382 APPENDIX. 



On heatiiJg to 130-140° C. :— 



/NH2 yNHa yO-NH, a, 



C0< -H20 = C0/ CO/ -aHaOrrCO/^ 



\O-NH4 \nH2 \O-NH4 NNH, 



Carbamate of Aiiirnonia. Urea. Ammonium Carbonate. Urea. 



By heating with stroug mineral acids or alkalies : — 



/^^^ H O /O-NH4 



NNHa \O-NH4 



Urea. Carbonate of Ammonia. 



[Kmhenberg.\ 



CORRECTION "FOR TEMPERATURE AND PRESSURE 

 IN THE HYPOBROMITE METHOD (LESSON XIX.). 



Theoretically i gram of urea evolves 372.7 cubic centimetres of N, but in 

 practice it is found from urine that about 343 cc. are obtained. Suppose 25 cc. 

 of N passes over into the gas-collecting tube, and that the temperature of thQ 

 room (0= 10° C. and the barometric pressure 755 mm. Hg, what is the volume 

 at standard temperature and pressure ? 



Let V be the required volume at 0° C. and 760 mm. Hg ; v be the volume 

 read oflf ; P = pressure of 760 mm. Hg ; J9 the barometric pressure of the room ; 

 T the absolute temperature = -273° ; < = the temperature of the room (in 

 degrees Centigrade + 273) ; then 



_ 25X755X273 



^- 760x283 -'3-9S«e. 



Next to urea, uric acid is the most important substance present in urine 

 which is decomposed by hypobromite of sodium. It yields 47.7 per cent, of 

 its N. But as the quantity of uric acid present in urine is very small, for 

 practical purposes it may be neglected. 



CORRECTION FOR TEMPERATURE AND PRESSURE OF 

 THE VOLUME OF A GAS, e.^., THE GASES OF THE 

 BLOOD. 



The volume of a gas must be reduced to the standard pressure, 760 mm. of 

 Biercury, and standard temperature, 0° C, according to the formula : — 



76o(H-aO 



