212 The Microscope. 



BUTTER AND FATS, 



DR. THOMAS TALYOB, 

 MICROSCOPIST U. S. DEPARTMENT OF AGRICULTURE. 



Abstract of paper read by Dr. Thomas Taylor before the American 

 Microscopical Society, at Cleveland, Ohio 



Since 1876, when my first paper was published on Butter 

 and Fats, in the New York Microscopical Quarterly Journal, I 

 have devoted a good deal of time to the investigation of this sub- 

 ject, principally with the view of finding a method by which I 

 could, by the aid of the microscope, detect butter from the but- 

 ter substitutes. As a result of many experiments, I find that a 

 person experienced in the use of the microscope may distinguish 

 the fats of various animals and of vegetables by following the 

 methods herein described. 



The experimenter should first procure a specimen of common 

 lard. This is composed mostly of crystalline starry forms which 

 represent the solid fats of the lard. Real lard is composed of 

 these and the oil common to lard. In very hot weather, when 

 the thermometer is up in the nineties, the crystals dissolve in 

 the oil, and perfect crystals cannot then be obtained unless cooled 

 slowly to about 70° Fahr. 



Place a drop of sweet oil on a glass slide 3x1 inches, with 

 the point of a needle. Place a small portion of the lard in the 

 oil, and mix them together. Place a microscopic glass disc over 

 the lard and oil mixture and press gently. If held up to the 

 light white granules will be seen if the temperature is not over 

 80° Fahr.; these are fatty crystals. Under a low power of the 

 microscope it will be observed that these crystals have stellar 

 forms with dark centres, and spines radiating from them. See 

 figure 7. 



To procure normal crystals of beef kidney fat, render a 

 piece of this fat in an iron pan, without water. Strain, and add 

 sufficient sweet oil to bring the fat to the consistency of butter. 

 Cool slowly for a period of from twelve to twenty-four hours. 

 Mount in oil as directed in the case of lard. The crystals in this 

 case present quite a different appearance from those seen in 

 lard. See Fig. 8. View them by polarized light, with and 

 without selenite plate. The beef crystals, to be seen to advan- 

 tage, require a power of at least 500 diameters, being very small, 



