1818.] of the Elements of Nitric Acid. 353 



the proportion of acid in dry nitrate of potash, we find, by cal- 

 culating the products of the first experiment, that 100 parts of 

 the salt are composed of 



Acid 49-9 



Potash 50-1 



100-0 



When we calculate the other experiments, the results vary 

 merely a few thousandth parts. Hence it follows from these 

 experiments that nitre is composed of equal weights of acid and 

 potash. 



This method gives, perhaps, a nearer approximation than 

 those which are founded on the composition of any other salt, 

 respecting which there must of necessity be a greater or smaller 

 degree of uncertainty. 



Note by the Editor. — Though I cannot pretend to account for 

 the source of the fallacy, I have not the least doubt that the 

 constitution of nitric acid, as deduced from the preceding expe- 

 riments, is inaccurate. It Iras been sufficiently established tiiafe 

 an atom of oxygen gas may be represented by one volume, aud 

 an atom of azotic gas by two volumes. We may of course 

 obtain the atoms that enter into combination, by simply doubling 

 the volume of the oxygen gas. If we do this, we see that, 

 according to Berthollet's experiments, nitric acid is a compound 

 of 1 atom azote + 4-442 atoms of oxygen. Now it is quite 

 obvious that the fractional part of an atom amounting to 0*442 

 cannot possibly exist as a constituent. Instead of 100 azote + 

 222-1 oxygen, the true number ought to be 100 azote + 250 

 oxygen. If any one prefers the theory of volumes, as explained 

 by Gay-Lussac, and adopted by Berzelius, to the atomic theory, 

 the objection is not in the least diminished • for, according to 

 that theoiy, one volume of azote can combine only with a cer- 

 tain number of volumes of oxygen, and not fractional parts of a 

 volume, as is indicated by the experiments of Berthollet. 



But it is easy to show by experiment that the composition of 

 nitrate of potash is not what Berthollet has deduced from his 

 experiments. I took 100 grains of pure and dry nitre, poured 

 sulphuric acid upon the salt in a platinum crucible, and exposed 

 it to a heat at first low, but gradually increased till it became 

 sufficiently intense to decompose bismphate of potash. The 

 residual sulphate of potash weighed 83-6 gr.; but 83-6 of sulphate 

 of potash contain 45-6 potash ; therefore, nitre is composed of 



Nitric acid 54-4 



Potash 45-6 



100-0 

 Vol. XII. N° V. Z 



