sale of the mercuric thiocyanate Pharaoh's Serpents,1 with which many of us amused ourselves as children, is now forbidden by law in several of the states, for the vapors from these toys are poisonous, and, more serious, children have been

No abstract

Nitrourea might be expected to dearrange1 in two modes to form on the one hand (1) nitroamide and cyanic acid, and on the other (2) ammonia and nitrocyanic acid. The nitro group would promote the dearrangement and the molecule would fall apart more readily than does the molecule of urea.We have found abundant proof of dearrangement of the first sort, but only meager evidence for that of the second. We have isolated nitroamide and cyanic acid from solutions of nitrourea and have prepared nitrourea by the combination of nitroamide with cyanic acid. Since nitrourea dissolved in water dearranges in part into nitroamide and cyanic acid, and since nitroamide decomposes into nitrous oxide and water, it follows that an aqueous solution of one equivalent of nitrourea may be used, with great advantage, for purposes of synthesis as if it were a solution of one equivalent of cyanic acid itself.Nitrourea decomposes on melting with the evolution of gas and yields a sublimate and a solid residue. The gases consist of water, nitrous oxide, cyanic acid, carbon dioxide and ammonia, and the solid materials of monoammonium cyanurate along with small quantities of ammelide, urea and biuret. These are the products which would be expected from the predicted dearrangements. The nitroamide breaks down into water and nitrous oxide. The cyanic acid in part escapes as such, in part combines with ammonia to form urea and in part polymerizes to form cyanuric acid, which combines with a portion of the ammonia to form ammonium cyanurate-and the latter substance by loss of water yields ammelide. Although nitrocyanic acid, OjN-NCO, is not a known substance, it would, from analogy with known nitramines, be expected to decompose into nitrous oxide and carbon dioxide. The presence of ammonia and of carbon dioxide in the products of the decomposition of nitrourea by heat suggests strongly that this substance does dearrange into nitrocyanic acid and ammonia, but constitutes the only real evidence which we have found on that point. The presence of biuret might perhaps be explained by supposing that it is formed, as Werner2 supposes it to be formed in aqueous solution, by the combination of cyanic acid with urea.We have found that 1 Cf. (a) Davis and Underwood,

Nitrourea dearranges into cyanic acid and nitroamide. It has been prepared from these two substances, and they have been prepared from it.The products from the decomposition of nitrourea by heat are those which would be expected from the two possible modes of its dearrangement.Nitrous oxide and cyanic acid are produced quantitatively when nitrourea is heated with water.A solution of nitrourea in coned, sulfuric acid contains nitroamide and may be used as a reagent for nitrations.Alkalies promote the decomposition of nitrourea; acids hinder it. A very slight alkalinity in the presence of a trace of moisture is sufficient to cause its spontaneous decomposition.An aqueous solution of nitrourea, being a source of cyanic acid, reacts with ammonia and with primary and secondary amines to form urea and substituted ureas.The yields are excellent, the manipulation is simple and the other products of the reaction are gaseous. The method is especially advantageous for the preparation of those substituted ureas which cannot be heated in water without decomposition. A number of urea derivatives, a few of them new, have been prepared by this method., -Di-n-propylbiuret and co-n-propyl-co-phenylbiuret have been obtainedas by-products in the preparation of urea derivatives from nitrourea and the corresponding amines.Moist alcohols react with nitrourea to produce carbamic and allophanic esters. Cambridge, Massachusetts

is determined in the first stage, the variation in P arises in the second stage. Thus they propose the preceding mechanism for catalyzed esterification.