402 Dr. A. E. Garrod. A Contribution to the Study [Apr. 



The final product represents but a small part of the yellow 

 present in the original specimen of urine,' conspicuous loss bei 

 entailed in the washing of the alcoholic extract, the washing 

 acetic ether, and especially in the precipitation with ether. 



I have not made any ultimate analysis of the product, since 

 an analysis would have little value without further guarantees of 1 

 purity of the product, and such guarantees could hardly be obtaii 

 in the case of a colloid substance such as this pigment is. A Ic 

 series of combustion analyses, if they yielded uniform results, woi 

 doubtless go far towards establishing its percentage composition, 

 in order to obtain the material required for such a series, very 

 amounts of urine would have to bo dealt with, and a correspond!] 

 large consumption of the materials employed in the extraction of 1 

 pigment would be involved. 



Properties of the Solid Pigment. 



In the solid state the product obtained by the above process 

 completely amorphous and brown in colour. It was so bygros 

 that it could not be completely dried in air, but in the exsiccator, 

 sulphuric acid, it lost its viscosity, and became quite hard. 



It dissolved in water with the greatest facility, readily in rectif 

 spirit, and much less readily in absolute alcohol. Acetic et 

 amylic alcohol, and acetone dissolved the pigment sparingly. 



The solubility of the product in alcohol appeared to undergo a pi 

 gressive diminution, through the successive stages of extraction, 

 after each evaporation of an alcoholic solution some of the pigmc 

 was apt to escape re-solution in alcohol. 



In pure ether, chloroform, and benzene it was quite insoluble, 

 mixtures of ether or chloroform with alcohol dissolved it to 

 extent. In its purest state the pigment was practically odour 

 when cold, but on the water-bath it softened and emitted a slij 

 urinons odour. 



Properties of Solutions of the Pigment. 



The solutions of the pigment in alcohol or in water reproduced 

 dilution the various shades of yellow and orange colour of not 

 urines. On concentration they passed through various shades 

 orange to a rich, warm brown. 



Blue litmus paper dipped into the solutions was slightly redder 

 and red litmus took a faint blue tint. 



When the solutions were placed before the spectroscope tl 

 showed no absorption bands, even on the addition of an acid, 

 blue end of the spectrum was absorbed, and the absorption 

 away so gradually towards the yellow, that even with concentrated i 



