FERTILIZERS. 92U 



pered Husks stood at the temporatiire of tlie room 3 months. After 

 the lapse of this period of time the presence of ammonia m each of the 

 fhisks was proved by Nessler's reaj^ent. I^itroiis acid was not found. 

 For a quantitative estimation of the anunonia formed four series of 

 experiments were made: 



(1) Ten flasks were charged as follows: To 200 cc. of water, 30 gm. 

 of humus and 5 gm. of nitrate of potash were added. Each flask was 

 sterilized with steam at 100- in three operations (I hour on each of 3 

 successive days). The flasks were closed with a layer of cotton and 

 a cork stopper and sealed with wax. 



(2) Ten flasks were charged as before, but sterilized by the addition 

 of 0.4: gm. of corrosive sublimate. The stoppered flasks were sealed 

 withi^araffin. 



(3) Control experiments were made with two flasks containing 5 gm, 

 of nitrate of potash and 2(»0 cc. of water each, one sterilized, the 

 other not, and with three flasks containing 30 gm. of humus in 200 cc. 

 of water, one sterilized with steam, another with corrosive sul)limate, 

 th(^ third not sterilized. 



(4) Tests of the influence of caustic alkali, heating, air, and sand on 

 the amount of ammonia formed. 



Three Erlenmeyer flasks (large) received as much sand (washed and 

 ignited) as was required to absorb 200 cc. of water with 30 gm. of 

 humus and 5 gm. of nitrate of potash. The fourth flask received the 

 same amount of sand, 200 cc. of water, and 300 gm. of humus. The 

 first flask was sterilized with steam, the second with corrosive subli- 

 mate, and the third and fourth were not sterilized. All four flasks 

 were closed with rubber stoppers carrying glass tubes through which 

 air which had been drawn through sulphuric acid and cotton was passed 

 from time to time (10 minutes each day). 



In the fifth flask were placed 200 cc. of water, 30 gm. of humus, and 

 5 gm. of nitrate of potash, and 20 cc. of concentrated caustic soda. In 

 the sixth flask the usual mixture was placed: 200 cc. of water, 30 gm. 

 of hunuis. and .5 gm. of nitrate of potash. The flask was sterilized over 

 an hour and was immediately examined for anunonia. The seventh 

 flask was charged like the sixth, but was not sterilized. It was imme- 

 diately examined for anmionia. 



The determination of anunonia was made as follows: C)ne-h;ilf of 

 the liquid was placed in a distilling fiask. a concentrated solution of 

 caustic soda was added, and the mixtur(» distilled. The distillate was 

 collected in a standard solution of sidphuric acid and the excess of the 

 latt(>r titrated with caustic baryta. The indicator used was rosolic 

 acid. Jn some cases ammonia Avas determined colorimetrically by 

 means of Nessler's solution in ordei" to avoid the heating of the 

 mixture. 



The flasks of series 1 and 2 were examined after standinu' 3 months. 



