RECENT WORK IN AGRICULTURAL SCIENCE. 



•CHEMISTRY. 



A digestion flask for obtaining the acid solution in soil 

 analysis, II. Snydeu {Minnesota ^Ui. Ept. 1H'J3, pp. 248-251, figs. 2). — 

 Digestion in porcelain beakers as proposed by Hilgard is open to Ibe 

 objection that the acid partly evaporates and consequently varies 

 somewhat in strengtli, and in using- the stoppered bottles recommended 

 by Kedzie "it is dithcult to obtain bottles that will stand so high a 

 pressure for so long a time, and it requires a very perfect-htting stop- 

 per to prevent any interchange between the hot solutions in the water 

 ])ath and the acid in the bottles." 



•'The flask [proposed by the author] has a capacity of 100 cc. The grouud-glass 

 stopper is iirovided with an exit tube that can be connected with a small glass tube 

 or a condenser. . . . 



■'A comjiact form of condenser can be made from a galvanized iron pail by perfo- 

 rating the bottom with holes a little larger than the glass tubes that are to be 

 inserted, and making the joints water-tight by means of rubber tubing. Long 

 glass tubes can be used without any condensing apparatus. A cover is also pro- 

 vided for the water bath with small openiugs to allow the condensing tubes to pass 

 through. 



"The soil is weighed direct into these digestion flasks, and the jiroper amount of 

 acid added. The flasks are then placed in the water bath and connected with the 

 condensers. At the end of the fourth day the solution and insoluble residue is 

 transferred to a casserole, and all of the remaining determinations are made in the 

 usual way." 



The results of comparisons of the three methods on soils of different 

 character are reported. 



"Under the same conditions the digestion flasks and the glass-stoppered bottles 

 give practically the same results, with the advantage as to rapidity and less lia- 

 bility of losses in favor of the digestion flasks. Both of the methods give higher 

 results for the potash and the alumina than the covered beaker. This is due to the 

 action of the acid upon tbe soils at a more uniform temperature and maintaining the 

 acid at its initial strength." 



A new gasometric method for determining nitrogen in nitrates, 



F. Gantter {Zfschr. analyt. Chem., 34 {1895), No. 1, p2>. 25-32, fu/. 1).— 

 The method is based upon the fects tbat (1) nitrates are reduced to 

 nitrites when heated in concentrated solution with phosphorous and 

 sulphuric acids, and (2) when nitrite solutions are heated with ammo- 



689 

 14467—^0. 8 2 



