Chemistry, inorganic and organic : with experiments and a comparison of equivalent and molecular formulæ / by Charles Loudon Bloxam.
- Charles Bloxam
- Date:
- 1867
Licence: Public Domain Mark
Credit: Chemistry, inorganic and organic : with experiments and a comparison of equivalent and molecular formulæ / by Charles Loudon Bloxam. Source: Wellcome Collection.
649/748 page 621
![winch Is now extensively used for the preparation of the murexide employed in calico-printing. The excrements of the boa-constrictor and of birds, which consist almost entirely of acid urate of ammonia, and guano, which has been formed by the partial decomposition of the excrements of sea-birds, are excellent som-ces of uric acid. The separation of the uric acid from acid urate of ammonia is easily effected by dissolving it in solution of potash, filter- ing, and adding hydrochloric acid, when the uric acid, wliich requires 10,000 pai-ts of cold water to dissolve it, is precipitated as a white crystalline powder. When a solution of potash is saturated with uric acid in the cold, and boiled down out of contact with air, small needle-like crystals are deposited, having the composition 2K0 . CigH^ISr^O^, and if this be dissolved ia water, and carbonic acid be passed through the solution, half the potash is re- moved as carbonate, and a granidar precipitate of acid urate of potash, KO. HO. CiuH.,]Sr^04, is deposited. Uric acid, therefore, is a bibasic acid, and the formula of the acid itself (G.^HJ^fi,) should be written 2H0. Ci^HaNp^. When uric acid is added by degrees to strong nitric acid, it dissolves with effervescence and evolution of heat; the solution, on cooUng, deposits octahedral crystals of a substance called alloxan (CgH^N^Og), which may be represented as formed by the oxidation of the uric acid according to the following equation— C,„H,N,0, + HO. NO, = C,H,N,08 + 2C0, + -t- NH,. Uric acid. Alloxan. Alloxan has the curious property of staining the fingers of a beautiful pink colour, and its solution gives an intense purple colour with sulphate of ii-on. A connexion is estabhshed, by means of alloxan, between uric acid and urea, which becomes important, because these two bodies, accompanied by a smaU quantity of alloxan, are always found together in the urine. Alloxan appears to be the intermediate stage in the conversion of uric acid into urea by oxidation, for if a solution of alloxan be boiled with peroxide of lead (PbO^) carbonic acid is evolved, and the alloxan is con- verted into urea by oxidation— CgH^N.Og + 2H0 + 4PbO, = C,H,N,0, + 6C0, + 4PbO. Alloxan. Urea. When sulphuretted hydrogen is passed through a solution of alloxan, the hquid is troubled by the separation of sulphur, and deposits prismatic crystals of alloxantine (C^^^fi^^), which is derived fi-omtwo equivalents of alloxan by the removal of two equivalents of oxygen— 2C3H,N,03 + 2HS = C,„HAOu + 2H0 + S,. Alloxan. Alloxantine. If 4 grains of alloxantine and 7 grains of crystallised alloxan be dissolved in half an ounce of hot water, and 80 grains of a cold saturated solution of carbonate of ammonia added, the carbonic acid is disengaged with effervescence, and the liquid assumes a brilliant purple colour, depositing as it cools splendid crystals, which have a red colour by transmitted light, and reflect a play of green and gold, like the wing of the sun-beetle. This magnificent substance is known as murexide, and appears to be formed according to the following equation— C.JIAOu + C,H,N,0« + imi, = C,,H,2N,„0,„ + 6H0. AUoxantine. Alloxan. Murexlilc.](https://iiif.wellcomecollection.org/image/b21496602_0649.jp2/full/800%2C/0/default.jpg)
