RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



Errors in manure sampling' and analysis, W. Frear {Froc. Soc. Prom. Agr. 

 Sci. 190,2, pp. 183-194). — The general plan of sampling employed "involved the 

 careful weighing of the entire mass of each manure, its immediate mixture, and 

 redut'tion by partings, with repeated mixing between successive partings, until 

 approximately aliquot jjortions of 50 to 75 lbs. each were obtained. Triplicate ali- 

 quots being taken, they were each finally subdivided, again mixed and parted, about 

 one-tifth to one-seventh of each triplicate l^eing reserved for analysis. Loss of weight 

 during handling was checked by frequent reweighings. 



"The weighings were made in a tared, metal-lined cask, having a cajmcity of 75 to 

 100 ]])s. This cask was frequently retared during the weighings to correct for slight 

 gains by small amounts of adherent matter, from which it was, however, kept as 

 free as possible by frequent cleaning. The average tare was judged to be correctly 

 represented by the average of the frequent tare weighings made. The scales employed 

 weighed to 7 gni." 



The analytical determinations, generally in triplicate, included: "(1) Nitrogen, 

 by the Konig method: Two hundred grams manure dissolved to a paste in 650 to 

 1,150 gni. of concentrated sulphuric acid, 10 to 20 gm. of the paste taken for determi- 

 nation by the ordinary Kjeldahl method; (2) nitrogen in air-dry substance: Immedi- 

 ately after air drying, later, as a check upon change in hygroscopic moisture; (3) 

 water-soluble nitrogen: One gram, washed on filter with 200 cc. of water, nitrogen 

 determined in insoluble residue; . . . (4) ammoniacal nitrogen: One gram dis- 

 tilled with 250 cc. of water and 5 gm. of suspended magnesia under 22 to 25 in. 

 vacuum for 30 to 45 minutes; . . . (5) hygroscopic moisture: Two grams in water- 

 oven to constant weight; (6) ash: Residue from 5 ignited at low red heat; (7) pot- 

 ash: In 10 gm. after carbonizing with sulphuric acid, by Lindo-Gladding method; (8) 

 water-soluble potash: In solution made from 10 gm., by boiling, Lindo-Gladding 

 method; (9) phosphoric acid: Five grams fused with sodium carbonate and potas- 

 sium nitrate, fusion analyzed by molybdate-magnesia mixture method; (10) matiere 

 noire: Ten grams treated as usual with weak hydrochloric acid followed, after wash- 

 ing, with 4 percent ammonia water; (11) potash and phosphoric acid, associated 

 with mature noire: In residues by Lindo-Gladding and fusion methods." 



The studies were made on 2 lots of manure. The losses of weight at the second 

 weighing were found to be 3.08 and 3.36 per cent, respectively; at the third weigh- 

 ing 4.6 and 7.98 per cent. "The large percentages of loss occurring during the thor- 

 ough mixing of the material declare strongly the need for expedition and care at 

 every other point to protect the manure from heat, wind, and large surface exposure 

 whereby volatilization might be increased; they further emphasize the need for 

 reweighing, at every parting, of the entire mass parted." 

 938 



