CHEMISTRY. 855 



the use of phosplio-wolfrainic ackl as ii i)iecii)itant for the albuminoids 

 is prefeired. 



The author suggests the following methods for the (luantitative 

 determiuation of wheat j)roteids : 



"Tutal nitrogen. — The Guuuiug luodilicatiou of the Kjeldahl mt-thod has lu^en used 

 throughout this work. More eoucordaut results have been i)ljtaiue<l with 1 gra. of 

 material thau with 2 gni. 



''Xon-ylittiii nitrogen. — Put 5 giu. of the material to bo cxamiucd into a 1'50 cc. 

 measuring liask. Add about 15 cc. of a 1 per cent solution of sodium thlorid aud 

 shako thoroughly. To tho resulting homogeneous mass add enough of the same 

 solution to till the tlask nearly to the neck. Shako the contents of tho tlask at inter- 

 vals of 10 minutes during 1 hour. Fill to the mark with salt solution, mix thoroughly, 

 aud let stand for 2 hours. Decant the liquid onto a 12| cm. dry filter of good ([ual- 

 ity, leaving the greater bulk of tho solid material in the flask. Tho filtrate will bo 

 clouded, but if refiltered through tho same filter into a clean flask it will generally 

 be perfectly clear. Determine the uitrogen iu 50 cc. of this extract. From the per- 

 centage of uitrogeu thus obtained subtract 0.27 per cent as corresponding to the 

 nitrogen obtained from the gliadiu soluble iu 1 per cent salt solution under tho con- 

 ditions ]ireseribed above. The remaining percentage of uitrogen is that eorrespond- 

 iug to the non-gluten nitrogen iu tho sample examined. 



"Gluten nitrogen. — This is the difieronce between total nitrogen and the uou-gluteu 

 nitrogen as obtained above. The gluten uitrogeu may also be found by subtracting 

 tlie sum of the edestin, leucosiu, aud amid nitrogen from the percentage of total 

 uitrogeu. 



"Edetitin and lencosin nitrogen. — To 50 cc. of the clear salt extract, obtained as 

 described above, add, iu a Kjeldahl digestion flask of 500 cc. cajiaeity, 250 cc. of 

 pure 94 per cent alcohol (188 per cent proof, redistilled). Mix thoroughlj'^ and allow 

 to stand over night. Collect tho precipitate on a filter (10 cm.) of good quality, 

 return to the flask, and determine the nitrogen, making proper correction for the 

 uitrogen in the filter. 



"If desired, these two jnoteids may bo separated by coagulating the leucosin at 

 60- C. and precipitating tho edestin by adding alcohol to 50 cc. of the clear filtrate 

 as before. The uitrogen iu each precipitate may then be determined. 



"Amid nitrogen. — Precipitate all proteids from 100 cc. of the clear salt extract 

 obtained as aboA o by adding 10 cc. of a 10 per cent solution of phospho-wolframic 

 acid, made by dissolving the pure solid in distilled water. Allow to settle before 

 filtering and determine the nitrogen in the char filtrate. . . . 



"[After] adding 20 cc. of concentrated sulphuric acid the water can be readily 

 boiled ofi", especially if tho flask bo protected from tho naked flame with a thin 

 sheet of asbcstus. When tho acid ceases to foam it is cooled slightly, sulphate of 

 potash added, and the nitrogen deteruuuation completed iu the usual way. After 

 adding the sulphate the time rctiuired for the digestion is but a few minutes. . 



"The difference between tho nitrogen found and tho total nitrogen of the sample 

 gives the amount of albuminoid nitrogen with eciual accuracy [to that separated 

 by means of cupric hydrate]. . . . 



"In case of bran, and perhaps immature or sprouted wheat, it may be necessary 

 to add a somewhat larger (|uantity of tho [phospho-wolframic] acid solution to pro- 

 duce complete precipitation of the proteids. In such cases tho filtrate should he 

 tested by tho addition of a few cubic centimeters of the acid. 



"(ilimlin nitrogen.— Kxtnu-t 1 gni. of tho material with hot 75 per cent alcohol. 

 [The material with 100 cc. of tho alcohol is heated on :\ water batli just ))elow the 

 boiling point of the alcohol, being frequently shaken during tho first hoiu- and 

 allowed to remain <|uiet during the succeeding hour, after which the hot solution is 

 decanted through a filter, 25 cc of hot alcolud added to the residue, healed on tho 

 bath lor 10 minutes, and filtered. Tho latter o])eratiou is repeated six times. The 



