NITROGEN. 69 



Julius Thomsen, * for the purpose of fixing indirectly the ratio H : O, 

 has made a valuable series of determinations of the ratio HC1:NH 3 , 

 which may properly be used toward establishing the atomic weight of 

 nitrogen. First, pure, dry, gaseous hydrochloric acid is passed into a 

 weighed absorption apparatus containing pure distilled water. After 

 noting the increase in weight, pure ammonia gas is passed in until a very 

 slight excess is present, and the apparatus is weighed again. The excess 

 of NH 3 , which is always minute, is measured by titration with standard 

 hydrochloric acid. In weighing, the apparatus is tared by one of similar 

 form, arid containing about the same amount of water. Three series of 

 determinations were made, differing only in the size of the absorption 

 apparatus ; so that for present purposes the three may be taken as one. 

 Thomsen considers them separately, and so gives greatest weight to the ex- 

 periments involving the largest masses of material. I give his weighings, 



TT/tj 



and also, as computed by him, the ratio ^T. 



First series. . 



Second series. 



Third series.. 



Mean of all, 2.14093, .000053 

 Reduced to vacuo, 2.1394 



From the sums of the weights Thomsen finds the ratio to be 2.14087, 

 or 2.13934 in vacuo. From this, using Ostwald's reductions of Stas' data 

 for the atomic weights of N and Cl, he finds the atomic weight of H = 

 0.99946, when O == 16. 



We have now, apart from the determinations of gaseous density, eleven 

 ratios, representing one hundred and sixty-four experiments, from which 



* Zeitsch. Physikal. Chem., 13, 398. 1894. 



