REPORT OF THE MICROSCOPIST. 97 



light and selenite plate ; Fig. 13, pressed lard under transmitted liglit ; 

 Fig. 14, rendered lard, strained to remove nitrogenous bodies ; Fig. 15, 

 the same crystal under polarized light and selenite plate ; Fig. 10, homo- 

 geneous olemargariue under i)olarized light and selenite plate; Fig. 17, 

 l)ure butter under polarized light and selenite plate; Fig. IS, beef fat 

 highly magnilied under polarized light and selenite plate. The magni- 

 fying ])0wer employed in the investigation of the above crystals, with 

 the exce]!tion of Fig. IS, varies from ten to live hundred diameters, antl 

 in Fig. IS from seventy-five to five hundred diameters. 



TO SEPARATE BUTTER CRYSTALS. 



The method employed to crystallize butter and separate the crystals, 

 so that they may bo seen by the naked eye, is this : Procure a speci- 

 men of pure butter and boil it in a test tube or tin pan for a period 

 of several seconds, pour the liquid portion off in a cup or other suita- 

 ble vessel, and put it in a cool place to crystallize; allow the cooling 

 process to continue from twelve to twenty-four hours. Eemove with 

 the point of a penknife a few grains of the butter thus treated, place it 

 on a slip of glass and pour over it a few drops of alcohol. The crys- 

 tals may then be easily separated from each other by means of a needle. 

 A solution of alcohol in a concentrated solution of pure carbolic acid in 

 the proportion of ten parts by measure of the first to one part of the 

 last, will prove more satisfactory in separating the crystals than alcohol 

 alone. If the crystals are viewed by a pocket lens they vrill a]ipear like 

 so many insect eggs. (See Fig. 1.) Beef and lard fats may be treated 

 in like manner, but in practice it will be found that the crystals of these 

 fats are not so easily separated, owing to their long spines interlocking 

 with each other, l^ine years ago, while making some experiraeuts with 

 butter, I first observed that boiled butter exhibited small crystals some- 

 what stellar, but gave no further attention to the fact until May last. 

 For the puri)ose of determining the real character of the crystals I pro- 

 cured a sample of pure dairy butter from Ohio. This was* boiled, and 

 when cold I examined it under a power of 75 diameters. To m3' surprise 

 globular bodies were found, having apparently a very fine fibrous struct- 

 ure. When subjected to polarized light a cross consisting of arms of 

 equal length was observed on each crystal. (See Figs. 2 and .3.) On 

 rotating the poles the cross of each crystal rotated. On rotating the 

 glass on which the specimen of butter was mounted the crosses remained 

 stationary, thus showing that the appearance of the cross depends on 

 the fact that the crystals are (1) globular, (2) polarizing bodies, (3) trans- 

 lucent, and (4) comparatively smooth. Were they opaque or non-polar- 

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

 rays of light, no image of the cross would be visilDle. But from whatever 

 cause the appearance of the cross on butter crystals arises, its constant 

 appearance on new butter under the conditions above described is a fact 

 beyond any question, and, so far as my experience 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, they exhibit all the colors of the rainbow and are 

 exceedingly interesting objects. (See Fig. 10.) 



In order to leave no room for doubt respecting these crystals being 

 peculiar to butter, I had cream churned, through the kindness of Mr. 

 Frank K. Ward, of AVashington, and a lino sample of granulated but- 

 ter made in my i^resence, a portion of which was secured ; also a portion 

 of butter from another lot made in my absence. The first lot was made 

 7 AG— '85 



