Chemistry and Physics. 



in the form of a ten per cent solution in five per cent acetic acid. 

 For qualitative tests five or six drops of the reagent are added 

 to 5 or 6 ccm of the liquid to be tested, after the latter has 

 been acidified with a drop of dilute sulphuric acid. A white, 

 voluminous precipitate appears immediately when considerable 

 quantities of nitric acid are present, while with minute quantities 

 of the acid small, brilliant, needle-like crystals are slowly formed. 

 At ordinary temperature the reaction will detect one part of 

 nitric acid in 60,000 of water, and it is still more delicate at 0°. 

 Unfortunately, there are other acids which also give precipitates 

 with the reagent, and thus chlorates, perchlorates, bromides, 

 iodides, nitrites, chromates, sulphocyanides, ferro- and ferricy- 

 anides, picric acid, and oxalates interfere with the test. 



To make the quantitative determination, the substance (con- 

 taining about 0*1 g. of nitric acid) is dissolved in 80-100 ccra of 

 water, ten drops of dilute sulphuric acid are added, the liquid is 

 warmed nearly to boiling and 10-12 ccm of the previously men- 

 tioned solution of the reagent are added. The vessel is then 

 allowed to stand 1^-2 hours in ice-water, the precipitate is fil- 

 tered on a Grooch crucible and washed with a minimum quantity 

 of ice-cold water. The precipitate is dried at 110° for three- 

 quarters of an hour, and the calculation is made from the formula 

 C 20 H 16 N 4 • HN0 3 , which contains only about one-sixth of its 

 weight of HN0 3 . Numerous test analyses, some of them made 

 in the presence of NaCl, CuS0 4 , and AgN0 3 , show excellent 

 results. 



It appears probable that this method will find considerable 

 practical application, for heretofore there has been no method 

 for precipitating and weighing nitric acid. — Berichte, xxxviii, 

 861. h. l. w. 



3. The Unity of Thorium. — Several years ago Baskerville 

 announced that he had obtained fractions of thorium oxide show- 

 ing varying specific gravities, which led him to believe that 

 thorium was not a simple element ; and in 1904 he advanced the 

 view, based chiefly upon atomic weight determinations with dif- 

 ferent fractions obtained by volatilizing thorium chloride, that 

 thorium contained three elements, berzelium, thorium (new), 

 and carolinium, with atomic weights 212, 220, and 255, respec- 

 tively. 



R. J. Meyee and A. Gumpekz have made a critical study of 

 the volatilization of thorium chloride and of the atomic weight 

 determination in such fractions, but they have been unable to 

 find any evidence of the splitting up of our previously accepted 

 thorium. They show that the method of determining the equiva- 

 lent weight of thorium used by Baskerville was probably entirely 

 unreliable (and was one which Kriiss and Nilson, who have done 

 the best work on this atomic weight, were also unable to use). 

 They produced fractions of thorium chloride which should have 

 corresponded to the so-called berzelium, etc., and obtained, by an 

 accurate method of equivalent weight determination, perfectly 

 constant results. 



