370 Prof. J. A. MacWilliam. [Mar. 19, 



Meronro-potassic iodide = doubtful haze. 

 Salicyl-sulphonic acid = marked cloudiness. 



When the white of egg solution is diluted 400 times : 



Acidulation with acetic acid and heat = no reaction. 

 Xantho-proteic test = no reaction. 

 Heller's test = no reaction. 

 Mercuro-potassic iodide = no reaction. 

 Salicyl-sulphonic acid = distinct cloudiness. 



When the degree of dilution is increased to 600 or 620 times, t 

 is still a distinct reaction with salicyl-sulphonic acid when the 

 tube is compared with control tubes containing (a) the dil 

 solution alone, and (fe) water with salicyl-sulphonic acid. 



And even with still higher grades of dilution (900 and 1000 ti 

 there is still an appreciable effect recognisable a little time after 

 addition of the reagent. 



The amount of proteid present in those dilute solutions is ex 

 ingly small. 



Taking the percentage of proteid (albumin and globulin) in w! 

 of egg as 12'2, the strength of the original white of egg sola 

 (1 in 20) would be less than 1 in 160. 



When this solution is diluted 400 times, the proportion of pro 

 is less than 1 in 64,000 ; when diluted 620 times, about 1 in 100,i 

 and when diluted 1000 times, proteid is present only in the very 

 minute amount of 1 in 160,000. 



(6.) Serum Albumin. Solutions containing serum albumin were 

 obtained by saturating serum with magnesium sulphate and then 

 filtering so as to remove the globulin ; the filtrate contained the 

 serum albumin. This fluid, when tested with salicyl-sulphonic acid, 

 gave an abundant precipitate. 



Again, when the serum is deprived of all its proteids by complete 

 saturation with ammonium sulphate and subsequent filtration, it then 

 fails to give the slightest sign of precipitation on the addition of 

 salicyl-sulphonic acid. On the other hand, the proteid precipitate 

 thrown down by ammonium sulphate, when redissolved in water, 

 gives a dense precipitate with salicyl-sulphonic acid. 



Similarly, when serum is deprived of its proteids by means of 

 alcohol, the remaining constituents are entirely unable to give the 

 characteristic reaction with salicyl-sulphonic acid. 



The delicacy of the action of salicyl-sulphonic acid as a test for 

 minute amounts of the serum proteids is very striking, just as in the 

 case of the egg proteids. 



The following reactions will serve as an illustration of this : 



Some ox serum was diluted with per cent, of salt solution to 

 the extent of 1 part of serum in 1000 parts. 



