98 REPOKT OF THE COMMISSIONER OF AGRICULTURE. 



of pure Alderney cream, the second from mixed cream. The samples 

 were kept apart iu separate boxes, boiled, cooled slowly, and examined 

 according to the methods described. Both samples j;aye the globular 

 crystals, showing the cross. These crj^stals varied in diameter from 

 fifteen ten-thousandths to one one-hundredth of an inch. Verj- large 

 crystals, such as the In.tter, show the cross but dimly, while the small 

 ones show it distinctly. To this date I hare received several samples 

 of butter from Tennessee, Ohio, New York, Maryland, Virginia, and tbc 

 District of Columbia. AH exhibited one or both forms of the crystals 

 common to butter, but generally the globular only. Pure market or 

 store butter, which has been exposed to high temperature for several 

 months, exhibits a greater number of the rosette forms, measuring only 

 about fifteen ten-thousandths of an inch. In general it may be said 

 that, as butter loses its freshness, either through age, heat, or other 

 causes, the globular crystals, with the cross which appears upon them, 

 tend to give way to the rosette-like forms shown in Figs. 8 and 9, while 

 inferior butter appears to show the rosette-like forms much sooner than 

 that of the best quality. These latter forms appear to result from the 

 breaking up of the globular crystals, in the center of which speck after 

 speck appears to expand into the rosette-like form and float away. 

 (See Fig. 5,j 



In examining the two butters received from Mr. Ward, I observed a 

 material diflerence in their appearance. Although all exhibited the 

 l)eculiar typical cross of St. Andrew, some brands exhibited globular 

 crystals much more bright in color than others. The butter received 

 from Tennessee exhibited a peculiar indentation in the large crystals ; 

 and so well defined is this peculiarity that this brand may at once be dis- 

 tinguished from all others I have yet exau\iiied. (See Fig. G.) Several 

 butters examined in May last, made fron milk of cows fed on dry feed, 

 exhibited crystals more brilliant in appearance than those fed on grass 

 iu July. I think it probable that the butter crystals of different breeds 

 may yet be distinguished from each other by some marked peculiarities, 

 although preserving always well-defined features common to butter. 



The globular crystals of some butters are exceedingly transparent ; 

 in this case a very low power of the microscope should be used for ex- 

 aminations ; an inch and a half objective serves the purpose. 



Exceedingly small globular butter crystals may arise from one or two 

 causes, such as from the oily characters of the butter, or by cooling the 

 boiled butter too quickly. All boiled samples should be kept in a dark 

 cool place to prevent the crystals from passing to the secondary stage 

 characterized by the rosette-like forms. At high temperature, such as 

 100° F., the globular crystals all dissolve. Should these precautions 

 be neglected effective crystallization will not take place and the cross 

 will not be discovered. 



MOUNTING BUTTER CRYSTALS. 



A practical microscopist will readily perceive that from the very nature 

 of the crystals great care must be exercised in mounting them. The 

 globular crystals should not be crushed; neither should they be exposed 

 to light except when necessary, or to a temperature of over 70° or 75'^ 

 F. At 95° 1 found the crystals of Tennessee butter dissolve while the 

 Ward butter crystals at the same temperature retained very nearly their 

 normal form. 



In order to crystallize solid fats and show their normal crystals it is 

 necessary first to boil them with sweet oil. When cold, the composition 

 should be of the consistency of butter. Cacao butter should be made 



