212 



THE AMERICAN MONTHLY 



[November, 



the matter of the correspondence for 

 the benefit of our readers. We first 

 received some time ago slides from 

 Dr. Taylor containing crystals from 

 the fat of beef taken from the caul 

 fat of the ox. We then, after ex- 

 amining them, obtained a sample 

 of butter known to be good and 

 subjected it to microscopic exami- 

 nation. It contained no crystals of 

 any kind except a few crystals of 

 halite or common salt. This was 

 a sign that the butter was good, ac- 

 cording to Dr. Taylor's test, for but- 

 ter ought to show no crystals of fats, 

 because the fats of the butter have 

 never been heated and allowed to 

 cool and crystallize after the man- 

 ner required by the condition for the 

 formation of these crystals. The but- 

 ter thus examined was then heated in 

 a watch-glass to boiling, over a Bun- 

 sen lamp, and allowed to boil vigor- 

 ously for a few moments, and then 

 set aside to cool. Examined shortly 

 after boiling, it contained no crystals, 

 but after several hours it was again 

 examined. It now presented a very 

 different texture from that proper to 

 butter ; was granular, and broke up 

 readily into a number of very small 

 rounded masses. A bit of it was 

 placed upon a slide and covered with 

 a drop of oil. In this it readily broke 

 up into a mass of very minute grains, 

 distinctly visible to the naked eye, 

 but very small. Microscopic exam- 

 ination showed these to be small 

 spherical bodies, with a general mu- 

 tual resemblance. 



The same facts as these were de- 

 scribed in Dr. Taylor's article in this 

 Jou}-naL 1885, p. 163, and there fig- 

 ures were given of the butter crystals. 

 Our observations were made for the 

 purpose of confirming this descrip- 

 tion, and were in accord with those 

 of Dr. Taylor. Very recently we 

 have received from Dr. Taylor a set 

 of thirteen very beautiful photo-mi- 

 crographs, illustrating this subject. 

 Two of these were taken by Mr. 

 Walmsley, of Philadelphia, and the 

 rest by Dr. B. Persh, of Washington. 



We cannot leave them without one 

 word upon their beauty as works of 

 photo-micrographic art, and perhaps 

 that word can be as well said at the 

 beginning as at the end of what I have 

 to say of them. 



Of the photo-micrographs, four are 

 of beef fat, and show plainly the 

 characteristic crystal (see page 164, 

 fig. 26-8) as figured in Dr. Taylor's 

 article already referred to. Two of 

 the micrographs are of lard crystals, 

 and are much better than the drawing 

 of the lard crystal, fig. 26-7. Two 

 more of the micrographs represent 

 the crystals of butter which here re- 

 semble figures 26-3, and 26-5 ; the 

 figures being rather diagrammatic, 

 while the micrographs look precisely 

 like the view of butter crystal as seen 

 in one focal plane. The other five 

 pictures are from slides of oleomar- 

 garine. Of these, two contain, evi- 

 dently, a great deal of butter, for in 

 the picture at least one half the crys- 

 tals are evidently butter crystals ; but 

 besides these are numerous crystals 

 of beef and lard. From these photo- 

 micrographs there would be no diffi- 

 culty in picking out at once the one 

 made from pure butter, and as these 

 were made from pure butter it fol- 

 lows that pure butter can be detected 

 any time, microscopically, in this 

 way. But while this study is full of in- 

 terest for the study of the various but- 

 ter crystals, and it is beginning to ap- 

 pear that various butters may be dis- 

 tinguished by slight variation in the 

 butter crystals, it is not necessary in 

 examining butter and its substitutes 

 to detect frauds that the butter crys- 

 tals be seen at all. The butter of 

 the stores is not so formed as to 

 give rise to any fat crystals. The 

 fats in it are never heated beyond 

 the temperature of the animal body, 

 and hence are not placed under the 

 conditions required for crvstallization. 

 Therefore, butter unadulterated 

 ought to show no crystals whatever 

 present. Only yesterday, Nov. 13, 

 we received from Dr. Taylor two 

 samples, one of butter, the other of 



