INDUSTRIAL A N D ENGINEERING CHEMIXTRY
August, 1924
There can be no question but that the Reichert-Meissl value is the most important single determination, especially when foreign fat is present in considerable quantity. By making use of the Reichert-Meissl and saponification values, however, the error in the quantitative interpretation is less than 10 per cent. The saponification value of the insoluble acids gives valuable corroborative evidence in case of adulterations with oleo oils or coconut and palm kernel oils. It is possible to make a mixture of these two groups of oils such that the saponification value of the insoluble acids will be equal to that of the insoluble acids of butter fat. It is not possible, however, to have mixtures of butter fat and these two fats in any proportion exceeding 10 per cent and still preserve the relation of Reichert-Meissl and saponification values of fat and insoluble acids of butter fat. The importance of a standard for normal butter, including the use of other constants than the Reichert-Meissl value and the density, must be apparent to every analyst. The lower limit of the Reichert-Meissl value, as fixed by the U. S. standard, is inadequate to meet the present requirements. By including a lower limit for the saponification value of the fat and an upper and a lower limit for the saponification value of the insoluble acids it would be possible to detect and determine smaller quantities of adulterants and also differentiate within much narrower limits. From the data obtained, as well as from other sources, the lower limit for the saponification value should not be more than 3 mg. less than the number of cubic centimeters of the Reichert-Meissl value. The saponification value of the insoluble acids should not be more than 2 mg. above or below the average value of 218-that is, a Reichert-Meissl value not less than 24, saponification value not less than 221, and saponification value of the insoluble acids not less than 216 or greater than 220.6
PLOTTITG AND USE OF
THE
TRIAXGLE GRAPH
The following values are assigned to the different constants: Maximum Minimum Reichert-Meissl value Saponification value
28.5 259.0
1.5
196.0
Construct an equilateral triangle. Plot the ReichertMeissl value from 1.5 to 28.5 on the right side of triangle, 6
Purdue Univ. Expt. Sta., Bull. a64 (1921).
831
and begin a t the lower apex with the value of 1.5. Divide this side into 54 equal spaces, each space representing a Reichert-Meissl value of 0.5. The upper apex will have the value of 28.5. Divide the base of this triangle into 63 equal spaces, representing the saponification value, each division having a value of 1. Draw a line connecting the Reichert-Meissl value of 2s with the point of the base having a saponification value of 228. On both sides of this line draw lines parallel to this line through each whole number of the saponification value. Draw a line from the point having a Reichert-Meissl value of 7 to the lower left side apex having a saponification value of 259. Draw parallel lines below and above this line with equal spaces corresponding to 0.5 Reichert-Meissl value. The right side of this triangle represents the oleo oil group, the left side butter fat, and the base the coconut oil group. Divide each side into 20 equal spaces, each space corresponding to 5 per cent for the respective fats. Through these points draw lines parallel to the three sides, respectively. The total will be 100. ILLUSTRATION OF USE-Find the analysis of the fat having a Reichert-Meissl value of 18.0 and a saponification value of 243. Locate the point on the base of the triangle representing a saponification value of 243. Follow the line upward until the point is reached where the line intersects the line having a Reichert-Meissl value of 18. From this point of intersection follow a line to the left parallel to the base until the side of the triangle is reached, marking the per cent butter fat. The per cent butter fat can then be read. From the point of intersection of the Reichert-Meissl value and saponification value follow a line parallel to the oleo oil side until the coconut side is reached. The figure a t this point gives the per cent coconut oil. The Reichert-Meissl value and saponification value given above will give for butter fat 51 per cent, coconut oil 49 per cent, and oleo oils 1 per cent. In general, locate the point of intersection of the ReichertMeissl value and saponification value. From this point to the left and parallel to the base gives the per cent of butter fat, from the point of intersection and parallel to the oleo side downward gives the per cent of coconut oil, and from the point of intersection parallel to the butter fat side and upward gives the per cent oleo oils.
New Quarters for Institute of Paint and Varnish Research HE United States Government having acquired the land
T and building occupied by the Institute of Paint and Varnish Research for the past fotu-teen years, it has been necessary to provide other quarters. The construction of a new laboratory building of moderate size has just been completed on the northwest corner of 22nd St. and New York Ave., N. W., Washington, D. C. The building is rapidly being equipped with modern apparatus for the examination of paint and varnish products. I t contains laboratories for chemical
PAINT A N D VARNISH
work, such as testing paints, varnishes, pigments, etc., from an analytical standpoint. The physical laboratory is equipped with instruments for color analysis, viscometry, light-resistance tests, and other general testing. Thebasement contains all the necessary equipment for the mixing and grinding of experimental batches of paint. Ontheroof arealarge number of exposure racks, where the various coatings for wood and metal are tested on small panels in order to determine the actual comparative durability values. RESEARCH LABORATORY
