REPORT OF THE COMMISSIONER OF AGRICULTURE. 27 



MICROSCOPICAL DIVISION. 



The inicroscopist Las been chiefly engaged during the past year with 

 iuvestigations relating to the general microscoiiic characteristics of pnre 

 dairy butter, oleomargarine, butterine, and other butter substitutes, 

 with a view of discovering some well-defined mode by which pure but- 

 ter and the various butter substitutes, offered for public sale, may be 

 distinguished from each other, thus protecting the public against fraud- 

 ulent compounds sold as pure butter. 



These investigations have necessitated hundreds of experiments with 

 the fats of various animals and of vegetables, as several of these fats 

 are largely" employed in the manufacture of all butter substitutes. The 

 want of a ready and scientific means of determining whether a substance 

 ottered for sale is really butter, or butterine, has long been felt by chem- 

 ists, butter inspectors, and the public generally. 



Because of the question among chemists in Europe, and in America, 

 as to the possibility of determining, by purely chemical means, butter 

 from oleomargarine, the butter laws of the United States, as well as those 

 of Great Britain, have been rendered inoperative, as regards the suc- 

 cessful prosecution of violators of the law relating to butter imitations. 

 Hence the great desirability of endeavoring, by the use of the micro- 

 scope, or other untried means, to discover a method, or methods, by 

 which the butter laws, generally considered, shall be rendered useful 

 and operative to the dairy interests of the United States. 



After many experiments in this direction, the microscopist claims to 

 have discovered that lard made from swine's fat always exhibits crys- 

 tals in stellar form, wholly composed of sharp, fatty, needle-shaped 

 spines radiating from a common center, while the fat of beef yields 

 foliated, serrated, and bi-serrated spines proceeding from a common 

 center, but much smaller than those of lard, while pure normal dairy 

 butter is wholly exempt from fatty crystals, and this distinction is con- 

 stant. He also claims to have discovered that when pure butter is boiled 

 in a test tube, without water, for a period of several seconds only, and al- 

 lowed to cool for a i)eriod of twenty-four hours, at a temperature of GO"^ 

 Fah., the butter thus treated becomes crystallized in globose forms, gener- 

 ally perfectly globular, and of sufficient size to be detected by the naked 

 eye. On subjecting these crystals to polarized light, in connection with 

 the microscope, the crystals exhibit on each globule of fat a well-defined 

 cross, resembling that known as the Cross of St. Andrew, thus distin- 

 guishing at onco the fatty crystals of the butter fi-om those of lard or 

 beef. In no case has he found crystals in any of them resembling those 

 found in pure dairy butter. In consequence of the novelty of this dis- 

 covery and its value to the dairy interests of the country, if verified by 

 others, he was directed by the Department to submit the result of his 

 investigation of fats to the members of the American Society of Micio- 

 scopists at their annual meeting held in Cleveland, Ohio, in the month of 



