

DAIRY PRODUCTS. 35 



hibit.3 on each crystal a well-defined figure resembling what is known as the cross of 

 Saint Andrew. la course of time, the period ranging from a few days to a few weeks 

 according to the quality of the butter used and the temperature to which it is ex- 

 posed, the crystals, which at first are globular, degenerate, giving way to numerous 

 rosette-like forms peculiar to butter. 



Oil page 5 lie says : 



About ten years ago, while making some experiments with boiled butter, I first ob- 

 served it exhibited small crystals somewhat stellar in form, but gave no further at- 

 tention fo the fact until May last. For the purpose of determining the real form of 

 the crystal of boiled butter I procured a sample of pure dairy butter from Ohio. I 

 boiied it, and when cold examined it under a power of 75 diameters. To my surprise 

 I found globular bodies. When I subjected them to polarized light a cross consist- 

 ing of arms of equal length was observed on each crystal. On rotating the polarizer 

 the cross of each crystal rotated. Onrotatingthe glass on which the specimen of butter 

 was mounted the crosses remained stationary, thus showing that the appearance of the 

 cross depends, probably, on the fact that the crystals are (1) globular, (2) polarizing 

 bodies, ('>) translucent, and (4) comparatively smooth. Were they opaque or non- 

 polarized or did they consist of long spines, causing great divergence of the rays of 

 light, no image of the cross would be visible; showing that the appearance of the 

 cross under polarized light and the conditions stated is not duo to any physical struc- 

 ture of the fatty crystals themselves. But from whatever cause the appearance of 

 the cros^ on the butter crystals arises, its constant appearance on now butter under 

 the conditions above described is a fact beyond any question ; and, as far as my ex- 

 perience goes, the better the quality of the butter the more clearly defined is the 

 'cross; it is black, large, and well defined. When these crystals are under polarized 

 light and a selenite plate combined they exhibit the prismatic colors, but the cross 

 proper is not visible in this case, although the crystals are still divided into four equal 

 parts and are exceedingly interesting objects. 



Dr. Taylor having thus directed the attention of scientists to these 

 important phenomena, it has not taken long to show that there is little 

 reason for the rather mean opinion of European chemists of the value 

 of the microscope in detecting adulterations of butter. In several cases 

 of prosecution before the District authorities the offenders have been 

 convicted solely on the microscopical evidence and have admitted the 

 justice of the sentence. If only fresh butters were exposed for sale, 

 and all adulterants were certainly once melted and slowly cooled, but 

 little more than this qualitative examination would be necessary. 



Prof. II. A. Weber, of Columbus, Ohio, has made some interesting ex- 

 periments with the microscope on fats, which in the main bear out the 

 conclusions of Messrs. Brown, Ilehner and Augell, and Taylor. As was 

 to be expected, however, he has shown that the appearance of the cross 

 on a crystal of natural tat does not show that it is derived from pure but- 

 ter. He says, in Bulletin No. 13 of the Ohio Experimental Station, Ex- 

 periments 7, 8, 9, and 10 : 



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

 ment 3 and the asc three experiments could only bo ascribed to a difference of condi- 

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

 and 5 to 20 per cent, of water. These ingredients constitute the most marked differ- 

 ence 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 ouuco of the oloo 

 oil used in Experiment 3 was mixed in a porcelain mortar with a small quantity of 



