Outlines of the clinical chemistry of urine / by C.A. Mac Munn.

  • Macmunn, Charles A., 1852-1911.
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: Outlines of the clinical chemistry of urine / by C.A. Mac Munn. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

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    white needles (Fig. 7, h). It was prepared synthetically in 1828 by Wohler from ammonium cyanate—CN.ONH^. When this is heated to 100° C. the atoms rearrange them- selves and form urea thus : — CN.ONH^ = CO(NH2)2. Urea may also be prepared by the action of ammonia on carbonyl chloride, thus :— GOCI2 + 4 NH3 = CO(NH2)2 + 2NH4CI ;* and by other methods. By taking up water it is readily changed into carbonate of ammonia, as occurs under the influence of a ferment. Urea is recognized readily by the characteristic Fig. 8.—Crystals of Nitrate and Oxalate of VvcKX.—[Frey.) a a, Nitrate of urea, h b, Oxalate of urea. crystals which it gives when treated with nitric and oxalic acid (Fig. 8), as it then forms nitrate (0ON2H4,NO3H) and oxalate [(CO]Sr2Hj2C2H20, + H2O] of urea respec- tively. It also can be made to give the biuret reaction, a property which it shares with the peptones. Thus, if crystallized urea be kept in a combustion tube over a small flame for a long time in the melted state, and the melted mass, after the tube is cold, be dissolved in water, the solu- * See Strecker-Wislicenus : Organic Chemistry, Eng. trans, p 92 • or the Appendix to Foster's Physiology. D