1891.] A New Test for Albumin and other Proteids. 



375 



such very dilute albuminous solutions does not clear up on boiling. 

 It remains persistent for days in the cold, the precipitate after a 

 time assuming the form of a marked cloud at the lower part of the 

 ?st-tube. 



The effect of adding salicyl-snlphonic acid to samples of albuminous 

 irine from which the albumin had been removed was tested in many 

 38, and always with negative results. The albumin was precipi- 

 ited by means of absolute alcohol (after acidulation, when necessary) 

 by saturation with ammonium sulphate. The proteid-free filtrate 

 ive not the slightest reaction in any instance when tested with 

 ilicyl-sulphonic acid in the usual way. 



The characteristic reaction of even minute amounts of albumin in 

 ic urine I found to be given, on the addition of salicyl-sulphonic 

 Did, in very numerous and various conditions in acid, neutral, and 

 Ikaline urine ; in urines rich in mucin, phosphates, urates, &c. ; in 

 les containing bile, sugar, and other abnormal constituents. My 

 ssults, obtained from the examination of a large number of samples 

 urine, have not indicated that the applicability of the test is com- 

 plicated or interfered with by any of the abnormal constituents 

 present. The urine of persons under the influence of various drugs 

 (e.g., alcohol, quinine, sulphonal, croton-chloral, iodide of potassium, 

 iloroform, salicylate of soda, strophanthus, &c.) has not shown the 

 lightest reaction with salicyl-sulphonic acid when shown to be free 

 albumin by other tests (after concentration) or when freed 

 >m albumin, if such has been present, by means of alcohol or 

 iinonium sulphate. 

 I have also examined the effect of salicyl-sulphonic acid upon 

 jlutions of various substances, many of which give precipitates with 

 Brtain of the well-known reagents for the detection of albumin in 

 pine solutions of strychnine, digitalin, morphia, nicotin, chloral 

 bydrate, atropine sulphate, aconitine, ergotin, caffein citrate, stroph- 

 ithin, sulphonal, gallic acid, quinine, bromide of potassium, copaiba, 

 3. and in no case have I seen any reaction at all resembling that 

 rielded by proteids. 



The conclusion to which my results up to the present lead is that 

 licyl-sulphonic acid is probably the most delicate and precise of all 

 lown reagents for the detection of proteids in solution. 



Note on the Nature of Salicyl-sulpTionic Acid. 



Salicyl-sulphonic acid is a whitish crystalline substance, readily 

 :>luble in water and in alcohol. On slow evaporation of its aqueous 

 jlution, it crystallises in long, thin needles. 



Its formula and formation are stated in Beilstein's ' Handbuch d. 

 rg. Chemie,' 2nd ed., vol. 2, p. 969. (For this reference I am in- 



VOL. XLIX. 2 c 



