523 



the flask cooled, tilled to the quarter-liter mark with aleohol, and the 

 solution shaken, in which operation concentration takes place. The 

 flask is again tilled to the mark with alcohol, the solution shaken, and 

 liltered alter half an hour. One hundred c. c. of the tiltrate (= 0.4 

 4;r;inis substance) are heated in a [)latinuni dish until tlus alcohol is 

 evai)orated, and the alcuhol-free solution heated to boiling' in a beaker 

 with 50 c. c. Avater. Ammonia is added until the solution is alkaline 

 (but not during boiling), the excess of ammonia driven off by heat, the 

 solution cooled and Altered, the Alter washed with warm water, and 

 the remaining phosphates of iron and alumina ignited and weighed. 

 Half of the weight is assumed to be Fe203+Al:j03. The operation 

 requires li to 2 hours. 



For determining the tiueness of Thomas slag, 50 grams of slag are to 

 be shaken iu a sieve not less than 20 cm. in diameter, made of wire 

 cloth, No. 100, Amandus Kahl, Hamburg. 



The loss by heating 10 grams of superphosphate for 3 hours at 100° 

 C. is taken as representing moisture. 



In estimating the total phosphoric acid in bone meal, tish guano, 

 animal fertilizers, crude phosphates, and super])hosphates, 5 grams of 

 the sample are to be dissolved in 50 c. c. aqua retjia composed of 3 ])arts 

 HCl sp. gr. 1.12 and 1 part HJSTO^ sp. gr. 1.25, or heated for one half 

 hour with 20 c. c. HNO3 sp. gr. 1.42 and 50 c. c. H2SO4 sp. gr. 1.8. 



Fertilizers containing nitro;jen. — The nitrogen iu blood, ground meat, 

 and similar organic materials may be determined according to the 

 Kjeldahl, or the soda-lime method. For determining the nitrogen as 

 nitrate iu mixtures, the method of Schlosing, Graudeau, or Lunge 

 maybe used, and the total nitrogen determined according to the Kjel- 

 dahl Jodlbauer method or a similar one. This latter method is to be 

 used iu case of Peruvian guano. With saltpeter a direct method is to 

 be used. The total nitrogen in commercial ammonia salts is to be esti- 

 mated by distilling with sodium hydrate solution. 



ANALYSIS 01' FEEDING STUFFS. 



i^af.— Ether, free from alcohol and water, is to be used in fat deter- 

 minations; the extraction is to be complete, and the weighed ether 

 extract must be soluble without residue in water-free ether. It is recom- 

 mended to make studies of the amount of free acids in the ether extract 

 as obtained by hot and cold extraction. For this the acids are to be 

 dissolved iu alcohol, the solution neutralized with normal soda solu- 

 tion as given by Fresenius, using phenolphthalein as indicator, and the 

 results calculated for oleic acid (1 c. c. tenth-normal soda solution^ 

 0.0282 grams oleic acid). A study of the value of the iodine number iu 

 fodder analysis is also recommended. 



The relative money values for protein, fat, and carbohydrates were 

 fixed for the present at 3 : 2 : 1. 



