618 EXPERIMENT STATION RECORD. 



The reactions which occur are as follows: 



K>S0 4 +BaCl 2 =BaS0 4 +2IvCl, 



BaCl 2 +K 2 Cr0 4 =BaCr0 4 +2KCl, 



4K 2 Cr0 4 +2As 2 :i +7K 2 S0 4 =3As..O,+2 Cr 2 (S0 4 ),+4H 2 S0 4 + 7H 2 0, 



4I+As 2 :! +2H 2 0=As.O,+4HI. 

 The solutions used are as follows: Crystallized barium chlorid 4.8 

 gin. per liter, crystallized potassium chromate 3.9 gm. per liter, arseni- 

 ous acid (dissolved iu 10 gm. of potash, afterwards slightly acidulating 

 with sulphuric acid) 4.95 gm. per liter. 



The volumetric estimation of phosphoric acid (New Jersey Stas. 

 Ept. 1896, pp. 118-121). — The results of comparisons of the official 

 method and of a modification of Kilgore's volumetric method 1 on 276 

 samples of complete fertilizers are reported. The volumetric method 

 used is described as follows: 



" Weigh 2 gm. of material into a porcelain crucible, evaporate ■with 3 cc. of mag- 

 nesium nitrate, ignite and dissolve in hydrochloric acid. To an aliquot part of 

 this solution (0.25 gm.) add 5 cc. of concentrated nitric acid, neutralize with ammo- 

 nia, and clear with a few drops of nitric acid. Heat on the water hath to 60 to 65° 

 C, add 50 cc. of freshly filtered molybdic solution for each decigram of phosphorus 

 anhyihid present, and digest at the same temperature for 15 to 20 minutes. 



"Decant the clear liquid on a filter as quickly as possible (a plain filter without 

 suction). Wash the precipitate by decantation twice with the nitric acid solution, 

 once with the potassium or ammonium nitrate solution, and transfer it to the filter 

 and wash with 150 cc. of cold water. Wash the precipitate with the filter into the 

 beaker, add an excess of the standard potassium hydroxid solution and a few drops 

 of the pheiiolphthalein solution, and titrate the excess of alkali by adding the 

 standard nitric acid solution until the color disappears. The number of cubic centi- 

 meters of alkali used, less the number of cubic centimeters of acid necessary to 

 neutralize the solution, is equal to the number of milligrams of pbosphorous anhy- 

 drid present." 



The reagents used were in all cases the same as those recommended 

 by Kilgore. The total percentage of phosphoric acid found by the 

 official and the volumetric methods tire tabulated. 



"The results secured were extremely satisfactory, the average results by the volu- 

 metric method being 10.72 per cent against 10.70 per cent by the official method. 

 Of these results, 150 were higher by the volumetric, 113 lower, and 13 identical with 

 the official method; the greatest variation was 0.16 per cent, and 114 samples varied 

 less than 0.05 per cent.'' 



A new method of estimating fat in animal substances (prelimi- 

 nary notice), E. Bog-danow (Arch. Physio]. [Pfluger], 68 (1897), No. 

 8-9, pp. 431-433). — It was found that when meat which had been extracted 

 with ether was boiled with alcohol considerable material was dissolved, 

 which on evaporating the alcohol was easily soluble in ether. By 

 extraction with ether alone 6.65 per cent of the total dry matter of a 

 sample of meat was removed. When a sample of the same meat was 

 treated with ether until practically as much fat as possible had been 

 removed and then boiled with alcohol, the alcohol evaporated and the 

 residue extracted with ether, a total amount of fat equaling 11.486 per 



'U.S. Dept. Agr., Division of Chemistry Bui. 46, p. 13; North Carolina Sta. Bui. 140 

 (E. S. R.,9, p. 416). 



