CHEMISTRY. 



23 



kinds of guano. The forniei- invariably gave nigJicr results than tlie 

 latter, the dift'ereuce ranging from 0.14 to .'5.1 1 per eent. It .sceiiis evi- 

 dent from these results that the guanin, urates, and similar nitrogenous 

 substances in guano are not decomposed by the dilute sodium solution 

 recommended for use in the distillation llaslc by HaselhofI". 



The determination of nitrogen in guano, E. Frank:] [Chem. Zf/j., 

 20 {1890)^ No, oojpp. oJi^'j, r,2G). — Comparative tests of the Jodljbauer and 

 Haselhotf extraction methods on 4 samj)les of Peruvian guano are 

 reported. The percentages of nitrogen found were as follows: 



Nitruijen in I'eruvian guano. 



The conclusion was reached that the soluble organic nitrogen in the 

 extract obtained in the Haselhoft' method is not comi)letely transformed 

 to ammonia by the action of the soda solution. 



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

 Ztg., 20 {18!)0), ¥o. S7,pp. 365, .?6Y;).— Tlie author states that the method 

 proposed by him has given better results in his laboratory than the 

 Jodlbauer method, and suggests that Franke's results were due to a 

 departure from his method. He reports the results of comparative 

 tests of the Jodlbauer and Haselhoflf methods made at his request by 

 Pfeiffer, which show a close agreement. 



The determination of nitrogen in guano, E. Franke {Chem. Ztg., 

 20 (1896), Xo. 13, p. i^^^).— Replying to the criticisms of Haselhoft", the 

 author claims that the organic nitrogen of Peruvian guano soluble in 

 water is not completely decomposed by soda solution. With th-e Ulsch- 

 Kjeldahl method, the ordinary Ulsch method, and the Ulsch method, 

 using 75 CO. instead of 20 cc. of soda solution, the author found in a 

 clear-water extract of guano 5.10, 3.30, and 3.84 per cent of nitrogen, 

 respectively. 



The works of Pfeifter and Thurman ^ are referred to as confirming the 

 author's conclusions. 



An investigation upon the use of Wagner's citrate method for 

 the determination of citrate-soluble phosphoric acid in ground 

 Thomas slag, F. Mack and M. Pa^^son {Ztschr. angcir. Chem., 1896, 

 No. 5, p. 129). — One hundred cubic centimeters of the phosphoric-acid 

 solution, obtained according to Wagner, is boiled in a 500 cc. llask, 

 with 10 cc. of concentrated sulphuric acid and a drop of mercury, as in 

 the Kjeldahl method for nitrogen, until the solution is colorless. After 

 cooling the mercury is precipitated by a 10 per cent solution of sodium 



' Landw. Vers. Stat., 46 (1895), pp. 1-20 (E. S. R., 7, p. 269). 



