402 Foreign and Miscellaneous Intelligence. 



and cooled, the oxalate of urea is deposited, from the solution, in white 

 crystals. These crystals are to be dissolved in boiling water, and 

 powdered carbonate of lime added until litmus paper is no longer 

 reddened by the fluid ; the precipitate, which consists of oxalate of 

 lime, is to be separated by the filter, and on evaporating the remain- 

 ing fluid, a white salt-like mass will be obtained, which is urea, con- 

 taining, however, in most cases, some oxalate of potash, soda, or 

 ammonia. The two first of these salts are derived either from the 

 oxalic acid or from the urine, when, to free the alcohol completely 

 from water, some potash or soda has been dissolved by it ; the oxalate 

 of ammonia comes from the ammoniacal salts in the urine which, at 

 the beginning of the process, were dissolved by the alcohol. On 

 boiling the crystallized mass with concentrated alcohol, the oxalates 

 are precipitated. 



The oxalate of urea has a sour taste, and forms dendritical crystals, 

 which, on being heated, melt and boil, giving out carbonate of am- 

 monia and cyanic acid ; the oxalic acid being decomposed into car* 

 bonic acid and carbonic oxide. They are very soluble in hot, but 

 much less in cold water ; at 60 F. 100 parts of water dissolve only 

 4.37 parts of the salt; if oxalic acid is added to the solution, part of 

 the dissolved urea is precipitated. Alcohol dissolves but very little 

 of it; 100 parts, of spec. grav. 0.833 and at 60 F., dissolve only 

 1.6 parts. According to Berzelius' analysis, it consists of 37.436 

 oxalic acid and 62.564 of urea, the oxygen in the latter being to that 

 of the former as two to three. It does not contain any water of 

 crystallization*. 



34. ON THE DISTILLATION OF NITRIC ACID. (By E. Mitscherlich.) 



During the decomposition of nitre by sulphuric acid, there are some 

 circumstances regarding the combination of the acid with the potash 

 of the nitre, which have hitherto been but little attended to. Of the 

 three compounds of sulphuric acid and potash with which we are 

 acquainted, the sulphate and bisulphate only require our consideration 

 with respect to the above process, the former of which is sufficiently 

 known ; the bisulphate contains twice as much acid as the sulphate ; 

 and water, the oxygen of which is to that of the acid as one to six ; this 

 water is very fixed, and is not even evolved during the fusion of the 

 salt at 392 F., but only when the salt itself is decomposed ; a pro- 

 perty which the latter has in common with the sulphate of the prot- 

 oxide of iron, and some other salts. It would accordingly, perhaps, 

 be better to consider the bisulphate of potash as a compound of 

 the hydrate of sulphuric acid and the sulphate of potash : it consists 

 of 58.80 sulphuric acid, 34.61 potash, and 6.59 water. 



If equal parts of the nitrate and the bisulphate of potash are distilled 

 with half a part of water, until the emission of red vapours begins, 

 which is the case at about 418 F., the water in the receiver will be 

 found to contain not more than 1 j per cent, acid of the nitrate em- 



* From Poggendorf's Annul, der Phys, uud Chemie. 





