p, q, r.—200 cc for total albumose nitrogen; filtrate from m, n, o, representing 4 grams lean and 6 grams of fat sample. s, t, u.-200 cc for total amido acid nitrogen representing 4 grams of lean and 6 grams of fat sample. Samples a, b, c were transferred to 500 cc nitrogen flasks for the direct determination of nitrogen by the Kjeldahl-Gunning method. Samples d, e, f were evaporated to dryness on the water bath, then dried to constant weight in air bath at 103°, and finally ashed at a dull red heat. Samples m, n, o were treated with a slight excess of moist magnesium carbonate, a evaporated to about 30 cc, filtered and washed with hot water to which a little moist magnesium carbonate had been added. The precipitate and filter were transferred to 500 cc nitrogen flasks and the coagulum adhering to the sides of the beakers was removed with hot sulphuric acid and transferred to the corresponding flask. The nitrogen was determined in the usual manner. The filtrates from m, n, o, (p, q, r) were concentrated to about 10 cc in small beakers and acidified with 1 cc of 50 per cent sulphuric acid, diluted to 30 cc and to each 50 grams of pure crystallized zinc sulphate were added. The mixture was then heated upon the water bath until the complete solution of the zinc sulphate took place. If too much zinc sulphate crystallized out upon cooling a little water was added, care being taken to have only a slight excess above saturation. The contents of the beakers were filtered through filters previously wet with a saturated solution of zinc sulphate slightly acidified with sulphuric acid. After the filtrate had completely drained through, the beaker and filter were washed three times with the saturated zinc sulphate solution, allowing the washing to drain completely before adding the next washing. The filter and precipitate were transferred to nitrogen flasks and each beaker washed with water and sulphuric acid, the washings being rinsed into the corresponding flask. If care has been used in avoiding an excess of zinc sulphate crystals there will be no trouble with bumping during the digestion for the determination of the albumose nitrogen. Samples s, t, u were treated as for coagulable nitrogen. The filtrates from the coagulum, not to exceed 30 cc, were rinsed into 100 cc graduated flasks, 15 grams of sodium chlorid were added and dissolved by warming gently. The flasks were placed in the ice box until cooled to 15° C. A 24 per cent solution of tannic acid was made up, filtered, and cooled in the ice box. When both solutions were cooled, 30 cc of the tannic acid solution were added to each 100 cc flask, which was then filled to the mark with cold water; the contents of the flask were thoroughly mixed and allowed to remain in the ice box over night. The following morning they were filtered rapidly and 50 ce of the filtrate transferred to nitrogen flasks for the determination of the amido acid nitrogen. With all of the determinations blanks were made to correct for the nitrogen in the reagents. From these data the nitrogen present as peptone nitrogen was calculated. The main purpose in the examination of the water extracts of the fresh meats has been to see if age of animal or condition of fatness has any influence upon the amount of water-soluble material, or upon its composition, also to what extent there is a variation in different parts of the animal. To this end the samples have been handled as nearly as possible in the same manner and with the same treatment after slaughtering. So far eight animals have been slaughtered and analyzed, but the data are still insufficient to admit of any general conclusions, and the present paper is to be regarded only as a report of progress. A tabulation of a few of the results is appended, selecting those for the round and rump, the rib and loin cuts of the first four animals slaughtered. a Prepared by precipitating magnesium chlorid with sodium carbonate, heating, filtering, and washing until no chlorids remained in the filtrate. Distribution of nitrogen in cold-water extracts of wholesale cuts, free from bone, from four different steers. a Grade Shorthorn steer, 3 years old and extremely thin. Grade Shorthorn steer, 3 years old and moderately fat. c Grade Hereford steer, 1 year old and moderately fat. d Grade Hereford steer, 1 year old and in fair condition as a stocker, much better condition than No. 18. e The albumose precipitate was washed only once; results too high. Distribution of nitrogen in cold-water extracts of the lean of wholesale cuts (bone and fat hand separated) from three steers.a a Steer No. 18 excluded as it was the first one slaughtered, and the hand-separated fat was weighed separately but was ground with the lean for analysis. Albumose precipitate washed but once. Distribution of nitrogen in cold-water extracts of wholesale cuts, free from bone and fat, a of four different steers. a The weight of the actual amount of fat (ether-soluble) is deducted from the weight of the cut. This reduces all cuts to a fat-free basis. b Albumose precipitate washed but once. In the first table it will be noticed that if the data concerning the albumoses and peptones are omitted, the round and rump cuts in every case give higher figures than the other two cuts. When the hand-separated fat is eliminated we find less variation; the round and rump cut gives higher results than the rib but is equaled or slightly surpassed in a few cases by the loin. When the fat is entirely eliminated, as shown in the third table, the difference is still less. However, in only one case does the rib cut (steer 18, coagulable nitrogen) give as high results as the round and rump cut; and in another case (steer 503, amido-acid nitrogen) as high as the loin. In six cases the loin cut gives higher results than the round and rump cut. In general, steer No. 505 gives the highest results, especially in the case of the amido-acid nitrogen, there being only one exception, namely, the coagulable nitrogen in the rib cut on the fat-free basis. A further discussion of these results will not be attempted at this time. For the purpose of making an extended study of the composition of beef extract there was prepared at the Missouri station (at the time of slaughtering) a cold-water extract a from a 5-kilo sample of the round of each animal. The filtered extract was coagulated upon the water bath, filtered, and concentrated with one or two filtrations as the concentration proceeded. The extracts have been finally concentrated to a semisolid mass, in which condition they appear to remain in a state of perfect preservation. The life history of the animals from which these extracts have been prepared is known and during the next year cooperation in the examination of these extracts will be requested, to determine the composition of pure beef extract and to learn to what extent variation may be expected. The president announced the following membership for Committee B on recommendation of referees: Messrs. B. B. Ross, R. W. Thatcher, A. S. Mitchell, Paul Collins, and W. D. Bigelow. The following committee was appointed to wait upon the Secretary of Agriculture and the Assistant Secretary and invite them to address the convention: Messrs. M. E. Jaffa, J. M. Bartlett, and W. A. Withers. On motion by Doctor Wiley, the vote on the amendments to the constitution was made special order for 12 o'clock, or following the presidential address, on Friday. REPORT ON PRESERVATIVES. By W. D. BIGELOW, Referee. SALICYLIC ACID. RAPID DETERMINATION OF SALICYLIC ACID. The methods of the association for the quantitative determination of salicylic acid are long and tedious because of repeated extraction with immiscible solvents. An attempt was made to simplify these methods by extracting a certain volume of the food, or an aqueous extract thereof, by means of a definite volume of solvent, evaporating to dryness an aliquot portion of the solvent used, and determining the salicylic acid in the residue. The total amount can then be calculated by a factor to be determined by experimental work. It is, of course, necessary that the solvent, under certain conditions to be adopted, should extract a uniform amount of salicylic acid uncontaminated by substances that a Trowbridge and Grindley, J. Amer. Chem. Soc., 1906, 28: 472. would interfere with the reaction by which the salicylic acid should finally be estimated in the residue. Owing to its rapidity and convenience, the ferric chlorid reaction has usually been employed for determining the amount of salicylic acid present. It is, therefore, important that the solvent employed should not extract tannin from the food. In order to determine what solvents should be most advantageously employed as far as delicacy of reaction and freedom from tannin or other interfering bodies is concerned, Mr. Charles S. Ash extracted 50 cc portions of claret containing salicylic acid in amounts varying from 0.025 mg to 0.5 mg and treated the residue obtained by evaporation of the solvent with ferric chlorid in the usual manner. The results are given in the following table: Comparative efficiency of solvents on salicylic acid dissolved in 50 cc of claret (Ash). 0.500 None. Good. Faint .250 .100 Good. .050 Good. .025 Good. Good.. Good.. Good.. Good. Good.... Faint Good. Good.. Good. trace. trace. Good. None.. Fair... Good.. Faint Good. Faint.... None.. Good. Good.. Good. Trace Trace Trace. Fair.. Nothing. Trace Good.. Good. Trace? None.. None.. None. (?) Good.. Good. None.. Trace? Good trace. Mr. Ash found that the first five solvents given in the table extract tannin in the order in which they are mentioned-that is, ether extracts the greatest amount and trichlor-acetylene the least. The last three solvents-carbon bisulphid, carbon tetrachlorid, and toluene-do not extract tannin, and the ferric chlorid reaction in the residue obtained by them from wine is clear and characteristic of ferric salicylate. It will be noted that the residue from the ether extraction gave no reaction whatever with ferric chlorid. This was due to the presence of tannin, which entirely obscured the reaction. With chloroform much better results were obtained, but even here the reaction was partially obscured by tannin, which was also true of the residue from dichlor-acetylene. The data given in the column headed "Ether and hydrogen peroxid" were determined by oxidizing with ammonia and hydrogen peroxid the residue obtained by evaporating the ether extract. This destroys the tannin and also partially converts benzoates and saccharin when present into salicylic acid. The salicylic acid was then again extracted with ether, the ether extract evaporated, and the residue tested with ferric chlorid. As previously stated, the greatest freedom from interfering substances attended the use of carbon tetrachlorid and toluene, the latter appearing to extract slightly more salicylic acid than the former, and thus affording a better test in the presence of a small amount of that substance. Chloroform was also very satisfactory, being inferior to carbon tetrachlorid and toluene in respect of dissolving interfering substances, though apparently slightly superior in the amount of salicylic acid extracted. 73673-Bull. 122-09- -5 Mgs. 100 Mgs. Mgs. 0520 6.0 6.2 6.2 6.0 Mgs. Mgs. Mgs. Mgs. Mgs. Mgs. Mgs. Mgs. Mgs. Mgs. Mgs. Mgs. Mgs. 63.2 63.4 60.8 60.6 61.6 60.2 60.0 60.2 60.0 49.4 49.6 50.4 51.0 49.6 30.6 30.6 30.6 30.6 31.6 32.4 29.8 30.4 30.8 24.4 24.8 24.2 24.6 25.4 14.6 14.6 15.2 14.8 15.2 15.8 14.8 14.6 14.8 13.4 11.8 12.0 13.6 12.4 6.0 6.0 5.2 49.2 24.6 12.4 5.6 5.2 5.6 3.0 3.2 3.0 2.6 2.4 2.5 80.0 80.4 79.4 78.0 83.0 80.4 82.0 79.8 79.0 69.4 68.0 71.2 SHORT METHOD FOR THE QUANTITATIVE DETERMINATION OF SALICYLIC ACID. From the results of the qualitative test made by Mr. Ash it appeared that it would be advantageous to confine the work with the quantitative method to carbon tetrachlorid and toluene. Accordingly, Mr. Ash applied the method to various types of wine containing known amounts of salicylic acid varying from 2.5 to 100 mg per 100 cc. One hundred cubic centimeters of the wine were acidified with 5 cc of sulphuric acid (1 to 3) and 50 cc of the solvent were added, gently but thoroughly mixed, and the solvent separated after centrifuging; 25 cc of the solvent were transferred to a weighed watch glass by means of a pipette. With toluene the best results were obtained using a watch glass 4.5 inches in diameter and with carbon tetrachlorid one 4 inches in diameter. The solvent was allowed to evaporate spontaneously and the amount of residue determined by weighing. The residue was then dissolved in 5 cc of neutral alcohol and transferred into a small casserole, the watch glass being washed thoroughly with neutral boiling water and the salicylic acid titrated with one-hundredth normal barium hydroxid, 1 cc of the reagent being equal to 1.38 mg of salicylic acid. An aliquot part of the solvent was allowed to evaporate spontaneously, the residue dissolved in 2 or 3 ce of alcohol and diluted with water sufficiently for the colorimetric determination with ferric chlorid. When the amount of salicylic acid present in the original sample was not less than 25 mg per 100 cc, the results obtained by weighing and titration were far superior to those obtained by the colorimetric method, but with smaller amounts the last method was the only one applicable. No tannin was found in any of the residues and the ferric chlorid reactions were clear and entirely characteristic of pure salicylic acid. In the gravimetric and volumetric determination small amounts of soluble substances were extracted by the solvent. The weight of the residue from 25 cc of the solvent used in extracting normal wine varied from 2 to 3 mg and its acidity was equal to about 0.5 cc of one-hundredth normal barium hydroxid. The results obtained by Mr. Ash on different types of wine are given in the table. In each case these results are the average of three closely agreeing determinations. |