CONVENTION OF OFFICIAL AGRICtJLTUEAL CHEMISTS. 431 



prescribed for detenuining caKeiu in milk, (b) AVe beat 10 giii. of milk diluted with 

 90 eo. (if water to -10° C. for 15 or 20 minutes, filter the preci])itate formed, and wash 

 with distilled water. The precipitate is tlien transferred to a small Erlenmeyer 

 flask, provided with a stopper, treated with 100 cc. of a 5 per cent solution of sodium 

 chlorid, and heated at 55° C. for 2 hours, with frequent agitation. The mixture is 

 then filtered, the remaining precipitate washed with water, and the nitrogen deter- 

 mine<i in both the precipitate and filtrate. The nitrogen in the precipitate represents 

 casein dilactate; that in the filtrate, casein monolactate. The sum of these two, sub- 

 tracted from the total nitrogen found by precipitation with acid, gives the amount of 

 nitrogen as casein. 



Report of associate referee on meat proteids, W. D. Bigelow. — Data are given 

 for the earlier work of the associate referee and R. Harcourt, heretofore published 

 only in part, and studies made during the year by the associate referee and F. C. 

 Cook are reported. Solutions were made of commercial i^roducts, including meat 

 extracts, beef juice, digested meat powder, and commercial x^eptones, and aliquot por- 

 tions were subjected to the action of bromin, zinc sulphate, phosphotungstic acid, 

 and tannin and salt. The filtrates from the precipitates obtaineil by the last three 

 reagents were divided into aliquot parts and treated with the four reagents mentioned 

 in different combinations. The amomit of nitrogen precipitated by phosphotungstic 

 acid was greater than that precipitated liy any other single reagent, except in the 

 products containing large amounts of peptones. The use of liromin alone was again 

 shown to be unreliable. 



The highest results from reagents in combinations were obtained from tlie tannin- 

 salt reagent followed by zinc sulphate in the case of the filtrate from zinc sulphate. 

 A marked influence was apparently exerted by the order in which the various reagents 

 were employed. While tannin and salt followed by zinc sulphate gave the highest 

 results, zinc sulphate followed by tannin and salt gave the lowest results. The 

 author cautioned against drawing conclusions from the data which were presented 

 merely as preliminary. A further study of the combinations of various reagents was 

 deemed advisable. 



A study of the nitrogenous constituents of meats, H. S. Grindley. — Cold 

 water extracts of raw and cooked meats were examine<l by methods which were 

 described in detail. The different determinations expressed in percentages of the 

 weight of original substance and in percentages of the total nitrogen soluble in water 

 were given. 



Eight samples of raw meats, 6 of boiled, and 6 of ])roiled or roasted meats were 

 examined. In the case of the raw meats the average percentages of total nitrogen 

 solul)le in cold water by the different methods of analysis were as follows: (1) Coag- 

 ulated by heat, 45.51; (2) precipitated by zinc sulphate, 4.18; (3) precipitated by 

 bromin in filtrate from zinc sulphate, 1.31; (4) proteid nitrogen, 50.99; (5) non- 

 proteid nitrogen, 49.01; (6) i)recipitated by bromin directly, .39.45; (7) precipitated 

 by phosphotungstic acid in hot solution, 42.95; (8) precipitated by tannin and salt, 

 48.80; (9) precipitated by phosphotungstic acid in cold solution, 49.17; (10) as free 

 anunonia, 2.86. In the case of boiled meats the average percentages were as follows: 

 (1) .3.24, (2) 15.15, (3) 5.42, (4) 23.79, (5) 76.21, (6) 11.97, (7) 10.21, (8) 22.71, (9) 

 26.79, (10) 6.16. The averages for all determinations were (1) 22.23, (2) 8.09, (3) 2.85, 

 (4) 33.16, (5) 66.84, (6) 2.3.50, (7) 24.73, (8) 30.87, (9) 32.05, (10) 3.69 percent. 



It was stated that while in general the triplicate determinations upon each sample 

 agreed fairly well, the results obtained by different methods upon different samples 

 varied greatly. The author considered it desirable to determine directly the amount 

 of coagulable proteids contained in water extracts of meats and announced that further 

 studies were being made upon this subject. Precipitation by bromin was found 

 unsatisfactory and precipitation by phosphotungstic acid gave but slightly higher 

 •results. 



