XVIII.—On certain isomeric transformations of fats

Abstract

XVII1.-On certain Isomeric Transformations of Fats.

Low-temperature Crystallization of the Fatty Acids and Glycerides.

“…A. The isolation of naturally occurring glycerides by the fractional crystallization of fats The isolation of naturally occurring glycerides by fractional crystallization, probably attempted before 1820 by Chevreul, was reported in detail by Duffy (42) in 1853. By a series of thirty-two crystallizations of mutton tallow from ether at 16°C., he succeeded in isolating 8 g. of tristearin from 2 kg.…”

The Polymorphic Forms or Phases of Triglyceride Fats.

“…It is remarkable that, as early as 1853, Duffy (11), building on the experience of earlier observers, actually discovered three melting points for "stearin" from mutton fat many times recrystallized. These three melting points agree rather well with the three melting points obtained for tristearin by the most reliable modern observers.…”

“…In 1907 Bomer (5), substantiating Duffy (11), showed definitely that a high-melting modification always resulted when triglycerides were crystallized from solvents, and felt therefore that the melting point of such a preparation was to be regarded as the true melting point. He also indicated more definitely than most the exact conditions for obtaining the low melting point.…”

“…Even these later investigations have invariably been supplemented and substantiated by studies of melting and crystallization behavior. 11. THE MEANING OF THE MELTING POINTS OF FATS I n the realm of commercial fats it has been appreciated for many years that the melting point of a sample depended on ( I ) the particular meltingpoint method used, and (2) the previous history of the sample.…”

“…Indeed, the literature . on the densities of tristearin in various states has probably not been greatly improved upon since the work of Duffy(11) and Kopp (23) about 1850. Duffy's results are given in table 4.…”