280 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



derived from pnro butter. He says, in Bulletin No. 13 of tlie Ohio 

 Experimental Station, Experiments 7, 8, 9, and 10: 



Experiment 7. — The difference between the behavior of the tallow fats in Experi- 

 ment 3 and the last three experiments could only be ascribed to a difference of con- 

 ditions. It is well known that table butter normally contains 4 to 6 per cent, of salt 

 and 5 to 20 per cent, of water. These ingi-edients constitute the most marked dif- 

 ference between butter and the rendered animal fats, as tallow and lard. In order 

 to test the effect of this mixture upon the tallow fats, about half an ounce of the 

 oleo oil used in Experiment 3 was mixed in a joorcelain mortar with a small quan- 

 tity of salt and eight or ten drops of water. ^4|t'ter the water was thoroughly incor- 

 porated the mass was transferred to a test tube and boiled for one minute, as in the 

 case of butter. It was then jxjured into a wooden pill-box and allowed to cool as 

 before. The cooled mass presented quite a marked difference in appearance from 

 that obtained from the same substance in Experiment 3. It retained to a great ex- 

 tent the yellow color of the oleo oil, was of a more granular nature, and in fact 

 resembled boiled butter in every respect. When a small particle was stirred up with 

 olive on on a glass slide it separated readily. When covered and viewed with a 

 pocket lens it revealed a mass of globules resembling insect eggs. Under the micro- 

 scope these exhibited essentially the same characteristics as those obtained from but- 

 ter m Experiment 1. The crystalline mass of the oleo globule seemed somewhat 

 coarser, and to this condition v,^as ascribed the fact that the cross, as well as the 

 colors produced by the selenite plate, were less sharply defined than in the globules 

 obtamed from butter. The slides prepared from this material were remarkably free 

 from the small detached crystals of fat observed in Experiment 3. 



Experhnent 8. — Having thus discovered that these globular masses may be ob- 

 tained from pure yellow fat by simply observing the conditions which obtain in but- 

 ter making, the following test was made : Nine grams of oleo oil and one gram of 

 lard were placed in a small beaker, and eight or ten drops of a saturated solution of 

 salt in water added. The mixture was then gently heated to melt the fats. After 

 shaking violently for a few moments to mix the salt solution -with the fats, the 

 mixture was boiled gently for one minute, and then allowed to cool, as before, in a 

 wooden pill-box. The microscopic examination of this preparation revealed globular 

 masses which could in no wise be distinguished from those obtained from pure but- 

 ter. The crystalline texture was dense, the cross of St. Andrew plainly marked 

 and the colors produced by the selenite sharply defined. 



Experiment 9. — A mixture of one part of lard to five parts of oleo oil was treated 

 as in the last experiment with like results. 



Experiment 10. — In this test a mixture consisting of 20 per cent, of lard and 80 

 per cent, of oleo oil was employed. Whether the consistency of this mixture was 

 pecuUarly adapted to the formation of the globules or Avliether possible variations 

 of conditions in manipulations were more favorable the writer is unable to judge 

 from a single experiment, but the fact is that in this case the individual " butter 

 crystals " were exceedingly large and characteristic. 



In Bulletin No. 15 of the Ohio Experimental Station, Professor 

 Weber shows that the conclusions in respect of the origin of fat crystals 

 and the behavior of butter and other fats under polarized light con- 

 tained in his Bulletin No. 13 and in this paper are correct in every 

 particular. 



Specific gravity. — The specific gravity of a fat is a physical prop- 

 erty of considerable importance in determining its character. For 

 instance, the specific gravity of butter fat is uniformly higher than 

 for any of the common fats used as adulterants therefor. Since the 

 fats used for butter substitutes all melt at about 40° C, or under it is 

 convenient to select that temperature for the determination of specific 

 gravities. Many investigators, however, make the determination at 

 100° P, We have found that a pure butter fat has a specific gravity 

 at 40° of .009 to .912, water at the same temperature being taken at 

 1.000. 



On the other hand, butter substitutes show a comparative density 

 of .900 to .905. 



In these conditions it would be reasonable to suppose tliat a butter 

 having less than .909 for specific gravity is adulterated, and the degree 



