THE FIXATION OF NITROGEN IN FAECES. 



By eric HANNAFORD RICHARDS. 



{Rothamsted Experimental Station.) 



In the course of a general study of the chemical changes taking 

 place in the manure heap, a number of experiments were made with the 

 object of determining the loss of nitrogen during the aerobic fermenta- 

 tion of urine, straw and faeces, both separately and in various com- 

 binations. In the very first experiment with faeces, however, instead 

 of finding a loss of nitrogen, appreciable gains were recorded, and this 

 opened the enquiry which forms the subject of the present paper. In 

 all the experiments a current of washed air was drawn for several hours 

 daily through the flasks containing the substance under examination, 

 any ammonia volatilized being retained by N/10 sulphuric acid. At 

 the end of the experiment the total nitrogen left in the fermented 

 substance, added to any nitrogen recovered in the wash flasks, was 

 compared with the original total nitrogen. 



The method of preparing the faeces for experiment was as follows. 

 A sample of about 500 grams is taken from a pailful of the droppings 

 and passed through a mincing machine. A fairly homogeneous pro- 

 duct is then obtained from which suitable portions can be readily weighed 

 out as required. In order to avoid loss of moisture, the prepared sample 

 is kept covered, except when actually taking sub-samples. In practice, 

 with reasonable speed, no difficulty is experienced on this account. 



A suitable amount of substance is weighed out in the Kjeldahl flask 

 direct, the latter being held to the hook of the balance by a wire loop. 

 In the case of horse faeces there is no difficulty in weighing out exactly 

 5 or 10 grams if so desired, but with bullock and cow faeces this is 

 impossible, and the approximate amount required is dropped into the 

 flask and weighed by differences. With cow faeces it is desirable to 

 place a glass or paper tube in the neck of the flask when introducing 

 the substance, thus avoiding the smearing of the neck and sides. The 



