Chemical Science, 429 



destroying the urea. The operation is easily practised by con- 

 tinuing to heat it until the disengagement of carbonate of ammonia 

 ceases, the residue then dissolved in boiling water, filtered, and 

 cooled, yields crystallized cyanic acid. The same end may be 

 obtained by dissolving the impure sublimate in hot nitric acid, which 

 destroys the urea, and on cooling the crystallized cyanic acid 14 

 obtained. *-'^ 



^ The urea may be obtained from the rough sublimate by means df 

 cold water ; the solution is to be evaporated, and the urea separated 

 by alcohol ; but the urea solutions always give crystalline grains 

 of cyanic acid, which substance is either very soluble in urea, or 

 forms some kind of combination with it. Repeated treatment with 

 alcohol is therefore required. Fourcroy and Vauquelin appear to 

 have observed this production of urea by the distillation of uric acid. 



Perhaps henceforward these transformations of the two essential 

 parts of urine, of urea into cyanic acid and carbonate of ammonia, 

 and of uric acid into urea and cyanic acid, may become remarkable 

 in a physiological point of view, and throw light upon certain dis- 

 eases, and on the irregular deposits of the urine ; in fact, it does 

 not appear very unlikely that when uric calculi are examined anew, 

 with great attention, concretions of cyanic acid may be formed; for 

 this acid, because of its insolubility and other resemblances with 

 uric acid, may very well form solid masses analogous to those of uric 

 acid. 



As a continuation of these researches, I have made some experi- 

 ments on the decomposition of cyanogen in water, especially to 

 observe whether, in this case, any cyanic acid or urea would be 

 formed. As water dissolves but little cyanogen, the same portion 

 was saturated with cyanogen, and decomposed twice in succession. 

 The liquor separated from a brown deposited substance, was yellow, 

 and being evaporated to the consistence of syrup, upon cooling 

 became a soft brown mass, of which one part dissolved in water, 

 whilst a yellow-brown residue remained. The solution being again 

 evaporated, there remained a crystalline mass, from which, either by 

 the action of alcohol or nitric acid, well-characterized urea could be 

 separated. - ■'•if' 



In this case the urea is formed from substances perfectly inorga- 

 nic, water and cyanogen ; probably cyanous acid and ammonia had 

 been produced in the course of the changes. The other substances 

 found at the same time were not examined, except to ascertain 

 they were not, and contained no cyanic acid. Two colourless crys- 

 tallizable substances appear to be formed at the same time, of which 

 one is a salt of ammonia. — Annalen derPhysik, xv. 619. — Annates 

 de Chimie, xliii. 64. 



"t6. Bromide of Carbon. Loewig.— This compound may be pre- 

 pared in two ways. Bromine is to be mixed with alcohol of spe- 

 cific gravity 0.887. As the former is added, the mixture heats, 

 and at last boils suddenly, evolving hydrobromic acid and free 

 APRIL— JUNB, 1830. 2 F 



