88 



Mr. E. Scliimck on the Colouring and [Recess^ 



substance the colouring-matter of urine, though it must be evident to any 

 one reading his account that it was a product formed by the action of hy- 

 drochloric acid on the extractive matter, and essentially the same as that 

 previously obtained by Proust. Scherer submitted his substance to ana- 

 lysis, and found its composition to vary exceedingly. Hence it may be in- 

 ferred that it consisted of a mixture of two or more substances. In my ex- 

 periments on the brown colouring-matters formed by the action of acids, I 

 obtained, as mentioned above, bodies having the same external appearance 

 and general properties, but varying in composition. The latter corresponded 

 on one occasion with the formula C^^H^ NO^; on another occasion the ana- 

 lysis led to the formula C^g H^j NO^q. Now, on calculating the composition 

 of a mixture of equal parts of the two bodies having respectively these 

 formulae, it will be found to agree tolerably well with the mean of the two 

 first analyses given by Scherer, as will be seen on comparing his numbers 

 with the calculated composition according to the formula 



Calculation. Scherer, 



C 60-87 61-37 



H... 5-31 6-10 



N... 6-76 7-03 



O 27-06 2.5-50 



100-00 100-00 

 It does not appear that Scherer took the precaution of treating his pro- 

 duct with alcohol, in order to separate the easily soluble resinous matter 

 which is always formed together with the pulverulent body when the ex- 

 tractive matters are decomposed by acids. Unless this precaution is taken, 

 the product is sure to contain more than one substance, and its analysis 

 must give very discordant results. On one occasion Scherer obtained by 

 the direct action of hydrochloric acid on urine a dark-blue powder, which 

 when dry assumed a coppery lustre like indigo, and must, indeed, have been 

 indigo-blue itself. The formation of a blue colouring-matter by the action 

 of acids on some constituent' of urine had been observed by Heller only a 

 short time previously. Neither of these chemists, however, was aware of 

 its true character, which was not discovered until long afterwards. 



Harley * succeeded in separating Scherer's colouring-matter into several 

 substances, to only one of which, in his opinion, the colour of ordinary 

 urine is to be attributed. This, according to his description, is a resinous, 

 amorphous body of a fine red or brownish-red colour, insoluble in water, 

 but easily soluble in alcohol, ether, and caustic alkalies, to which he gave 

 the name of urohcematine. On being incinerated it leaves a little oxide of 

 iron, and hence Harley infers that it is allied to the hsematine of blood, of 

 which it is perhaps only a modification. By a process similar to that em- 

 ployed by Harley, Marcet f obtained from urine a resinous rose-coloured 

 Jom-nal fur praktische Cliemie, B. Ixiv. S. 26i. 

 t Bibl. Univ. de Geneve, 1852, p. 144. 



