546 APPENDIX. 



matters of the urine ;" of Virchow,* " On the pigments in the 

 urine ;" of Heller,t " On uroerythrin as a constituent of the urine 

 in diseases ;" and of Kletzinsky J " On uroglaucin, considered as 

 an oxide of indigo." G. E. D.J 



(55) Addition to p. 445, 2 lines from the bottom. The 

 volumetric method is on many accounts to be preferred to deter- 

 minations by weight, in the analysis of the urine. This method 

 has not only the advantage over weighing of being more rapidly 

 accomplished, which is especially desirable in the case of urine- 

 analyses, in which, for the most part, a large series of observations 

 are necessary for the attainment of reliable results, but it has the 

 further advantage of rendering all long-continued evaporation 

 unnecessary, and this is a great advantage, in consequence of the 

 decomposition of the urine, which this process always induces. 

 This method, after having been for a long time employed in 

 testing metals, has been adopted by Liebig in the analysis of the 

 organic juices. We have already considered in detail (vol. i, 

 p. 287) Fehling's method of determining the sugar in the urine. 

 The following method for determining the amount of phosphoric 

 acid in the urine was recommended to Breed by Liebig. A 

 solution of perchloride of iron, of definite strength, is added to 

 acid urine, or to urine which has been acidified with acetic acid, 

 until no more phosphate of iron is separated; the quantity of 

 phosphoric acid in the urine is then calculated from the volume of 

 the iron-solution which has been employed. The solution of the 

 perchloride of iron is prepared by dissolving 15'556 grammes of 

 iron in aqua regia, and then carefully evaporating the solution to 

 dryness in a water-bath, in order to remove the excess of free acid 

 without decomposing and volatilising any part of the perchloride 

 of iron. The residue is dissolved in 2000 c. c. of water ; 1 c.c. 

 of this solution will precipitate 0*010 of a gramme of phosphoric 

 acid (that is to say, 10 millegrammes). In the place of this solu- 

 tion we may employ one of undetermined concentration, the 

 strength of which may be tested by a solution of phosphate of 

 soda, whose amount of phosphoric acid has been previously deter- 

 mined. The solution of perchloride of iron must not, however, 

 contain any of the protochloride. In order to ascertain whether 



* Arch. f. pathol. Anat. Bd. 6, S. 259. 



t Arch. f. Chem. u. Mikrosk. 1C53, S. 361. 



Ibid. p. 414. 



Ann. d. Ch. n. Pharm. 13d. 78, S. 150. 



