had gained -iVo-ths of a grain, 

 and a quantity of water was moreover collected, which weighed full 

 four tenths of a grain. From the amount of the oxygen contained 

 in the water, together with that which caused the increase of weight 

 in the iron, Mr. Davy infers that 100 parts of ammonia contain 

 nearly 20 of oxygen. 



We may therefore consider oxygen as existing in, and as forming 

 an essential element of all the three alkalies ; so that this principle 

 of acidity, as it is termed in the French nomenclature, might now 

 equally be called the principle of alkalization. 



From analogy alone, it is reasonable to presume that the alkaline 



