REPORT OF THE MICROSCOPIST. 



Sir: I have the honor to submit herewith my fifteenth annual re- 

 port. In consequence of an increasing demand for information regard- 

 ing the cliaracteristics of butter substitutes, I have found it necessary 

 to devote most of my time during the past year to the further inves- 

 tigation of the polarizing properties of animal and vegetable fats, as 

 determined by the use of the microscope, and to devising such other 

 ready, sure, yet inexpensive methods of distinguishing oleomarga- 

 rine from milk butter as may be readily employed by microscopists 

 and others. 



The recent enactment by Congress of an oleomargarine law, which 

 is severe in its penalties, has rendered it all the more important that 

 the methods employed in the detection of butter substitutes should 

 be of the most reliable character, so that on the one hand no one may 

 be unjustly punished for a violation of national or State law, or on 

 the other allowed to escape its penalties. 



Pending the appointment of a microscopist in the Bureau of Inter- 

 nal Revenue and the fitting up of a laboratory in that Bureau, I have 

 made a number of examinations of suspected butter, at the request 

 of the Commissioner of Internal Revenue, some of which proved to 

 be oleomargarine. 



I have devised during the present year a new and reliable method 

 of detecting cotton-seed oil, benne oil, and ground-nut oil in oleomar- 

 garine or other butter siibstitutes. I have also detected borax in but- 

 ter, oleo, neutral lard, oleomargarine, and butterine, not observed 

 heretofore. I have found borax in each of twenty samples of butter 

 recently received from the State of Illinois. In December last a but- 

 ter dealer of this city received from a New York firm ten tubs of 

 what was represented as fresh butter. The lack of butter odor led 

 the merchant to suspect that he had received oleomargarine. At his 

 request I examined samples of this butter under the microscope, but 

 failed to discover in them crystals of fats common to oleomargarine, 

 While well-defined crjrstals of borax (polarizing bodies) were present 

 in abundance. On boiling these sa,mples the atmosphere of the room 

 became highly charged with the odor of butter. Repeated experi- 

 ments satisfied me that all the samples were old butter deodorized 

 with borax and by other means. 



The following paragraph from the columns of the New York Sun, 

 republished in the Farmers' Revieiv June 23, 1886, may give a clew 

 to the reason for adding borax, a deodorizing salt, to old butter: 



A process of renovating old and rancid butter, now being worked at New Hamil- 

 ton, Orange County, New York, as follows: The rancid stock is purchased in New 

 York City and in Western markets, and costs the concern an average of 10 cents a 

 pound. At the renovating works it is placed in large vats and sui-rounded by boil- 

 ing water. When the butter is heated to the right degree all impurities rise to the 

 euxface of the melted compound. They are skimmed oflE, and the remaining liquid 



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