522 THE POPULAR SCIENCE MONTHLY. 



oxygen and the hydrogen may be removed from the ammonium car- 

 bonate, the simplest answer will be that the hydrogen is removed by 

 oxidation and the oxygen by reduction. Experiment has confirmed 

 my expectations. If an aqueous solution of ammonium carbonate is 

 submitted to electrolysis, reversing the current and employing plati- 

 num or graphite electrodes, small quantities of urea are formed, which 

 may be isolated and identified as such with certainty. By the evolu- 

 tion of hydrogen and oxygen, alternately at short intervals, the hydro- 

 gen is removed by oxygen, and the oxygen is eliminated by hydrogen, 

 and urea remains. 



Since both oxidation and reduction are continually taking place in 

 the body, the solution of the question how urea is formed is given, 

 viz., from the ammonium carbonate which is first formed it is pro- 

 duced by further oxidation and reduction. 



Here we have urea produced without the body, under conditions 

 which may be assumed to exist within ; above all, the temperatures 

 were such as are noted in animals. For this reason this synthesis is 

 particularly adapted to show an acceptable process of the formation 

 of urea in the organism. The question, by what means the organism 

 effects the oxidations and reductions, whether electrolytically or chem- 

 ically, of course, remains unanswered, but this will also be solved as 

 soon as the processes taking place in the animal system are better 

 known. 



This synthesis also distinctly shows what developments physiology 

 is to expect from pure chemistry. The experiments made on animals, 

 by which the conversion of ammonia into urea in the organism was 

 first established, did not teach a single fact which would have indi- 

 cated that this conversion is the result of two directly opposite proc- 

 esses. This supposition was arrived at, independently of the experi- 

 ments with animals, by purely chemical considerations, and it was 

 simply necessary to furnish the experimental evidence of their correct- 

 ness. In this, as in all similar cases, the physiological experiment will 

 disclose the occurrence of synthesis and decompositions ; and it will 

 be the province of pure chemistry to discover the ways and means by 

 which the organism produces the results. Both physiological and 

 chemical experiments will have to be jointly and yet independently 

 made, if the chemistry of the living organism is to be established. 



Though we must confess that our knowledge of the chemical proc- 

 esses in the animal body is still very incomplete, we must recognize 

 that the investigations made in this direction have given us much 

 information. Though the substances which react on each other are 

 known in the fewest cases, we have obtained hints regarding the man- 

 ner in which they react. It has been shown why we are obliged to 

 assume that oxidation takes place. We are also acquainted with proc- 

 esses which indicate reduction, others in which decomposition takes 

 place with the assimilation of water, or synthesis with the elimination 



