142 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



BEEF-FAT. 



Crystals of Leef-fat are very unlike iliose found in wliat is known 

 commercially as '*bleo." Manufacturers of oleomargarine generally 

 prefer oleo, because it is more digestible than beef-fat and approaches 

 nearer the character of pure butter. Rendered beef -fat, when cooled, 

 shows crystals of a branched and foliated character, radiating from a 

 common "center and very distinctly marked. Plate I represents crys- 

 tals of the fat of the omentum, kidney, marrow of femur, and round 

 of beef. (See Figs. 21, 23, 23, and 24.) Generally each group of 

 branches is imbedded in a mass of translucent fat (see Fig. 23, Plate I), 

 imperfectly represented by photography, yet distinctly seen by the 

 microscope. 



OLEO. 



**01eo," an extract of beef-fat, is used very extensively in combi- 

 nation with neutral lard, which gives the substance toughness, pre- 

 vents it from crumbling, and produces a closer resemblance to but- 

 ter. Butter substitutes thus made cut and spread on bread like 

 butter. As sold, oleo is not unlike butter. It has a slight taste of 

 butter when fresh, but is much • firmer to the touch. It has also a 

 slight animal odor. Every specimen I have examined has contained 

 borax, used, as I am informed, for the purpose of destroying the ani- 

 mal odor. This it accomplishes to a great extent. When oleo is 

 heated to a temperature of about 300° F. and cooled slowly, it yields 

 crystals of a globose form, which exhibit a cross, as in Fig. 17, Plate I. 

 These break up in course of time into highly stellate forms, the spines 

 of which resemble thorns and proceed from a common center (see 

 Fig. IS). The primary oleo crystal is generally of a rich orange color, 

 although it sometimes appears pure white and very small, say about 

 the one-thousandth of an inch in diameter. (See description of oleo 

 crystals, Plate IV.) I have produced oleo crystals as large as the one- 

 hundredth of an inch in diameter by boiling Armour's oleo with yel- 

 low oxide of lead. These have a dull orange color and appear very 

 smooth. They also break up into highiy spinous crystals, but as 

 thus far observed do not show such forms as Figs. 5, 6, 7 and 8, com- 

 mon to butter, Plate I. See the spinous crystals of oleo, Plate IV, as 

 compared with tertiary crystals of butter, D, 10, 11, and 12, and with 

 those of lard, 19 and 20, Plate I. Compare also crystals of beef -fat, 

 21, 22, 23, and 24, with those of oleo. 



I have found in all my experiments, using fresh material, that 

 when oleo is boiled in cotton-seed oil, say one-third oil to two-thirds 

 oleo, the globose crystals are invariably small as compared with those 

 of butter. In color the butter crystal is either yellow or pure white, 

 while the oleo crystal is of a deep orange or white. In butter the 

 small immature secondary crystals, Fig. 2, Plato I, represented by 

 small white globose bodies, differ from the very small crystals in Fig. 

 17, which show a cross, however minute they may be. Compare 

 also the butter crystal, Fig. 1, Plate I, 110 diameters, with the oleo 

 crystals. Fig. 17, 140 diameters. Oleo crystals. Fig. 2, Plate IV, 

 are also 140 diameters, and represent the largest crystals of oleo I 

 have seen, produced without the aid of chemicals. In Plato IV, 

 Figs. 1, 2, 4, and 11, represent globose crystals of boiled oleo as seen 

 by polarized light; Figs. 3, 5, 6, 7, 8, and !» their first change in proc- 

 ess of decay. Fig. 12 represents a crystal of oleo and neutral lard 

 compounded with salt and water and boiled after the fashion proposed 



