8 



rapid work, those adopted by the Association of Official Agricultural 

 Chemists. Inasmuch as many who will receive this bulletin do not 

 have access to these methods, they are given below : 



PREPARATION OF THE SAMPLES. 



Samples of cereals are ground in a small mill until they pass a sieve with a half- 

 millimeter mesh. 



DETERMINATION OF MOISTURE. 



Two grams of the substance in a flat-bottomed aluminum dish are dried for five 

 hours at the temperature of boiling water. Experience has shown that after this 

 time no further loss of weight takes place. 



DETERMINATION OF ASH. 



Char from 2 to 3 grams of the substance and burn to whiteness at the lowest pos- 

 sible red heat. If a white ash can not be obtained in this manner, exhaust the 

 charred mass with water; collect the insoluble residue on a filter, burn, add this ash 

 to the residue from the evaporation of the above aqueous extract, and heat the whole 

 to a low redness till the ash is white. 



DETERMINATION OF ETHER EXTRACT. 



Extract from 2 to 3 grains of the substance dried as for the determination of the 

 moisture, with anhydrous and alcohol-free ether, for sixteen hours. Dry the extract, 

 by exposure to the full heat of boiling water, to constant weight. 



ALTERNATE METHOD FOR ETHER EXTRACT. 



In determining hygroscopic water, as above, continue the drying until the loss of 

 weight in thirty minutes is reduced to 1 milligram or less; extract the dried sub- 

 stance for sixteen hours as directed, dry again, and give loss of weight as ether 

 extract. 



Anhydrous ether. To prepare the anhydrous alcohol-free ether required for estima- 

 tion of fat, take any of the commercial brands of ether, wash with two or three 

 successive portions of distilled water, add sticks of solid caustic soda or potash 

 until most of the water has been abstracted from the ether. Carefully cleaned 

 metallic sodium, cut into small pieces, is now added until there is no further evolu- 

 tion of hydrogen gas. The ether thus dehydrated must be kept over metallic sodium, 

 and should be only lightly stoppered in order to allow any accumulating hydrogen 

 gas to escape; and it may be drawn off with a pipette as required. 



ESTIMATION OF NITROGEN. 



REAGENTS. 



(1) Acid. (a) Standard hydrochloric acid, the absolute strength of which has 

 been determined by precipitating with silver nitrate and weighing the silver chlorid, 

 as follows : 



To any convenient quantity of the acid to be standardized add a solution of silver 

 nitrate in slight excess and then 2 c. c. of pure nitric acid of 1.2 sp. gr. ; heat to the 

 boiling point, and keep at this temperature for some minutes, but without violent 

 ebullition, and with constant stirring, until the precipitate assumes the granular 

 form. Allow to cool somewhat, and then pass the fluid through the asbestus. Wash 

 the precipitate by decantation, with 200 c. c. of very hot water, to which have been 

 added 8 c. c. nitric acid and 2 c. c. dilute solution of silver nitrate containing 1 



