RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



The determination of nitrogen in guano, E. Haselhoff {Landic. 

 Verfi. *S7a/., 13 (ISfli), No. 3 and I, pp. 280-292). — The author presents 

 results of a number of determinations of the nitrogen in guano by 

 means of the Jodlbauer method, which appear to indicate that this 

 method is unreliable when applied to guano. As a check, ammonium 

 comjiounds and nitrntes were washed out of a second weighed portion 

 in each case, and the nitrogen in this extract determined by the Ulsch 

 method and in the residue by the Kjeldahl method. The results 

 obtained by this means were as a rule considerably higher than those 

 furnished by the Jodlbauer method, irrespective of the j)ercentage of 

 nitrate or moisture in the samples. 



On the constant error in the determination of nitrogen by 

 ■weighing the platinum obtained by igniting the ammonio-platinic 

 chlorid, L. L. de Koninck {Chem. Ztg.^ 18 {1894), No. 93, p. 181G).— 

 It is shown that in the determination of nitrogen by igniting the 

 ammouio-i)latinic chlorid and weighing the metallic platinum there is a 

 plus error of about one tenth per cent of the total found, due to the 

 difference in specific gravity of the original substance taken and the 

 platinum obtained. Thus in a substance actually containing 10 per cent 

 of nitrogen there will be found by this method 10.01 per cent, an error 

 Avhicli may be disregarded in ordinary analysis. 



On the determination of the value of phosphoric acid insoluble 

 in water, E. Wrampelmeyer {Landw. Vers. Stat., 45 {1894), No. 3 and 

 4, pp. 187-194). — The results of determinations of the availability of the 

 phosphoric acid in 24 samples of phosphates including different phos- 

 phorites, Kedonda phosphate, Thomas slag, ''prepared" phosphate, 

 pure iron and aluminum phosphates, etc., by means of Jensch's 5 per 

 cent citric acid solution, Schei bier's acid ammonium citrate (1 per cent 

 excess of acid), Petermaun's ammoniacal ammonium citrate (1 per cent 

 pxcess of ammonia)^ and H. von Liebig's acid oxalate of potash solu- 



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