24 



The uranium solution is made of such strength that 1 c.c. = 

 0.005 gr. phosphoric anhydride. As regards the composition of 

 milk ashes, we refer to page 8. 



For a complete analj'sis of the ashes, not less than 500 c.c. of 

 milk should be taken. For the method of analysis to be pursued, 

 we refer to Fresenius, Quantitative Analysis. 



Coagulation and Determination of Albu- 

 minates and Fats. 



In the method until now commonly used, the coagulation was 

 effected by acetic acid or carbonic anhydride. This method orig- 

 inates with Hoppe-Seyler, but gives inaccurate results, as has been 

 proved by the investigations of Liebermann, Manetti, Musso, 

 V. Nencki, and the author (see Kritik der Verschiedenen Methoden 

 zur Bestimmung der Albuminate und Fette, Fresenius'' Zeitschrift, 

 1880, and YeiQvs&n^KForsehungen, 1879, 7, 301. 



A very reliable and quick method is Ritthausen's, who proposes 

 to effect the precipitation of the albuminates and fats by means of 

 sulphate of copper solution. From a neutral or slightly acid solu- 

 tion, the coagulation is easily effected in the cold. The accuracy 

 of the method has been veriiied by a long series of examinations 

 of milk in which it has been employed. 



Eitthausen proposes to dissolve 63.5 grs. pure sulphate of cop- 

 per in crystals to 1 liter. 10 c.c. of this solution contain 0.2 gr. 

 CuO. A second solution contains 50 grs. caustic potash in 1 liter 

 of water. Its specific gravity is 1.048. Author uses the same 

 solutions, but has modified Ritthausen's method by using a smaller 

 quantity of sulphate of copper. 



The coagulation is carried out as follows : 10 c.c. milk are 

 weighed in a beaker covered with a watch-glass, and then diluted 

 with 100 c.c. water. After mixing well, the solution of sulphate 

 of copper is gradually added until the precipitate settles well, 

 while the liquid becomes perfectly clear. For this 2.5 to 3 c.c. of 

 copper solution are required, while Ritthausen uses 5 c.c. 



Then potash solution is added to decompose the excessive 

 quantity of cupric sulphate. For this, one-half the volume of the 

 copper solution is required. The coagulated albumen enclosing 



