591.] A Neiv Test for Albumin and other Proteids. 



When a similar solution is made with white of egg and the proteid 

 loved by thorough saturation with ammonium sulphate (after slight 

 cidulation) and nitration, the proteid-free filtrate gives no precipitate 

 rith salicyl-sulphonic acid. But if some of the precipitate thrown 

 lown by the ammonium sulphate, after being washed with a 

 saturated solution of the salt, be redissolved in water, the solution 

 proteid so made gives a copious precipitate when tested as before, 

 considerable amounts of ammonium or magnesium sulphate 

 present, a few crystals may form and sink to the bottom of the 

 3, apart from the presence of any albumin. This, however, does 

 at all interfere with the working of the test, as such crystals, 

 iting in the fluid at first and then sinking to the bottom, bear no 

 semblance to the uniform turbidity or opalescence dependent on the 

 jsence of albumin. These salts are easily removed by dialysis.) 

 Similarly, when the white of egg solution is treated with a large 

 3ss of absolute alcohol (after slight acidulation with acetic acid), 

 as to precipitate all the proteids, and is then filtered, the filtrate 

 aws no precipitate when tested with salicyl-sulphonic acid ; re- 

 )val of the alcohol from the filtrate does not influence the result. 

 . the other hand, the alcoholic precipitate, when (after being washed 

 rith absolute alcohol) it is redissolved in water and tested, gives 

 striking reaction : a large amount of proteid is at once thrown 

 3wn. 



With very dilute solutions made with white of egg, I have com- 

 the delicacy of the action of salicyl-snlphonic acid as a test for 

 )teids with a number of other reagents more or less commonly 

 iployed, and I have found the former to be by far the most delicate 

 id precise of all. 



The white of egg solution was successively, diluted to various 

 3es 1 part of the white of egg solution (1 in 20) in 100, 200, 

 ), 400, 600, 620, 900, and 1000 parts of water or of f per cent, sodic 

 loride solution. 



With the first degree of dilution (1 part of the 1 in 20 white of 

 solution in 100 parts of water or salt solution) the following re- 

 Its were obtained : 



Boiling after faint acidulation with acetic acid = no reaction. 

 Xantho-proteic test = slight reaction. 

 The cold nitric acid test (Heller's) = slight reaction. 

 Mercuro-potassic iodide = haziness of the fluid. 

 Salicyl-sulphonic acid = marked cloudiness. 



With the second degree of dilution (1 part of the white of egg 

 lution in 200 parts of water) : 



Boiling after faint acidulation with acetic acid = no reaction. 

 Xantho-proteic test = no reaction. 



