188 DETERMINATION OF PROTEIDS OF BLOOD. [BOOK I. 



Determination of Water, Total Solids, and Salts of the Serum. 



As the processes are exactly similar to those mentioned at page 

 177, they require no further notice here. 



Determination of the total amount of Proteids contained in the Serum, 

 and of the Serum-albumin. 



Precipita- 5Q to 100 c.c. of water are boiled, and an accu- 



tionbyheat. ra tely weighed amount of serum (about 15 or 20 

 grammes) poured in. The fluid is boiled for some minutes, a drop 

 or two of very dilute acetic acid cautiously added with a glass rod, 

 until the precipitate separates in flakes from a perfectly clear (i.e. 

 not opalescent) liquid ; the precipitate is collected on a weighed 

 filter, washed with water, then with boiling alcohol, dried at 110 C. 

 and weighed. By this process all the proteids of the serum are 

 precipitated together ; by subtracting the weight of paraglobulin as 

 determined by other methods, that of serum-albumin is found. 



Precipita- a . Hop pe-Seyler's method \ 



tionby ^ n accura t e ly measured or weighed quantity of 



alcohol. rtn J . - i i i -,! ,1 



serum, say 20 grammes, is mixed in a beaker with three 



or four times its volume of spirits of wine, and set aside at the 

 ordinary temperature for some hours; the precipitate is then col- 

 lected on a weighed filter free from ash, and washed, first of all 

 with spirits, then with hot absolute alcohol, then with ether, and 

 lastly with warm water. 



There are thus left on the filter only proteids and insoluble salts. 

 The filter is washed with spirit so as to displace the water, and is 

 then dried at 120, allowed to cool in an exsiccator, weighed, &c. 

 The filter with its contents is then ignited, and the weight of ash 

 deducted from that of the proteids. This method is of universal 

 application to albuminous fluids, and is useful as it enables one to 

 obtain in one operation, not only the amount of proteids, but 

 alcoholic and ethereal extracts, in which other constituents may be 

 determined. 



6. Schmidt's method 2 . 



A weighed portion of serum is neutralized with acetic acid, mixed 

 with ten times its volume of strong alcohol, set aside for 24 hours, and 



1 Hoppe-Seyler, Handbuch der^physiologisch- und pathologisch-cliemisclien Analyse, 

 3 e Aufl., p. 312. 



2 A. Schmidt, "Weitere Untersuchungen des Blutserums, &c." Pfluger's Archiv, 

 Vol. xi. p. 10 (1876). This method has lately been subjected to examination by Prof. 

 F. A. Hoffmann of Dorpat, who found it reliable. (Virchow's Archiv, Nov. 1879, 

 p. 255.) 



