ABSTRACT

The source of the nitrogen is the protein constituents of the food, and a man on ordinary diet excretes on the average 30 to 35 grams per diem, almost entirely in the urine. By the transformation of ammonium cyanate, HN4.CNO, a salt which can be made from wholly inorganic materials, urea CO(NH2)2, was obtained by Wohler in 1828. As the formula indicates, this change is due to a mere rearrangement of the elements present in the molecule, without addition or subtraction of anything. Such a transformation is called in chemical language an isomeric change. The discovery of new remedies depends more and more on a combination of chemical and physiological knowledge. A large number of researches have been carried out on aromatic compounds containing the elements phosphorus, arsenic, and antimony, which in the periodic scheme are members of the same family as nitrogen.