Melting and congealing points

It will be noticed that the specific gravity is abnormally low, and does not correspond with pharmacopoeial requirements, while the melting, and congealing-points are also very low. The refractive index is lower than has ever been found for pure aniseed oil, which has a value between 1-5530 and 1-5565, or thereabouts. The slight deztro-rotation indicatea nothing, as some samples of pure star-anise oil are faintly dextro-rotatory. 

Cloud Point. An empirical cloud point analysis is performed by stirring a sample of fat while it is being cooled until the oil has clouded enough to block a light beam of known intensity. Both cloud point and congeal point values are more closely related to consistency than melting points. A definite relationship exists between the cloud point results and the solid fat index values at 92°F or 33.3°C. Cottonseed oil that has not been winterized or hydrogenated will have a cloud point of 30°F to 38°F or —1.1°C to 3.3°C. Winterized cottonseed salad oil, with the hard fraction removed, will have a cloud point of approximately 22°F to 26°F or —5.6°C to -3.3°C. 

D87. Open or closed capillary tubes are used to measure the melting point of many of the natural waxes. The congealing point (ASTM D938) is the temperature at which a melted wax ceases to flow, and is more consistent than melting points for some waxes. 

The waxes are used in the production of a wide variety of materials, eg, petroleum jellies, crayons, lubricants and plasticisers, printing inks, hot melt adhesives and even chewing gum. The FT hard wax fraction is unique amongst industrial waxes in that it has a high congealing point coupled with... 

Needles or cryst mass. Odor of hyacinth, mp 33. d 1.0397. bPL0 72.6" bp, 102.5" bp,0 117.8" bp 133.7 bp 151.0s bp 162.0s bpIM 177.8s hp, 199.8) bp , 224.6" bp, 2503 . n 1.58190 n 1.57580. When smallamounts of impurities are present as in the natural article (cinnamyl alcohol from storax), it remains fluid at lower temps than the melting point. Minimum congealing points specified by the Essentia] Oil Assn are 33.0s for cinnamic alcohol pure 28.0s for cinnamic alcohol prime 20.0s for cinnamic alcohol from storax. [s oxidized slowly on exposure to heat, light and air. So] in water, glycerol. Clearly sol in 3 vols 50% ale. Freely sol in ale, ether, other common organic solvents. 

It is noteworthy that the use of the earliest analytical techniques for the systematic study of essential oils, such as SG, relative density, optical activity, and refractive index or melting, congealing, and boiling points determinations, is generally applied for the assessment of pure compounds and may be extended to evaluate essential oils composed of a major compound. Classical methods cannot be used as stand alone methods and need to be combined with modern analytical techniques, especially GC, for the assessment of essential oil genuineness. 

API (acetaminophen in this case) is heated above the wax melting point, but below that of the drug component. This process results in a suspension of the drug particles in the molten wax. When a nozzle is used to spray the atomized suspension onto cooled air, the molten droplets of suspension congeal, thus allowing the liquid components to encapsulate the solid API and resulting in packets of API particles encased in solidified wax. 

Benzoic acid will begins to sublime at around 100 °C [2], and will form a feathery sublimate near its melting point [5]. Other workers have noted that melted benzoic acid will congeal between 121°C and 123°C [9]. 

Evidence for these equilibria comes from the Raman spectra, which show an absorption peak (or unresolved peaks), probably attributable to Cu,Clj. Addition of CuCI or Cl causes this peak to increase or decrease as expected by the above equilibria. The system thus probably contains at least four anionic species, and the impurities account for the depression of the melting point. In accordance with this interpretation is the fact that the material is oily and never forms a crystalline solid with a true freezing point, but congeals to a glass. it about 0 °C. 

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