The weights of flask and fat at boiling point, from which specific gravities were calculated, are as follows: I have never made determinations by this method before, and may have overlooked some precautions that are necessary. My results with No. 3 seem too low for pure butter, but aside from this I have no reason to suspect that they are wrong. I should have liked to have had more time to give to this matter, but the sample came so late that I was unable to repeat the determinations. At present Professor Henry is away and my assistants are all away on vacations, so that I have to give my attention to many things aside from work of this kind. I trust that the outcome of these examinations may be a method satisfactory to all. Very truly, yours, Dr. H. W. WILEY, Department of Agriculture, Washington, D. C. S. M. BABCOCK. The weights of fat taken for estimation of volatile fatty acids and cubic centimeters of deci-normal alkali required, were as follows: The amounts for 5 grams given in furnished blanks are calculated from these. S. M. BABCOCK. COLUMBIA, MO., July 20, 1889. DEAR SIR: Since I sent yon the results of butter analyses I repeated all the examinations, with the exception of the specific gravity of No. 1. (The bottle which you sent to Dr. Schweitzer arrived broken; the contents of it had to be filtered and some of the fat was lost.) For the determinations of volatile acids I made two blank distillations for each analysis. The work was carried out with the same care as before and with the additional help of a little more experience I repeated these analyses for my own information and send you the results, thinking you might wish to use them in place of those which I sent you first or in addition to them. Respectfully, Dr. H. W. WILEY, Chemist, Department of Agriculture, B. VON HERFF, Columbia, Mo. Washington, D. C. STATE UNIVERSITY OF MISSOURI, COLUMBIA, Mo., July 12, 1889. DEAR DOCTOR: The samples and letter arrived here in good time, but we were so torn up by internal difficulties, that I felt obliged to turn over the whole matter to the assistant chemist of the station, who has done the work very faithfully. Dr. H. W. WILEY, Department of Agriculture, P. SCHWEITZER. Washington, D. C. SPECIFIC GRAVITY. The water-bath used consisted of a porcelain casserole of 375 cubic centimeters capacity. The picnometer was held by a wire which kept the flask about one-half centimeter from the bottom of the vessel. The thermometer inserted in the briskly boiling water did not rise above 98°, but if a few drops of fat were swimming on the surface of the water the temperature reached 100°. The specific gravity of the fat was taken at the same temperature at which the flask was graduated. The diameter of the neck of the picnometer was 8 millimeters. A narrow neck would be perferable. Weight of picnometer empty, 9.7587. Capacity of picnometer at the temperature of boiling water. STRENGTH OF DECINORMAL ACID (HCl.). Sodium carbonate C. P. was ignited in a platinum crucible, weighed after cooling, emptied in a beaker, and reweighed. Dissolved in water, heated and titrated with the acid, using cochipeal, freshly prepared, as indicator. When nearly neutral the liquid was boiled, to expel CO2, and then the titration completed. The point of neutralization can thus be very accurately determined. After the digestion with soda lye the alcohol was driven off by blowing air into the flask by means of a rubber bulb. This is done in a few minutes, and saves at least one-half hour's time. The condenser was used for subsequent distillations without cleaning it. Weighing.-5.5 cubic centimeters melted fat were measured and run into the flask. The desired weight was obtained by means of a glass rod. If done in this manner the weighing is very easy. NOTE. It was impracticable for us at the time to determine the strength of onetenth normal acid by precipitation with silver nitrate; it was carefully done by sodium carbonate. If it is necessary the determinations can yet be made by precipitation. R. C. KEDZIE. The melting point of the fats was determined in the manner directed in the bulletin (No. 19), with the exception that it was necessary to use a test tube 24 centimeters in diameter and 21 centimeters long. Instead of the rubber bulbs a foot-bellows was used for stirring the water, which proved very convenient. The thermometer was graduated to one-fifth of a degree, each degree occupying a space of .5 centimeters which enabled the reading to tenths with tolerable accuracy. The specific gravity was determined in specific gravity flasks of a capacity of 50 grams at 60° F. These were placed in boiling water contained in an iron dish at a temperature of a fraction of a degree less than 100° C. Much more difficulty was experienced in obtaining constant results with water than with the fats. The following are the results of the estimates of the amounts of water at 100° F. which the flasks contained. The contents of each flask were therefore assumed to be 48.100 grams. Taking the density of water at 100° C. as .95865 (The Analyst, April, 1889, page 67), and at 150.5 as .99910, and assuming water at 150.5 as unity, the specific gravity of water at 100° is .959514. .95865.99910.959514. The 48.100 grams of water at 100° will then occupy 48.100.95951450.1295 cubic centimeters. Fat No. 1 (Flask No. 1). a.... Weight of fat, 43.0594 50.1295.85896 specific gravity. b....Weight of fat, 43.10150.1295.85894 specific gravity. Fat No. 2 (Flask No. 2). a.... Weight of fat, 43.0594 - 50.1295.85396 specific gravity. a.... Fat No. 3 (Flask No. 2). Weight of fat, 43.278950.1295 = .86334 specific gravity. b....Weight of fat, 43.2794-50.1295.86335 specific gravity. Reagents for the estimation of the volatile acids were made as directed. Soda-lye solution was made from E. Merck's natr. caustic in Bacill. N 10 stand. soda solution was used, prepared by means of water and making up to 250 cubic centimeters. Its accuracy tested by of potassium tetroxalate. KH C2O2H2C2O1+H2O=253.52 Caldwell. Monatomic equivalent = 84.567. |